Aren't microinverters outputting 240v AC while strings are typically around 400V DC?goldbrick wrote: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.SageBrush wrote: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.
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.goldbrick wrote: 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.
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).