Battery costs just fell 27% in a year. The world's energy agency says 24/7 solar is no longer a pipe dream. Here's the plain-English version — and why UK plug-in solar owners should care.
The news that actually matters this week
The International Renewable Energy Agency published a report this week with a headline that would have sounded like wishful thinking five years ago: 24/7 solar power is now economically real.
Not "almost there." Not "viable by 2035." Real, now, in the sense that solar-plus-battery systems are being built that provide continuous power at prices competitive with gas-fired plants.
The main driver is one you've probably felt in your own shopping: battery costs have crashed. According to BloombergNEF, the cost of a typical utility-scale battery installation fell by 27% in 2024 alone — and by more than half since 2022. Chinese manufacturers advancing lithium-iron phosphate chemistry are the main reason. The same basic technology is in your phone, your cordless tools, and increasingly, home battery storage units.
So what does a giant solar farm in Abu Dhabi's desert have to do with your balcony panel in Birmingham?
More than you'd think.
The cost curve is the story
Here's the thing about battery costs falling 27% in a year: that's not a one-off. It's a trend that's been running for a decade and shows no sign of stopping. Every year, the battery that would let you store your midday solar generation and use it in the evening gets a bit cheaper.
Right now, a home battery unit compatible with UK plug-in solar setups costs roughly £800–£1,500 depending on capacity. That's still a meaningful addition to a £400 plug-in solar kit. But two years ago it was closer to £2,000–£3,000. Two years from now, at the current rate of cost reduction, it could be £500–£800.
The point isn't that you need to buy a battery today. The point is that the gap between "solar panels that generate when the sun shines" and "solar that actually covers your evening electricity use" is closing fast.
What IRENA actually said
The International Renewable Energy Agency — an intergovernmental body representing 170 national governments — released their "24/7 Renewables" report alongside a summit in Athens. The headline finding: solar-plus-storage systems can now provide power for more than 95% of the time at competitive costs in countries including the UK, China, India, and Brazil.
The remaining 5% — the very worst periods of sustained cloud or no wind — is where gas and nuclear still earn their keep as backup. But the framing has fundamentally shifted. The argument used to be "renewables need gas as baseload." The new framing is: gas is an emergency backup for rare edge cases, not the core of the system.
Britain's own grid is already moving this way. On 22 April 2026, GB's electricity mix hit 98.8% zero-carbon — gas fell to just 1.2% of supply — while solar was covering over a third of national demand. That's not a distant forecast. That already happened.
The intermittency argument is running out of road
For years, the standard objection to solar was "but what about when the sun's not shining?" It was a fair point. It's becoming less fair every year.
In the UK, solar doesn't stop working when it's cloudy — it just generates less. A heavily overcast day might mean 15–20% of clear-sky output. A partly cloudy afternoon might mean 50–70%. On Britain's better spring and summer days, solar is increasingly dominant on the grid.
The 24/7 coverage story is a grid-level one for now — we're talking about gigawatt-scale projects, not individual homes. But the underlying dynamic is the same: as storage gets cheaper, the hours your solar panels can't cover shrink.
What this means for plug-in solar owners right now
Practically speaking, nothing about your 800W plug-in kit has changed this week. It still generates only when the sun shines. It still offsets the electricity you'd otherwise buy from the grid during daylight hours.
But the trajectory is worth understanding:
Battery pairing is getting more viable. Several home batteries are now compatible with plug-in inverters — some directly, some via your home's wiring. The economics of adding storage to a plug-in setup will look meaningfully different in 12 months.
The grid is cleaner, more often. On high-solar days — the days your plug-in panels are working hardest — the grid electricity you're not buying is also likely to be clean. When you offset electricity on a sunny afternoon, you're increasingly offsetting gas or nuclear rather than wind or other solar.
Your knowledge of your solar window matters more. Whether or not you have storage, timing your energy use to match your generation window is still the single highest-return habit for plug-in solar owners. Run the slow cooker, charge the devices, put the washing on — during your peak hours, not in the evening when you're drawing from the grid.
That's the question the Sun Hours app answers: when is your window open today?
The UK is not Abu Dhabi. That's fine.
The IRENA report's headline example is a 5GW solar farm in Abu Dhabi's desert, with batteries to deliver 1GW continuously around the clock. The UK is not going to build that. We get clouds. We get rain. Our winter days are short.
But the same report notes that renewable-plus-storage systems can provide 95%+ coverage in the UK at competitive prices — not just in desert conditions. Germany, which gets similar sun to the UK, already has 60GW of solar installed and over 1.5 million balcony solar systems.
The intermittency argument against UK solar was always weaker than it sounded. Battery costs falling 27% in a year makes it weaker still.
The question is no longer if solar works here. It's when your best hours are today.
Know exactly when your solar window is open
While battery prices fall toward the tipping point, the question that matters today is still the same: when are your panels generating? Sun Hours answers it with a 7-day kWh forecast personalised to your UK postcode. Free on Android. No account.