Off-Grid Solar Power Systems

A solar power station without connection to the grid (Off-Grid or Stand-alone Solar Power System) ensures independence from energy suppliers. An important component of such a system are batteries that allow the use of solar energy not only during the day but also at night.

When the sun shines the controller uses the power of the photovoltaic modules to charge batteries and to supply electrical appliances through a battery inverter. Sometimes the charge controller can be built into the off-grid inverter housing.

For example, if at some point the solar power station generates 4 kW and the power of the working electric appliances is 5 kW, then consumption from the batteries will be only 1 kW.

If the power plant produces more power than needed at that moment, the «excess» energy will be directed to charge the batteries, thus forming a energy storage system.

The Off-Grid power plants could be random size: from micro-systems for caravan or boat to scale industrial solutions.

In its simplest form, the autonomous micro-power station can run without the inverter supplying devices wich work with direct current on 12 volts. Such could be lighting, ventilation, car refrigerator, phone chargers and many others.

The capacity of the conventional energy storage system smooths the 24/7 or weekly changes in the insolation, but is not enough to compensate for changes in available annual solar power. This means that it is not possible to conserve the summer solar energy for the winter.

If an estimate of the power of a solar plant and the capacity of a storage system is made for the summer months, an obvious energy deficit will be observed in the winter. In the «winter forecast», we will receive a surplus of energy during the summer period that we could not use. In this way the optimal solution is demand for a compromise with a moderate deficit in the winter and acceptable losses in the summer.

For comfortable use of an autonomous system, it is necessary to plan the energy consumption of the site in advance for approximately match with the production. For example, space cooling in the summer can be implemented using electricity and heating in the winter — by using а pellet stove. The same applies to provide hot water.

In certain cases, for example in a gloomy weather, a diesel generator can be used to quickly charge the batteries to the required level.

Automatic generator start

The autonomous system is more complex and more expensive than the on-grid solar power station. In many cases, however, its construction appears to be beneficial and carried out much faster in comparison with the procedure for connecting to the electricity network.

Sometimes self-sufficiency and independence play a more important role than the economy. Own power plant ensures financial protection and confidence in tomorrow.