We have two solar setups on the homestead. One is being used to generate electricity for the greenhouse and fish pumps for the aquaponics system. The second system is generating electricity for our office. The office is basically a 16ft pull behind trailer that we converted into an office. It’s used to charge our cell phones, laptops, phone line, wireless router and DSL modem.
The homestead is not in any way connected to the electrical grid.
That being the case we have learned a lot about solar. When we first moved out of the city to live this new lifestyle, we were under the delusions that all we needed was a simple 25 watt solar panel and a dolly toted battery and we would have all the power we needed. We quickly realized that for solar to really supply power needs, you need a lot of it. There are also other things you need.
Electricity from the grid is cheap! When I say the grid, I mean your local power company. In the US, the average price for power is around $0.12 per 1000 watts (1kwh). The reason people think their electric bill is so high is because they have a million+ appliances hooked up. Go around your house and count how many things you have plugged in.
We have 1000 watts of panels to supply power to our greenhouse that is only consuming 243 watts of energy inside. But that is not nearly enough power. I know, I know. You say, but Zac, you are only using 243 watts of energy and you have 1000 watts of panels…what gives?
Keep in mind that my pumps should be running 24/7. The panels would need to be taking in energy 24/7 in order to be effective. On average, they take in around 3.9 – 4.7kw every day. There are only a few hours every day where the sun is in perfect line with the panels and in optimal position to generate maximum energy.
So lets see what we have here.
Greenhouse power = 243 watts x 12 hours running time = 2916 watts.
That is not a problem since my panels on sunny days produce that much and more.
But what happens if I want to run my pumps 24/7 as should be done for an aquaponics system?
Greenhouse power = 243 watts x 24 hours running time = 5832 watts.
Uh-Oh. That is a BIG problem since my panels don’t come close to producing that even on perfect sunny days. What about days with partial cloud cover or total cloud cover? Now you see that you need a lot more solar than maybe you thought before. If you don’t have big energy consumption, than you will probably be fine. I think ours is minimal. We want to be able to use our laptops and have a phone line, but that is about it. We have learned to live without lighting and appliances in the home.
It doesn’t matter if you are building a 1kw system or a 30kw system. There are five main things you will need to complete that setup. I wish I would have had a list like this when I was starting out.
1. Solar Panels, also called PV or PhotoVoltaic.
There are ton of different varieties of panels out there to choose from and prices can vary. Two big things you want to keep in mind are:
- What voltage system will you be building? 12, 24, 48? The higher the voltage the easier it is on your system to produce and maintain energy. We started out using 12 and went up to 24. We think that is a good middle ground. Many houses with large solar arrays are 48 volt systems. Solar panels are made for a particular voltage so you need to decide what that is going to be before you get started.
- Before buying a brand of solar panel, read the online reviews. See what others are saying about its performance. We use Grape solar panels on our system.
2. Combiner Box
This is where your solar panels will terminate into. There are a few companies that sell prewired combiner boxes these days that are very handy. You will pay more, but it will save you from doing some wiring on your own. I’ve done both. With the prewired combiner box, you just mostly plug in your panels into the sockets provided by the box and then run cable out to the charge controller. I really like the combiner boxes sold by Midnite Solar. They come with a handy diagram that is easy to read and understand. Simple. Connect your panels, run them into the fuses inside the combiner box and then run the line out. Easy peasy plug and play up to this point.
3. Charge Controller
This is where things can start getting hairy. Listen, if solar was a complete no brainer for the average lazy fat MSG addicted American who only cares about when the next football game comes on, they’d be selling plug and play systems for your home at Walmart…but alas. There are a lot of good charge controllers out there and some bad ones too. Again, read the reviews. Midnite Solar produces some good stuff and easy to program for the newbs like me. You need to purchase a controller that will be based on your system voltage, and understand how cold it gets where you live will effect the voltage your panels produce. If you have a 150 volt charge controller and 3 panels in series(connected positive and negative together) then you could produce over 160 volts on a cold morning and at that point you will be sadly looking into your controllers warranty info. Again, Midnite Solar (they should be an advertiser) is a good solution as they provide a HyperVoc setting on their systems that essentially protect the controller. We currently run the Midnite Classic 150 for the aquaponics and the Midnite Solar – The Kid for the office. We also have a Midnite Classic 200 in storage as a backup if we ever need it.
I’ll say right off the bat, if money is no object, go with AGM’s. They are no hassle and zero maintenance. The 2 big questions for deciding what batteries to use is what kind and what voltage. We chose 24 volts for our two systems and will probably continue to do so for any additional systems one day for the houses. There are just a lot more equipment options I’ve seen open to 24 volt systems unless I’m going to spend some big bucks on a giant 48 volt house system. So then the other question: AGM, Gel Cell or Lead Acid? If you have the money to spend on Gel Cell, you might as well just buy AGM’s. If money is tight and you don’t mind having the extra effort in maintenance, lead acid batteries are going to be your best option. SAMS has some pretty good deals on 6 volt lead acid batteries and if you happen to screw them up while they are still under warranty, you can exchange them at the store no problem although the clerk at the automotive desk might give you the evil eye for unloading so many hundreds of pounds of dead batteries on his counter. 🙂 But I digress.
5. DC to AC Inverter
You will need an inverter to make all this power you are now producing useful. There a number of brands out there and we have been using SAMLEX. They are not my favorite company to deal with as their customer service is about as easy to talk with as handling a cactus…especially if you are a newb like me. I’m not sure I like the quality of their products as I seem to have had a few fail me. But they are the company that you will see for sale at most of the online retail locations. The inverter will connect directly to your batteries and from there goes out to your appliances you wish to use. I would advise that if possible, get one with a built in GFCI (ground fault circuit interrupter). This is essential for us since our pumps in the greenhouse are submerged in fish tanks and nobody wants to get electrocuted.
Your solar panels are connected to your combiner box. Your combiner box is connected to your charge controller. Your charge controller is connected to your battery bank. And your battery bank is connected to your inverter. That’s it!
Take a look at our diagram above. This is how our set-up is wired for our greenhouse. Pay particular attention to the wiring of incoming and outgoing power. We learned that its important to make sure that incoming amps are put into a different battery than the outgoing power. I believe this is the most efficient manner in which you can wire your system. Also of note is the “Battery Life Saver” in the diagram. Again, read the reviews. There are some that say that it is unneeded and they don’t really work…but the reviews from hundreds of people say otherwise. I think it was a wise investment and would recommend one.