That depends. In all cases, some measurements are required:
- For solar panels you must meter all electricity that is generated.
- For solar hot water heaters and geothermal heat pumps you do not need to measure the heat that is effectively extracted from the sun or ground.
Here are details on what measurements are required and why:
- Solar Panels. You need to measure the amount of electricity generated by your solar panels because:
- It’s possible for a building to function solely on the energy generated from the Solar Panels and Portfolio Manager needs to know the energy usage to determine the efficiency of the building.
- The electricity generated by Solar Panels is a product that on its own is valuable and can be transferred/sold.
- It’s generally easy to measure the energy from Solar Panels because most systems have some kind of metering.
- However, if your solar panels generate a nominal amount of electricity (i.e. less than 1 % of your total energy), you can exclude them from your property.
- Solar Hot Water Heaters. While you don’t have to meter the energy that a Solar Hot Water Heater generates, you do need to measure the energy used to pump the water through the solar system, and the energy from any regular water heaters (which you will likely need). The solar heating raises the temperature of the water and makes the regular water heater’s job easier. You don’t need to quantify the “heat” that you’ve effectively extracted from the sun (in the Solar Water Heater) because there isn’t a simple or accurate way to do this. This is more analogous to being able to use fewer lamps because you have the window blinds open, but you don’t need to quantify the light coming through the window.
- Geothermal Heat Pumps. While you don’t have to meter the energy that a Geothermal Heat Pump generates, you do need to meter the electricity used by the Geothermal Heat Pump to heat and cool. You do this through your regular electricity meter. It’s fine to have a single electric meter that tracks both the electricity for the Geothermal Heat Pump and the electricity for the lights, plug load, etc. You don’t need to quantify the “heat” that you’ve effectively extracted from the ground because there isn’t a simple or accurate way to do this.
For more information, refer to our technical reference on Green Power.