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Estimates of solar PV will improve with launch of new PV Guide

Posted by Cathy Debenham on 11 February 2013 at 9:46 am

The estimated performance of solar PV systems will be significantly more accurate in future, following the publication of the long awaited new PV Guide, and the newly updated standard MIS3002 issue 3.0.

The new standards for solar PV installations were finally launched last week by Climate Change Minister Greg Barker MP at Solar Power UK's restarting the market roadshow. "This should become the 'go-to' guide for PV system installers," he said. "Its widespread use will improve the reliability of installations, increase customer confidence in PV and help us all benefit from quality focussed engineering solutions."

Customers will see much more accurate performance estimates as a result. To date estimates have been based on the SAP calculation for solar radiation in Sheffield. As a result systems in the south of England have generally performed much better than predicted, and those in northern Scotland, have fared worse.

Going forward predictions will be made based on regions, and there is a data sheet that allows installers to look up irradiance according to the exact slope of the roof (or incline of panel) and orientation.

While it was previously thought that the south west was the best place for solar PV, the new figures show that the south east beats it. An ideal installation in Zone 2, which covers Kent and Sussex, should produce 1132kWh per kWp compared with 1093kWhs in the south west (Cornwall and Devon). Not surprisingly the lowest generation figures are in Shetland, where an ideally sited system is expected to generate 714kWh per kWp.

Another major change in the new guide is the calculation for shading, which will now be much more accurate. The new guidance also bans drilling slates in most cases, and updates the way that wind uplift and system fixings are calculated.

Installers can choose to start working to the new MIS3002 v.3 immediately if they want, but they must work to it from 7 May 2013.

The PV Guide, MIS3002 issue 3 and the irradiance datasets can be downloaded from the MCS website.

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