Why do people seem to cling to the foolish notion that reducing solar output will solve anything? All it will do is lead to people using twice as many solars!
Simple construction fixes that would move the production (not the output) of solars into T2 levels, yet remain reasonable:
1) Carbon Plates instead of coal dust. The coal cost per solar is increased by a factor of 4, plus a little energy to compress them.
2) Reinforced Glass instead or regular glass: Essentially adds the cost of an alloy plate per solar (well, 6/7ths of it).
Not drastic changes, but ones that require a compressor, more materials, and a bit of extra energy to make.