Overnight solar power comes from a battery, not the roof. Short answer: panels sit at zero watts from sunset to sunrise (the physics is settled, see can solar panels work at night for the whole yes/no question), so the real engineering choice is which storage architecture carries your house through the dark hours. There are four, they differ in cost, efficiency and what they do during an outage, and the 2026 answer isn't the 2020 answer. For what the inverter itself does after dusk, our piece on what solar panels do at night covers the standby behaviour in detail.
In short: a home battery pays off where the gap between what you pay for evening power and what you're paid for exports is wide. Battery costs are falling fast. IRENA puts a four-hour utility-scale battery at about USD 140 per kWh installed in 2025, close to 30% lower than a year earlier and around 95% below 2010 (IRENA, July 2026). Home systems cost far more per kWh than that, so your payback still depends on your tariff.
Panels going dark at night isn't a flaw to fix, it's physics doing exactly what it promised.
Why Do Solar Panels Stop Producing Power at Sunset?
Photovoltaic cells convert photons into electrons through the photoelectric effect, first explained by Einstein in 1905. A silicon cell needs photons above the band gap (around 1.1 eV for crystalline silicon) to knock electrons loose. Noon sunlight delivers roughly 1,000 watts per square meter, plenty to push a typical 400 W panel to rated output. Full moonlight is about 1/380,000 as bright as the Sun, which works out to a few milliwatts per square meter, roughly five to six orders of magnitude lower.
Below the inverter's minimum start-up voltage (it's listed on the inverter's datasheet), the array can't push current through the electronics at all. Most inverters log this as "no production" and disconnect from the grid as a safety measure.
Cloudy nights, urban light pollution and even a bright full moon don't change this, because the light is far too weak to lift a panel above an inverter's start-up voltage. Better cells don't change it either; HJT and TOPCon at 23 to 25% efficiency still track total photon flux, and the flux runs out at sunset.
What Does Real Production Look Like Through a Day-Night Cycle?
A south-facing array climbs through the morning, peaks around solar noon, then tapers to zero toward sunset. Overcast days cut that curve sharply, but the shape stays the same.
Once the inverter trips off, panels and inverter sit at zero watts until morning. Monitoring apps like Enphase Enlighten, SolarEdge mySolarEdge, and the Tesla Solar app all show a flat line at zero from sunset to sunrise. That flat line isn't a fault.
Two things matter for sizing. The first is how much you use. Ofgem's typical medium UK household uses 2,500 kWh a year (about 6.8 kWh a day) and its high figure is 3,800 kWh (about 10.4 kWh a day), values that apply from 1 July 2026. The second is how many cloudy days you want to ride out: off-grid designs add extra days of storage for that, while a grid-tied home can fall back on the grid. The first sets the minimum useful battery; the second decides how far above it you go.
How Does Battery Storage Cover the Nightly Gap?
Battery storage paired with a hybrid or AC-coupled inverter is the only practical way to run solar-powered loads through the night. During the day the hybrid inverter routes surplus solar (after home loads are met) into the battery, whose lithium cells are efficient: Enphase quotes 96% round trip for the IQ Battery 10T cells and 89% once its inverters are counted, and Tesla quotes 89% solar-to-battery-to-home for the Powerwall 3 (manufacturer datasheets). After sunset the inverter draws from the battery, only pulling from the grid at the reserve floor.
In a 2026 system, typical sizes are 10 to 14 kWh usable, with expansion units for heat-pump or EV households. The Tesla Powerwall 3 holds 13.5 kWh and delivers up to 11.5 kW continuous, the Enphase IQ Battery 10T holds 10.08 kWh, and the Sigenergy SigenStor combines a battery and hybrid inverter in one modular unit. Any of the three can carry a typical household overnight.
Lithium iron phosphate (LFP) chemistry has become common in home batteries, and it's a big part of why warranties got longer. The Enphase 10T uses LFP and carries a 15-year warranty, while the Powerwall 3 datasheet lists 10 years. At one full cycle a day, 15 years means roughly 5,500 cycles, which is the workload a battery has to survive if you cycle it daily.
What Are the Four Practical Architectures for Overnight Power?
DC-coupled hybrid puts the battery on the DC side of a single inverter handling both solar and battery. SolarEdge Energy Hub, Sungrow SH-RS, and Fronius Symo Gen24 are common examples. It skips one conversion step, which makes it the cleanest option for new systems; Tesla quotes 89% solar-to-battery-to-home for the Powerwall 3, a figure that includes inverter losses.
AC-coupled retrofit gives the battery its own inverter that bolts onto an existing grid-tie system. The Enphase IQ Battery 10T is a plug-and-play example. The extra conversion steps cost some efficiency (Enphase lists 89% for the whole 10T system), but you keep your existing inverter, which usually makes it the cheapest upgrade for a newer system.
