A load list is a list of every appliance you’ll power from your off-grid system, with watts and hours per day for each. It’s the basis for daily energy use and thus for panel and battery sizing. This guide shows you how to do one.
Step 1: List Every Load
Write down everything that will run from the system: lights, fridge, fan, phone/laptop chargers, TV, pump, power tools, etc. Don’t forget small loads (router, LED strip); they add up.
Step 2: Get Watts for Each
- Label or manual: Many appliances show watts (W) or amps (A). If amps: W = A × V (e.g. 2 A × 120 V = 240 W).
- Plug-in meter: Most accurate for variable loads (e.g. fridge, TV). Use running watts for continuous loads; note surge for motors (for inverter sizing).
- Estimate if needed: LED bulb ~5–15 W; laptop ~30–65 W; small fridge ~30–80 W; TV ~20–100 W.
Step 3: Estimate Hours per Day
How many hours does each run on a typical day? Fridge: 24 h (but compressor only part of that—use run time, often 4–8 h). Lights: how many hours they’re on. Laptop: 2–4 h. Be realistic; round up a bit if unsure.
Step 4: Multiply and Add
Wh per appliance = Watts × Hours per day
| Appliance | Watts | Hours/day | Wh/day |
|---|---|---|---|
| Fridge | 50 | 6 | 300 |
| LED lights | 15 | 4 | 60 |
| Laptop | 45 | 3 | 135 |
| Phone | 10 | 2 | 20 |
| Total | 515 |
That total is your daily energy use in Wh. Add ~10% if you use an inverter for AC loads.
Step 5: Use the Number
Plug daily Wh into:
- Peak sun hours formula for array size.
- Battery formula (daily Wh × days of autonomy ÷ DoD) for battery size.
Or enter everything into the WattSizing calculator (you can enter individual loads or the total Wh) to get full system recommendations. A good load list is the foundation of a system that’s neither undersized nor oversized.
