Pylontech runtime calculator
Choose your model and fill in what you know. If you do not know your average load, start with 300 W for a quiet night and 600 to 800 W for an evening with cooking, TV and lights.
Nominal capacities from the Pylontech datasheets. The calculation runs in your browser; nothing is sent anywhere.
The formula, step by step
Runtime in hours = capacity × state of health × usable window × inverter efficiency ÷ (average load + inverter's own consumption).
- Capacity is the nominal energy of one module multiplied by the number of modules.
- State of health (SOH) is what is left of that capacity. A battery at 92 % SOH stores 92 % of its new capacity. Our SOC and SOH guide explains how to read it.
- The usable window runs from the current state of charge down to the cut-off you set in the inverter (minimum SOC, "shutdown" or "discharge depth"). From 100 % to 10 % is a window of 90 %.
- Inverter efficiency covers the conversion from the battery's 48 V to your 230 V sockets: usually 90 to 95 %.
- The inverter's own consumption is easy to forget. A hybrid inverter typically draws a few tens of watts just by being on, all night long.
| Model | Nominal capacity | Usable from 100 % to 10 % |
|---|---|---|
| US2000C / US2000B Plus | 2.4 kWh | about 2.2 kWh |
| UP2500 | 2.84 kWh | about 2.6 kWh |
| US3000C / Force-L1 module | 3.55 kWh | about 3.2 kWh |
| US5000 / UP5000 | 4.8 kWh | about 4.3 kWh |
These are battery-side figures for a battery in perfect health. The energy that reaches your sockets is a few percent lower, which is why the calculator applies the inverter efficiency on top.
What a house really draws at night
The single number that changes the answer most is your load, and most people guess it too high in the evening and too low at night. Rough orders of magnitude:
| Situation | Typical average |
|---|---|
| Night baseload: fridge, freezer, router, standby | 100 to 250 W |
| Evening: cooking, TV, lights, dishwasher | 400 to 1,000 W |
| Heat pump running in winter | 1 to 3 kW while it runs |
| Oven, kettle, induction hob | 2 to 3 kW, for short bursts |
The average is what counts for runtime, not the peaks. A kettle at 2 kW for three minutes costs 0.1 kWh; a heat pump at 1.5 kW for three hours costs 4.5 kWh, a whole US5000.
Why the battery stops earlier than the sum says
- One low cell ends the night. Discharge stops when the weakest cell reaches its limit, even if the display still shows 10 or 15 %. Packs that rarely reach 100 % drift apart; see how to balance Pylontech cells.
- The state of charge drifts. The BMS counts the current in and out and only resets its estimate at a real full charge. After weeks without one, "40 %" can mean 30.
- Cold. Cold cells sag sooner under load. In an unheated garage, expect less in January than in June (winter guide).
- High loads. Big peaks cost a little more energy in losses, and if they exceed what the stack can deliver, the inverter takes from the grid or trips.
How many batteries do I need?
Turn the formula round: hours wanted × average load ÷ (usable window × SOH × efficiency) gives the energy to store, then divide by one module's capacity and round up. The last line of the calculator does exactly that. Covering 12 hours at 500 W with US5000 modules in good health takes two. Remember that adding modules to an existing stack has its own rules (addresses, cabling, BMS versions): our battery bank guide covers them.
If the night is the expensive part of your bill, storing cheap off-peak energy may matter more than adding capacity: see Pylontech and dynamic electricity tariffs.
Measure it instead of guessing
A calculator gives you an order of magnitude. Your own data gives you the answer. Pylon-Monitor reads every battery and every cell from the Console port, and the free online dashboard works out the autonomy at your own average discharge over the last seven days, how full the battery will be at sunset and how much will be left at sunrise. The Health check also flags the things that shorten a night: a cell drifting away, a battery colder than the others, a state of health falling behind.
Frequently asked questions
- How long does a Pylontech US5000 last?
- From 100 % down to a 10 % cut-off, a healthy US5000 delivers about 4 kWh to your sockets. At an average of 500 W including the inverter’s own draw, that is about 7.5 hours; at 250 W, about 15 hours.
- How do I calculate battery runtime?
- Capacity × state of health × usable window (current charge minus cut-off) × inverter efficiency, divided by the average load plus the inverter’s own consumption.
- Why does my Pylontech run out before the calculated time?
- Usually one low cell reaching its limit first, a state of charge that has drifted without a full charge, cold cells, or a load higher than estimated. A regular full charge and balancing fix the first two.
- How many Pylontech batteries do I need for one night?
- Multiply the hours by your average load, divide by the usable window, state of health and inverter efficiency, then by one module’s capacity and round up. 12 hours at 500 W takes two US5000.
- Can I use 100 % of a Pylontech’s capacity?
- Not quite: the inverter cut-off keeps a reserve, and Pylontech rates the usable depth of discharge below 100 %. Most installations stop between 5 and 20 %.
See the autonomy of your own Pylontech stack at your real pace, every battery and every cell, with three years of history on the free online dashboard.
Order now — €59 One-off purchase, €59 all in. No VAT, no subscription.