Solar Photovoltaic System Basics (Webinar) | TPC Training

Here you can find Solar Panels and technological accessories related to Solar Energy: Click Here If you want to learn about Solar...

Here you can find Solar Panels and technological accessories related to Solar Energy: Click Here

If you want to learn about Solar Panels, to advise you before buying or to build your own Solar Panel: Click Here

hello everyone and welcome to today's tpc webinar entitled fundamentals of solar photovoltaic systems my name is ryan smith i'm going to be your presenter today during today's session um as we get started to really talk about this fundamental um concepts and some maintenance procedures with solar photovoltaic systems i wanted to let everyone know as you're flowing in um a couple of the little housekeeping items before we get started first things first uh this webinar is being recorded and the video recording of this presentation will be made available on our tpc training website uh within about two business days from this event so be on the lookout for that secondly i'd like to also indicate that this session is live so that means you're actually free to ask any questions you like throughout the session in the q a box if you look at the bottom of your screen you should see a q a button that you can type in your questions beware there's a chat button too that we're not going to be monitoring so you want to avoid using chat and instead use the official q a so we can monitor the different questions coming in and finally with that recording will be a pdf of these slides available uh for download at that time so um that's kind of a little bit of of some of the housekeeping to get out of the way the last thing i want to check in with everyone here who's flowing in is just to learn a little bit more about who's here by doing a little introductory poll with everyone as we start to talk about some of the pv stuff we're going to talk about today and some of the fundamentals i'm going to launch a poll for you all right now and so a window should be popping up on your screen with three questions the first question being how comfortable are you with explaining how solar panels work in terms of the function of how they produce electricity are you very comfortable explaining that somewhat comfortable kind of neither here nor there are you pretty uncomfortable you're not really sure how to explain it or you just really don't know how to explain it uh the second thing uh how often do you work on solar panels in your daily job is it often is it occasionally every now and then rarely or never right now and that's okay if you never work on them now that's the point of learning about some of the fundamentals to get started and the third question we have is which statement best describes your interest in the solar topic i am presently responsible for maintaining and operating solar panels i may be operating or maintaining solar panels in the near future or i don't work on solar panels now but i want to learn more about them just a little bit more about who's here and what you're hoping to learn okay we got a good collection of answers coming in i'll give you just a few more moments to make your selections yeah you can go ahead and click each answer you want to indicate and then hit submit at the bottom of the three question poll it should release your answers there okay good i think we're getting a good evening out of the answers coming in i'm going to go ahead and end the poll and then share the results with everyone here so you should see a different window popping up with all the results from today's poll as you can imagine the level of comfortableness i guess the level of comfort um on explaining how a solar panel works it's across the board so really it's an even split from people who are somewhat comfortable to people who are somewhat uncomfortable explaining how solar panels work in the whole photovoltaic process so we're going to explain that and break that down a little bit in today's webinar the second question is how often do you work on solar panels so most of you do not presently work on solar panels at all and i which kind of leads us to the prevailing answer from number three which is most of you are coming into this session having not worked on solar panels and not working on solar panels presently but you do want to learn more about them and so that's really going to be the motivation for this session it's going to be the basics it's going to be kind of starting off the uh the breaking down of some of the terms of solar panels how they work how to maybe understand some of the things you might start seeing on spec sheets for solar panels and what to look out for during the initial installation and maintenance of these solar panels so i'm going to go ahead and stop sharing the results i appreciate your input thanks so much all right so that window should have disappeared from it if it didn't go ahead and just hit the x button and we'll go ahead and get started so the really the breakdown of today's session is going to be all about first and foremost explaining the fact that these devices are primarily electrical devices so solar power can't really be fully understood unless we understood electricity itself electricity is a big part of what tpc does in the training business you know learning about electricity and how to do electrical troubleshooting and all those types of skills apply when you're trying to understand how solar panels work as well so that means we really have to break down the three fundamental basics of electricity and how it works to really understand how a solar panel works that's electrical current electrical voltage and resistance and knowing how those three work together is important and how they're related is really important in understanding a solar panel so this is where we're going to start is kind of on the electrical thing real quick and understanding some of the terms there then we're going to jump into for a few minutes of the solar photovoltaic process so the process of converting the sun's light into energy and and how that works knowing a little bit more about the materials used in solar panels and how they're put together and then finally we're going to end today's session on just some of the best practices we have documented on how to maintain and take care of solar panels as as someone who might be responsible for that now or in the future first and foremost these three here i could tell you even if someone's been working as an electrician for 30 years right still need to refresh yourself on knowing the difference between electrical current electrical voltage and electrical resistance and kind of how they all play together it can get pretty easy to mix up current and voltage they might be kind of intermixed in terms of terminology or you know which one causes which does current cause voltage or does voltage cause current that kind of stuff it's really important as we start understanding iv curves which we're going to talk about today for for a solar photovoltaic panels or the short circuit current or the open circuit voltage all the stuff that is going to be on the spec sheet for panels we have to know first and foremost let's talk about current so current really is the amount of electrons flowing through the wire and that's able to be produced think of it as a flow of water through a pipe is similar to a flow of electrons