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A solar power system is only as good as the components that make it up. If you’re going to set one up for your house or RV, you need the right accessories. Each system will be different of course, but the following provides an overview of what you need to buy.
The most important solar panel accessories are MC4 connectors, extension cables, monitoring systems ,AC/DC disconnects and racking mounts. Additional tools and parts may be needed depending on your setup.
Solar panels (photovoltaic modules, PV modules) come in different sizes and watt ratings. 250W is the most widely used in homes and RVs, but 100W, 300W and 400W are available. Solar panel sizes usually refer to the panel’s wattage rating, rather than its physical dimensions.
The panels are either monocrystalline or polycrystalline, with mono panels being more efficient. Most PV modules have a 12V or 24V rating, though, 36V, 40V and others are available.
Solar panels can be rigid or flexible. Rigid panels provide more power and more durable. Flexible or thin film panels are lighter and can be installed on curved roofing. The type of solar panel you choose determines what racking mount is required.
A solar array refers to two or more solar panels connected in a series or parallel. Before you buy, determine how much solar power you need so you can get the right number of solar panels.
PV modules for homes can be mounted on the roof or the ground. There are advantages and disadvantages for both. Solar panels for RV can be mounted flat or tilted. Mounting hardware is available for both, and in many cases the steps are similar, i.e., use bolts or mounting tape. The difference is the mount itself, with titled mounting adjustable to varying angles.
Solar panels convert the sun’s energy into DC current. An inverter turns DC power into AC power. There are many types of inverters, the most popular being string and micro inverters. The size (in watts) of your inverter must be at least equal to the total wattage used by all devices running on solar.
String inverters are connected to solar panels by strings inside the inverter. Micro inverters are set at the rear of each panel. Both can be effective when set up properly, but micro inverters provide better performance overall though more expensive.
Inverters can be installed in grid tied systems, but it is essential in off grid homes. The inverter and battery (or batteries) provide off grid solar homes and RVs with storage and AC conversion. AC charging inputs are built into some inverters for times when solar panel output is low. These chargers are designed for heavy loads and use power from the grid.
Grid tied inverters have a different configuration. They don’t need batteries because they are linked to the grid. The drawback here is if the utility grid goes down, there is no battery backup. That is why many homes and RVs have portable solar generators.
Batteries store the energy used by solar panels for use in evenings, for emergency and / or backup power. Grid tied homes do not necessarily need a battery because any excess power produced by their solar power system is sent to the grid. Off grid and hybrid systems need a battery (or a series of batteries) for extra power. Batteries are also used in solar powered RVs.
There are four main types of solar batteries, lithium, flooded, AGM and gel. Each one has different capacities, life cycles and depth of discharge.. Most solar batteries are 6V, 12V, 24V, 36V or 48V.
Flooded lead acid batteries are affordable and widely used. Gel and AGM are good alternatives while lithium is the best performance wise. For off grid homes and large RVS, lithium batteries are the best option. For occasional RV camping trips, lead acid batteries, AGM or gel will do. Your solar power system setup will decide what type of battery is required, if any.
Solar Wires, Cables and Connectors
Wiring, cables and connectors link the various components together. The connections transfer energy from the solar panel to the charge controller, battery and to the inverter. Solar power systems use insulated copper or aluminum wire. Colors are used to identify which wires are positive and negative.
Solar connectors come in different sizes, but the most widely used is MC4. Solar panel kits usually include MC4 connectors and the required crimping tool. If you buy a solar panel kit you probably have all the connectors and wiring to complete your setup. Different setups require different cables and wiring. Among the most commonly used are:
- Battery to inverter cable
- Battery to inverter cable
- Charge controller to inverter wire
- Solar panel to charge controller cable
- DC loading wire
- Branch connectors
- Crimp connectors
A charge controller functions as a current regulator. It manages energy flow to and from the batteries and prevents overcharging, overheating and overloading. There are two charge controller types used, MPPT and PWM, and they can be installed in off grid and hybrid solar power systems. Grid tied solar systems don’t need a charge controller.
Charge controller capacity is measured in amps. Get a controller that can match the capacity of your battery and solar panels. If your PV module system is 14 amps and 12V, your PWM charge controller has to be at least 14 amps. To be safe, add another 25% to the controller’s amps for cushion. So for a 14 amp system, you need a 17.5 amp controller.
An MPPT charge controller converts extra voltage into current and produces up to 25% more power than a PWM controller. Another benefit of an MPPT controller is its ability to absorb high voltage from PV modules into a low voltage battery.
A system monitor provides real-time information about your solar panel. A charge controller may provide information about the electrical flow and current. A battery monitor may display information about the depth of discharge, how energy is left and recharge notifications. A solar panel monitor notifies you of any changes in production output and potential problems.
There are many types of system monitors. Some are bare bones while others serve as all in one resources. Some monitors incorporate Bluetooth technology and have apps, allowing you to monitor the solar panel via tablet or smartphone.
The racking mounts are used to install a solar power system on a roof or the ground. There are different types of rack mounts, so the components will vary. Widely used parts include end caps, wiring clips, brackets, rails and more.
Racking mount kits are available for home and RV solar panel installation. A solid support structure for the roof / ground is required however. You should inspect your RV or house before putting up a racking mount to ensure it can handle the weight.
Most solar racking mounts are aluminum and very sturdy. Once you’ve mounted the panels, it’s going to be very difficult to remove it. Even mounting tape used for tilted mounting on RVs are super strong. This is understandable as nobody wants their solar panels to fly off when there’s a strong wind.
Balance of System
A balance of system (BOS) provides additional controls for a PV module. A BOS contains different components, including but not limited to loaders, circuit breakers, fuses, combiner boxes, junction boxes and AC/DC disconnects.
Each solar system will have a different BOS as some setups need more distribution controls than others. All BOS however, have safety mechanisms built in. Your solar power kit will provide details on what type of BOS needs to be used.
AC and DC Disconnects
These are manual switches that can shut off power from an inverter. Many inverters have a built power panel, though the deign structure varies. Other inverters don’t have a disconnect and you have to buy them separately. Check your inverter manual on what type of AC/ DC disconnect to get.
A combiner box is an electrical container that allows solar panels to be installed in parallel. To connect a couple of 12V PV modules, wire the module output to the box terminal. The box allows you to connect the wires to the controller. Circuit breakers and fuses are stored in the box as well.
Going through a solar panel accessories list may seem daunting, but it’s something every solar system owner should do. The more research you do, the better prepared you’ll be for any configuration you want. Even better is the fact that solar kits are available that include most of the stuff you need. You can also be certain they’re compatible with each other.