The Truth About Solar Back-Up Systems: Possible, Not Perfect

As more homeowners across Ireland install solar PV and battery systems, one question keeps coming up:

“If the power goes out, will my solar system keep my house running?”

It’s a fair question — and one we completely understand.
After all, no one likes the thought of being left in the dark during a storm.

The reality? Solar and battery systems can help during short outages, but they’re not designed to replace the grid entirely. Here’s why.

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When Power Cuts Usually Happen

Most outages happen in winter, often at night, and usually during bad weather — exactly when solar generation is at its lowest.

Even if you have a home battery, it’s typically already been working hard that evening to reduce peak-time electricity use or to store energy during cheaper night-rate hours.

So when a blackout hits, your battery may already have done its job for the day — leaving little stored energy to fall back on.

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Why “Off-Grid” Isn’t as Simple as It Sounds

For a solar system to run your home when the grid is down, it needs to be able to isolate itself completely from the ESB network.

That means:

• Re-wiring your fuse board to separate essential loads

• This mitigates the power heavy loads from accidentally draining your back up energy too quickly

• Installing isolation equipment that can safely disconnect from the grid

• Ensuring everything meets Safe Electric and SEAI standards

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This isn’t part of a standard solar installation — and it shouldn’t be.
It’s a specialist setup designed only for specific cases, carried out by certified electricians.

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To be clear:

All Activ8 electricians are fully qualified and RECI-registered, and every one of them completes our 12-week Activ8 Solar Academy training.

We’re more than capable of this type of work — we simply choose not to offer off-grid changeover installations because, in most homes, they’re not a practical or necessary solution.

For a solar system to run your home when the grid is down, there needs to be adequate energy on standby to power the home.

• This entails increasing the number of batteries needed which are set aside for power outages. We would suggest a minimum of 5-15kWs depending on the homes usage which should be always available.  

• These batteries can be recharged through solar the next day if they go empty, but again, assuming weather conditions and time of year for storms, it is not guaranteed to do so.

• This is an expensive addition to a system, which will only be availed of on power outage.

What You Could Expect from a “Back-Up” Solar System

Even if everything is installed correctly, it’s important to understand what such a system can realistically do.
In the event of a power cut, it could keep your essential loads — lights, fridge, broadband, heating controls — running for a period of time.
But it wouldn’t be life as usual.

You’d need to limit the use of high-draw appliances like kettles, ovens, hobs, washing machines, dryers, showers, and hairdryers. And depending on weather conditions, your battery may or may not recharge from solar generation the next day.

In short: it can help you get by, but it won’t fully replace the grid during extended outages.

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What Activ8 Installs as Standard

Every Activ8 solar installation includes a dedicated back-up socket — built right in.

If there’s a power cut, this socket allows you to:

• Plug in an extension lead

• Power a few essentials directly from your battery

• Make use of whatever stored energy remains at that moment

It’s a simple, safe, and short-term solution — perfect for keeping lighting, your broadband running, or your fridge ticking over.

But it’s not designed to power your whole home or keep everything running for hours on end. Once that stored energy is used, the system will wait for grid power to recharge.

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When to Consider a Generator

For those living in rural or high-impact areas where power cuts can last a day or two, a small generator with a changeover switch can still be the most reliable option.

It works independently of the grid, daylight, or your battery’s state of charge — meaning you can keep key circuits running for as long as needed.

And just to be clear:

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We’re not promoting fossil fuels.

A generator is simply a short-term, practical back-up option — not a permanent or everyday energy source.

Our Focus: Everyday Reliability

At Activ8, we design solar PV and battery systems to perform efficiently, safely, and sustainably every single day of the year.

Our goal isn’t to over-engineer for rare events — it’s to make sure your system works brilliantly 99% of the time.
That’s what gives you real value, reliability, and energy independence.

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Key Takeaways

• Power cuts usually occur when solar and batteries are least effective

• True off-grid systems need specialist isolation work

• Every Activ8 system already includes a back-up socket for short-term use

• Our electricians are fully qualified and Activ8-trained

• For longer outages, a generator connection is a practical short-term option

• Solar and batteries are about everyday savings and sustainability, not long-term off-grid living

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In Short

Solar PV and batteries are incredible technologies — they make your home more efficient, resilient, and sustainable.
But when it comes to back-up power, the key is to stay realistic and practical.

At Activ8, we’ll always give you the honest picture — so you can make smart energy decisions that work for  your home, your budget, and the Irish weather.    

Our  knowledgeable team will help you through every step of the process, from solar grant applications to  installation.