Heating vs. Cooling: Which Is More Efficient for Mini Split Systems?

Heat Pump Efficiency

Mini split heat pumps are designed to operate in both heating and cooling modes, but their efficiency varies depending on the temperature outside. In heating mode, mini splits can achieve an efficiency of 3-4 units of energy for every unit of electricity used, which is often referred to as the coefficient of performance (COP). For example, a mini split with a COP of 3.5 can provide 3.5 units of energy for every 1 unit of electricity used. In contrast, heating systems that burn fossil fuels typically have an efficiency of 80-90%, meaning they convert 80-90% of the energy in the fuel into usable heat.

Power Requirements

To determine the power requirements for a mini split system, we need to consider the size of the system, the desired heating or cooling capacity, and the efficiency of the system. A typical mini split system can require anywhere from 5-40 amps of power, depending on the size and capacity of the system. For example, a small 12,000 BTU mini split system might require around 10 amps of power, while a larger 36,000 BTU system might require around 25 amps. In an off-grid system, it’s essential to consider the power requirements of the mini split system when sizing the solar array and battery bank.

Solar Integration

To integrate a mini split system with a solar array, we need to consider the power requirements of the system and the available solar power. A rule of thumb is to size the solar array to provide at least 50-75% of the daily power requirements of the mini split system. This will ensure that the system can operate during periods of low solar production or at night. For example, if the mini split system requires 1 kWh of power per day, we might size the solar array to provide 0.5-0.75 kWh of power per day. This will provide enough power to operate the system during periods of low solar production.