negatively little charged electrons through the wire and again we can break this down in more detail if you take a basics of electricity course but i'll just kind of keep it brief for now we got all the electrons flowing through the wire what's behind them pushing that's the voltage so basically if you think about um a water hose analogy right the water flowing through a hose if you turn that hose on is the current and then how open you made that spigot or that that faucet at the house and how open that is is the voltage so if it's fully open that's a high voltage which will cause more current or water to flow and then the size of that nozzle at the end where it sprays out into wherever it's spraying into that's the resistance so if there's more resistance that means less current will flow in this system and that resistance can be found in whatever devices are usually hooked up to that that um device providing the voltage so for instance you know loads we call them applica appliances light bulbs motors and that kind of thing so which part of the equation are we really going to be talking most about and where does a solar panel come into play well the solar panel is if you see my little red laser pointer here a solar panel really is the thing in the electrical circuit that provides a voltage for that electrical circuit and it's actually an alternative way to provide a voltage than what we normally do in this day and age we normally get our voltage our push for our electrons to flow through our homes and our businesses through our electrical grid which is connected to all of our you know hundreds of miles of utility wires and power plants throughout this country this time we're able to produce a voltage directly from the sun's light whether it's on our own roof or a nearby uh a location that's producing electricity from the sun instead of from our utility grid and that's really what solar power is all about is creating this push on the electrons to move and to power our tvs and our lights and all that kind of stuff in another kind of way so thinking of the push the the more push the more voltage the more current to answer that question i posed to you just a moment ago can you have current without voltage well the answer is no you cannot have any current without some sort of push to make that electron current flow now let me put it the other way can you have a voltage without current and the answer is absolutely yes so you can have a voltage you can have that potential we call it that's another word to describe voltage you can have that push or that potential happening but but without an actual completed path to make that electron flow so that's kind of the difference you can have a voltage without a current a kind of waiting push ready for current to flow as soon as you make that path but you cannot have a current without a voltage so really the way they all play together is that one volt of electromotive force or what we call that's what voltage used to be called in days past we kind of change that term to be volts so one volt of voltage or electromotive force will force one amp the way we measure current of current to flow through a wire in this case to one ohm so the way we measure resistance or how much the appliance or device is holding back or even the wires themselves everything has resistance is holding back that current the more resistance that builds up around the solar panels and in the system the less current will be able to flow from those solar panels and the dimmer your lights are going to be connected to those solar panels this is how they all play together in terms of math if any of you here like math this is kind of how it all comes together so e is that electromotive force or voltage we call it i is it's interesting i was always curious about why we use the letter i for current even the letter i isn't in the word current well the uh the letter i comes from initially from the french word of an intensity so current was first kind of observed as an intensity of current the more the more current flowing the more intense that feeling was if you touched that wire right and so that kind of eye stuck around but it turned into the word current over the years since you know the 1800s and then r is resistance which makes sense to us so this pie chart really indicates that if if you know the voltage of your solar panels and you know the resistance you're going to be hooking up the device to if you know any two of these ingredients in your electrical system you can find out the third ingredient by doing a little bit of math so the way this works let's say you you don't know the voltage you don't know what the voltage is but you know what the current that's flowing and you and you've measured the current the amps that are flowing and you measure the resistance you just cover up the part you don't know so let's say you covered up this this letter e with your hand you see an i and r left over next to each other so that means you take the i times the r so you take the number of amps times the number of ohms of resistance and that gives you the number of the number of volts that are are in action or required to make that many amps go through that many ohms uh in a lot of cases we'll know the voltage of our panel because it's on the nameplate and we'll we will know the resistance because that's on the nameplate of the device let's say but we're not sure how much current is going to flow and let's say how big our wires need to be to hold that amount of current so a common application is we cover up the i because we're not sure how many amps are going to flow and then we find out that e over r because e is on top of the r this time so if we cover up the i it'll be e over r or voltage divided by current to get the number of amps so let's say we have you know 10 10 volts or let's say 24 volts and 2 ohms that's 24 divided by two and that gives us 12 amps that will flow for instance so they all play together and then one interesting way to bring them together in terms of how to understand solar panel name plates and ratings is this power so we sometimes mix up the term power in other words what our meters are reading in the backyard of our homes and our businesses is voltage right or so it's measuring some sort of voltage or current flowing well it's none of the above it's actually both um together multiplied so if you take the voltage at any given moment coming into your facility and you multiply it by the current flowing in that moment of time that gives you a measurement of volts times amps then you put that together to get watts watts and so watts is the measure of power and that's really what you're going to see in a solar panel nameplate is how many watts does that solar panel give you so that means how many amps times volts together in combination can that solar panel give you let's say the solar panel is out for 24 hours so it's going to give you a certain amount of volts coming from that solar panel we're going to talk about the magic of how that happens and then how many amps it delivers and the magic of how that happens you multiply that together over 24 hours and that gives you watts times hours and that gives you what we call watt hours or multiply that by a thousand to make it easier to read it's kilowatt hours or a thousand watt hours delivered in that day let's say or however long you want to say over the course of a month usually is how our