What is an off-grid PV system?

The term off-grid encompasses many different system designs as it simply signifies an electrical system that is not connected to the electric grid. Off-grid power systems are installed to provide electricity in areas where the normal grid does not exist. The most common off-grid power system is a photovoltaic (PV) system with batteries. PV modules are used to generate electricity when the sun is shining, but 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.