There are so many options when it comes to installing an off-grid solar system that it can be a little overwhelming. What size panels should I get? How many batteries do I need? What is a charge controller? It can all seem so complicated. Below I will break down our solar system which has been working well for us. I will also include some of the upgrades that we are planning to install within the next few months.
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Here is a list of components we used for our off-grid solar system.
Main Solar Components
- LifePO4 Batteries
- 24v 3000w Inverters
- Solar Panels, Ours no longer made. These are better.
- 70A Charge Controller
- 50A Charge Controller
- Battery Monitor
- MK3-USB Interface
- 120/240V Gas Generator
Wiring Components
24 VDC Wiring Components
- 4/0 AWG Cable
- 8 AWG Cable
- RJ-45 Data Cable
- Positive Buss Bar
- Negative Buss Bar
- Fuse Holder & 250A Fuse
- Extra 250A Fuse
- Battery Disconnect Switch
Solar Panel Wiring Components
120/240 VAC Wiring Components
- 10-2 Romex Wire
- Square D Box
- Square D 20A Breakers
- 120/240 – 30A Outlet
- 120V – 20A Outlet
- 10-4 Cable
- 120/240V 30A Plug
Keep reading for all the nitty-gritty details and a cool video tour.
Solar Panels
Solar panels come in a wide variety of sizes, varying in the number of watts and voltage they produce. Many of the solar panels you will find on Amazon for example will be in the 100 to 200-watt range. This is because they are physically smaller in size and can be shipped through UPS.
However, you can get a much better deal on solar panels if you buy larger panels from an online retailer such as Unbound Solar on the West coast or The AltE Store on the East coast. The downside is you may have to pay freight shipping to receive them if you do not live near a local pick up point.
There are some good deals on Amazon for smaller solar panels. I would recommend purchasing these if you were planning on building a smaller system.
The solar panels we are using are:
- Astronergy 345W panels. We have four of these panels running in a series-parallel configuration.
- Astronergy 365W panels. We have six of these panels running in a series-parallel configuration.
Our total solar output is 3570 watts under full sun. We have two different sized solar because we built our solar panel array as we went, as we had money. When we tried to expand our system the 345W panels were discontinued, so we had to upgrade to the 365W ones.
It would’ve been better to have purchased all the same size panels all at one time but since we are doing this debt-free we were not able to do that. It all worked out fine in the end and we are very satisfied with the system we have now.
Wiring
The wiring you use between your solar panels and your charge controller will depend on how many amps your solar panels are producing and how far your panels are from your charge controller. It would be best to consult a wire sizing chart or the store where you purchased your solar panels and charge controller to make sure you get the right-sized wire.
That being said most likely 10 AWG Solar Cable will be sufficient for most situations.
Here’s how we have ours wired.
We have two panels wired in series with the positive and negative wires going to Y connectors. The other two panels are also wired in series and connected to the same Y connector. From the Y connectors, we have one positive and one negative 50 foot 10 AWG wire going our charge controller. We used an MC4 connector kit to build our own wires to the length that we needed, rather than buying more expensive premade wires.
Charge Controllers
Like solar panels, there is a wide variety of charge controllers from different manufacturers. The two main types are PWM and MPPT, charge controllers. I would strongly encourage you to only consider MPPT charge controllers since they are much more efficient than the older technology in the PWM charge controllers.
You will need to size your charge controller to the solar panels you have or to the ones you will have if you plan to expand your solar panel array.
This was is a mistake that we made. We had a 40 amp Renogy MPPT charge controller which worked fine for the number of panels we had in the beginning. However, it was too small for what we planned to expand too. Therefore, we had to upgrade to the Victron charge controllers we have now. It turned out better in the end since the Victron charge controllers are much better charge controllers and work together in the complete Victron system.
Wiring
From the charge controller to your batteries you will also need wiring and a fuse. Like the wiring from your solar panels to your charge controller, the size will depend on the number of amps your charge controller producers and the length of wire.
For our system, we are using 8 AWG wire. We currently do not have a fuse between our charge controller and our batteries but we will be upgrading that soon.
Batteries
Like solar panels and charge controllers, there is a wide variety of batteries to choose from. The three main types are flooded lead-acid batteries, sealed lead-acid batteries, and lithium batteries. Flooded lead-acid batteries have the lowest upfront cost but have a shorter life expectancy.
Flooded lead-acid batteries also require regular maintenance, need to be vented, can only be safely drained to 50% of their capacity, and are extremely heavy. These are what we started off with but have since upgraded to a much better option Lithium-ion Phosphate Batteries or LifePO4 batteries from Battle Born Batteries.
The LifePO4 batteries we are currently using have a higher upfront cost but over time are actually less expensive than flooded lead-acid batteries. They can be drained to 100% of their rated capacity without damaging the battery, require no maintenance or venting, and are much lighter. Battle Born Batteries also have a much longer life expectancy, being able to be drained and recharged 5000+ times.
Wiring
The wiring from your batteries to your inverter will depend on how large of an inverter you have and the voltage of your battery bank. A 12V battery bank will require larger wiring than a 24V battery bank with the same size inverter.
Not only will you need the wiring to connect your batteries to your inverter you also want to install a fuse or circuit breaker for protection and a battery shut-off switch.
We are using 4/0 AWG Cable, a fuse, and a large 300A battery shutoff switch from Blue Sea.
Inverter
The size of your inverter will depend on the loads you need to power. We have two 3000W Victron inverter/chargers.
With this inverter, we can run a standard household refrigerator, chest freezer, a 20-year-old Maytag top load washing machine, all of our lights, and electronics in our home.
Not only does our inverter power all of our electrical devices in our house it also acts as a charger for our batteries when our solar panels do not produce enough energy. We simply plug it into our backup generator and it quickly chargers our batteries back up to 100%.
