Solar battery backup, often described as EPS or an emergency power supply, can support selected loads during a power cut when the system is designed for it. A battery purchase alone does not establish backup capability. The inverter, isolation arrangements, wiring and commissioning all matter.
What can an EPS supply power?
The answer is the circuits and appliances included in the design, within the system’s power limits. Lighting, communications equipment and a fridge are different loads from an electric shower, EV charger or large cooking appliance. Starting currents can be higher than normal running demand.
Ask for a clear list of supported circuits and any loads that must be disconnected. “Whole-home backup” still has a maximum output and limited stored energy.
Capacity and power are different
Usable capacity in kWh indicates stored energy. Output in kW indicates how much power the system can supply at once. A large battery may still have a modest inverter output.
As a simplified example, 5kWh of available energy supplying a constant 0.5kW load gives 10 hours before losses. Real duration is lower once conversion losses, reserve settings and changing loads are considered. This is an illustration, not a backup guarantee.
Will solar keep charging during an outage?
Only if the particular backup configuration supports it. Some systems can manage compatible solar while isolated from the grid; others cannot. The controls must handle changing generation, full batteries and load changes. Confirm this capability for your exact design.
Is EPS the same as an uninterrupted supply?
No. Transfer times vary. Sensitive equipment may restart during switchover, and critical equipment can require a separately specified UPS or other protection. Do not assume a marketing backup claim means uninterrupted operation for every appliance.
Compare the complete installation
Ask about usable energy, continuous and surge output, transfer behaviour, reserve settings, manual procedures and maintenance. Include any gateway, changeover equipment, circuit alterations and commissioning in the price.
Our AC versus DC coupled battery guide explains storage arrangements. Read can a home battery power a house in a power cut? for further practical questions.
Design backup around your needs
Renew-Able Solutions assesses home battery storage in Edinburgh, East Lothian and wider Scotland. Tell us which appliances you want to support, their power demand and the duration you need. We can then assess an appropriate design and its limitations.
Reviewed 27 September 2026. Earlier product price tables have been removed because they do not describe a current complete backup installation.
