As the adoption of solar power solutions and solar energy storage batteries grows across the UK, many homeowners are thinking beyond just generating their own electricity. One of the most common questions we get at Viable Power is about maintaining power when the grid goes down. With domestic solar energy in the UK becoming more advanced and accessible, options for backup power are expanding — but knowing which solution is right for your home isn’t always that straightforward.
Two main options dominate the conversation: Emergency Power Supply (EPS) and Whole Home Backup. While both give you power security, they serve very different purposes and involve varying levels of cost, complexity, and capacity. This article breaks down the differences, shows how brands like FoxESS and SIG Energy can help, and explains how Viable Power works with you to select the right system.
What is EPS and How Does It Work?
EPS is a clever feature found in many solar energy storage batteries, such as those offered by FoxESS and other leading manufacturers. It allows homeowners to power essential appliances during a grid failure — things like lights, mobile chargers, and medical equipment, without needing a full-house backup solution.
EPS works by isolating specific circuits in your home from the grid when a fault is detected, preventing electricity from feeding back into external lines and endangering utility workers. Once isolated, the battery system takes over and starts delivering power to these priority circuits.
One key feature of EPS is that it’s flexible in design. Some homeowners choose a basic system with a single emergency socket for plugging in critical devices. Others opt for more sophisticated installations that automatically power selected circuits such as refrigeration, essential lighting, broadband routers, and even the home EV charging point for electric vehicles. The transition can be manual or automatic depending on how advanced the system is.
Manufacturers like FoxESS offer systems that include an EPS box or integrated inverter solutions. Their All-in-One series, for instance, can automatically switch over within 1.5 to 2 seconds — quick enough to ensure minimal disruption.
Whole Home Backup: Complete Home Protection
While EPS is about prioritising essentials, Whole Home Backup takes a different approach. It is designed to keep your entire house running during a grid outage — including high-power appliances like electric heating, ovens, and washing machines.
For this to work, you need a significantly larger solar energy storage battery, powerful inverters, and often an automatic transfer switch (ATS) that detects grid failure, and instantly shifts the load to your battery bank. Systems like the FoxESS All-in-One and PowerQ series or Tesla Powerwall are well-known for providing this level of backup.
Because a whole home backup has to deal with your house’s full energy demand, these systems are built with scalability in mind. FoxESS, for example, offers modular battery units that can grow with your needs — starting with 10.4 kWh and scaling up to 80 kWh for large properties . Switching times are often so fast — around 20 milliseconds — that most households won’t notice when the grid drops.
Which is Right for Your Home?
Deciding between EPS and Whole Home Backup is as much about understanding your household’s needs as it is about budget.
For most homes in urban areas, EPS is often sufficient. UK power outages tend to be infrequent and short, averaging about two outages every five years. If your main concern is keeping essential services like lighting, communications, and refrigeration running during a rare event, EPS offers a cost-effective, simpler alternative
FoxESS systems are particularly well-suited for this because of their flexible EPS solutions, offering both single-socket and whole-circuit backup options. These can be integrated into existing solar setups or installed as part of a new system, with room to upgrade later if your needs change.
On the other hand, for rural properties, those who work from home, or anyone relying on medical equipment, whole home backup is often essential. Power cuts in rural areas, especially those served by overhead lines, tend to be longer and more frequent. Whole home backup also appeals to homeowners who want the convenience of uninterrupted power without needing to think about which devices to prioritise.
Although whole home backup carries a higher upfront cost, for some homeowners it offers the only viable level of protection. Systems like the FoxESS PowerQ can offer peace of mind through scalable storage and fast automatic switching.
In both cases, your backup system will be even more effective when combined with energy efficient home improvements. Upgrades such as high-performance insulation, LED lighting, and smart heating controls reduce overall electricity demand, so your battery storage will last longer during outages while increasing the year-round value of your solar setup.
Why Partnering with Viable Power is Crucial
Choosing between these solutions, it’s about getting the best advice to tailor the right system to your needs and home. That’s where Viable Power comes in. As a trusted solar installer specialising in solar power solutions for UK homes, we help clients weigh up options from FoxESS, SIG Energy, and other leading brands to find the system that genuinely fits your lifestyle.
We don’t just install systems — we design bespoke solar energy solutions. Our approach includes a deep understanding of how much backup power you actually need, what appliances you want to keep running, and how much storage capacity makes sense for your home. For homeowners on tighter budgets, we often recommend starting with an EPS system that can be expanded over time, rather than overinvesting upfront.
The Role of SIG Energy
SIG Energy also plays a key role in providing advanced solutions that support both EPS and whole home backup. Acting as a distributor, they supply batteries and inverters from leading brands that can meet most backup requirements
Why Now Is the Right Time to Act
With energy costs fluctuating and the UK’s ageing grid facing growing strain, backup power solutions are quickly becoming essentials for modern homes. Solar energy storage batteries with EPS or whole home backup can help protect your property from outages while maximising self-use of solar energy. Integrating myenergi devices like the Eddi solar diverter into these systems can further enhance their value, and allow you to redirect surplus solar energy to heat water even when the grid is down
Let Viable Power Help You Choose the Right System
At Viable Power, we take pride in offering honest, expert advice to help homeowners make informed choices. Whether you’re new to solar or looking to upgrade with a solar energy storage battery and backup solution, we’ll guide you through your options. From FoxESS EPS systems to SIG Energy’s whole home backup solutions, we’ll ensure you get a system that makes sense for your current and future needs.
Ready to explore your backup options? Contact Viable Power today for a free consultation and take the next step toward energy independence.
