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Residential solar systems are generally Hybrid solar systems, providing a portion or all of the electrical requirements of the house/property. How much of the daily requirement of electrical energy one wishes to provide from solar, will determine the size of the solar system that needs to be installed. This will also determine the amount of autonomy from the grid the system owner will have.

Here are some illustrative examples:

What Size Inverter Do you Need?

The first step is to determine what size inverter the customer needs. The Inverter size (in kVA, or sometimes kW) should be approximately 30% bigger than the largest amount of power that is required at any one time. The inverter needs to provide enough power to run all the appliances that might be working simultaneously.

Secondly, one needs to ascertain the daily requirements of the property and then break this down to a daily kWh consumption value. This can then be used to calculate how many panels would be needed to provide this amount of energy. In the Plettenberg Bay area, 1kWp of panels (mounted ideally, ie. North-facing, at 30 degree pitch) will provide approximately 4.5kWh per day. So, if the daily requirement is 22kWh of electricity, then we need to install about 5kWp of panels. This would be 9 of our 550Wp panels.

The battery capacity is, to some extent determined by the Inverter size (there will be a minimum battery size due to the Amp transfer capability of the chosen battery), the balance of the system specs, and the specific amount of energy that one might want to ‘have in reserve’. The more energy is consumed during the night, the more energy needs to be stored, ideally, if this energy is going to come from the solar system and not be supplemented by the grid.