utilities measure kilowatt hours used so you take the volts and amps being used multiply it by the number of hours it was being generated and you get kilowatt hours and that's normally how our electrical utilities charge us for our electricity or if you're going to be one of the lucky folks who have their solar panels hooked up as a net metering solution that you can actually charge back the utility a certain dollars per kilowatt hour uh based on how these are producing their volts and amps over the number of hours so obviously at in the middle of the night midnight a solar panel is going to produce zero kilowatt hours um but as the sun comes up and things start increasing um in terms of light then they're going to produce more kilowatt hours but you average it out over the course of the day to get a kind of average kilowatt hours or total kilowatt hours for the day or for the month so watts is important watts are not volts and watts are not amps they're a mixture of both that's that's another important one so once we kind of get that down take some practice to really start talking the talk of watts kilowatts voltage amps this is where we can start really talking about the solar panel itself i know you haven't even seen a picture of a solar panel yet on the screen but it's coming now so to understand how photovoltaic works if you think about it now photo that's light right so photons and that kind of thing volts is creating voltage right so voltage so creating light or secreting volts from light in other words creating volts from the sun's light because that's the most intense energy free of freely available light we have so is there a way to create voltage and electricity immediately from light and the answer is yes we discovered it over the last several decades so let's talk about that the first and most important building block of what it takes to convert light into voltage is what we call the solar cell and this is what one looks like this is not a solar panel that sometimes can get confused a solar cell is not a solar panel this little thing is just a frac you know one inch wide by one inch long so it's a tiny little thing they come in different shapes and sizes but in this case this can fit in the palm of your hand this is a single cell and what this does is magically the sun will shine on this cell and immediately be turned into electricity and that's one thing that's uh pretty amazing about solar power is that there is no moving parts in a solar panel or a photovoltaic system they literally just sit there never moving never uh you know having any vibration or strain or you know bearings and and misalignments and pumps and motors and that kind of thing generators to do what they do they they just do what they do naturally just from the sake of what they are and so we got to talk about that but essentially this this is able to immediately take the sun's energy turn it into uh electrical energy instantly and so a cell about this big can do that and produce about 0.5 volts of of push or potential we call it for an electron to flow that's remember that's not amps that's not you know powering my light bulb yet we have to know how many amps it's going to pull through and how many watts it can do so we get there but for instance does anything in my house let's say your own home what voltage does your cell phone need to plug into a wall right what voltage does your television or your refrigerator need to plug into the wall right well it's not half a volt that's for sure they need a little bit more push on their electrons to get them to work because they have high resistance so and ends up being you know in today's modern day we in the united states power our devices on 120 volts so we need 120 volts so this single solar cell is not going to work for us we need more so what do we do well thankfully through the magic of uh electrical circuits we can string together multiple of these cells in a row and then each time we get a new one in the row we add that 0.5 volts again so we get point five volts and then one volt and then one and a half two two and a half three three and a half four until we get a whole solar panel that can be you know 30 volts 35 volts or even more depending on how many cells you can fit into a single what we call solar module and that's really how we can get a system up to 120 volts but before we start building blocks with these solar cells i want to show you one more thing about this solar cell let's talk about energy in versus energy out this is the most important thing to consider um and this is where you can start really impressing your co-workers and colleagues about your knowledge of solar power is this idea of efficiency of a solar cell so we all know that the sun's light is shining on a solar panel and then that solar panel through what it does or that solar cell right it takes the sunlight's energy in watts it seems strange to con consider the sun's energy to be watts we usually think of a light bulb or something in watts but yeah the sunset energy can be measured in watts and then on the output of this solar cell it takes a smaller proportion you see that smaller sized arrow here is the electrical energy that it's giving us in watts so the number of watts coming in from the sun turns into a smaller amount of watts being produced by the solar panel so we didn't we weren't able to harness all of the watts from the sun in these solar panels unfortunately but what we normally find out in a given case let's say we want to learn how effective or how efficient is this solar cell in providing us the energy from the sun's light well uh the the efficiency it number is what we talk about so we take whatever is coming out and we divide it by what it came in to provide us with that amount of power and that gives us an efficiency for instance if we got 100 watts of the sunlight's power and the solar cell produced 15 watts of power on its output we can do the math uh 15 divided by 100 and that's 15 so that that's 15 over 100.15 or 15 that's the efficiency of this solar cell for every 100 watts it's given it only produces 15 watts right and that's typical so what we find is a typical this is another really good thing to just impress your coworkers with hopefully is a typical solar cell efficiency right now of the typical material for solar cells which we're going to get into is about 15 to 20 percent efficient when it's brought to market granted when these are sitting in a laboratory you know in the national renewable energy laboratory for instance in a very ideal condition these can get up to you know 30 40 efficient in the lab but once they're out in the real world with clouds coming over and day and night and leaves and dirt and wind and all this stuff the the typical efficiency of a solar cell is at 15 to 20 percent so that doesn't seem great right 15 efficient if if anyone said yeah i'm 15 efficient at getting my job done that's not very effective but you got to remember that the sun's light is freely available it's going to shine on that rooftop or shine on the ground or wherever you install these freely right and it's not really going to cost you money and so getting 15 of something that's free well that's free that's freely available energy at that point as long as you can incur the cost of installation so that's something to consider here um another fun fact is that the word we use to indicate the sunlight's energy in watts available