Installing a small Off Grid Solar System.

Yesterday was the big day when I finally got started on our off grid power system! It's small, and it's temporary, as we will need to go much bigger in the future....but it's setup and it's awesome!

Our temporary setup consists of:

265watt Canadian Solar Panel

30A Sun Yoba PWM Solar Charge Controller

12V 220Ah Deep Cycle Battery

800Watt DC-AC power inverter

I figured this post could serve to help others interested in setting up a small system to understand the basics. That said, let me give you a little break down of what an off grid system (of any size) consists of.

Number 1: The Solar Panel

Obviously, to have a solar power setup, your going to need something to convert that solar energy into electricity. This is where your panel comes into play. There are many options of solar panels on the market today, and the cost has come down dramatically over the years. It's likely not best to shop for a panel online, as they weigh a fair bit, and will likely eat up any price savings on shipping costs. Phone around to local suppliers and compare their prices, but typically at the time I am writing this, a cost of around $1/watt is typical. For example, we chose to purchase a 265 watt panel from Canadian Solar, at a retail price of $280 CAD. The amount of panels you will need is based on how big of a battery bank you plan to have. Do a little research on the amount of sun you get per day on average for your area in order to make this calculation. For my situation, we get an average of 5 hours per day. Panels very seldom are operating at absolute maximum output, so its best to round down a bit when making calculations.

My recommendation is to have an array of panels capable of charging your battery bank from 50% up to 100% within the amount of avg sun hours your have in the day. For example, If I estimate my panel will give me 250watts times 5 hours a day, I come up with a total of 1250watts. Since you don't want to discharge your battery bank beyond 50% (in order to prolong its life), my one panel should be ideal for charging a battery bank of 2500Wh (watt hours). At 50% discharge, a 2500Wh battery bank will need 1250watts to be brought back up to 100%.

The system I put together for the time being, has a battery capacity of 2640Wh, so I'm right where I want to be.

Number 2: The charge controller

Your charge controller is the middle man between your panels and your battery bank, It's job is to ensure efficient charging of your batteries, without over charging and without allowing them to be discharged past your set parameters (80% is best, 50% is typically more realistic).

There are 2 main types of charge controllers: PWM or MPPT. Here is an exert from Enerdrive.com that explains the difference a little better than I would.

"Modern charge controllers use Pulse Width Modulation (PWM) to slowly lower the amount of power applied to the batteries as the batteries get closer and closer to fully charged. This type of controller allows the batteries to be more fully charged with less stress on the battery, extending battery life. It can also keep batteries in a fully charged state (called “float”) indefinitely. PWM is more complex, but does not have any mechanical connections to break.

The most recent and best type of solar charge controller is called Maximum Power Point Tracking or MPPT. MPPT controllers are basically able to convert excess voltage into amperage. This has advantages in a couple of different areas.

Most solar power systems use 12 volt batteries, like you find in cars. (Some use other voltages and the same advantages apply to these systems as well.) Solar panels can deliver far more voltage than is required to charge the batteries. By, in essence, converting the excess voltage into amps, the charge voltage can be kept at an optimal level while the time required to fully charge the batteries is reduced. This allows the solar power system to operate optimally at all times.

Another area that is enhanced by an MPPT charge controller is power loss. Lower voltage in the wires running from the solar panels to the charge controller results in higher energy loss in the wires than higher voltage. With a PWM charge controller used with 12v batteries, the voltage from the solar panel to the charge controller typically has to be 18v. Using an MPPT controller allows much higher voltages in the cables from the panels to the solar charge controller. The MPPT controller then converts the excess voltage into additional amps. By running higher voltage in the cables from the solar panels to the charge controller, power loss in the cable is reduced significantly."

While MPPT is a great option, if your looking to pickup something to last you on the cheap until you upgrade, a simple PWM like I am running right now will do the job just fine! The unit seen in the video of our setup can be purchased here for about $40 http://amzn.to/2tmcQPL An MPPT controller on the other hand, can easily run upwards of $500

Number 3: The Batteries

It's important to note that with batteries for a solar setup, you do NOT want to use any kind of regular automotive battery. Basically, if you see a rating for cold cranking amps on it, it's no good for this. Your typical car battery is designed to give a very strong surge of power, for a very short period of time. Obviously running a cabin is not such a situation where that would be useful.

Find yourself a good deep cycle battery. Specialty solar batteries are fantastic, but often carry that niche market price tag. The solution? Golf cart batteries are a good option, as well as heavy deep cycle batteries for RV or similar use. We chose to go with this battery for the time being

http://usbattery.com/products/12-volt-batteries/us-185hc-xc2/

The main reason is that it had the best storage capacity for the price point that I could find locally.

In Order to determine the capacity of a battery, multiply the Amp hours (Ah) by the voltage. This will give you the capacity in watts. 220AH multiplied by 12 volts gives us aprox 2.6KW or 2600watts of storage capacity. So if I don't want to bring it down beyond 50% charge, I have 1300 watts to work with. This particular batter retails for $320 CAD

What can I power with 1300 watts? A lot! If you take a look at your devices, the wattage rating on the power supply is the amount of watts consumed per hour. A cell phone for example, charges at about 5 watts per hour. A new LED household lightbulb takes around 10watts.

Say we have 5 LED bulbs on at 10watts each. Add 2 cell phones at 5w each, and throw in a 32" LED tv that takes 30watts. In total, we are using 90 watts of power at this point. With 1300 watts of storage useable in the battery, we can run ALL of these things constantly for 14.4 hours straight. 1300 divided by 90 = 14.4 Not that it would take 14 hours to charge a cell phone, but you get the picture.

Number 4: The Inverter

Last but not least, you need an inverter to convert the DC power of your battery, into useable household AC power. Unless you are only running 12v accessories that you would typically plug into your cars 12v outlet, an inverter is a necessity. Inverters are simple enough to figure out, just do the math on the total power consumption of all the devices you plan to run at one time. If you plan to have 10 items that all draw 100 watts each at any given time, your going to need an inverter that can handle a continuous draw of 1000watts and therefore should buy an inverter rated at 12-1500watts. Most inverters CAN run exactly what they are labeled as, but usually only for a few minutes. In the small print, they will tell you they are rated for slightly less wattage when ran continuously. For example, my 800 watt inverter in this setup will run 750w constant, or 800watts for 5 minutes before overheating and shutting off as a safety.

There you have it! Add up these 4 components and you have yourself an off grid power system sized to your needs! I hope this was simplified enough to make sizing a system a little bit more understandable to somebody just starting out!

I'll be sure to update here, facebook, and youtube with how the system is working out, and what we are doing to grow it as time goes by. Thanks for stopping by the blog, don't be a stranger! Always happy to chat.

Cheers,

-The Happy Hermit