Standalone AC backup only kicks in during an outage and otherwise sits dormant. Best for homes with frequent outages where economics aren't the driver; it covers overnight loads only when the grid is also down. The Generac PWRcell can be set up around backup, though it also works as a regular solar-plus-battery system.
Bidirectional EV charging (V2H) turns a car into a house battery far bigger than any wall unit. The F-150 Lightning came with 98 or 131 kWh packs, and Ford sold its Charge Station Pro to feed the house. Ford stopped building the Lightning in December 2025, though, so that route now means a used truck. Other EVs offer vehicle-to-home or vehicle-to-load, but support varies by model, region and charger, so check the car's spec before you plan around it. The capacity is huge, as long as the car's plugged in every night.
| Architecture | Datasheet efficiency example | Best fit | Example hardware |
|---|---|---|---|
| DC-coupled hybrid | 89% solar-to-battery-to-home (Powerwall 3) | New systems, fewer conversion steps | SolarEdge Energy Hub, Sungrow SH-RS |
| AC-coupled retrofit | 89% whole system, 96% battery cells (IQ Battery 10T) | Existing grid-tie system | Enphase IQ Battery 10T |
| Standalone AC backup | Not applicable (outage-only) | Homes with frequent outages | Backup-only battery with a transfer switch |
| Bidirectional EV (V2H) | Varies by car and charger | EV owners, huge capacity | Ford F-150 Lightning with Charge Station Pro |
How Should You Size a Battery for Overnight Loads?
Work out what fraction of your daily use sits between sunset and sunrise. That split differs from house to house, so use your own meter data rather than a rule of thumb. Round the overnight figure up, add a buffer for cloudy-day recovery and the reserve floor, and for many homes you land in the 10 to 14 kWh class that current batteries ship in (13.5 kWh for the Powerwall 3, 10.08 kWh for the Enphase 10T).
Heat pumps and EVs change everything. An EV charging at 7 kW for five hours draws 35 kWh, well over twice what a 13.5 kWh battery holds, and a heat pump running through a cold night is a big, steady load too. Either one pushes you toward a larger battery, or toward charging on an off-peak tariff instead.
Want a precise number? Pull 12 months of half-hourly smart meter data, filter 6 PM to 7 AM, and sum by day. The 90th percentile day is a sensible sizing target, because it covers all but the heaviest nights.
When Does Battery Storage Pay Back Versus Grid-Only?
It depends entirely on your tariff and export rate. In the UK, Smart Export Guarantee rates run from 1p to 25p per kWh, but the best open-access rate in Which?'s April 2026 comparison was 6p, and the biggest payouts need a specific supplier plus a battery. Meanwhile the price cap sets electricity at 26.32 p/kWh for October to December 2026 (Ofgem). That gap of about 20p per kWh is the arbitrage a battery exploits: store your own solar instead of exporting it for 6p, and avoid buying at 26p in the evening.
In California, the net billing tariff (NEM 3.0) applies to interconnection applications from April 15, 2023 and credits exports at the utility's avoided cost instead of the retail rate. The CPUC said at the time that solar-plus-storage customers would pay off their systems in 9 years or less on average. Where exports still earn full retail credit, a battery adds backup more than savings, and PV-only usually wins. Check your export tariff first.
Cost trajectory matters too. IRENA found battery costs fell faster than any other energy technology in 2025, at the utility scale. Home prices lag that trend, but if your solar already covers daytime loads and you can wait a year or two, the math tends to improve.
Are There Cheaper Workarounds Without a Battery?
Yes, two, each with trade-offs. Load shifting runs high-draw appliances (dishwasher, washer, EV charger) during daylight while panels produce. Smart plugs make scheduling easy. You won't kill overnight grid pulls, but you can trim them with zero battery spend.
Off-peak grid tariffs charge a fraction of the daytime rate in an overnight window aimed at EV charging and heat pumps. Octopus Go runs from 00:30 to 05:30, and Intelligent Octopus Go lists 7.6p/kWh for a guaranteed six hours between 23:30 and 05:30 (Octopus Energy), against 26.32p on the price cap. If your loads sit inside that window, you're already paying a fraction of the standard rate without storing anything, often the best move for EV owners without a battery yet.
Summary
Solar panels stop producing at sunset because the photovoltaic effect needs photons that night doesn't supply. Battery storage is the only practical way to cover overnight loads from daytime solar, and the economics now work for many UK and US households on time-of-use tariffs. Plan for 8 to 14 kWh of usable storage for a normal night, and more with a heat pump or an EV charging overnight. If a battery isn't in the budget, load shifting and off-peak tariffs capture part of the same benefit at no capital cost. Either way, the panels are working exactly as designed when they go dark.