March 2011 Analysis

Well, my final numbers are in for March 2011 and I am very pleased. The total kWh produced was 577.65 which equates to approximately $463.28 this month. Not bad for a March that seemed like there was lots of rain.

It helped that the last week had three or four days in a row that were very very sunny with very little cloud cover. I was producing 35kWh those days which really helped the bottom line.

For the month it was approximately $14.94/day income and the target was only $12.05 so I was producing above target which is more than one can ask for!

The kWh/kWp/day was 3.529.

Here is a graph of the results of the power produced vs. target to give you a better idea how the system is working.

I guess the last thing of note is that 4 days in March had less then 2kWh produced. One day had 0, and another 2 days fell in the 2-3kWh. These days were likely snowy and or pouring rain with extreme cloud cover.

Analysis of Solar Production as the Days get Longer

As the days get longer, and the sun gets higher, it would only make sense that the panels would produce more and more energy until mid June and then would slowly produce less and less as the sun got lower again.

However, I noticed back in January that there was one day where there was some 'bursts' of sun that brought the panels up to near max efficiency, approximately 4.3 kWh AC. On February 3rd, I assumed that with an amazingly clear day, with only sun in the sky, I would reach the same 4.3 kWh, but I didn't. The day still turned out to be the best day yet, 18.95kWh.

So I thought about it and can't explain while the max didn't get reached, I could explain how the total energy produced would increase even if the max output at any one point wouldn't be increased. And that is simply that on shorter days, the max output is a very sharp peak where as longer days will have a flat top and a much longer curve to the graph, with no distinct peak. Here is a simple chart that shows this and it is only a difference of 5 or 6 days!

The values you see there are averaged over 5 minutes so you can't actually see the 4.3kWh but you can see that the curve is flattening out at the top with the blue line (Feb 3rd).

It is 8:45AM today and the panels have already reached 1kW/h production which was not reached until 9:45 on February 3rd so if the weather stays the same, you can bet that the 20kWh for the day is attainable today!