We get asked about small off-grid systems pretty often, and are now working with local battery manufacturer Ojai Energy Systems to design several PV+Storage kits. In the meantime, we thought you might like to know what goes into the building of a basic off-grid system.
Before getting into the hardware, though, you need to first determine the electrical needs of the thing(s) you want the system to power. The simplest way to look at this is via watts per hour (how long you plan on using the thing(s) powered by the system times the wattage rating of the thing(s)). Next, determine the average sunlight hours for the region you are planning on needing the system to provide power. With this information, you can then use a free software tool like the one found here Renogy solar calculator to approximate your solar PV system wattage.
And while you are at the renology site, take a look at the four kits they have available to see if any of these will satisfy your needs:
Renogy has four types of off-grid kits: RV, starter, bundle and premium.
–The Solar Panel Bundle is a basic kit that comes with a simple PWM charge controller and MC4 connectors. The bundle has no mounting components or tray cable and is not recommended for a beginner, but perfect for someone who is looking to expand on a system. The charge controller is also basic, sometimes not the easiest to use and will probably not be a top choice if you intent to expand your solar panel system in the future.
–The Starter Kit and the Premium Kit are both great choices for new solar users. They contain more components and so are more expensive. Both feature the company’s best selling 100-W mono or poly solar panels as well as MC4 connectors, mounting hardwar, and charge controllers. The only real difference between these two kits is the efficiency of the charge controller. The Starter Kits come with a standard PWM charge controller with an 82% charging efficiency and may not be the best choice for expanding the system in the future. The Premium Kits come with an MPPT charge controller that is easier to use, uses maximum power point tracking, and has a 92% charging efficiency. So the Starter Kit may be perfect for a new solar user on a strict budget, but Renogy always recommends the Premium Kit for the energy harvesting advantages of the MPPT charge controller.
–The RV Kit is designed specifically for off-grid applications in which the solar panel and the battery will be a long distance apart. The kit comes with 100-W mono or poly panels, a PWM LCD display charge controller, mounting hardware, MC4 connectors and a 40-ft long tray cable. Despite its name, the kit is actually quite useful for many different applications beside RVs, such as longer length boats, garages and sheds.