Help CenterPV Calculations
Usage profiles: day, night, continuous
Calculation5 min readUpdated: 2025-06
An appliance's usage profile determines when it consumes energy during the day. This parameter directly influences battery bank size — not panel power.
| Profile | Active hours | Battery impact | Panel impact | Examples |
|---|---|---|---|---|
| Day | 6h–18h | Low (PV direct) | High | PC, pump, AC |
| Night | 18h–6h | High (all stored) | Medium | Lighting, TV, fan |
| Continuous | 0h–24h | Medium (50% stored) | High | Fridge, alarm, WiFi |
Wh_via_battery = Wh_night + (Wh_continuous × 0.5)Only this fraction sizes the battery bank
A household with only "day" profile appliances can have a 2× smaller battery than an identical household with the same appliances on "night" profile. Always ask the client about their real habits.
1
Identify habits
Ask when each appliance is on. A night fan vs a day fan = very different sizing.
2
Fridge = always continuous
Never set a refrigerator to "day" or "night" profile — it runs 24/7 on a compressor cycle.
3
Lighting = always night
Even in a hybrid installation, evening lighting goes through the batteries.
Common mistakes
- Setting a refrigerator to "day" or "night" profile instead of "continuous"
- Guessing the client's habits instead of asking them directly
- Assuming a "day" appliance has zero battery impact (the night buffer still applies)