Progress report, net metering

The above photograph is our meter taken on August 20, 2010. This meter was installed on June 8th of this year. When it was first installed it read "00000". Now it indicates we have 182kwh in credit with Allegheny Power. Considering for the past 40 days we have been into a lot of cloudy and partly cloudy weather, we're doing OK. This number shows the surplus power we generated, not the PV total output.
Through the Enphase Enlighten website which displays and archives our production data, I have prepared a report comparing our actual total PV output to our program we use to predict performance for potential customers who have had a site assessment done by us.
I have a field in the software where I can adjust system efficiency to help make the predictions fit the real world. Normally I use 90% system efficiency for potential customers. This predicts a slightly lower number than what they may see for real. I would rather under promise and over deliver. Our system is calibrated at a brutal 95% efficiency. This is the same efficiency as the Enphase microinverters. One must allow for line losses too, however the Mage PV modules have a higher tolerance for its power rating method which tends to cancel out the other losses.
So, how did we do so far?
From June 8th through to the end of that month, we produced 390kwh. If you adjust that for a full 30 days, you would have 585kwh. We predicted 507kwh, and overshot the prediction by 78kwh. yeah!
July is our only full month so far. We produced 545kwh, we predicted 497kwh. Again overshot by 48kwh. yeah!
So far in August, up to the 19th, we produced 288kwh. If you extrapolate out to 31 days, it would be 446kwh. Our prediction is 497kwh (same as July). Here we undershot the prediction by 51kwh. boo! This was mostly due to persistent cloudy weather patterns. If we have a week of more clear weather, we will easily surpass the prediction.
To date, we only have a small data set to work with. It would take two years of data to confirm everything is true. I feel confident that both the system and the predictions are within tolerance. These two items are quite important to a customer considering making the plunge into PV.