Friday, March 12, 2010

Solar Array Powered Up and Some Graphs

The installer powered on the solar array on Tuesday after the inspection. After he left, I installed current sensors for the solar breakers and ran those along Cat-5 back to the ECM-1240. I was debugging the charting and got it pretty much sorted out by Wednesday night. Here's the first few RRDTool graphs from Thursday.

You can see it generated nearly 21 kWH yesterday. I'm really happy with that as we typically use 22-25 kWH/day. I didn't expect to get that much production in March. Does this mean the assumptions I made in my Solar Spreadsheet may have been a little pessimistic? There's still a lot of rain & overcast in March (of which we're seeing today), so it will probably average out. We'll have to wait for April to get a good full month to compare.

With a southeast facing roof, you can see we catch the morning sun very early. The array woke up around 6:22AM and peaked around 11AM. Once the sun passed over the top of the roof around noon, production started to drop and around 2PM it started to decline rapidly. By then, it produced about 80% of the total for the day. I wish I had room on the west facing roof to catch the afternoon sun, but it would only fit maybe 4 panels - good for another 1kW. Maybe when we get an EV ;) Production stopped almost exactly at 6PM. You can see some of the spikes in production as the sun was behind some clouds.

This is just a net usage graph. Solar production for the day caught up to our daily usage by noon. Between 3-4PM, production fell below our usage and about 9PM, all our credits were used up. For yesterday, we basically paid the utility for electricity for the 3 hours from 9PM-12AM. Pretty cool.

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