The Environmental Audit Committee and Energy and Climate Change Committee say ministers are right to make changes, but are doing so "clumsily".
Government plans include restricting access to solar subsidies to houses meeting energy efficiency standards.
Thousands of solar industry jobs could be at risk, the committees warn.
On Wednesday, a group of companies and environmental groups won a legal judgement against one of the changes.
Central to their campaign was the Department of Energy and Climate Change's (Decc) plan to halve abruptly the level of feed-in tariff (FiT) that small-scale solar installations attract, from 43p per kilowatt-hour (kWh) to 21p.
The FiTs are paid by energy companies to householders and communities to subsidise solar electricity generation.
It had been expected that the new tariff would come into effect from 1 April; but in October, the government said it would apply to anyone installing their solar panels after 12 December.
The High Court ruled that changing the tariffs before the end of an official consultation period was "legally flawed".