Money is not inheritly bad, just think of it as a tool to make accounting easier.
The problem with capitalism is the unconstrained protection of capital and overreliance of commodification to all sorts of human activities, thus creating unjust hierarchies. Some things might be suitable in a market setup, but most large scale issues concerning many stakeholders need to be managed in a more democratic way by the community. In any of these cases we would still need a convenient way to do accounting, so money will still exist.
Even if we do abolish money in a solarpunk society, the Lagrangian multipliers of whatever optimization goal the community has agreed upon will still be there, so we will just have to account for the active constraints in a more implicit manner. It would be much easier to communicate with each other with the Lagrangian multipliers themselves
We can argue that in a solarpunk society monetary value of stuff and labor becomes more connected with the actual environment and social values they represented. But what does this actually means? In the current capitalist society no economic theory (neoliberal or socialism) can explain economic notion of “value” in a consistent manner (neoliberal theory easily turns into circular reasoning while Marxism theory requires implausible mathematical assumptions), so this is something economists in a solarpunk society has to figure out.
Spatial and temporal variability are main talking points against variable renewable energy technology adoption and in favor of conventional ones. Now we know where this fixation over constant energy originates from.