Off Grid Solar Systems Basics
Posted by Tim Harper on
An off-grid solar system, also known as a standalone solar system, is designed to generate and store its own electricity without the need for a connection to the electrical grid. It typically consists of three main components: solar panels, a charge controller, and a battery bank.
The solar panels are the primary source of energy for the system. They convert sunlight into DC electricity which is then fed into the charge controller. The charge controller regulates the amount of electricity flowing into the battery bank, ensuring that it is charged at the optimal rate and preventing overcharging or damage to the batteries.
The battery bank is where the excess electricity generated by the solar panels is stored for later use. The size of the battery bank will depend on the system's energy needs and the amount of sunlight available in the area. Batteries used in off-grid systems are typically deep-cycle batteries, designed to withstand frequent charge and discharge cycles.
In addition to these core components, an off-grid solar system may also include an inverter, which converts the DC electricity stored in the batteries into AC electricity for use in household appliances and electronics. Some systems may also include backup generators or other backup power sources to provide electricity during periods of low sunlight or high energy demand.
Below is a simple graphic that illustrates how an off-grid solar system works;
1. Solar panel (PV module)
Solar panels or modules are made of solar cells. A solar cell is an electrical device that converts the energy of light directly into electricity (DC) using the photovoltaic effect. The process of conversion first requires a material which absorbs the solar energy (photon), then produces electrons, which the flow to an external circuit. Silicon which is a key component used in the production of PV modules, is one such material that uses this process.
2. Charge controller
Charge controllers may also be called solar regulators. These components regulate the amount of energy that is passed on to the battery bank. Some charge controllers / solar regulators have additional features, such as a low voltage disconnect (LDV), a separate circuit which removes loads (energy draws) when the batteries become overly discharged, and additional circuitry that eliminates potential overcharging; both of which reduce the life of the battery banks.
3. Battery Bank
This stores the energy produced by the solar panels allowing it to be used on demand – day or night, sunny day or cloudy. Properly engineered off-grid systems ensure that there is enough energy produced and stored to provide ample average power throughout the power producing and non-producing cycles. When it comes to solar battery banks, each is designed for a specific charge or discharge level. Some are manufactured wet cells, manufactured sealed or gel cells, each coming with their own set of pro/cons. Costs of battery banks varies significantly, however battery performance and service life are a key consideration in any solar system installation.
An inverter’s basic function is to “invert” the direct current (DC) output (the power from the PV modules) into alternating current (AC). AC is the standard used by all commercial appliances, which is why many view inverters as the “gateway” between the photovoltaic (PV) system and the energy consuming loads.