East/west Solar Installations Generate Around 30 percent Higher Yields
- Published: Thursday, 30 October 2014 09:11
Photovoltaic installations with east/west orientation generate around 30 percent more solar power than south-facing systems fitted to flat roofs of the same size.
This is due to lower angles of inclination that allow the solar modules to be fitted without any gaps between the rows, meaning that roof space is put to full use. The imminent cuts to subsidies in the UK are boosting the attractiveness of east/west installations in the region, especially for businesses which consume the solar power they generate on site in order to reduce their ongoing electricity costs. Mounting solutions manufacturer Renusol has developed the FS10 system, a bespoke piece of equipment for east/west installations that also lowers assembly costs.
“East/west installations are not yet widely used in the UK, where the majority of PV systems are still south-facing. When the feed-in tariff is high, this solution generates the best returns. However, when the subsidies for solar power are low, east/west systems frequently prove more economically attractive,” explains Jason McCabe, Technical Application Engineer UK & Ireland at the mounting systems manufacturer Renusol, which is represented across Europe and the USA. “Many businesses face high electricity bills as a result of their machinery running all day long. East/west systems generate power more consistently over the course of the day than south-facing systems, allowing businesses to cover a large proportion of their energy consumption with solar power produced on their own roofs. Since a kilowatt hour of electricity generated on site is generally cheaper in the UK and Ireland than purchased electricity, the initial cost of installing a PV plant often pays off after just a few years.”
While south-facing solar installations require their rows of modules to be spaced further apart to avoid shadows being cast by the modules and causing yield losses, in east/west installations solar modules can be fitted more tightly together on roofs often at inclinations of around ten degrees. This means that on a roof area of 12 x 30 metres, for example, 126 modules can be installed as opposed to 88. At a module output of 250 watts peak (Wp), the entire system produces an output of 31.5 kilowatts peak (kWp) in comparison with 22 kWp. The annual yield of an east/west installation is approximately 24,000 kilowatt hours (kWh), making it some 30 percent higher than that of south-facing systems, which only generate around 18,000 kWh of electricity a year.
“Since east/west installations require fewer mounting materials, they incur reduced direct installation costs. What’s more, the larger the system, the lower the installation costs in general,” reports Heinz Schuld, Head of Application Technology at Renusol. “Renusol has succeeded in reducing installation costs even further by developing the innovative and rail-free FS10 mounting system for east/west installations. The modules are simply secured between two foot supports and two crest supports, lessening both the cost of materials and installation time.” To mount the modules, all installers need is a 13 mm combination wrench. Thanks to the ten-degree angle of inclination, the aerodynamically enhanced east/west mounting system is also suitable for flat roofs with low load-bearing capacities.
As the Renusol mounting system does not require the use of rails, water can drain away freely, even during heavy rain, preventing it from accumulating and possibly overloading the roof or leading to the roof covering deteriorating more quickly. The lack of rails also means that the system can compensate for any unevenness in the roof without difficulty and be fitted around obstacles, such as chimneys or air-conditioning units, more easily.