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No — solar panels use sunlight to generate electricity, so they don’t produce power after dark.
In the UK, solar panels produce electricity for 6 – 17 hours per day, depending on the time of year.
In Winter, when we have shorter days, solar panels generate electricity between 08:30am and 15:30pm.
In Summer, when we have longer days, solar panels generate electricity between the hours of 05:00am and 22:00pm.
However, that doesn’t mean your home goes dark when the sun sets.
Combining your solar set-up with a battery storage unit allows you to harness the sun’s power throughout the entire 24-hour day.
A battery storage unit, otherwise known as a Battery Energy Storage System (BESS), is a battery installed at your property to store energy that can be used at a later date. In simpler terms, imagine it as a power bank for your home.
These batteries vary in size but an average 10kWh to 13kWh battery, such as the Tesla Powerwall 3, would measure approximately 1,000mm (height) x 600mm (width) x 200mm (depth).
Adding one to your green home set-up, you can charge it up as follows:
Those with a battery storage unit can use cheap, often renewable energy from the grid when demand is low. This electricity is charged at around £0.06 pence per kilowatt hour (kWh) instead of the much higher on-peak rate of £0.25 pence per kilowatt hour (kWh). Charging the battery up using this cheaper electricity then enables the customer to use the battery during the day when electricity prices are at a premium. Here, with a 10kWh battery, you’d be charging it up for £0.60 per day. That same 10kWh of electricity directly from the grid during the day would cost you £2.50, making a daily saving of £1.90.
Suppose your solar panels are producing excess electricity. In that case, you can either sell this back to the grid on Smart Export Guarantee tariffs for around £0.15 pence per kilowatt hour (kWh) or you can use this free solar power to charge your battery storage unit for free and then draw on this electricity when required. This is great if you are a higher electricity user in the evening, i.e. you’re at work during the day or when the nights draw in, and you want that extra warm feeling from using free solar power that you’ve stored up during the day. Here, even better than using cheap “off-peak” electricity, you can now harness your solar energy and use it for free when required.
To harness the full benefits of your solar panel set-up, pairing it with a battery storage unit enables you to benefit from:
You will generate free electricity from the sun. This electricity can be used for your immediate consumption or to charge your battery storage unit for use later in the day/night (perfect for Winter). It can also be used to sell excess electricity back to the grid via a Smart Export Guarantee tariff. Essentially, enabling you to sell it for around £0.15 pence per kilowatt hour (kWh), so your energy supplier can then sell it back to your neighbour for £0.25.
A battery storage unit can be charged using unused solar power or it can be charged up using cheap “off-peak” electricity between the hours of 12am – 7am (depending on the supplier and tariff). You can then draw on this electricity, meaning you’re either using free stored solar energy or cheap “off-peak” electricity. If you are away on holiday, it can also be usedto simply charge at night for £0.06 pence per kilowatt hour (kWh) and then sell back to the grid for £0.15 pence per kilowatt hour (kWh).
The first thing we need to remember with solar panels, especially in the UK, is that they produce most of their energy during the long summer months. At the same time, this is when our electricity consumption drops, meaning during these months, most of that electricity will be exported to the grid and/or used to charge a battery storage unit for use later in the day.
Overall, the average UK home with solar panels will consume around 60-70% of its solar generation. The remaining 30-40% will be exported to the grid or used to charge a battery.
Here is how the average UK home breaks down in terms of the percentage of annual electricity by month.
NOTE: You can use these percentages of your annual electricity consumption to gauge how your usage will vary throughout the year. If you don’t know what your ‘Estimated Annual Energy Consumption’ is, you can find it on your latest energy bill.
| Month | % Annual Electricity Consumption | Kilowatt Hours (kWh) |
| January | 9.9% | 267 |
| February | 9.7% | 262 |
| March | 9.0% | 243 |
| April | 7.2% | 194 |
| May | 7.1% | 192 |
| June | 7.1% | 192 |
| July | 7.1% | 192 |
| August | 7.1% | 192 |
| September | 7.3% | 197 |
| October | 9.0% | 243 |
| November | 9.6% | 259 |
| December | 9.9% | 267 |
| Total | 100.0% | 2,700 |
If we consider a solar array that would produce the required output for an average UK home (2,700kWh), we would install around 8 x 430W panels.
Here is how we calculate this.
First, we need to calculate our kilowatt peak (kWp), which is the maximum output of a solar panel system under standard test conditions.
The combined kilowatt peak (kWp) would be 8 x 430W = 3.44kWp.
Remember, 1,000 Watts equals 1 Kilowatt, so the calculation is 8 x 430W = 3,440 / 1,000 = 3.44kWp.
Factoring in location, tilt, orientation and system losses, the average UK system produces 950kWh/kWp.
The total annual production is 3.44 x 950 = 3,268kWh.
Real-life set-ups will work at around 85% of the manufacturer’s standard test conditions, giving us 2,770kWh of annual solar energy production.
