I don't know, we want people to pay the price of the electricity.
Obviously we can see it as each person has an allotment of the total generation, there is a case for that, but the marginal price is important as well.
If someone uses additional electricity then this requires a gas plant to be turned on/up. That's the key issue.
If you force someone to sell electricity for 15p when it costs them 30p to buy more of it then they are going to go bankrupt.
Also, we could sell electricity to other countries - how much should we charge for that? Generators might be selling to someone for 15p when someone else is offering 30p. That is leaving free money (from their perspective) on the table.
Fixing
In a way, though, we are fixing aren't we if we aren't on an agile tariff.
The supplier is offering to sell us at a price for the upcoming period.
Are we saying we would force wind farms to accept less money than they are offered?
In which case I'd say they should charge what they can and we claw some back through an 'excess profits tax' which is what should have been done (properly) after the Russian invasion of Ukraine.
Use that tax revenue to support those in need rather than giving everyone cheaper electricity at a time when additional electricity has become much more expensive to generate.
Owning your own generation
Having your own solar panels means that you get the benefit when the electricity price goes up.
Ripple offer a scheme to invest in a wind farm and you get the share of the benefits. That seems like a possible way to guarantee/limit your own costs.
Renewable future
In the long run in countries like the UK where there isn't a lot of hydropower, electricity is going to be extremely cheap at some points in time (when it is windy or sunny) and very expensive at others (when it is neither).
Hence why it is sensible to encourage people to buy batteries, EVs and smart water heaters which can be heated at times of surplus!