Load calculator
What you run, for how long, and the big loads that decide everything. Learn the ideas behind it in Lesson 22: Load list: what you actually use.
List what you will run. Watts × hours × quantity × duty (the share of time it actually draws) gives watt-hours per day. Start from the examples and change them to match your own appliances.
| Item | Watts | Hours/day | Qty | Duty | Season | Wh/day | Remove |
|---|---|---|---|---|---|---|---|
| 1,008 | |||||||
| 400 | |||||||
| 480 | |||||||
| 360 | |||||||
| 1,000 | |||||||
| 275 | |||||||
| 250 | |||||||
| 1,800 | |||||||
| 480 |
Winter: 5.6 kWh/day · Summer: 4.3 kWh/day
Everything on at once: 3,240 W. A realistic peak (the two biggest loads together plus some of the rest): about 2,442 W. That number helps size the inverter.
Biggest daily users: Furnace or stove blower fan (1,800 Wh), Fridge (efficient) (1,008 Wh), Well pump (1,000 Wh). Start your efficiency work there.
Motors such as pumps and fridges can draw two to several times their running watts for a moment when they start. Check the label or ask the installer.
A planning estimate, not a design. Take it to a qualified professional before you buy or build.