To many, it may seem somewhat surprising that rooftop PV deployment has been the segment of dominance in the UK until now. Talk of ROCs and CfDs certainly dominates the press, and the concerns of many in both the government and the domestic PV sector.

But, the reality of UK solar PV activity cannot be disputed: rooftops have been the main driver of deployment so far.

The tipping point however is just a matter of days away. As this occurs, the UK will officially have more ground mount than the FiT-driven rooftops that were instrumental in the UK becoming a PV region of global significance back in 2011.

There are no prizes for understanding the growth of the ground-mount segment in the past 18 months. The story here though is the silent success of the domestic rooftop segment that has been one of the leading markets for component suppliers for the past few years.

Figure 1: Cumulative growth of the UK solar PV market split into the percentage contributions from rooftop and ground-mount deployment. Data shown for Q4’14 represents the quarter-to-date figures as of 28 October 2014, as supplied each week by NPD Solarbuzz to the UK’s Solar Trade Association.

To many component suppliers and distributors, the UK (including the mini boom in Northern Ireland) is a stable and attractive rooftop market, with a domestic demand that typically trends at the 80-100MW per quarter now.

Whether retrofit, free solar, warehouse selling, IKEA-pitched, social housing or new build-driven; the sub-4kW demand has been hard to miss in the past few years. Drive around any housing estate in the UK now, and it is almost impossible not to see solar panels on some of the rooftops.


Figure 2: Glenrothes, Fife: one of thousands of domestic PV installations completed each month in the UK under the small-scale FiT scheme. Source: Finlay Colville, NPD Solarbuzz, May 2014.

Admittedly, the telephone and television marketing does seem to have subsided in the past few weeks – for some time, it seemed various telemarketing sales agents were sitting on the redial button to every household in the UK!

For those wishing to escape from the weekend cold calls by taking a visit to the local IKEA store, it has been hard to exit any branch in the UK now without seeing a Solibro panel proudly adorned by a couple of Hanergy salesmen advocating the benefits of putting thin-film CIGS panels on your house.

Such is the continued appeal of the rooftop market in the UK despite all the FiT adjustments in the past few years that, had solar farms not existed in the UK, the market would be vibrant with rooftop stories, and how successful the adoption rates were.

Anyone walking the aisles at the UK solar PV exhibitions can easily see a clear divide between component suppliers and installers that care little about the solar farm revolution and what the RO changes will mean for the industry. The rooftop market is a secure and safe bet, with system and component ASPs that simply mean higher margins than volume sales on the ground.

In fact, many suppliers have, whether intended or not, stuck to the domestic rooftop segment. Some simply have no well-defined USPs for the solar farm developers or don’t get enough product from HQ to pitch to solar farm developers: others merely choose to take the single-crate deliveries that are needed for the local installer base, including some surprising names such as SunPower, Panasonic and SolarWorld.

Figure 3: IKEA promotional marketing, as part of the deal struck with Hanergy in the UK, to sell thin-film panels to domestic consumers. Source: Finlay Colville, NPD Solarbuzz, October 2014.

Solar farming at large

Right now, UK solar PV deployment is approaching 50:50, in terms of capacity on roofs and on the ground.

So, in some respects, the protestations of the village hall discerners (“We are not opposed to renewable energy per se, but we think solar should be on the roofs, etc.”) may have to be re-evaluated. Do many of them know that rooftops have dominated UK solar PV activity until now? And how many of them actually have chosen to prosper from the government FiT scheme over the past few years, while at the same time teaming up to oppose a site being installed in the nearby farm?

If solar farms didn’t exist, the press would be awash with stories of domestic rooftop activity, and the success of the segment in approaching the 2GW level. But the alarm bells are firmly on the ground today in the UK and how administrators can put a brake on the speed and scale of ground-mount solar farm deployment.

As we look at the overall split in rooftop and ground-mount capacity, there is little doubt that the ground-mount activity will gradually increase its overall share level. This is expected to continue through 2015, regardless of what happens in the current CfD auction.

Other countries cite the importance of energy security and long-term supply diversification, but for now, the UK is firmly betwixt and between as regards solar deployment levels, not to mention how to play the whole renewables thing with a single authoritative voice ahead of the May 2015 elections.

Maybe the competition between rooftops and solar farms has only now begun in earnest, and will evolve based on the success of developers such as Lightsource and Solarcentury that are presently talking up the potential of the, as yet, only untapped sector within the UK solar community – large commercial rooftops. Whether this shifts the rooftop/ground equation remains an open question and one that will not be fully known for another 12 to 18 months.

But for now, from the air, the refractive index driven anti-reflection properties of silicon nitride passivation layers are having their impact on the colour of the landscape, albeit often only when descending from 30,000 feet to one of the countries provisional airport locations.