Voltage spikes cause drops in solar PV performance
Posted by Rob Palgrave on 12 November 2012 at 10:36 am
A members of my local Friends of the Earth group installed solar PV on her roof at the start of the year. This is in Surrey. The generated energy is much lower than expected, and the installer has not been able to resolve the issue so far. Suspicion falls on the compatibility of the inverter to match the (apparently) very spiky local grid connection. I'd be interested to hear from anyone who has had a similar experience, or can shed light on the issue.
The installation comprises: 18 Schott Perform Mono 180—190 wp (9 front roof and 9 back roof), 3.42kWp net capacity; east/west facing roof 30 deg pitch; Sunny Boy inverter
After the feed-in tariff claim at the end of first 6 months (30 June 2012) British Gas commented - the reading (680kWh) was only 48% of what would have been expected over this timeframe.
The installer was asked to attend – they checked everything out on site, said they could see nothing wrong but would contact manufacturers etc. Which lead nowhere.About 2 weeks later an alert appeared on Bluetooth display re the inverter saying “voltage spikes”. The daily graphs had started going flat between 11 and 4 approx. (About 22 July by this time and hot weather).
Installer came back in – explained grid normal voltage setting 230v (standard G38/1) but made a call to Sunny Boy and was instructed to change setting to 250v – apparently legal supply should be about 230 but with parameters of operation 250v should be adequate – and the owners were told to contact electricity distribution company SSE to have a voltage monitor installed. There have since been flat periods in graphs (but no error messages).
A voltage monitor was duly installed for a week and SSE has written to the solar PV owner confirming that there are voltage spikes above and beyond their legal parameters. Apparently this will require serious work in the area with electricity switch off throughout. That was in August and nothing has happened by end of October.
Have voltage spikes have been affecting the system all along (including first 6 months)? SSE were non-committal.
The explanation given by SSE is that they get spikes in electricity supply in hot weather. If no spikes in first 6 months what can be done to establish the problem? Installer seems unable to envisage this possibility although there were no evident outages in this period per graphs. Is the problem truly solved – the installer says yes.
About the author: Rob Palgrave is a guest blogger
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