Derate Factor For Solar Panels

The derate factor for the pv module nameplate dc rating accounts for the accuracy of the manufacturer s nameplate rating.

Derate factor for solar panels. For most photovoltaic systems this figure provides a reasonable estimate for determining energy production. Other factors including energy conversion losses wiring inefficiencies and module heating are unavoidable. Shading derate factor pvwatts definition. Some factors like shading on the photovoltaic panels can be eliminated through the pv installation process.

Like everything else pv modules degrade with time. Several specific factors known as derate factors can reduce the amount of solar electricity created by a pv system. The derate factor is the loss of power efficiency due to all the factors that interfere with a perfect system. The dc to ac derate factor involves the conversion of dc electricity to ac electricity because solar panels create dc electricity and your house uses ac electricity see electricity article this website.

Diy solar design tips to improve dc to ac derating while many of the derate factors may be unavoidable you can take steps to reduce your system losses. The aging or derating factor is usually covered by the manufacturer performance warranty. Use the derating factor to account for such factors as soiling of the panels wiring losses shading snow cover aging and so on. Some manufacturers include the initial lid at year 1 with values varying from 2 5 to 3 5.

Field measurements of pv modules may show that the pv module powers are different than the nameplate rating or that they experienced light induced degradation upon exposure even crystalline silicon pv modules typically lose 2 of their initial power before power stabilizes after the first few hours of exposure to sunlight. For the default value of 1 00 pvwatts assumes the pv modules are not shaded. Most major brands listed in the table below guarantee a maximum of 20 de rating over 25 years with different milestones during that period. The default derating factor on the solar goods diy solar calculator is 83 percent.

The photovoltaic pv derating factor is a scaling factor that homer applies to the pv array power output to account for reduced output in real world operating conditions compared to the conditions under which the pv panel was rated. Converting dc to ac requires additional devices including a transformer. The derate factor for shading accounts for situations when pv modules are shaded by nearby buildings objects or other pv modules and array structure. This includes factors such as the dc to ac derate factor age shading sun tracking etc.