Frequently Asked Questions

Creating your report

What countries does SolStats cover? SolStats covers Europe at the moment. We may add additional countries in time. If you would like us to include your country please let us know.

My roof isn't a rectangle - can I still use SolStats to estimate my solar power? Our software allows you to use any shape of roof. Just click on each corner of your roof - as shown in the example below.
          roof shape

I want to understand which part of my roof is the best part to put solar panels - how can I do this? To find out where you can generate the most electricity, create a report for each area of roof you are interested in and compare the results. The example below shows two separate roof areas where solar panels could be installed. By comparing the two reports the owner of this house can determine the best location - which will be a combination of roof area, orientation and angle.
          roof option 1           roof option 2

My roof has dormer windows - can I exclude these from the calculation? Yes - just click on each point of the roof area to identify the roof as shown below. You can drag a point into the correct position by clicking on it and dragging it.
          roof dormer windows           roof drag and drop

How do I specify that I have a flat roof? For flat roofs please set the Angle to 0.

I have a rectangular roof but in the report it shows that the corners are not all 90 degrees You have two options to fix this. You can go back and adjust the points you have used to identify the corner of your roof then generate another report. Note that the points can be dragged and dropped to new locations. Alternatively, if you know the size of your roof you can use our advanced options to set the roof length and width. Click on 'Advanced' on the home page and follow the instructions there.

I have a different electricity tariff - how can I use this? Click on the 'Advanced' link at the bottom of the page. In this section you can change the electricity tariff as well as other settings. See the help link for more information.

Can I use different solar panels from the ones you specify? To specify your own solar panels click on the 'Advanced' link at the bottom of the page. Here you can specify the solar panel width, height and peak power that SolStats will use for your report.

Understanding your report

The report says my roof area is __m² and I disagree! Our software uses the points you have selected combined with the roof angle to determine the area of your roof. If this is not accurate for your roof please move the points (you can drag and drop them) and/or change the angle and create another report.

The report says I can fit __ solar panels but it looks like I can fit more than this. Our software uses an algorithm to estimate the maximum number of solar panels you could fit. This works well for simple roof shapes like squares and rectangles. If you roof is a more complex shape then you may be able to fit in more solar panels than the report indicates. In any case you will need to have an installer visit your property to get an accurate estimate.

Why do you include a temperature chart in the report? The efficiency of solar panels is affected by the temperature. As the temperature increases then the solar panels become less efficient. For a crystalline solar panel for every 1°C over 25°C the solar panel performance reduces by 0.5% (source: DTI Sustainable Energy Programmes).

Units used

Electrical Energy is measured in Watt hours (Wh) or Kilowatt hours (kWh). One Watt hour of electricity is used when a 1 Watt appliance is switched on for 1 hour. So a 60Watt light bulb left on for an hour uses 60Wh of electrical energy. A 1kW electric radiator switched on for 2 hours uses 2kWh of electrical energy. A Kilowatt hour is equivalent to 1,000 Watt hours. (Note: electrical energy is also measured in Joules. One Watt hour is equivalent to 3,600 Joules.)

Solar Irradiation is measured in Kilowatt hours per square meter per day (kWh/m²/day). This is the amount of solar energy a square meter receives in a day. So if your roof gets 1kWh/m²/day and you have 10m² of roof area then your roof receives 10kWh per day. This solar energy is equivalent to running a 1kW electric radiator for 10 hours. The term 'Solar Energy' used in the report refers to the Solar Irradiation.

Solar Panel Power is measured in Watts. A typical solar panel might generate 245Watts of Peak Power (see below for definition). A solar panel generating 245Watts for 10 hours would produce 2,450Watt hours (or 2.45kWh) of electrical energy.

Peak Power is the electrical power generated by a solar panel under Standard Test Conditions (STC). STC defines the solar irradiance as 1,000W/m², the temperature as 25°C and the air mass as AM1.5 (air mass represents how much the sunlight is reduced as it passes through the Earth's atmosphere). Under these conditions the electrical power generated by the solar panel is measured and this is called the Peak Power of the panel.

Data Sources

We make use of a number of sources of data and data services to create your custom SolStats report. These are:
Google is used for their Google Maps service to locate your roof and identify the roof corners.
thematicmapping have a database of country borders which we use to identify which country you are requesting data from.
Photovoltaic Geographical Information System from the European Communities (and copyright European Communities 2011) provides the level of solar energy, average temperature and solar power for your roof location.
Trinasol website is used for the solar panel dimensions and performance.
Ofgem have information about the feed-in tariffs available to home owners as well as the UK average electricity prices.