let's say in a certain location is something we call insolation so not insulation like we see in wires or in our wall but in soleation with an o the solar radiation of a certain area so you get more insulation or watts per meter squared in some a place like you know southern california or texas or florida because you're closer to the equator then you do somewhere further north like seattle or um or michigan because the sun is not as direct up there for instance so that's kind of an example of insulation and it's good to know about that okay so the sunlight is coming into the cell the sunlight is coming out of this cell taking a look at the cell it's still it still might be a mystery right to anyone listening about okay it's creating energy but how right it's there's got to be something moving right there's got to be something working and it's pretty amazing it all happens at the sub-atomic level so to to help uh just refresh some of our memory from high school physics class bring yourself back to high school or junior high or maybe even elementary school sometimes i didn't learn about this in elementary school but some people i i know are learning about technology school about electrons protons neutrons and electrons that's what this all comes down to with solar photovoltaic you might remember that electrons the the parts of an atom that flow through a circuit are negatively charged so what manufacturers of solar panels do is they take a semi-conductive material so not a conductor you may have heard of conductors if you're any electrical folks on the call know what a conductor is because you see that word all the time in the national electrical code conductor something that conducts electricity readily that's you know metal steel um copper aluminum that kind of thing versus the opposite of conductor which is an insulator that's you know rubber wood um glass that kind of stuff what we need to make a solar panel work is something in between something that's not quite a conductor like metal but it's not not quite an insulator like rubber it needs to be somewhere in between and a really good candidate for something that's kind of conductive in only certain situations is silicon so this is something naturally occurring in the earth that is that can be found in large quantities that is a semiconductor there's other materials out there like gallium arsenide and other things that we're experimenting with but silicon the element silicon is the perfect semiconductor for this and so what we do is by itself silicon is not super useful as in a solar panel until you start doping it we call we call doping the silicon and so what you're going to see is that the top layer the the layer that's facing the sun is doped with an n-type semiconductor so that silicon is turned into a negative charge or n type versus the bottom layer that's kind of in the shade underneath is a positive type semiconductor p p-type usually we use the element boron to dope this semiconductor here and we use the element phosphorus to dope with the silicon kind of add in to the silicon as an additive um on the bottom end so what that ends up doing is it produces an extra electron in the cell structure the crystal structure of the um solar panel on the top end so there's electr an actual an extra electron floating around in this layer of the material right here well electrons are negatively charged and if you've ever held two magnets together how do they attract and how do they repel well you we know that a negative and negative repel so anything negatively charged repels a negatively charged electron floating around in here and anything positively charged attracts that electron however right so you see okay an electron is negatively charged where does it want to go it wants to go to this positive side but thanks to this separator here this membrane the electrons can't flow just directly down so what's the only other way is to travel on this line we provided to it and it's going to leave the solar panel feel the pull to that negative that positive side but instead it's going to go all the way through our home or our business it's going to power the devices and then come back out all used up and flow here so this is actually this arrow is showing electric current flowing that way but that's not actually not right it's going the other way so the holes of the electrical current are going that way which they some people call the holes of the electrical current anyway the electrons go this way this way over over and back down again and then they fill in the extra spot available for those electrons down here and then through this membrane they can replenish and start the process over again so it's really it's really an amazing process that all is kick-started by the sun's light so nothing's going to happen with that until that electron is allowed to jump suddenly from one area of this material to another thanks to the ultraviolet and infrared and all that fun light the energy in the sun's light makes this process happen and it's amazing how it just magically happens with enough solar power with the sun shining and so it just happens time and again naturally you don't see anything rotating and moving in here and that's what really makes solar panels pretty good in terms of maintenance and we're going to talk about the maintenance so we've been talking about the cell right that single one little inch tab that you see on a solar panel obviously there's way more to it than that so the way we build them together typically is we see a cell we bring a cell for a photovoltaic panel and we put them all together in a string like we mentioned to kick up that voltage a little bit and that turns us into a single module if you want to talk the talk again the term module is really what the industry uses to indicate the solar panel so that single that single off the shelf device with a bunch of cells put together in series is called a module or another word for it is a solar panel right so put all the cells together into a module you put a bunch of modules together and to kick up that voltage even further from panel to panel to panel to kick up the current or to kick up the voltage whatever you need and that gives you an array so basically a bunch of panels together give you a photovoltaic array and then you put a bunch of arrays together to really start providing some let's say a full house worth of electricity or a full businesses worth of electrical needs for whatever whatever it is that gives you a system but the system isn't just all the panels together the system also includes all the other stuff which we're gonna just touch upon at the end of this but that goes beyond the basics so we don't really have time for it but includes energy storage like batteries voltage regulation and inverters and combiners and a bunch of other fun things so here's a panel right um provided off the shelf from the manufacturer you can see if you kind of count you can see one two three four five six cells in this row six times one two three four five six seven eight 9 10 11 12 6 times 12. so that really gives you about 72 different cells put together at what is it half a volt for cell let's say that's that's going to be about 37 volts for this single panel right and you can look at its spec sheet to verify that and so this panel in and of itself can't produce enough voltage but then the more you put together more panels you put together