The plummeting cost of solar panels has caused the government to revise upwards its forecast for solar energy use.
This has influenced the government's decision to reduce solar subsidies from this month.
But the solar industry said the cuts were a mistake and would prevent it from competing with fossil fuels.
The price of solar panels has reduced by 70% in the past few years as subsidies in many countries created a mass market and drew in Chinese manufacturers.
In the UK this prompted the government to withdraw subsidies from large-scale solar farms - above 5MW - from the end of March.
That in turn has created a temporary solar boom as firms race to connect to the grid in the coming days.
The Solar Trades Association said as much new capacity has been installed in the first three months of this year as in the whole of 2014.
But after April it expects installations to fall 80%, because most firms will not be able to compete.