goldbrick said:SageBrush said:Reliability aside, I would avoid micro-inverters due to the high i^2 losses. I personally also find the parallel wiring scheme
to more difficult to work with and my impression from a few projects is that a lot more cabling is used.
I'd think micro-inverters would require smaller cables and generate less heat in the cables (i^2*R losses). The power through the wires = V*I and with micro-inverters the voltage is much higher so the current is much less. That is the reason long distance power lines are such high voltage; it reduces the transmission losses.
Aren't microinverters outputting 240v AC while strings are typically around 400V DC?
goldbrick said:I'll probably sketch out the design with both configurations before I decide. I am a bit worried about the reliability factor (more active parts means more chances of failure to me...) but the reliability is supposedly good and they are covered by a warranty. And if one or two fails, I'd still be generating power from the remainder of the panels.
FYI, if you go with String inverters, you're still probably going to want DC optimizers on your roof (due to shading issues and safety issues*). This means that you'll still have an electronic component on your roof under each panel, whether it's a micro inverter or optimizer. Also, some micro inverters can service two panels, resulting in half as many components.
For ground-mounted, unshaded systems facing the same direction, string inverters have the lowest TCO and lowest # of components. However, string inverters have a shorter warranty than micro inverters, as they're handling significantly higher amounts of power.
* Each power optimizer is equipped with the unique SafeDC™ feature which is designed to automatically reduce modules' DC voltage to a safe level whenever the inverter or grid power is shut down (unless connected to a StorEdge™ Inverter that is operating in backup mode).
https://www.solaredge.com/us/products/power-optimizer