[RE-wrenches] utility line voltage issues

[Michael Welch]

Please check my math, I did it pretty quickly.

CA has over 450 MW of distributed PV systems. At around, say, 4.5 average daily sun hours (it is probably more, averaged over the state's systems), that would be 540,000 MWh each year.

If the utilities are dropping out of spec, say, 1% of the time, that's 5,400 MWh of loss each year. At 15 cents a kWh (the average is probably more) that turns out to be $81,000 worth of losses to us.

That does not seem like a whole lot , but the number will grow as fast as PV installations are.

Maybe it is time for a class-action lawsuit against the utilities. Or time for the dream Wrench organization to file with the CPUC for relief in the form of stricter utility specs, or petition UL for looser inverter specs.

One question, why are inverters required to drop out for out of spec voltage and frequency? It seems to me that the UL requirements are overly limiting in that regard. I mean, if the utility can do it with their huge plants, why can't we with our little ones?

William Korthof wrote at 10:06 AM 8/16/2009:
 
>I'm beginning to wonder if the allowed voltage range for grid-tie inverters (+/-10%) is too sensitive in some networks and contributes more harm than benefit. This is close to home.
>
>We actually have a significant number of customers who've had trouble with grid voltage causing their systems to go offline at various times. I think most or all are SCE customers.