A load analysis is a listing of everything you expect to power in your off-grid home with the power consumption and hours in use summed and averaged to estimate normal daily energy consumption. For most off-grid homeowners, a load analysis should reflect winter living habits, when consumption is greatest.
It’s a rigorous and time-consuming process, but necessary. For system designers, it serves four purposes:
- Lists and quantifies actual loads, so the system can be sized to meet the home’s needs.
- Helps identify ways to use less energy to achieve the same result, which can reduce system size and cost.
- Helps identify overlooked or inappropriate loads, potential problems, and special cases, so that alternative ways of achieving the desired results, while using less electrical energy, can be suggested.
- Serves as a document of record. That is, if a system proves insufficient in the future, a record was kept of how much energy use was expected. Actual consumption can then be reevaluated, and loads reduced or the system expanded.
For the client, a fifth benefit arises that is really the most important of all: a valuable self-education process. Most of us who have lived with utility power have taken it for granted: We use it as needed and pay the bill each month. We have had little reason to know how the energy is used: how much and for what. The load analysis process is an excellent consciousness-raising activity. By understanding how and where you’re using solar electricity, you are far more likely to be satisfied with your power system—and its limits and blessings—over the many decades you will own it.
Many PV system installers or dealers offer forms to help the load analysis process. For more information, read “Getting Started with Renewable Energy: Professional Load Analysis and Site Survey,” available from Home Power Web Extras at www.homepower.com/webextras. Once you have an understanding of how to perform a load analysis, you can use an inexpensive measurement device, such as the Kill A Watt meter, which allows you to plug in any AC device and measure its power and energy consumption.