The ugly truth behind grid-tie solar systems. Part 1, FarmCraft101 solar. Watch before you buy!

welcome to farm craft we recently had a solar system installed and in this video I'm gonna go through how it works and explains some of the ways different solar systems are designed there are many different ways to put together a solar system not that kind of solar system and the main subject of this video is going to be a grid-tied solar system I've also retrofitted my system with a battery backup and I will go through that in a later video this is a 90 100 watt solar array or 9.1 kilowatts there are 30 panels that each produce 305 watts of power had Maxima a grid-tied system is definitely the cheapest way to get into producing your own solar power and it has some pros and cons that I will go through here's the basic setup of a grid-tied system you've got your solar panels producing electricity goes to an inverter your inverter converts the DC power from the panel's to AC power that your house can use the inverter output is hooked to the power grid if your house is using a lot of power there's going to be a voltage drop then the power would be sent to the house actually the proper way to say it is the electricity will flow to the path of least resistance if there's a voltage drop at the house then that's where it's going to go if the house is not using as much power as the inverter is producing then the electricity will go back up the grid which will run your meter backwards and save you money obviously if the Sun is not shining you're not producing any power and you just get your power from the grid like you normally would grid-tied systems are by far the cheapest systems out there for example our system cost twenty three thousand dollars wait wait wait there's a tax credit and then with a 30 percent tax credit it comes to around seventeen thousand dollars all right now relax let's do the math I use about $200 worth of electricity every month in this system will generate most of that so $200 a month times 12 months is 2,400 dollars per year so 17,000 divided by twenty four hundred dollars a year comes out to just over seven years now this is a little overly optimistic so we actually calculated an eight and a half year breakeven and everything that we generate beyond that is going to be free power so even though we're talking about big numbers here this can make good financial sense but there's a catch if the grid goes down everything shuts off that's right even though you have solar panels if the power grid goes down you cannot produce any power these inverters are designed to not back feed the grid which provides a safety factor for linemen that are working on the grid when it's down that also makes the installation of them much cheaper because they don't have to worry about transfer switches and automatic change overs that happen when the grid goes down so what are the advantages to a grid tied system they work at a much higher voltage and that has several advantages one is you need a lot less wire when you can go all the way up to 360 volts your amperage for the same amount of power is much lower and therefore you don't need as big a wire or as many wires to transmit the power to the next step of your operation for those that aren't as familiar with electricity it's useful to think of it as water flowing through a hose the amount of water flowing through the hose is the amperage and the pressure that the water is under is the voltage the bigger the hose the more water you can get through also the greater the pressure the more water you can get through power is a function of both the pressure and the volume of water delivered in electricity power is expressed in watts and it equals volts times amps this means if you have a lot of pressure you don't need to deliver as much water to produce the same amount of power put in electrical terms if you have high voltage you don't need as many amps to deliver the same amount of power can use a smaller wire what I have here is 30 36 volt panels they are arranged in groups of 10 to make a 360 volt output each group of 10 panels is wired in series and then those 3 groups of 10 are wired in parallel and that is all hooked to one single wire to transmit up to the shop and it's important how many wires you go to will really increase your expense I have one wire in the ground here if I remember right it's an 8 gauge copper wire it goes down right there and goes through a ditch up to the building and I'll show you that next so this is the other end of that wire again looking back down at the array and you can see I've got a solar disconnect right as that enters the building in my area and I think most areas code is going to require a disconnect and they are going to want to disconnect on each wire that you have in the ditch so the older technologies you weren't allowed to go or you weren't able to go up to as high a voltage so say you were transmitting at 96 volts well to do the same amount of power I'd have to have 4 wires in the ground or I'd have to buy much bigger wire which gets expensive really quickly and I would also lose more in the transmission when you have high voltage you don't need as big of a wire and you have a lot less amperage so you're able to transmit power with less loss that's why the power lines overhead like these up here those are operating on I think this is a sixty eight hundred volts I'm not sure but they operate on high voltage until they get to your