The Four Main Elements of Most Solar Power Systems
There are four main elements in most Solar Power systems. The four elements are the following: First, your Solar Panels, which gather energy from the sun. Second, your Charge Controller, which regulates the electricity coming from your panels to avoid damaging your battery bank. Third, your Battery Bank, which stores the energy coming from the panels for use during non-sunlight hours. Fourth, your Inverter, which most setups include in order to power common AC appliances.
Step 1: Connecting Your Charge Controller to Your Battery Bank
Your battery bank could consist of a single led deep-cycle battery or an entire bank of expensive lithium-ion batteries. Regardless of your battery bank, our first step is to connect our bank to our charge controller.
Every battery bank is different. Many people wire several 12-volt batteries together in parallel to reach higher amp/hour storage, and some have a combination of batteries wired in a combination of series and parallel to reach desired voltage and amp/hour ratings. For this article, we’ll be explaining the connections with the assumption that you have either one battery or a few batteries wired in parallel.
Every charge controller is different, so be sure to read the manual for your specific design. Most solar charge controllers have a few features in common which will be going over here:
Solar charge controllers have input terminals. These input terminals are openings on the bottom of the charge controller connected to screws accessible on the front face.
To connect our battery bank to our solar charge controller, we first unscrew the metal screws marked “Battery” on the front of the charge controller. This opens space inside the input terminals, allowing us to push in our bare wire. We should have two wires: A wire that connects to a positive terminal on our battery, and a wire that connects to the negative terminals of our lead battery. Each of these wires should have one end that has bare cable. We first insert the negative bare wire into the marked opening, then the positive bare wire into its marked opening before tightening the screws back down. Be sure not to strip your screws during this step!
Step 2: Connecting Your Solar Panels to Your Charge Controller (MPPT vs PWM)
Many solar panels use MC4 connectors that look like this:
We can connect these MC4 connectors using a variety of methods, including an adaptor kit.
Most users will find it easiest to simply get additional PV wire and attach two MC4 connectors that will connect to the solar panel.
Then strip the insulation on the other end of the wire to reveal the bare wire which we can then insert into our charge controller.
The steps are similar to our battery connections. We first unscrew the screws on the front of our charge controller marked solar power, then we first insert the bare wire from our negative solar power connection followed by the bare wire from our positive solar connection.
After we’ve inserted our two wires, we screw the two screws on the front of the controller back in.
Step 3: Connecting Your Battery Bank to an Inverter
Every inverter is different. Some are heavy-duty inverters meant to support high loads, some are smaller. Before we connect our battery bank to our inverter though, we need to talk about disconnects.
It’s always a good idea to have a disconnect in-between your battery bank and your inverters. For example, if your wires are rated to handle 170 amps, it’s a good idea to have a 150 amp breaker or fuse. This ensures that the current flowing through your wires doesn’t exceed their rating, which could result in melting insulation or fires.
You can use either breakers or fuses for this purpose. Some choose to go with breakers instead of fuses. When breakers are triggered, all that’s required to reset them is to flip a switch. If a fuse breaks, it means going out and buying and installing a new one. The breaker will be installed between the battery bank and the charge controller. The inline fuse will be installed between the panel and the charge controller (usually before parallel pigtails or additional wire).
Circuit Breaker Inline Fuse
So we first attach one of our wires through our disconnect (breaker or fuse). After we’ve incorporated our disconnect, we can take a look at our inverter. Most inverters have bolts on the back that are marked for connections with battery banks. You can see pictures of SanTan inverters below:
Many inverters will have a screw-and-bolts system that looks somewhat similar to most battery terminals. We attach our wires from our battery bank to the inverter, screwing the bolts tightly to ensure a good connection.
WARNING: Many inverters will draw more than 50% of your batteries charge before disconnecting. Allowing your battery to drop below 50% charge will damage them and shorten their lifespan.
Step 4: Safety Checks
A few things to keep in mind:
Be sure that your wires are rated for the level of amps that you’re planning on passing through them. The higher your projected amp load, the lower your gauge (thicker your wires) has to be.
Be sure that your connections are insulated and kept out of the elements. This is particularly true if you’re planning on leaving your solar panels outside. Wire corrosion can occur even underneath insulation, though it can be hard to detect.
Make sure your battery bank never drops below 50% if you’re using standard deep cycle batteries. Some choose to connect their inverters directly to their charge controller to avoid this.
You can check how much power is passing through different parts of your system by incorporating a volt meter. You can ensure that dangerous levels of amps are never drawn by including disconnects like breakers or fuses.
Getting a handle on all the different parts of your solar setup may seem daunting, but hopefully, now you’ve got a better grip on the different parts. We first connect our Battery Bank to our Charge Controller by loosening the screws on the face. After we’ve connected our battery, we can insert the wires from our Solar Panels and screw everything down into place. After that’s connected, we’re ready to begin powering our appliances through our Inverter. We need to make sure our wires can handle our current. We ensure this by using disconnects like breakers, fuses, or volt meters to ensure we’re not passing dangerous levels of current.
If you want to figure out how many solar panels you need try our solar calculator here.
Good luck with your solar setup!