Before you install solar on your home, you'll want to think about whether you want your system to be grid-tied or off-grid. Grid-tied systems allow you to receive credit for excess electricity that you produce and receive electricity from the grid when your usage exceeds the production of your panels. Off-grid systems are not connected to the electrical grid and require a battery back-up or a supplemental power source to power your home the sun is not out.
Grid-tied systems are connected to the grid through an interconnection process and you are compensated for your energy production through a net metering contract. Utah has excellent net metering and interconnection policies that make it easier and cheaper for solar customers to connect to the grid. The solar contractor for SCS will work with you to submit the applications for interconnection and net metering with the utility. Thanks to recent changes to the rules and policies, this process is relatively simple and streamlined.
Interconnection refers to the technical and physical connection of a solar energy system to the electrical grid. A small-scale, residential photovoltaic project is the easiest to safely connect to the electrical grid. There are a few pieces of equipment that are directly related to interconnection:
- The power inverter
- External disconnect switches (not required for systems under 10 kW)
- Circuit breaker panel
- Electrical meter
Interconnection allows a homeowner to use the power generated by their solar PV system while it is generating a sufficient amount of electricity, and use utility-generated electricity from the grid when the energy demand is greater than the amount of energy produced by the solar PV system. Unless there is a battery backup system in place, any excess energy generated by a solar PV is fed back into the grid, which helps to reduce the load that the utility needs to generate.
Net metering is the process by which residential energy producers are credited for the excess energy that they feed back into the electrical grid. Net metering is a billing arrangement between the customer and the utility; in Utah, residential energy customers served by Rocky Mountain Power are credited ‘kilowatt-hour for kilowatt-hour” for any excess generation beyond what they consume. These kilowatt-hour credits roll over month to month, until the end of the annualized billing period (which is April to March). This means that if a solar PV system generates 100 extra kWh in July, the customer’s bill in August is credited 100 kWh. After the annualized billing period, any unused credits are granted to the utility, and customer starts accruing credits in the next billing period to use over the course of the 12 months.