The fact that you can correct for externalities with certificates seems to be a consensus with economists. But people seem to be unable to understand how they work.

The EU/countries in the EU have a CO2 certificate system AND other regulation (promotion of solar/wind, etc). When the point of a certificate system is for the market to allocate the efforts to that place where you can save CO2 most efficiently. The added regulation only distorts the certificate market without actually helping to reduce the CO2 produced, as the amount of CO2 produced is set by the amount of certificates issued. And by funding solar, you just make certificates cheaper and increase pollution in another sector.

Another weird thing is, that certificates are grandfathered to companies to keep the prices down, when the gifted certificates result in an opportunity cost of using them (since you could sell them at the same price), making the price rise at just the same rate as if the company had bought them. The only result of grandfathering being that it gifts money to established companies, distorting the market.