An off-grid solar system is one that has no connection to the utility grid. It therefore provides all of the electricity for the residence or business, and the owner is responsible for all of the repairs and maintenance.
Staying on the grid is arguably easiest for many people. As Just Energy Ohio points out, solar systems tied to the grid are generally reliable and efficient. Also, if the property owner is leasing the solar system, the solar company is responsible for the repairs and maintenance. On the other hand, being tied to the grid makes the property owner completely dependent on it. In the event of a societal collapse, the property owner will have to hope their power company somehow survives. If they are already off the grid, however, they will be well-prepared to weather such a breakdown.
The first step in going off the grid is to conduct a “load analysis,” in which the property owner estimates the amount of energy they typically use. Utilities measure electricity consumption in kilowatt hours (kWh), and utility bills will tell the property owner how many kilowatt hours they used during the last billing period. Using a year’s worth of bills provides even more information. The property owner should also factor in any energy conservation methods they are using, plus data about the amount of sun they get in their area. Doing all this will help the property owner determine how much energy they use and how many solar panels they will need to install. They will also need to find the best place for the solar panels—and that place may not necessarily be the roof. Solar panels need to be where they will get maximum sunshine and minimum shade.
An off-grid system will need all of the same items as a conventional system: solar panels, an inverter, safety equipment, and a monitoring system. In addition, it will need a charge controller, a battery bank, and a generator. The latter will act as a backup source of energy for those days when the sun doesn’t shine. The battery bank stores any excess energy and the charge controller keeps the battery bank from overcharging. The charge controller also helps maintain the batteries, so getting a good one is vital. Since an off-grid system produces all the energy that a building will need, it will probably be somewhat bigger than a grid-tied system. It is best to get the system components from a local source, for they will also probably have the parts and tools needed for any repairs.
The battery bank will likely be the weak link in the system. While solar panels and inverters can last for at least 20 years, a battery bank has to be replaced every 10 or 15 years – and that’s with good care. The battery bank will need to be cleaned and have its connections checked regularly to prolong its life. It will also need water. The most important aspect of its care, though, is fully recharging the batteries regularly every few days. Even the Tesla Powerwall, which needs little or no maintenance, has only a 10-year warranty. Made by the car company of the same name, it’s a wall-mounted lithium ion battery. It comes in two sizes with the larger battery storing up to 10kWh. Up to nine Powerwall batteries can be linked together in a bank – but a single Powerwall battery costs at least $3,000.
Solar systems work well in many climates, but extreme heat reduces their efficiency. They are at their best on cool, sunny days. Solar panels that can track the sun are more efficient than those that don’t. While getting an off-grid solar system is not something that should be attempted without a lot of thought and preparation, the independence makes it worth it.
Elizabeth Eckhart is a freelance writer with an interest in energy conservation, living off the grid and the outdoors. You can link to her on Twitter at @elizeckhart