Photovoltaic Arrays on Flat Roofs – An Aspect of Yearly Energy Production

Abstract:

Insolation of the total area of PV arrays is the precondition of their smooth, undisturbed regime. On flat roofs the PV arrays are arranged typically in rows. In many design guides whilst checking their insolation a typical fault is that the distance between the rows is adjusted to the solar altitude at noon in December. Nevertheless in this case the undisturbed insolation is guaranteed only theoretically for a moment: just at noon, practically for a few minutes. It is to be pondered by the designer, how long should be the period of the obstruction-free solar access: if it is four hours, the altitude at 10 or 14 oclock must be considered. Certainly the result will be a greater distance between the rows however in this case less energy collecting area can be put on the roof. There are two options: either to insist on the operation in December at the cost of less energy collecting area or to abandon the energy production in this period in order to have larger energy collecting surface. The question is the yearly balance: irradiation round the year onto a smaller surface or to make use of the less irradiation on a bigger energy collecting surface.

References

[1] www. naplopo. hu.

[2] http: /www. naplopo. hu/tudastar/napsugarzasi-adatok.