To see what our solar array will generate throughout the year, we need to look at the likely generation by month. Remember, solar panels rely on light to generate electricity, meaning that Spring and Summer are the biggest months for solar generation in the UK.
In the Winter, when it’s cloudy and the days are short, solar generation falls but doesn’t stop altogether.
Here is how it breaks down for our 8-panel set-up:
| Month | % Annual Solar Production | Solar Production kWh |
| January | 2.8% | 78 |
| February | 6.0% | 166 |
| March | 9.4% | 260 |
| April | 11.6% | 322 |
| May | 12.8% | 356 |
| June | 11.2% | 311 |
| July | 13.2% | 366 |
| August | 13.2% | 367 |
| September | 9.7% | 268 |
| October | 5.8% | 161 |
| November | 2.0% | 54 |
| December | 2.3% | 63 |
We can now compare our consumption to the likely output of the solar panels to determine where the deficits in solar production will be.
| Month | Consumption (kWh) | Solar Generation (kWh) | Deficit |
| January | 267 | 78 | -189 |
| February | 262 | 166 | -96 |
| March | 243 | 260 | 17 |
| April | 194 | 322 | 128 |
| May | 192 | 356 | 164 |
| June | 192 | 311 | 119 |
| July | 192 | 366 | 174 |
| August | 192 | 367 | 175 |
| September | 197 | 268 | 71 |
| October | 243 | 161 | -82 |
| November | 259 | 54 | -205 |
| December | 267 | 63 | -204 |
As we can see from the above, from March through September, our solar panels generate enough electricity to meet our consumption demand. However, that is only if our consumption occurs during the hours in which it is generated. If not, we either sell that solar generation to the grid (as mentioned above) or store it by installing a battery storage unit.
Our recommendation for this example scenario is to opt for an 8.8kW inverter with a 16.1kWh battery.
The larger inverter allows for a higher peak demand. An 8.8kW inverter lets you run your home, charge an EV, and route surplus PV into the battery (or vehicle) immediately.
The larger battery i.e. 16.1kWh instead of a 10kWh battery, means more free or cheap electricity can be stored and the less chance of you drawing higher “on-peak” electricity when the battery runs dry. This also maximises your earning potential when selling “off-peak” electricity back to the grid.
A lithium-ion battery should last for around 6,000 cycles. If it is charged and drained daily, that’s a lifespan of 16.5 years. Remember, by this point, as we have seen with the cost of solar panels, battery costs should continue to fall as the technology improves and demand increases.
“…battery costs should continue to fall as the technology improves and demand increases.”
Here is data from ‘Our World In Data’ showing how lithium-ion battery prices have changed over time. As more people buy these products, the price will continue to fall.
Source: https://ourworldindata.org/grapher/average-battery-cell-price?country=~Average
We can’t rule out that some customers may wish to opt purely for a battery storage unit rather than combining them with a solar array.
In this case, let’s assume that you use all of your energy during “on-peak” hours i.e. 7am to 12am, which are charged at £0.25 pence per kilowatt hour (kWh). Again, let’s use the example of the average UK home with an annual electricity consumption of 2,700kWh.
2,700kWh x £0.25p per/kWh = £675 per year
Let’s assume you install a 10kWh battery storage unit to meet your maximum electricity demands of 9kWh per day in the Winter months. You fully charge your battery storage unit each night using “off-peak” electricity charged at £0.06 penceper kilowatt hour (kWh).
2,700kWh x £0.06p per/kWh = £162 per year
This saves you £513 per year.
Depending on where you are in the UK, the type of house you have, and where the installation needs to be carried out, a 10kwh battery, depending on the brand, e.g., Tesla Powerwall, would cost around £5,500 to £6,500.
This would therefore give a return on investment (ROI) range as follows:
| Install Cost | ROI (based on £513 saving per year) |
| £5,500 | 10.7 years |
| £6,500 | 12.7 years |
With a lifespan of 16.5 years, this would leave around 4 to 6 years of profit equating to £2,000 to £3,000. Not to mention the CO2 emissions you would have cut from the environment.
Since panels stop working after sunset, battery storage is vital in increasing the benefits you can reap from your solar panels.
Popular options: Tesla Powerwall, GivEnergy, and LG Chem RESU
Example: A 10kWh battery can typically power lighting, refrigeration, and internet for a night, depending on usage.
Combine solar with other renewables like:
These operate day and night, complementing solar’s daytime output.
Capture heat from the panels and convert it into usable thermal energy for heating or supplemental power.
| Benefit | Details |
| Backup Power | Stay powered during grid outages |
| Energy Independence | Rely less on utility companies |
| Lower Bills | Use your own energy day and night |
| Supports Grid Stability | Reduces peak demand strain on the UK grid |
| Eco-Friendly | Clean, silent, emission-free |
If your goal is:
…then yes, storage is a smart addition.
If your home is already energy efficient and you’re on a tight budget, a grid-tied solar system without batteries can still save you money.
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