Are you considering harnessing the sun’s power and wondering how much you can save on your average monthly electric bill with solar panels?
Installing solar panels allows you to generate free, renewable electricity, reducing your reliance on the grid and significantly lowering electricity bills. It’s one of the most impactful upgrades a homeowner can make for long-term financial and environmental gains.
According to the Energy Saving Trust, households in London can save between £510 and £690 per year, depending on how much of the electricity they use themselves and whether they receive export payments like the Smart Export Guarantee (SEG).
But what real-world impact can solar have on your average monthly electric bill, and what factors influence those savings?
Quick Takeaways:
- Solar panels can reduce your average monthly electric bill by 50% to 70%, depending on your location, usage patterns, and system design.
- Savings can reach 80% or more if you incorporate battery storage to reduce nighttime grid usage.
- On an average UK energy bill of £145/month (gas and electricity combined), a 50% saving on electricity equates to about £72.50/month in savings. If you save 80%, that’s £116/month.
- You can save around 14p for every kWh you store in a battery and use later when the sun isn’t shining.
- Your potential savings depend on several factors, including system size, panel efficiency, battery storage, geographical location, and energy usage habits.
What is the Average Monthly Electric Bill in the UK?
Energy prices in the UK are largely controlled by the Energy Price Cap, which limits what suppliers can charge for each unit of electricity and gas.
As of January 2025, the average annual energy bill for a dual-fuel household in Great Britain is £1,738, which equates to about £145 per month.
When looking at electricity alone:
- The average annual cost is approximately £772.74
- This equates to around £64.40/month
These figures are for a medium-use household and can vary depending on region, supplier, and usage. Energy prices remain volatile due to fluctuations in wholesale markets and ongoing regulatory adjustments by Ofgem.
The January 2025 price cap rose by 1.2%, adding roughly £21 annually to typical energy bills.
What is the Average Monthly Electric Bill with Solar Panels?
Installing solar panels can drastically reduce your electricity costs. With a well-designed system, homeowners typically reduce their electricity bills by 50% to 70%. This can rise to 80% or more with battery storage included.
A 4 kw solar system, the standard for many UK homes, can generate around 3,700 kWh of electricity annually.
This output can offset a large portion of household electricity needs, especially when combined with smart usage habits and battery storage to make the most of the generated power.
Example Calculation:
- Average electricity bill: £64.40/month
- 50% savings: £32.20/month
- 80% savings (with battery): £51.50/month
The Energy Saving Trust confirms that you can save around 14p per unit (kWh) by using stored solar energy instead of buying from the grid during peak times.
How to Estimate Your Monthly Savings with Solar Panels
Here’s how to estimate the impact on your monthly electricity costs:
1. Determine your daily electricity usage:
Look at a recent bill, most households in the UK use around 2,900 to 4,000 kWh per year, depending on occupancy and appliances.
2. Choose the right system size:
For example, if your daily usage is 10–11 kWh, a 4 kw system should comfortably cover most of it.
3. Apply a savings estimate:
If you offset 50% of your usage with solar, and your current bill is £64.40/month, you’re looking at a monthly saving of £32.20. Offset 80%, and it jumps to £51.50/month.
4. Adjust for seasonal variation:
Solar output is higher in summer than in winter, so savings fluctuate. However, over a year, they average out substantially.
What Factors Affect How Much You Save?
Several key factors influence how much solar panels can reduce your monthly electricity bill:
- Size of the Solar System:
Solar systems are typically sized between 3 kw and 6 kw for residential homes in the UK.
- A 4 kw system produces around 3,700 kWh/year.
- The larger your system, the more power you can generate—and the more grid electricity you can avoid buying.
Larger systems also offer more opportunities to earn money through SEG export payments by selling unused energy back to the grid.
- Solar Panel Efficiency:
Solar panel efficiency affects how well your system converts sunlight into usable electricity.
