Solar pv

Despite being actively involved in solar pv since 2010, and running my own MCS accredited installation company since 2011, we didn't get our own system until August 2013. Reason being, we first needed a re-roof. The existing Rosemary tiles were in a poor state and, with no felt behind them, were prone to working loose and allowing wind driven rain into the loft. There was no way the current roof covering would last the life of the solar array so we decided to get it replaced and, taking advantage of the scaffolding, get the panels installed at the same time. Local firm, Adams Roofing were contracted to do the roof works, while Steve 'Spiderman' Adams (no relation) and I got the panels fitted.


We have a hipped roof, with the hip roughly south facing and the rear of the property tending towards west. Pitch is approx. 50 degrees. The layout, while far from ideal for solar pv, lends itself to 6 south facing panels and 7 west facing. In order to maximise generation potential, I looked beyond the standard 250W panel ranges for something a little larger. I eventually settled on LG Electronics' NeonX 285W monocrystalline panels, as these offered the perfect blend of high output and quality at reasonable cost. 13 x 285W panels gives us  a 3.705kWp system. Pretty good for such a relatively small roof area. The panels are matched to a PowerOne Aurora PVI 3.0 inverter (3.3kW max output), which converts their DC voltage to AC that can be used around the home or exported to the national grid. As the system is MCS accredited, it qualifies for the government backed Feed in Tariff incentive, along with further payments for exported electricity. The system is predicted to generate around 3000kWh of electricity per annum and should pay for itself within 8 years.

7 panels at the rear of the house (nearly west facing)

6 panels on the hip (nearly south facing)

I did the electrical work in advance, locating the inverter and associated switchgear in the 'cupboard under the stairs' - the old coal store in the garage. I liked the idea of the old 'dirty' form of fuel being replaced by this new, clean energy source. A benefit is that the inverter will run much cooler than if it were placed in a loft, as is commonplace. It is also adjacent to the incoming mains point, so AC losses are minimal. The only downside to this set up was the hassle in running (and adequately protecting) the DC cables from the roof, down through the house and into the garage.

PowerOne Aurora inverter

Inverter and switchgear in the old coal store

I had a spare Owl Intuition-pv monitoring system lying around, so this was hooked up to allow us to keep an eye on what the system is doing, via the internet. So far so good: the arrangement of the arrays gives us a nice steady generation profile from morning to evening, as the west facing array takes over from the south one as the sun moves around the house. The following chart shows a typical generation day (29/9/13) with low cloud cover.

Generation profile 29/9/13

The orange spikes, showing electricity imported from the grid, are mainly down to our care-free use of the kettle. However, it is plain to see from the chart that, during daylight hours, we are exporting virtually all of what we generate. Obviously it makes sense to make use of this 'free electricity' and plans are afoot to do just this...

J.