There has long been a consensus in the solar sector that pointing solar panels to the south was optimal for virtually all applications – in the northern hemisphere, at least. This has left homeowners with east/west-facing roofs with fewer options. Tilting solar panels at an angle to face south can make them susceptible to wind damage, and the increased cost of such a project is a big deterrent.
Although the updated solar panels don't face due south, there has been discussion as to whether or not south-facing panels are optimal. Zep Solar recently designed an east/west-facing system for commercial buildings with flat roofs. Zep engineers argued that the lower noon peak is compensated for by having more kilowatt hours collected during the early mornings and late afternoons.
One reason east and west may be the best direction to point solar panels is that peak energy usage occurs in the morning and evening. With the angle change, however, overall efficiency is reduced. Because of the reduced efficiency due to bad angles on east/west-facing roofs, many states either do not offer rebates for them or offer reduced rebates – although, this is beginning to change.
Recently, TRA Snow & Sun worked with a homeowner in Las Vegas to develop a new way to mount solar panels on east/west roofs so that they are tilted partially to the south. Nevada offers a rebate to residents who install solar panels on or around their homes, but panels have to be facing mostly south in order to qualify. In addition to the required angle, solar panels must be able to withstand winds up to 120 mph.
Our solution was to engineer an aluminum roof mounting system to suit the east/west orientation that also enabled the installation and met all the requirements for Nevada's rebate program. The elevated solar racking system made it possible for the homeowner with an east/west roof to obtain a $10,000 rebate, as well as the benefits of morning and early evening sun.
Such designs have the potential to open up a huge part of the residential solar market that has previously been underserved.
‘We are happy to have found a solution to the problem of east/west-facing roofs that can be duplicated on other projects,’ says Jake Owsley, a solutions specialist at TRA Snow and Sun. ‘It will enable other NV Power customers to qualify for rebates when they become available.’
David Bloom works at TRA Snow & Sun in American Fork, Utah.