Does it make sense to use my rooftop to generate solar power?

Solar conversion has a key role to play in the transition to 100% clean, renewable sources of heat and power. It is expected to contribute about one fifth of the global electric power supply (corresponding to between 14 and 22% of total power generated, IEA 2015) by 2050, as more efficient and competitive technologies become available.

Today, we are a long way away from that target. Solar power covered a little under 1% of global energy demand in 2014 (REN 21). The distribution obviously varies considerably from country to country as a function of local climate and level of investment. In the UK, for instance, the Sandbag app indicates that solar contribution to the UK energy production at the time of writing (February 13, 2016 at 3pm) is 3.9%. Even though higher than the global figure, this contribution is still far below the 11.4% that the Solutions Project expects from solar energy in the UK 2050 energy mix.

The Solutions Project, 100% United Kingdom

A new generation of free, web applications makes it extremely easy to do an initial assessment of financial and environmental benefits that come from generating solar energy from rooftops. They enable anyone to create a business case for putting solar panels on residential, commercial or public buildings, and start planning how to do it.

IYWTo, projects to plan solar units

All the tools we have reviewed start the journey from the property’s address: the rooftop is visualised on a map. From the rooftop’s area and orientation, the tools calculate the number of solar panels needed and their capacity. Some implementations, like Solarcentury, require the area to be drawn and roof’s orientation and angle to be manually entered, while the most advanced systems, like Project Sunroof and Mapdwell, do all of that automatically.

From the number of solar panels, the tools estimate the cost of the solar system’s components and installation. All the tools then evaluate the benefits that a solar energy system would generate in terms of savings and revenue. This is done by comparing the solar energy capacity with the property’s average electricity consumption and bills, and by calculating corresponding renewable energy incentives, such as feed-in- or export tariffs.

Finally, the tools calculate the financial break-even point as well as the CO2 emissions reduction contribution. The whole process, which takes only a couple of minutes, tells whether it is worth exploring this opportunity further, from both financial and environmental perspectives.

A second type of, more advanced, solar energy calculators exists to support the design, modelling and costing of complete solar systems. These are mostly B2B applications targeted to construction and energy professionals. Three of these tools stood out: Helioscope, Quick Solar, Energy Toolbase.

Because solar energy regulations and incentives are at the national, state and regional level, all these tools are highly localised. Most of the tools we have mapped and reviewed originate in the USA and apply to some states. Solarcentury and Helioscope instead are designed for the UK B2C and B2B markets respectively.

This article is therefore just the beginning of the mapping of innovative digital tools to plan solar systems on rooftop. If you use or know of other similar applications in your region, please let us know or add it directly to our growing project directory here.