More than 125,000 UK homes put solar on their roof last year. That's according to the UK's Department of Energy and Climate Change (DECC), which recently published statistics on small-scale solar PV installations. The numbers also show that a total of 700MW of solar, the equivalent of powering 212,000 homes, was installed on buildings and in ground-mounted solar farms thanks to the Feed-in-Tariff (FiT) over the course of the year.

All seemingly good news, but here's the rub: The growth in demand for residential solar in the UK has meant that --  for the first time since 2012 -- the tariff paid out for that size of system will reduce, not just because of the automatic reduction every nine months but instead because of the healthy number of installations towards the end of last year. Furthermore, slightly larger solar PV installations between 10kW and 50kW – often on schools, village halls or business units – grew by over 50 per cent between October and December 2014 as compared to the previous three month period.

In short, there weren’t quite enough installations to trigger a reduction in the tariff for this size of scheme.

“These latest statistics show that the FiT solar PV market is seeing healthy growth with plenty of solar going up on domestic and commercial roofs as well as small solar farms," said David Pickup, business analyst for the Solar Trade Association. "We are particularly pleased to see good levels of growth in the large rooftop market with 33MW of solar – 164 installations – installed in the last three months of 2014. That's more than double that in the previous quarter.”

But the Solar Trade Association warns that this isn’t enough. "As we have shown in our model of the Feed-in-Tariff budget, we need to see more solar going up on roofs and more gradual reductions in the tariff to get to the industry’s goal of subsidy-free solar," Pickup explained. "Our Solar Independence Plan sets out how we can restructure the Feed-in-Tariff to get more solar for very little extra money and give a path to zero subsidy.”

The largest projects that can qualify for the Feed in Tariff – those between 50kW and 5MW that include small solar farms and big factory roofs – saw deployment high enough to trigger a reduction in tariff, but this reduction was due to happen anyway because of the nine month automatic degression rule, the Solar Trade Association stated.