house and then that's transformed down to go into the house they don't send voltage around it at 240 volts because they would lose so much the amperage would be so high and these wires would be prohibitively large so the high voltage helps you in your transmission it decreases the the size of the wire the number of wires and every wire you'd have in the ground I'd need a different disconnect so if I had two or three wires I'd have three disconnects here this is also an AC disconnect which required by my power company so now let's go inside and see what this is hooked to so here we are at my inverter and in this metal clad armored cabled wire is my three hundred and sixty volts DC code in my area requires that the DC line is in metal cladding and then this is my inverter now this is a grid-tied inverter so what this what this inverter does is it senses the grid so it sees a sine wave doing its thing and it says okay I've got power in my DC line so it inverts that power from three hundred and sixty volts to two legs of 120 to make a 240 volt single-phase like like the standard power is around here it synchronizes that power with the sine wave that it senses in the grid and and then it puts it back into the panel box it puts it in this line and goes directly into my my grid power the advantages of this inverter the 360 volt input allows the inverter to be much smaller and to generate more power in a more compact and much cheaper package a simple way to think about it is you're taking 360 volts down a little bit to make two legs of 120 you're not doing a huge jump up I think that's where inverters have the most struggle so when you get a battery back up you're going down to the voltage of your battery bank which is often times as 48 volts for a decent-size system and taking power from 48 volts up to a 240 volt AC system is more difficult requires a lot more engineering and hardware in your inverter in order to accomplish and makes everything more expensive now just to show you I'm gonna go into the battery backup side of things later but right here I've got my battery backup inverter and I don't know if you can see how much bigger it is but this thing probably weighs more than twice as much and it's much deeper it's wider and it's taller I mean everything about it is bigger and and that's because this is capable of taking 48 volts DC and making it into 240 volts single-phase power let's go look at where this service panel is hooked into the grid the other end of this line is that panel we were looking at beside the inverter so when the grid-tied inverter is making power it is coming back up this line it's coming into this box now if I've got a voltage drop to the house because there's loads at the house that need to be met the currents gonna pick the path of least resistance it'll go here and it'll get used it'll never go through the meter it'll just go straight to the house if the house doesn't have a voltage drop in other words there's not a big load there sucking up a bunch of power then it will go back into the the meter and run backwards down into the ground up the power pole backwards through that transformer and back into the line and back down to someone else's house so how does this inverter send power back into this into the grid well basically it's just upping the voltage a tiny bit maybe a tenth of a volt I'm not sure exactly how much but it doesn't take much the the resistance of the grid or the impedance of the grid is very low it allows current to flow readily so even just a tiny voltage difference here will readily flow into the grid and go either backwards through my system and back up the power lines or it will go to my house which is on a different panel but it's connected through the same input is this here you can see the power output it's it's cloudy right now it's getting ready to rain and I'm getting 2,000 watts at 378 volts and it's putting out 251 volts ac see it's constantly adjusting those numbers to keep the flow going the way it needs to go so here we are on a sunny day midday and we're getting just under 80 100 watts so I've got 305 watts per panel at 36.4 volts now this is a solar edge system and that's a relatively new technology and it has optimizers what an optimizer it's this device right here and each panel has its own optimizer you look down each one each one has one and that basically communicates through the power line with the inverter so that the inverter is able to handle each panel separately and that makes the system more efficient it used to be when you had series these 10 panels are wired in series when you had things wired in series if one panel didn't perform as well as the rest then the entire series was cut down to that lowest common denominator in this system at least what I'm told is that this this prevents that so you can actually knock out a panel and the rest of them will continue to produce so that's the basics of a grid-tied system in the next video I'm going to show you how to retrofit a system like this with a battery backup inverter so that you can use it when the grids down [Music] [Music]

Channel: FarmCraft101

Views: 1,473,231

Rating: 4.7264957 out of 5

Keywords: solar panels, solar array, solar panel, solar power, solar system, grid tie system, grid tied, grid tied solar, grid tied solar system, grid tied inverter, solar inverter, battery backup, off grid, off grid power

Id: m5wv4HcRNKw

Length: 12min 16sec (736 seconds)

Published: Fri Oct 06 2017