About SunWise

SunWise provides a solar savings calculator that is powerful, simple, and free, allowing you to estimate what you could save with residential solar power. Read on to 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
Couple looking carefully at solar power calculations on laptop

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.

  • 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.
  • System Capacity: Larger homes can fit more solar panels than smaller ones, and can therefore generate more power. A standard residential 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)
  • 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.
  • 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.
  • Financing: There are various different ways to pay for your solar power system. The SunWise calculator allows you to estimate how your your savings will be affected by paying in full up front, or by various finance options. You should always take financial advice before purchasing. Consult your local specialist for advice.
  • Electricity Costs: The SunWise calculator allows you to see how your future savings will be affected by the present and future cost of electricity. For more information about how electricity costs have increased in recent years, plan your solar installation.
  • Incentives: Some states offer tax rebates or other incentives to solar power customers. Check with your local specialist for details.
  • Lifespan: Modern solar systems can be expected to last significantly longer than 25 years. However, most manufacturers offer a 25 or 30 year performancy warranty, so we calculate the expected savings at that time to produce a conservative estimate. If your system lasts longer than this — and the vast majority will — your savings will be even greater.