About SunWise

Discover what's special about SunWise, and check out the technical details of how our solar calculator works.

What's Special about SunWise?

Many solar calculators are fiddly and hard to use, or give only limited information about the projected output of your system, or demand your email address and phone number before giving you the data you're looking for.

SunWise is different. We know that solar power is a big investment, and it's important to plan carefully in order to make a wise decision. We want you to have all the facts, without the hard sell or confidentiality concerns, so that you can decide what's best for you.

So we don't charge a fee, and we won't ask for your contact details. We just give you the data with our simple, comprehensive calculator, and let you have all the time you need to think about the best way forward for yourself and your home.

When you're ready — and not before — simply click on one of the links to our trusted suppliers, and contact them to get a detailed survey and quotation.

Calculate your savings
Solar panels

How Does the SunWise Calculator Work?

At SunWise, we believe it's important for people to have all the facts before investing in solar power. We therefore want you to know how our model works, so that you can understand how we predict the savings you could make. These details can seem a little technical, and you don't need to read them unless you want to, but we'd like to give you the option anyway.

  • System Capacity: Larger homes can fit more solar panels than smaller ones, and can therefore generate more power. A standard domestic solar panel measures ~39 x 66 inches, and generates around 0.4 kW. An average sized home would be able to fit around 20 panels, though the details of course depend on the exact design of your roof. Adjust the settings on the SunWise Calculator to match the space available on your roof. Here's a rough rule of thumb:
    • Smaller homes: 3-5 kW (6-13 panels)
    • Medium homes: 6-8 kW (15-20 panels)
    • Larger homes: 9-12 kW (22-30 panels)
  • Solar Panel Degradation: It's normal for solar panels to become slightly less efficient over time. The SunWise calculator takes these effects into account, assuming an average degradation of 0.5% per year over the life of the panels. This allows you to make a conservative estimate of the likely savings.
  • Efficiency: The efficiency of solar panels depends on many factors, including the orientation and slope of the roof, and partial shade from surrounding trees or other structures. The SunWise calculator allows you to adjust the efficiency to estimate the impact of these factors. For a more accurate assessment of your particular property, please consult your chosen specialist installer.
  • Geographical Location: The most significant contribution to your system's power output will be your geographical location. The SunWise calculator takes account of regional variations in solar intensity, using data obtained from the National Renewable Energy Laboratory. Simply select your state on the map or using the drop-down menu. Obviously there are regional variations within individual states — your chosen specialist installer will be able to give a more accurate estimate for your location.