the higher the voltage can be so this semiconductor material again it's the silicon and there's two different types of silicon out there in the market right now and i think another really great way to talk the talk and to really start understanding some of these photovoltaic systems is to talk monocrystalline silicon or polycrystalline silicon are the two kind of most widely available silicon alternatives but again there's other stuff out there that people are trying out uh like amorphous silicon we'll talk about briefly gallium arsenide is another semiconductor compound that's used cadmium telluride is another one that's come up over the years so once you get that right device that does something with its electrons once the sun's light hits it then we're then we're starting to have something we can work with but talking about silicon which is still one of the more common ones is the polycrystalline versus the monty crystalline you can kind of see visually the difference in how they look so polycrystalline here it's it's poly it's many different types of crystals so it's kind of the natural way in which um in which silicon comes together and it's kind of jagged different crystal structure because of that it's uh cheaper to make something like polycrystalline monocrystalline is is manufacturing the silicon to be all uniform in in texture and in crystal structure in this system so this is the one we saw earlier right and this is a polycrystalline what are the pros and cons here well you'll notice when you start looking at spec sheets and just start exploring different solar panels and things like that polycrystalline has less efficiency but it's cheaper to produce so that's kind of a trade-off if if you have let's say space to spare on your rooftop or your yard or your your location if you have no space constraints and you have as much space as you need you can probably be more cost effective with getting polycrystalline panels but if you have a limited amount of space let's say you know a limited 100 square feet on top of a roof or something like that monocrystalline is more efficient but it's also more expensive because it takes longer and more intensive to produce than polycrystalline so more expensive but they're more efficient so if you're if you're strapped for um for space the monocrystalline is the way to go and then there's the other consideration of amorphous so amorphous silicon is really kind of a free-flowing crystal structure without actually much crystal structure to begin with at all and because of that whoops it it is more flexible so this is an example of an amorphous silicon panel it can be bent it can be kind of rolled up it can be put on a curve curvaceous surface like a like a windowsill or a sloped roof or as used as a solar shingle a lot of companies are offering amorphous silicon in the sense of solar shingles that can be just laid in any sort of application because it's amorphous and kind of random it's less efficient than the other two that are crystalline but you can see how you can see how maybe it can be used in more areas because it's flexible it's easy to roll out it's easy to deploy you know on the top of your car some solar powered cars that are out there solar powered plane that we talk about in our two-day photovoltaic class um a solar powered you know a small uh what do you call it uh a dune buggy or you know a golf cart is solar-powered golf carts with amorphous on top that can be you know you don't need a whole panel on the car you can just line the top of the car with these things so these are kind of the real value here even though they're not as efficient they are more flexible okay so there's different kind of products out there on the market and what you find in each of these solar cells these solar options is what we call the iv curve this is this is getting to the this is about the level of complexity i'll get to when it comes to house how photovoltaic panels work and then you know i'll just talk a little bit more after this about the whole maintenance uh and some of the best practices of care for these panels and then i'll see which questions we can take at the end okay so the iv curve iv is not you know intravenous it's not something you put in your arm but it is iv if you recall back to earlier it's the current voltage so current and voltage curve this thing can't have its cake and eat it too so to speak you can't have maximum current and maximum voltage at all times you have to trade off current with voltage so if you want this panel to push harder and provide more voltage then you should expect less current and if you want more current you're gonna have to expect a trade-off in the voltage and so that's really um what this curve is telling us that let's say we want just uh so we start here right on this side of the the curve where there's zero zero amps flowing through the wire when does a does a solar panel have zero amps flowing even though the sun's shining it's when one side to the other of the panel is not connected to anything right if it's not connected anything the solar panel is not going to give you any current so that's what we call an open circuit where you know the positive and the negative lead of the solar panel are just sitting there without anything connected to it but if you put an electrical meter on both of those positive and negative leads those those connectors on the solar panel it'll give you a reading and that reading is the open circuit voltage or voc open circuit voltage that's if this panel doesn't have any load attached to it it'll give you this voltage that's the best case that's the highest voltage you can possibly ask for obviously that doesn't mean too much to us if we're trying to hook these up somewhere right and so the voltage starts dropping off a little bit as we try to get some current flowing and if we take it all the way to the other side we'll start being able to see more and more current flow until we kind of even out so um we kind of even out and max max out at this current that that this solar panel can produce or the solar cell can produce up to the point where we have no voltage being produced and all the current being produced how does that work well i want to ask anyone here how do i get the most current to flow as possible on a device well if you've ever pranked someone or ever had the misfortune of experiencing this you put the hot and the neutral together or the plus and the minus wire directly together and you cause what we call a boom right or a short circuit um you don't you want to avoid that short circuits are you try to avoid that but there is a a good metric for for solar panels is their short circuit current so how much current will they pump out at yeah if you for any reason lost your resistance and went completely wire to wire from positive to negative um that's the short circuit current so that's the maximum current and the maximum voltage but then somewhere in between is a sweet spot and that's right here usually along the the iv curve where the the current has dropped off just a little bit from its maximum and the voltage is dropped off just a little bit from its maximum where you put them together voltage and amps together it gives you the most watts possible right because if the panel operated here you wouldn't get much watts with the volts and amps together over here you wouldn't but right here is the sweet spot so this is where you