10.4.2006 / D.J. Spiers, Naps UK

Naps UK grid-connected PV system shows excellent performance and also shows how reliable our performance prediction program is!

A 4.8kWp grid-connected PV system was installed in February 2004 at Friars Court Farm, Clanfield, Oxfordshire, which has a range of sustainable energy projects and exhibits. The modules are mounted on a concrete base in a field using standard ground mounted structures. A buried cable connects the array to the inverters and ac connection point in a farm building about 100m away. There is a large wall-mounted display and the site receives many visitors who are shown this system and its performance.

Data is stored in a Sunny Boy Control data logger and the system performance has been carefully monitored by Naps. The first 12 months of full operation yielded 870 kWh/kWp/year. The accepted average for UK is 750, so this represents a really excellent performance by UK standards. Perhaps even more impressively, our proprietary computer program NSDP predicted an average year performance of 849 kWh/kWp/year for this system, using long term meteorological data for Oxford. This excellent agreement between the actual and predicted performance gives us great confidence in our computer-generated predictions.