This plan is indeed radical. It punishes suppliers would can produce energy cheaply and efficiently by taking away their profits. It rewards suppliers using Russian gas by letting them sell for higher prices than everyone else.

All excess revenues above the cost of production would be taken by the state.

It incentivises renewable energy suppliers to turn off their generators, which will worsen the problem. If a wind turbine (for example) is broken or is due maintenance, it will be cheaper to turn it off than to repair it. Building new turbines will be financially suicidal.

What would make sense? Taxing profits or taxing income. This is not radical but it works well.

They also want to reduce consumption during peak hours using some crazy voucher scheme. Instead, they need to charge different rates to consumers at different times of the day. This is so simple and un-radical it is already common in many places.

They want to use the tax income to renumerate energy consumers (ie everybody). There is one simple and known way to do this, called UBI. The tax is re-distributed equally as a subsidy every resident.

In fact, the most effective solution is to raise a tax on all electricity energy and gas consumption, per kJ used. (Ideally prices are also set depending on time of day.) This further inflates the price and drives unessential consumption sharply down. This tax revenue is redistributed as a UBI. So people who use very little electricity make a good income. But every extra unit you use is very expensive.

You also need a way for consumers to measure the cost. For example website showing the price of boiling a kettle and of other common activities, in euros.

The solution is exactly the same for businesses.

The big advantage of the existing plan? Governments can choose the criteria for receiving grants and vouchers. So it can be selective, choosing (to some extent) who gets money. This power is the life-blood of politicians. It allows them to trade favours with businessmen. For example,

measuring the growth in energy costs as a proportion of revenues to trigger quailification for supports.

So the ROI government is planning to subsidise only the thirstiest energy consumers, the same ones they already have a strong political relationship with.

This is why the subsidies/vouchers/grants system is appealing to them. It allows them to look like they are solving the problem, while really setting up a scheme to trade influences with their political allies, and worsening the problem.