want to kind of operate your cell and if you find yourself let's say i'm starting to measure more volts and this is where the care and maintenance comes in if you're doing your measurements once a once a year or every six months on these and you start seeing the voltage go over here or over to there we know that we might want to start doing some more inspection on these panels okay so that's kind of on the cell level we all know that solar panels don't exist all by themselves they need a bunch of extra equipment to be able to work in their system as well and so at the end of the day those electrons start flowing down that wire on the top layer that we saw earlier and they're producing what we call direct current or dc power that direct current it means the electrons are flowing in one direction they're not flowing back and they're not alternating they're just going straight into the home or straight into the business unfortunately your businesses are homes they don't operate on dc power in most cases they operate on ac or alternating current where the the current's fluctuating 60 times every second so to get that power from a pv panel photovoltaic panel into a language that our devices in our homes and businesses can can use we need something we call an inverter and so an inverter is a good part of a whole system where the dc power produced by the panels needs to be turned into alternating power through an electronic device called an inverter these are really uh again for a whole new week-long class just on how inverters work there's a lot of complication in there with all the electronics but at the end of the day they turn dc power into ac and so one way we could wire in a solar panel into a system is that get the panels directly into dc loads there are such things like light bulbs like leds you may have been hearing about these leds dc powered motors or batteries based systems that power off of dc only they're rare and they need special connections and things and they normally powered off of batteries like our phone or our laptop when it's not plugged into the wall that kind of thing or if we want it to speak our normal language of our homes or we can plug stuff into a regular outlet we need that inverter so the panel produces dc goes into the inverter the inverter does its magic and now we have ac alternating current over to ac loads like our motors our refrigerator our tv and so on and so forth all right so just for the next few minutes i want to talk a little bit about care of our solar panels right and kind of what are some best practices we can't get into them all but what i can share with you is that the national renewable energy lab we call them nrel nrel they produced an exhaustive report that you could all can read immediately after this webinar if you like and just really dive into those 100 pages of best practices for operation and maintenance of photovoltaic and energy storage systems and this is the third edition that just came out in 2019 and it's really an exhaustive look at some considerations you should have for care of your solar panels and so i'm going to highlight some of the things that that we found most interesting in this report that that are really good to highlight on this webinar and then we'll take time for questions definitely find this report for yourself it's freely available through the national renewable energy lab first and foremost what are some pm or preventative maintenance activities we can we can run on our solar panels themselves that's what we're going to focus on we're not going to get into all the peripheral equipment like inverters necessarily we don't really have time but as you can imagine these solar panels even though they're not moving so you're not dealing with you know bearings breaking down or vibration and that kind of stuff what you do have in its place is the fact that these are out in the elements right so they're out in the dust and the snow and the rain and the bird poop and you know all the other stuff the ice that can happen um and all that kind of stuff so cleaning uh needs to be really part of the plant on how you're going to clean the photovoltaic panels at the end of the day you want to try to avoid just doing it yourself just kind of you know haphazardly wiping it down with you know steel wool or just whatever brush you have laying around or whatever a cleaning solution you have laying around because these these laminations on top of the solar panels are very specific you know chemical compound that can be compromised if you use harsher types of solvents or more abrasive materials imagine scratching the glass for instance on the top of the solar panel you're immediately just obstructing the ability for light to get through to the cell and that means the efficiency of this panel starts dropping and you get less money for your dollar so it's really good there's a lot of official and regional module pv module cleaners available for cleaning services you know that they can charge just a one-time fee and they'll do a full cleaning with the with the correctly rated equipment for your system but if you're going to do it yourself again not recommended but use soft bristled brushes or try to avoid using brushes altogether okay snow removal is another thing for people like me we're coming at you in chicago illinois uh snow removal is a reality for anyone above that level of latitude where we get snow um a good kind of thing that designers of solar panels do is they tend to angle up the solar panels in the winter time the fall and the winter so you know a six-month rotation of going up onto that rooftop let's say and angling up the solar panels a little bit the main reason we do that is because now the sun is at a angle so that the sun is hitting these more dead on if these are south facing so if the sun is more directly hitting these solar panels then it'll get more output because it's facing the sun more directly and then another benefit that this higher angle provides i think you see where i'm going here is that the snow will just more naturally fall off the solar panel as well and help you avoid some of that snow removal so it kind of serves a dual purpose for um for maintenance of the solar panels but at the end of the day even snow um and this you'll see this in the nrel report as well um the snow is uh sometimes is still a consideration because the rooftop might only be able to handle so many pounds and i one of you asked a great question um before the session began about you know what roofing materials am i allowed to use for my solar installation and the answer is well you're allowed to use pretty much any roof there is you just have to have different considerations there is but certain roofs have different um total load requirements or total pounds that can be loaded on there and the nrel report i'll refer that multiple times is really exhaustive about analyzing the different types of roofing materials and how much it might cost to replace and repair them in considerations so yeah snow removal still might need to happen even though these naturally slide off at higher than 30 degree angles you still might have to go up there and clear out snow just to make sure your roof doesn't cave in so be aware that dust so dust agricultural industrial pollen cleaning same thing with the cleaning considerations and then finally any good pm and really i will take this to a pdm a predictive maintenance