What happens to excess solar power generated off-grid?

Off-grid solar power systems are designed to provide electricity to isolated or remote areas that are not connected to the main electricity grid.

When excess solar power is generated in an off-grid system, several things can happen, depending on the system configuration and components. Here are a few examples:

Battery storage

One of the most common ways to handle excess solar power in off-grid systems is by storing it in batteries.

The surplus energy charges the batteries, which then serve as an energy reservoir for later use, typically during periods when solar generation is low, such as at night or during cloudy days.

For example, a cabin in a remote location may have a solar array and a battery bank.

When the solar panels produce more energy than the cabin's appliances are using, the excess power is used to charge the batteries. Later, when the sun isn't shining, the stored energy in the batteries is used to power the cabin.

Diversion load

Another method to manage excess solar power in off-grid systems is by using a diversion load or dump load.

A diversion load is an electrical device, such as a water or space heater, which consumes the surplus energy to prevent overcharging of the battery bank.

For instance, suppose a farmer has a solar-powered water pump system for irrigation.

When the battery bank is fully charged, and there's still excess solar power being generated, a charge controller can redirect the surplus energy to a diversion load like an electric water heater.

This way, the extra energy is used to heat water for domestic or agricultural purposes, preventing battery overcharge and making use of the otherwise wasted energy.

Hybrid systems

In some cases, off-grid solar power systems can be paired with other energy sources, such as wind turbines, hydroelectric generators, or even backup diesel generators.

The excess solar power can be used to charge batteries, power diversion loads, or reduce the need for backup power from other sources.

For example, a remote village might have a solar-wind hybrid system where both solar panels and wind turbines are used to generate electricity.

During the day, when there's excess solar power, it can charge the battery bank or be used to power diversion loads, reducing the need for wind-generated power.

In this way, the excess solar power is used to increase the overall system efficiency and decrease reliance on other energy sources.

Energy sharing

In some off-grid communities, excess solar power can be shared between multiple households or buildings through a microgrid.

A microgrid is a localized energy grid that can operate independently from the main grid, allowing for more efficient use of excess power among the connected users.

For instance, a small off-grid community may have a shared solar power system where each household has its solar panels and battery storage.

When one household generates excess solar power, it can be shared with other households on the microgrid, allowing the community to maximize the use of renewable energy and minimize the need for backup power sources like diesel generators.

In summary, the management of excess solar power in off-grid systems can involve battery storage, diversion loads, hybrid systems, and energy sharing via microgrids.

The specific method used depends on the system configuration, available resources, and the energy requirements of the users.

These approaches ensure the efficient use of excess solar power, prevent battery overcharging, and maximize the benefits of renewable energy in off-grid settings.