Brownout backup calculator
List the appliances you want to keep running during a brownout. The calculator checks every MARSTEK system for two things:
- Power — can it run everything at the same time? (sum of watts vs. the product's continuous output)
- Energy — does the battery hold enough for the hours you entered? (watt-hours vs. usable battery energy)
Quick add:
| Appliance | Watts (each) | Qty | Hours of use during outage | |
|---|---|---|---|---|
| LED bulb | ||||
| Electric fan | ||||
| Refrigerator (inverter type) | ||||
| Wi-Fi router | ||||
| Phone charging |
Assumptions
365 WRunning load (all at once)
3.3 kWhEnergy needed for this outage
| Product | Usable energy | Can run everything at once? | Covers your outage plan? | Runtime at full load |
|---|---|---|---|---|
| VENUS E Mini | 1.63 kWh | ✅ Yes (1,500 W) | ❌ No (49%) | 4.5 h |
| VENUS E 3.0 | 4.15 kWh | ✅ Yes (2,500 W) | ✅ Yes | 11.4 h |
| MARS I PLUS (3×) | 12.44 kWh | ✅ Yes (6,000 W) | ✅ Yes | 34.1 h |
| V6000 | 12.21 kWh | ✅ Yes (6,000 W) | ✅ Yes | 33.4 h |
| V500 | 1.63 kWh | ✅ Yes (500 W) | ❌ No (49%) | 4.5 h |
| M1200 | 0.83 kWh | ✅ Yes (1,800 W) | ❌ No (25%) | 2.3 h |
| M2200 | 1.81 kWh | ✅ Yes (2,400 W) | ⚠️ Partly (55%) | 5 h |
Estimates only. Appliance watts are typical values — check the label on your appliance. Motors (refrigerators, pumps, aircon) can draw several times their running watts when starting; leave headroom. A site survey by a qualified installer is required before purchase.
How the numbers are calculated
- Running load (W) = Σ watts × quantity.
- Energy needed (kWh) = Σ watts × quantity × hours ÷ 1,000.
- Usable energy (kWh) = battery capacity × usable % × efficiency %. Defaults are 90% / 90%; adjust them under Assumptions. VENUS E 3.0 and VENUS E Mini manuals specify 90% depth of discharge; for other products the 90% default is an assumption, not a manual figure.
- Runtime at full load = usable energy ÷ running load.
- Battery capacities and output ratings come from the product manuals and datasheets (see each product page). MARS I PLUS uses the 6 kW inverter rating and the number of 5.12 kWh modules you choose.
Estimates only
Appliance watts are typical examples — check the nameplate on the actual appliance. Motor loads (refrigerators, pumps, aircon) can draw several times their running power when they start. Solar recharging during the day is not included. A site survey is required before quoting.
Related: brownout preparedness guide · choose a product