perspective on these panels um is if if you can use ir scanning an infrared thermography company a specialist to come in and do a correctly calibrated infrared thermography scan of these panels you can really see where the problem spots are that maybe your naked eye cannot it'll show for in the case of this example right here which part of that solar panel which cells are giving us issues if cells are heating up like this you can see the red these cells are much hotter than the ones around them that might mean they're they're starting to fail and there's something physically going wrong with them versus what's going on around them and each time one of these gets hotter than the rest that extra heat if you think about one thing i forgot to mention is if you have that 100 watts of solar power coming in and only 15 watts coming out where do the other 85 watts go they can't just disappear they all come out of the solar panel as heat right so heat that is just rising up off the solar panels they get really hot if anyone has ever touched a solar panel in operation it's really hot so if there's extra heat being get given off of these panels beyond the manufacturer's specifications that means the solar the heat is rising and that means in in turn that we're getting less efficiency for our dollar so that's just some initial considerations there other ones checking the torque all manufacturers and all electrical equipment have a manufacturer's spec for torque so how tight these screws and connections need to be in terms of foot pounds or or newton meters of force and using a correctly calibrated torquing instrument uh to tighten those down as of the 2017 national electrical code is part of is a real uh big motivator for starting to officially require all these torquings to be done at least every five years or if not sooner depending on the manufacturer's recommendations especially if you're outdoors in a in a volatile environment with wind and snow and rain that can happen all this kind of stuff has to do with being out in the in the environment right checking your torques checking for corrosion and yellowing yellowing is another really interesting thing um where the coating that's on top of these panels can actually come directly from the manufacturer causing a unwanted chemical reaction with the with the cells and i think i have a picture of them coming up of what these yellow cells and they can straight off the shelf can actually just have have a manufacturer's defect that was in action during shipping that can cause problems so just the visual inspection making sure the yellowing doesn't happen in galvanization there's no rusting happening so a lot of visual inspection is is involved in place of mechanical replacements and inspections here's a cleaning so cleaning panels you see this very soft bristled brush using the right amount of um solvents here in this case and again we always recommend using panels an interesting tidbit here that we're finding is that proper cleaning does make these panels up to 20 more efficient right so that's not 20 efficient that's that's high but 20 more so let's say you're you're only pulling 12 efficiency right that's less than the 15 we want but then you start cleaning these things you clean all the dirt and the bird poop off of them and you get somewhere from 12 um watts you're producing to 15 right and then you get back up into the specs so this is what they looked like before and over here you can see what difference that can make in terms of letting light through here's that yellowing i wanted to tell you about so you can kind of it's subtle but you can see it if the panels are starting to look yellow you can you can see that there's an issue there as well another thing that can happen straight from the manufacturer especially if these are being shipped to you the frame can get bent and be defective in terms of not sealed properly these cells are supposed to be sealed off from the elements in the environment but if the glass ever gets shattered or broken in manufacturing or shipping you immediately start seeing issues with the panel and then when that rain water gets in with electrical electrons flowing a lot of short circuits and issues happen inside the panel from there as well interesting uh pie chart from the iea is kind of the breakdown of the different uh main causes the failure rates according to customer complaints for solar panels and that is um so i'll just talk for a little bit um just maybe two or three more minutes and i'll try to take as many of your questions as possible i want to honor your one minute or sorry your one hour time commitment here so i want to make sure to honor that for you but 20 is that optical failure so the biggest one is that if these things are fairly failing because they're not able to get um they're not able to get the process of photovoltaics happening and the light through to them power loss so they're just not producing as much as they used to and that's because connections are coming loose over time or whatever and then all the kind of uh connected stuff right it has to do with it other than that uh let's see kind of all the same stuff other than the panels i just would say that this nrel report check it out because it starts getting into things like ac wiring so not just the panels themselves but you have all the wiring and all the conduit that goes all around to the inverter and the disconnect switches and all the other stuff that you have to make sure you're torquing as well checking their position inspecting them for not only corrosion but yeah water and insects man oh man snakes rats mouse birds making nests and that's a big one birds making nests inside these panels like this so these birds said oh these these are nice and warm spots to sit and this is straight out of that report and so thank you for letting me use this um bird poop right it's just a reality of having stuff on a on a rooftop they affect the solar panels performance significantly so that's something you want to be aware of as well nesting can happen inside these connector boxes and combiner boxes as well so it's always good to run that visual inspection going back to this some of the electrical testing testing that open circuit voltage remember that you pull the panel out of service it's not connected to anything and then you measure that voltage is it still what the manufacturer gave you it's good to have an electrician do that because you're still dealing with live dc voltage which can seriously shock you if you're not careful ballasted this is another thing about roof systems and i'm going to actually go to that right now roof systems so there's a couple different ways to approach attaching these to the roof ballasted or directly connected or attached to the roof ballasted means you know they're you're just weighing them down so they're not going to go anywhere with cinder blocks or just extra weights obviously that's not going to work on a roof like this one that's highly sloped or pitched but on a flat roof maybe ballasting is more cost effective this is where it comes back to the roofing material question about if you're using a softer material like sbs styrene butadiene styrene and some of these softer materials on the roof they might not handle the ballasting very well and they might start breaking down you might need direct connections at that point but you definitely want to leave if you're connecting