Some Basic Parameters of the PV System to Date

There are some handy parameters that can be used to estimate the power or revenue generation of a PV system. Often people will take the kW of the system and multiply it by the expected parameter to get expected value such as kW hours per year or dollars per year. These numbers are relatively easy to calculate. Ideally people are using the most realistic values possible if they want to estimate their expected outcome.

An example is, how many kilowatt hours should I generate from my 5 kW system on my roof?

First, here are my parameters for our 4.9 kW DC system [5 kW string inverter]:

Variables	kW	Dollars
Mean [4.9 kW]	15.81	$12.68
Per [1 kW]	3.23	$2.59
Min [4.9 kW]	0.05	$0.04
Max [4.9 kW]	35.13	$28.17

In this case, applying my parameters to a hypothetical 5 kW DC system, we could estimate mean daily kW production over the year to be 5 kW * 3.23 kW per kW = 16.15 kW per day. Multiply that your FIT contract price and this would be your daily income averaged over the year. 

You can use the values above to estimate your highest and lowest income as $28.17 / 4.9 * your DC kW.

Oh, and you can see that you'll have some bad days too - $0.04 / 4.9 kW will give you $0.01/kW on dark snowy, snow-covered panel days. 

Revenue to Date

A quick post to provide my monthly income to date from the solar panels. Movember is not complete - it is just to 24 Nov 2012.

Sum - Revenue, daily	Years
Date	2010	2011	2012	Total Result
Jan		$136.10	$205.18	$341.29
Feb		$220.57	$258.66	$479.22
Mar		$449.77	$456.57	$906.34
Apr		$395.30	$501.84	$897.14
May		$428.51	$607.72	$1,036.24
Jun		$567.19	$573.10	$1,140.30
Jul		$616.75	$611.45	$1,228.19
Aug	$131.53	$528.09	$577.23	$1,236.85
Sep	$351.28	$423.49	$480.85	$1,255.62
Oct	$360.90	$313.65	$270.70	$945.25
Nov	$285.03	$253.69	$193.78	$732.50
Dec	$62.74	$176.31		$239.05
Total Result	$1,191.47	$4,509.43	$4,737.09	$10,437.99
as of:	2012-11-24

Note how the revenue for the dark and dreary October was lower than previous years. With only 6 sun days left for November, I hope it picks up a bit or it will be another low income month.

December 2010 Power Production

December was generally -8 to -1 with about 10 cm snowfall mid-month. The second half of the month was almost always overcast. A thaw with rain melted all the snow on 27 Dec.
The panels were snow-covered most of the second half of the month and power generation was significantly reduced (see chart, Whr/day). The overcast days which were slightly below 0C did not provide sufficient radiant heat to warm the panels and melt all the snow off. This was clearly shown in the previous postings of the snow-covered panels. Partly sunny days just after Christmas resulted in some snow melt and snow sliding off about half of the panels (see earlier post with photos). This resulted in an increase in generation on 27 Dec.
The remaining days of December were very overcast with heavy dark cloud. Even the melt that occurred on 29 Dec was not sufficient to increase production even though the panels were clear. The increase on 31 December showed the benefit of clear panels and a little sunshine. Fortunately, the clear panels is helping increase generation during the first week of January which are a little more bright. Happy New Year!