Sunday 25 March 2012

Solar panel performance beats SAP 2009 estimates

For the fourth month running our solar panels have comfortably exceeded the estimates given under the SAP2009 guidelines. With 7 days still to go before the end of March the estimate for the month has already been reached and the weather forecast of sun for the next 5 days is looking promising for a good output by the end of the month.
PV GIS vs SAP solar PV generation compared

When choosing the solar panels, the output estimates supplied by PV Solar UK were substantially higher than other companies and didn't conform to the SAP regulations. However so far these estimates using PV-GIS are proving a more accurate guide to the output of our system. Over the summer months the difference is less marked but over winter & spring the numbers are at least 10% higher than the SAP figures.

For example in January SAP2009 gave an estimate of 93kWh, PV-GIS 112kWh and the actual was 112. Dec was 68 for SAP2009, 101 for PV-GIS and an actual of 103kWh generated.

On current trends it appears March actual output will beat both the SAP figure of 210 as well as the PV-GIS figure of 241kWh electricity generation.

Monday 19 March 2012

Maximum Peak Output from Solar Panels

Another record was reached yesterday with the output from our solar panels. The peak output reached 2960W, comfortably passing the previous maximum of 2760W. This is only the instantaneous output and was achieved after a cloud had passed, cooling the panels and therefore increasing their efficiency. So for our 3010kWp panels we are achieving a peak efficiency of 98.3% at the moment. It will be interesting to see how that changes over the summer months.

We have also achieved another record today with a total daily output of 17.5kWh but with the lengthening days I expect this will happen very frequently until we reach mid June.

Maximum peak output of solar panels

Sunday 11 March 2012

February Makes New Records

February has broken records for our solar generation, not all of them good!

You can see the stats for our solar panels generation data here but the key records are:

  • First day with no electricity generated due to snow lying on the panels
  • Lowest non-zero day (heavy snow cloud gave a paltry generation of 0.2kWh total
  • Highest generating day since installation and first over 10 kWh
  • Longest generation day (earliest start and latest finish)

It is also good to see that the shading issues that covered the roof over the winter are now over. Due to the sun now being higher in the sky in the afternoons it misses the trees and we get full sunshine through to sunset now.

Same roof with shading in late afternoon in early November