Before you begin
What this tool needs
Use the rating plate for medical devices, pumps and boilers if it differs from the preset.
Solar is modelled at conservative Irish winter output because severe outages are most likely then.
Reading the answer
What your result means
Battery size decides how long the unit lasts. The inverter rating decides whether it can start and run the load at all.
A recommendation beyond 5 kWh means you should trim the list or look at a professionally designed hybrid system.
Boundaries
Assumptions and limitations
Working assumptions
- Each load uses a representative wattage, and a representative share of the time it spends actually drawing power.
- Usable AC energy includes approximately 15% conversion loss.
- Portable solar assumes 1.2 equivalent winter sun-hours and 80% system efficiency.
Where to be careful
- A hardwired boiler or pump needs an electrician-designed connection. Never backfeed a house circuit.
- Medical users should register as vulnerable customers and maintain a device-specific emergency plan.
Common questions
Questions about this tool
Can a portable power station run an electric shower?
No practical portable unit can support a normal Irish electric shower. Heat water another way during an outage.
Why does a well pump need so much surge capacity?
Motors can briefly draw several times their running power when starting. The inverter must survive that peak even though the average energy use is modest.