What is an off-grid PV system?

An off-grid photovoltaic (PV) system with batteries is used to provide electricity in areas where the normal grid does not exist. Solar PV module are used to generate electricity when the sun is shining. The sun is a variable resource - it sets everyday and is frequently hidden by clouds - therefore an off-grid PV system uses batteries to store some of the energy generated by the PV source for later use. This is similar to how a rainwater collection system functions. It can be helpful to make this comparison between the two systems as a rainwater collection system uses simple components that are common in most parts of the world that serve similar functions to the more complicated components in an off-grid PV system. In the simplest sense both of the systems capture a variable natural resource - rainwater and sun - when it is abundant and store it for later use when it is more scarce. To do so both of them have six basic components: a form of collection, a means of distribution, a way to regulate in-flows, storage, a way to regulate out-flows and a means of consumption.

Rainwater collection system

Rainwater collection system: 1. The roofs surface collects the rainfall. 2. The gutter and pipes distribute the rain water. 3. A valve is used to regulate in-flow of water to avoid overfilling the tank. 4. A tank stores rain water for later use. 5. A valve is used to regulate out-flow of water to avoid emptying the tank completely. 6. A sprinker can consume water from the tank as needed.

Off-grid PV system

Rainwater collection system: 1. The PV modules collect the sun's rays and convert it into electric energy 2. Wires distribute the electric energy created from the PV modules. 3. A charge controller is used to regulate in-flow of electric energy to avoid overcharging the battery. 4. A battery stores electric energy for later use. 5. The charge contoller or a Low voltage disconnect regulates out-flow of electric energy to avoid emptying the battery completely. 6. A light or other appliaces can consume electric energy from the battery as needed.