Can off-grid solar systems effectively support electric heating?

Sizing the System for Electric Heating

To support electric heating, off-grid solar systems must be sized to meet the heating load, which is typically higher than summer loads. A common approach is to calculate the total annual heating load in kWh and then determine the required solar panel array size, battery bank capacity, and inverter rating. For example, if a heating system requires 3,000 kWh of electricity per year, and the system is designed to produce 50% of the required energy, the solar panel array should be sized to produce at least 1,500 kWh per year.

Load Calculation Techniques

A load calculation worksheet can help determine the required solar panel array size and battery bank capacity. The worksheet should consider factors such as the heating system’s efficiency, insulation levels, and climate. For example, if a well-insulated home in a mild climate requires 3,000 kWh of electricity per year for heating, the worksheet might indicate that a 4 kW solar panel array and a 12 kWh battery bank are sufficient. However, if the home is poorly insulated or located in a cold climate, a larger solar panel array and battery bank may be required.

Panel, Battery, and Inverter Sizing Considerations

When sizing the solar panel array, battery bank, and inverter, it’s essential to consider the system’s efficiency and capacity. For example, a 4 kW solar panel array with a 90% efficiency rating will produce 3.6 kW of usable energy. The battery bank should be sized to provide at least 2-3 days of backup power in case of prolonged periods of low solar production. The inverter should be rated to handle the peak load and should have a high efficiency rating to minimize energy losses.