A solarpunk society is going to have many of the conflicts any human civilization tends to see. By working on fundamental inequalities and striving to provide safety nets and stability, we can remove a lot of motivations for crimes, but there'll always be people who'll try to cheat others, take harmful shortcuts, or commit crimes for reasons other than necessity. Serial killers spring to mind. Even within a fairly equal society you may have people who feel they could have had more, that they've been cheated out of a birthright of capitalist millionaire-hood or some good-old-days existence, real or imagined

How do you handle law enforcement, how do you contain genuinely dangerous people?

There'll also be groups outside solarpunk communities. People who ascribe to old world values, who prioritize extraction and hoarding of resources, who push their externalities like waste onto others or their environment. They might be upstream, poisoning your water. Personally I see it as a fairly postapocalyptic setting, focused mostly on people rebuilding in a more thoughtful, deliberate, and inclusive way, so I don't think it's a stretch to say bandits and accelerationist survivalists will still be around on the fringes. Perhaps someone wants what you've built and they don't want to share it with you, perhaps they disagree with the entire premise of your society and want it to stop existing.

How do you negotiate with these people? How do you work out some kind of arrangement that improves things? Can you avoid violence when the other people glorify it?

Even if you don't think that stuff fits, that it's not utopian enough, any community will be plagued with conflicts over the best way to accomplish something, even if most members agree overall on the goals. Environmental movements are full of disagreements over which tradeoffs to accept.

Here's an example from something I've been thinking about recently: society needs a certain amount of steel and concrete, especially when rebuilding. You can reduce the overall amount, but that has other tradeoffs, you might need to harvest more lumber, deforesting certain areas, or cut back on housing or civil services, worsening peoples' lives. Or you meet the required amounts - steel and concrete both take tremendous amounts of heat to produce. Your community could build a solar furnace using a ton of pivoting mirrors, and a parabolic concentrator, or a traditional fired furnace/kiln. The former will cover much more land, destroying habitats, and any birds who cross through the solar flux. The traditional system will produce lots of CO2 and other pollutants, and require fuel whose extraction process also damages habitats and will cost money or trade goods for as long as it runs. This kind of conflict is almost worse because most people involved want to do the right thing and have considered the options, they just prioritize different aspects of the problem.

The genre is new enough that there isn't really a cultural collection of recognizable tropes. Which is really a big reason why I made this.

In the first campaign, there is one story about a high-stakes medical emergency and two stories that are similar to conflicts you might find in cyberpunk fiction, but reframed by the context in which they take place. You can read through the stories in the campaign module. Or join a play session. I think you'll have fun.