“We want to run the house on solar” sounds like a clear brief until somebody asks what the house uses, when it uses it and which appliances must stay on during an outage. A load list helps you answer those questions without pretending to design an electrical system yourself.
Start with one ordinary day. List the appliances you actually use, including their typical operating times. Keep unusual demands—a workshop session, a large gathering or seasonal cooling—in a separate note so they do not disappear into an average.
Give each appliance a useful row
Use five columns: appliance, power information, hours of use, time of day and whether backup power is essential. Add where the information came from. A measured reading, a manufacturer specification and a guess should not look equally certain.
Nameplate ratings do not necessarily describe average consumption. Appliances that cycle or change operating mode need more care than a simple “rating multiplied by time switched on” estimate. If you do not have reliable information, write “unknown” and ask how it should be measured safely.
Work one small example
Suppose, purely for illustration, a lamp uses 10 watts while operating and is on for five hours. Its estimated daily energy is 10 × 5 ÷ 1,000 = 0.05 kilowatt-hours. Four identical lamps used the same way would total 0.20 kWh. These are invented inputs to explain the arithmetic, not a claim about your lighting.
Write the units beside every number. Watts describe power at a moment; watt-hours or kilowatt-hours describe energy over time. A row that says only “500” cannot tell an installer whether you mean watts, hours or something copied from a bill.
Draw a second picture: what runs together?
A daily total loses the pattern of the day. Mark which appliances overlap in the morning, afternoon and evening. A cooking appliance operating briefly at the same time as other loads raises a different planning question from a small lamp left on for several hours.
Ask the installer to explain how starting demands, continuous power limits and the intended backup circuits affect the proposal. Do not translate your spreadsheet total directly into an inverter size. Installation conditions, equipment compatibility and local electrical requirements need professional assessment.
Compare your list with bills, without forcing a match
Collect several bills if available, and note the dates they cover. Your first load list may omit refrigeration cycles, standby use, shared equipment or seasonal differences. A mismatch is a reason to investigate, not to adjust numbers until the spreadsheet looks convincing.
The US Department of Energy’s homeowner’s guide to solar places household energy needs alongside roof suitability and other planning considerations. Its policy and purchasing context is American; local approvals, tariffs and installer requirements will differ elsewhere.
Take questions, not a finished design
Bring the list, recent bills, your uncertainty notes and a short description of what you want from backup power. Ask the installer which assumptions most affect the quote and which loads the proposed system would exclude. Request a written explanation of the operating limits you would need to understand.
The best first spreadsheet is one you can explain and correct. It should make the conversation more specific, while leaving electrical design, safe measurements and installation to appropriately qualified professionals.