There may also be renewed enthusiasm for solar stocks among investors, Mr. Krop said, as the prices of panel components like polysilicon, wafers and cells have been edging up since the beginning of the year.
He worries that SunPower, First Solar and others may be overstating prices of panel sales that go to the companies' installation divisions and recognizing revenue aggressively.
That has allowed Chinese producers to drive down the price of panels by three-quarters over the same period.
It is undeniable that massively subsidised demand has been largely responsible for recent sharp drops in the price of panels.
Its price rose from $25 a kilogram in 2003 to as much as $250 this year, abruptly halting the downward march in the price of panels.
But as other costs of solar systems also decline, marginal increases in the price of panels may not be as important, Mr. Kann said.
But large German subsidies for solar installations caused a sharp spike in the price of panels from 2006 to 2008 as supply tightened.
In the past six years, the price of panels has dropped by around 70%, making it as cheap as fossil fuels in some areas.
First, hefty investment in sunnier countries means the price of panels will keep falling without much help from British taxpayers; government cash might go much further in a year or two.
