Sunday, September 06, 2009

Solar Power - Monitoring Output

The SolarCity web based monitoring system didn't work at first, there was a problem with the data-logging board in the inverter but they were helpful and sent someone round to fix it. So now we can track how much power we are generating. The graph updates every 15 minutes, and it reports the amount of power every half hour, so when it shows 1.7 KWh that is equivalent to 3.4KW averaged over 30 minutes. So far the highest peak instantaneous output reported on the Inverter is about 4.2KW.

We are still waiting for the energy consumption metering to be added, which puts a second line on the same graph.

The day shown was a typical day up here on top of the mountain, it was cloudy elsewhere, but we had basically clear sky all day. and generated over 25KWh.


  1. Thanks for posting this entry. It seems your system is only a few weeks old. In case you are curious about the integrity of the installation or its
    relative performance with respect to its practical design capacity, you
    are invited to visit our benchmark website
    When you enter a set of key parameters, you'll get a calculated nominal
    output, under the set of operating parameters.
    Good Luck.

  2. Hi Steve, I visited your site, which seems to be under construction, although there is some potentially useful information and formulas there. The First Solar 75W thin film panels that I have are not covered by your model. It would be useful to have a calculation of the variation over the year for a particular physical orientation of the array vs. the position of the Sun over the year. I don't remember enough polar coordinate system geometry to figure it out.

  3. Hi Adrian,

    Thanks for your feedback. The site is a new front, which I'm trying to nurse into full deployment. Full functionality is available at I could not read the product label of FS-275, nor could I find detailed datasheet, but I did record a site 'Cockrof' with available info. At solar noon, you should have about 2.2KW of output. Since this is the first FirstSolar site I know, I would like to help you ascertain if everything is proper. Also your work on temperature logging is rather interesting. We should collaborate, since we hope to get into solar thermal monitoring later.
    Thanks and May the Sun always warm your face and your panels!


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