- Entry-level panels may offer 15–17% efficiency.
- Premium panels reach 20–23%.
Higher efficiency means more energy from the same roof space—critical for homes with limited space. Though premium panels cost more upfront, they generate more electricity and better long-term returns.
- Geographical Location:
Homes in southern England benefit from more sunshine than those in the north or Scotland, affecting how much electricity solar panels can generate.
However, solar panels still work well across the UK, including in overcast areas. Even diffuse light (cloudy conditions) still generates electricity, just at a reduced rate.
- Seasonal and Weather Variations:
Solar output peaks between May and August, when days are longest. During this time, some homes can cover nearly 100% of their electricity needs with solar.
In winter, shorter daylight hours and weaker sunlight mean lower generation. You’ll rely more on the grid during these months—unless you have a battery system or a flexible electricity tariff to charge it overnight.
- Electricity Usage Habits:
How and when you use electricity make a massive difference.
Solar panels generate power during the day, so the more you use them during daylight hours, the less you rely on grid energy. For example:
- Running your washing machine, tumble dryer, or dishwasher in the afternoon
- Charging devices or EVs when solar generation is at its peak
Adjusting habits or using smart home devices can help align usage with solar production for maximum savings.
- Battery Storage:
A battery allows you to store unused electricity for later, such as evenings or cloudy days.
- For example, a 5 kWh battery can power essential appliances for several hours.
- A good battery setup can reduce grid reliance to 20% or less.
Though batteries add to installation costs, they increase your energy independence and long-term savings.
You can also use time-of-use tariffs to charge batteries at night cheaply and use the stored power during peak hours.
- Roof Suitability:
The layout and characteristics of your roof are vital for performance:
- South-facing roofs get the most sunlight.
- East and west-facing roofs are still viable, though less optimal.
- Shade from trees, buildings, or chimneys reduces output.
- A larger, unshaded roof allows for more panels and greater savings.
Your installer should assess your roof’s solar potential as part of your quote.
- Regular Maintenance and Inspections:
Solar panels require minimal maintenance, but keeping them clean and unobstructed ensures peak performance.
- Rain usually keeps them clean if installed at a 15°+ tilt.
- Trim trees to prevent shading.
- Check panels annually for debris, damage, or faults.
Your installer will provide a maintenance guide to help you keep your system in top shape.
Real-Life Example: Energy Savings in Action
Case Study: Retired Couple near Coventry – Energy Saving Trust
A couple in a detached bungalow installed a 4 kw system, a battery, and a solar diverter. The system included 16 panels and aimed to offset most of their usage.
- Annual consumption: 2,750 kWh
- Solar generation: 1,800 kWh used directly or stored
- Grid import: ~950 kWh annually, mostly during winter
Results:
- Predicted savings: 10% and a 7-year payback
- Actual savings: Paid off in 5.5 years
- Return: After 10 years, the system had paid for itself twice over
- Monthly bill from March to October: Often less than £1 (e.g. £0.79 in August)
They also take advantage of time-of-use tariffs by charging the battery overnight in winter and using it during the day when electricity is more expensive.
Final Thoughts: Is Solar Worth It for Monthly Bill Savings?
Installing solar panels can significantly reduce your monthly electricity bills while making your home more sustainable and energy independent.
With the right setup, usage habits, and location, most UK households can expect to save hundreds of pounds a year, especially if they include battery storage or adopt flexible tariffs.
Bottom line?
✅ Reduce energy bills
✅ Earn from surplus energy
✅ Increase your property value
✅ Protect against energy price volatility
Solar panels are no longer just for eco-conscious early adopters—they’re a smart investment for savvy homeowners seeking to future-proof their energy costs.
Sources and References
- https://energysavingtrust.org.uk/advice/solar-panels/
- https://www.ofgem.gov.uk/energy-price-cap
- https://energysavingtrust.org.uk/case-study/installing-solar-and-saving-energy/