AC to DC Derate Factor

[tirane]

What is the AC to Dc derate factor? Is it the potential energy lost as the electricity is converted from the panels into potential electricty for use by the home. I saw it on PV WATTS but I really dont understand it all from thier description

[SunRayPower]

System derate factor in PV Watts and other tools

What is the AC to Dc derate factor? Is it the potential energy lost as the electricity is converted from the panels into potential electricty for use by the home. I saw it on PV WATTS but I really dont understand it all from thier description

In every system there are losses that prevent it from achieving optimal output or the heretical maximum. The derating function in PV Watts attempts to account for the losses by capturing losses (or gains) in the following categories:
PV module nameplate DC rating (panels typically have a +/- 5% and some panels are underrated to grantee production)
Inverter and transformer losses
mismatch
diodes and connection losses
DC wiring losses
AC wiring losses
Soiling
System availability
Shading
Sun-tracking
Age

PV Watts default derate faction of .769 may not be applicable to all systems. It could be better or worst. But with that derating a 1000 Watts system would deliver 769 Watts in 'perfect' conditions.