To properly size a solar PV system for your home, it is important to understand how much energy you consume and how it affects your utility bill – and budget. Once you understand your energy consumption you can determine how much you want to reduce your bill, how much you want to spend on solar, and in turn, the appropriate size for your system.
What’s a watt?
A watt (W) is a unit of instantaneous power. In the solar industry, this refers to the capacity or size of the system.
What’s a kilowatt-hour?
A kilowatt-hour (kWh) is a unit of energy, which is the use of power over time. You are billed by your utility company per kWh.
How can I find my past electricity consumption?
Sign up for your utility’s online service, if available. You will be able to retrieve your past 12 months of kWh consumption. If your utility does not offer an online service, you can add up your total kWh consumed from your past 12 electricity bills. Always look at kWh use on an annual basis, since your consumption fluctuates over each season.
How am I charged on my utility bill?
Depending on your utility company, different rate structures may be available. For residential customers the rate structures offered are flat, tiered and time-of-use (TOU). Although uncommon for residential customers, demand charges may be included on your bill.
Flat rate – You are charged the same amount per kWh no matter how much, or when, you consume.
Tiered rate – You are charged the rate of various tiers. Each tier has a designated amount of kWh that can be consumed before being charged at the next higher tier. The rates increase with each tier, with typically two to four tiers in total.
Time-of-use (TOU) rate – The rate you pay per kWh is based on the time of consumption, with designated peak and off-peak times. Once you install solar, your utility may require you to change to a different rate structure required for solar customers. For example, you may be required to move from a tiered rate schedule to a TOU rate.
Reduce before you produce
There are several easy and cost-effective ways to make your home more energy efficient, such as replacing incandescent light bulbs with LEDs (light-emitting diode) and installing smart power strips to more extensive retrofits like air sealing and adding insulation to your home. As your house becomes more efficient, you will consume fewer kWh, which will allow for a smaller solar PV system to be installed and save you money. Energy-efficient improvements also can make your home cleaner, heathier and safer.
To learn more about energy efficiency measures you can do for your home, visit Home Energy Efficiency.
