Solar Panel Calculator

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Installing solar panels is a big step, no matter what the size of your potential array. For that reason, it’s important that you understand what you’re getting into, and what you’re likely to get out of it. While you will need an EPC inspection, which will tell you more about the specific capabilities of your home, this free solar rate calculator can help you to check your potential savings, compare different size arrays, and make the best decisions for your home before you move forward with your investment.

  1. Enter your postcode below then use the slider to select your roof direction. Use the + button on the map to zoom in.
  2. Choose the picture where the angle best matches the roof on your home.
  3. The average domestic solar array is 3-4 Kw. Consider comparing multiple sizes to see which is best for your home.
  4.  How much shade is on your roof?
  5. What percentage will you use?  – If you do not have a smart meter, you will likely be paid for 50% of the energy you produce.
  6. You can find the exact rate on your electric bill.


How to Use the Free Solar Calculator?

Hopefully you can use this free tool to calculate your potential income and savings with a solar installation. You can use the calculator to:

  • Compare different size arrays
  • Decide if an array is worth the investment
  • Check how much you should be paying for an array

Once you have that data, you can use it to decide on the right array for your home or property, and check the potential profit you will have over 20 years.

If you’re seriously considering installing solar after using our tool, let us help you get started. Thousands of homeowners have used ExpertSure’s free comparison tool to save money on solar installations.

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How Are Savings Calculated

Our solar rate calculator determines the likely energy output of your PV array based on your home, location, and roof pitch as well as the size of the array. It uses this data, along with your energy bill and the current Feed in Tariff rate to calculate your likely savings.

Energy Production – Solar panels produce energy which is measured in KwH or Kilowatt hours. This production depends entirely on the sun, average exposure to the sun, and sometimes, the quality of the sunlight. So, while a 3.5 Kw solar array will likely produce 3,000 KwH per year (about 2/3rds of your average electric usage) in prime conditions in the UK, you will generate less energy if your roof is shaded. Factors that affect energy production include location, the roof pitch, shading, and the installation size – our solar rate calculator takes all of these details into account.

  • Roof Pitch – 45 degrees is the optimum angle to catch the most light as the sun moves through the sky throughout the day. A good angle ensures that panels are exposed to the sun from sun-up to sun-down, no matter the weather.
  • Shade – The less shade on your roof the better.
  • Direction – Solar noon is the midpoint of the day, and the point when the maximum amount of radiation from the sun hits the earth. Because the sun is due south at noon, your panels will ideally be installed on a south facing roof. However, you can still collect a considerable amount of power without a south facing roof.


Feed in Tariff – The Feed in Tariff or FIT is a government sponsored subsidy where you are paid for all of the electricity you generate. Most importantly, your rates are locked in for 25 years from when you install your panels. Because FIT rates drop almost every year, installing sooner means that you get a higher rate. And, even more importantly, we update our calculator every time the FIT rate changes, so that you get an accurate quote. The 2016 FIT rate is 3.76-4.46 pence per KwH depending on the size of the installation.


Export Tariff – This tariff is the rate that you are paid for energy that you don’t use. The 2016 export tariff is 4.85 pence per KwH. While this is technically based on the amount that you generate, this rate is typically estimated to be at 50% unless you have a smart meter installed, or have a solar array of 30 Kw or more.


Energy Cost – How much you pay for energy directly affects your costs. Solar allows you to simply cut out a large portion of your electric bill because you’re generating your own power rather than buying it from the grid. And, the more of your own power that you use, the more you can save. Why? The current average cost of electric is 11-12p per KwH, meaning that you’ll save more than twice the amount if you use all of your electric. Unfortunately, this isn’t always possible.

We update our calculator frequently to ensure that all of the data is correct and your solar estimates are as accurate as possible.


How much co2 will you save with solar panels?

Going green is a big part of investing in solar panels, and while the investment benefits can be considerable, there are environmental perks as well. This calculation gives you a good idea of how much Co2 you will save by using solar.

Co2 Emissions by Power Plants – The National Grid PLC estimated that commercial power stations produce an average of 392 grams of Co2 per KwH of electricity. This is an average because coal plants produce much more while others like nuclear produce less.

Solar Co2 Emissions – Solar panels produce an average of 88 grams of Co2 per KwH from manufacture until they are defunct. This includes everything, from acquiring raw materials to production to transport and installation.

Essentially, solar panels produce 77.56% less C02 per KwH of electricity.


Installing solar panels can be a great decision for your home, for the environment, and for your savings. In fact, with an average return of 4.8% over 25 years, solar panels offer a return comparable to most ISA and investment accounts. Hopefully you can use our free calculator to determine if solar is a good fit for you.

If you’re considering solar, use our free comparison tool to request quotes from local installers and we will do the work for you. We’ll send you the top quotes from local installers, and help you to save as much as 47% on the cost of your solar installation.

Get this calculator on your site free. 

Ready to earn £4771 or more in government solar payments?

Select your area and fill in the fast form to start the process now!

Filwood Green Business Park
1 Filwood Park Lane

0800 234 3036