Sizing starts from the load, not from a catalogue page. Two numbers decide 90% of projects: daily consumption and the backup window.
Take the kWh from a recent electricity bill and divide by the number of days. A household using 900 kWh a month averages 30 kWh/day; the battery does not need to cover all of it, only the portion you want to shift or back up.
Decide what must keep running and for how long. Whole-home backup for 24 hours is a very different battery from essentials-only for 6 hours, and it is a conversation about the customer's expectations, not about our price list.
Batteries degrade and loads grow. Sizing exactly to today's load is the most common mistake; use the parallel expansion limit to leave room instead of oversizing the first order.
Use these to pick two candidate models, then confirm against the real load list.
| Typical load to carry | Daily kWh to shift | Starting capacity |
|---|---|---|
| Essential loads only (fridge, lights, internet, phone charging) | 3–5 | 5.12 kWh |
| Essentials + well pump or circulation pump | 6–9 | 10.54 kWh |
| Essentials + heat pump or A/C for part of the day | 10–14 | 16.07 kWh |
| Whole house incl. heat pump / EV top-up | 15–20 | 20.99 kWh or 23.04 kWh |
| Villa with pool pump and EV charging | 25–40 | 38.40–46.08 kWh |
These figures assume a LiFePO4 bank at 90% usable depth of discharge with a day of autonomy for the listed loads only. They are a starting point for the conversation, not a design.
| Range | Voltage class | Pairs with | Typical use |
|---|---|---|---|
| Wall / ground home battery | 51.2 V (low voltage) | 48 V hybrid inverter, up to 15 batteries in parallel | Retrofit and single-phase homes |
| Stackable home battery | 153.6–460.8 V (high voltage) | HV hybrid inverter, up to 5 clusters | Villas, three-phase homes, larger banks |
| Battery rack | 358.4–716.8 V | HV hybrid inverter or PCS, up to 10 racks | Indoor commercial, offices, retail |
| Outdoor cabinet | 358.4–716.8 V | Plug-and-play with mainstream hybrid inverters and PCS | Sites with no plant room |
| All-in-one 125 kW / 265 kWh | DC 844.8 V with integrated PCS | Grid-tied or PV + genset hybrid, self-contained | Peak shaving, factories, microgrids |
Mixing voltage classes is possible on the same site but not on the same inverter channel. If you are quoting a multi-building site, send the layout and we will map it to models.
Country, daily kWh, what must stay powered and the inverter brand if you have one. We reply with one or two SKUs and the certificate list for that market.
