7.2 kH

Today, March 16th, the day after washing the PV panels and a fairly cold, windy, absolutely clear day, the system registered 10.54 kWh, the best performance to date. As I intermittenly scanned the display at about 1:00 pm today (local noon) I was pulling in a maximum of 1723 W AC. So...861 watts AC per installed DC kilowatt.

SMUD installed a digital bi-directional meter on the main service panel, but my PV production meter is an induction disc type. It was installed at a 0000 reading, but damn if I can remember the exact date. Damn. Exact yearly data would have been nice, but instead I'll rely on the monthly data from my bill. I'm uncertain why they installed one meter that can be read remotely while the PV production meter must be read manually. My neighborhood hasn't yet migrated to digital meters. When it does, they might just come in and replace the PV meter as well.

But...the PV production meter is stamped 7.2Kh on the front. From my own time calculations and inverter display, I can calculate that one revolution of the disc is...7.2 watt-hours. But what does the Kh stand for? Seems to me Wh would be more appropriate.

Edit 1/16/2009:

After multiple queries on SMUDs internal forum boards regarding the reasoning behind the Kh...there apparently isn't one. K is simply a disc constant, the variable K used since the earliest days of metering. Nothing more, nothing less. Like many aspects of digital conversion, we still use Kh to describe incremental energy through the meter, even though digital meters aren't calibrated in the same way electromechanical meters are. There are no discs anymore, but we still use the term.

We do the same thing in digital relays -- manufacturers continue to use torque as a way to describe how the relay operates even though it's all just 1's and 0's now.