Please do not make us your primary source for everything solar and the electrical part of the process. We are learning as we go and sharing that information.
When considering solar, it seemed like a no-brainer. Buy some panels, some batteries and maybe one or two random parts then put them all together and plug in to our travel trailer. Pay a bit upfront, but the government will hopefully help us be green and sustainable, and the panels will pay themselves off after 5 years and still have 15 more years of life, right?
Wellllll…. (frown-ish face), not quite. Looking back, do we regret doing solar? Nooooo, I think we would have just waited to buy everything and install them until after we were settled in because money has been tight. I suppose living on a combined salary of $30,000 (gross) and building a tiny house will do that to a couple. So below we outline the parts we had to buy, costs of everything, and a general how to do it yourself.
A. Costs (including taxes)
$860 4 x 280-watt solar panels (picked up from a warehouse in Phoenix)
$1200 8 x 225 amp hr 6v Trojan batteries (also picked up in Phoenix but at a battery shop)
$1050 1800-watt Pure Sine Waive Inverter (Amazon- pain in the butt to get because everyone was out of stock)
$600 Midnite Classic 150 Charge Controller (Online Solar Supplier)
$30 2 Gauge AWG, 30 ft. Wire (Amazon)
$45 9 x Plastic Totes to store batteries and other equip. (Dollar General)
$15 4-Way Solar Wire Connector (Amazon)
$20 Misc. Fuses and Switches (Lowes)
$80 Treated Lumber and Hardware for Homemade Solar Panel frame (Lowes)
$25 15 Amp Extension Cord (Amazon)
TOTAL = $3925
B. Off-Grid Solar Basics
Basic Components: solar collectors, charge controller, batteries and inverter
1. The average DIY solar set-up is arranged to change the tilt of the panels twice a year, thus achieving just over 70% efficiency. Newer, very expensive 2 axis sun tracking systems can achieve 100% efficiency but at a great cost. Your panels in the Northern Hemisphere will be tilted, approximately, to the south at an angle of your latitude +15 degrees in the winter and your latitude – 15 degrees in the summer.
2. The electricity generated by the panels will be fed through the charge controller, which supplies the required voltage to your battery bank, thus maintaining your batteries at an appropriate voltage.
3. The battery bank receiving a current from the charge controller should be maintained at 80% or more capacity for prolonged battery life. Battery banks should be sized accordingly.
For instance, we use an average of 2.5 kwh per day and our battery bank is capable of storing 10.8 kwh.
4. The current from the batteries is fed to the inverter. We chose a pure sine inverter because it is capable of powering anything you might plug in to your typical household outlet. It is more expensive so your particular household set-up may not require this. The inverter changes the voltage from, what is in our case, a 24 volt battery bank to our household 120 volts. The inverter also converts DC to AC (AC being what you need for typical household electricity).
5. Also keep in mind that, as of 2014, you get 30% tax credit for what you spend on solar from the federal government, and Arizona shells out another 25% so we will be getting back 55% of what we paid for the system. Save your receipts!
C. Tips and Help
– Once you’ve decided to design and build your own off-grid solar system, the first step is to size your system appropriately. You can do this by looking at your electricity bill and finding your average electricity usage. A handy tool in this process is a Kill-A-Watt meter. Using this, you can assess the energy uses of individual appliances.
– After sizing your system, the first consideration should be your battery bank. The bank is where your electricity is sourced from and must be sized correctly before considering your solar panel needs. Before you get started, you should learn a lot about batteries. Trust me, it is worth your time and it will save you money in the end.
– After you’ve done this, you’ll need to pair that with an adequate supply of solar power for charging. Your solar panel array will need to be sized according to the formula: X AH * 14.5 (assuming a 12v battery bank) volts charging * 0.05-0.13 (depending on your usage) charge rate * 1/0.77 system derating = Y watts of solar panels
– It’s time to get educated about how electricity works. Remember the terms “series” and “parallel”? How about “amps,” “watts,” “ohms,” and “volts”? You need to become very familiar with all of these terms before you get started.
– Want some Forums? The one below is very helpful:
Northern Arizona Wind and Sun
– Want more information or have questions? Feel free to email or message us!