to a roof uh making sure that there is that four to six inch air space between roofs the roof and modules for airflow because these do get hot and so we don't want them just melting in place or breaking down just because there's no place for air to to move um weatherproofing any holes in the roof itself to prevent leaks a lot of roofing companies you know work closely with the module um the module installers to make sure that they're covered in the warranty for the roof but not always especially if you didn't communicate clearly with that professional roofer so make sure you can discuss warranty inspection upon initial installation of these things and making sure that these cuts into the roof and these connections into the roof are made in such a way that there's not going to be water leaking into the rooms in the building sloped roofs uh the report enroll report talks about this as well and that is on sloped roofs you get you can get more of direct access to the sun potentially because if you're in the winter it's at an angle however there's a lot more cost associated with maintenance because you can't really just walk up there anymore you have to have lifts and things so the report estimates some of the cost ideas including this one right different types of roofing thermoplastic ethylene polyvinyl chloride bituminous this is straight out of that report as well asphalt different types of roofing materials and kind of the estimates that they're seeing from all their data of how much it costs to repair this roof if something needs to be repaired with that solar panel and how to repair that part of the roof 20 bucks per meter square square meter think about that three feet by three feet 20 bucks 20 bucks 15 bucks 40 bucks it kind of varies by type and here's how many hours it would take to repair one meter squared of that roof and finally i will close i know i only have five minutes left but i'm going to try to answer a few of your questions and in the meantime always feel free to ask more questions in a follow-up um in the email i'm going to send you and we can we offer a two-day classes right so i can only get so far into solar before we really need to spend more time uh take a two-day class so we'll come to you and offer another photovoltaics class for you online or in person so one thing to consider is we've talked mostly about this right the solar panel array but there's all the other um attached devices that we were mentioning combiner box which takes all the dc signals combines it into one disconnecting that dc which is important as part of the code requirements taking us to the breaker panel for dc that can break disconnect the solar from the rest of the system the inverter we talked about ac disconnects ac breakers and then the kilowatt hour meter which may or may not be a net meter and then going into the the home for um for use by our appliances but also out to the grid for us to pay back so there's all sorts of devices this is just a quick taste of not only are we maintaining these but we're maintaining one two three four five six seven plus different things as well and um highly recommend you read that nrel report to get a little bit more info and then reach out to us if you continue to have some more questions so um let's see here for now i think we can really start seeing if you have any questions we've got a good amount of curiosity on the line i apologize in advance can't get to all the questions but um yeah we got we had this good question i'm i'm happy i was able to answer this one about where does that remaining energy go if the efficiency is so low and the answer is absolutely it all gets dissipated as heat so those 85 watts for every 100 watts let's say goes up into the air as heat will there be a separate training for the rest of the components in a solar system yeah inverters batteries etc you know what based on demand we can definitely do stuff like that our company kind of specializes in electrical systems so inverters batteries i think it's definitely something we can do is a further webinar topic by the way jade learning if any of you have taken electrical courses with jade they're they're offering a new solar powered class um some of you asking about uh some of the requirements for solar you know what's required for installing this way or that way i would just answer that by saying there are a whole set of requirements in article 690 if you want to write this down 690 for solar-powered photovoltaic systems in the national electrical code so you know this this book is a thousand pages long you can spare yourself that unless you want some good reading but you can flip to chapter six of the nine chapters and go to chap uh article 690 and read all about the requirements from the national electrical code they have requirements for wire protection as you can imagine out in the elements they have requirements for the dc part of the circuit disconnects and switches and grounding and all that fun stuff um there's there's a lot to go into that in terms of coatings in terms of all that fun stuff hot spots typically be on an entire cell you would think it would be especially in these um monocrystalline cells which you know if one part's getting hot it's kind of spreading through the crystal structure for polycrystalline maybe it will be more piecemeal depending on kind of the jagged material here in my one minute remaining um you know this is a great question we can talk about environmental impacts so one one attendee is talking about um what is the solar industry doing to reduce the negative environmental impacts that come from the production of solar panels for instance right the silicon has to be mined out of the ground right i wish i could answer that in 30 seconds but unfortunately it's a really good question and i can't answer it all but but the industry and i'm sure the national renewable energy lab can attest there's smart people all over the place looking at ways to get solar-powered materials created with less environmental impact and making sure that the environmental savings or the savings in let's say greenhouse gases and that kind of thing during operation of the solar panel far outweighs the costs of mining it out of the ground and better yet the cost of mining silicon out of the ground to make a solar panel is hopefully can be made to be far less than what it takes to mine coal and natural gas which are the alternatives right to solar power so there's all sorts of analysis going down from from a large scale perspective i've been part of those analyses before in previous work and there's a lot of complexities there obviously as electricity is used by everyone you're never more than you know one foot from an electrical panel at any time so just keep that in mind that it is being worked on and it's kind of a something is better than nothing kind of approach it's way better than the alternative but it's not perfect either so there's kind of a lot of opportunities for people to do more work with solar panels and improving them so thank you all for your great questions i again apologize in vance i can't get to all of them but let's definitely talk some more feel free to call this number up and and talk to us and see if we can answer any of your more questions and get you into more training opportunities for solar and for electrical and all these other great things so thank you so much for your time and have a great day ...