If you produce something and systematically sell it for profit it's perfectly normal. It's not your kids' lemonade stand or a garage sale we're talking about here.
The challenge is to do it in such a way that still stimulates the practice, not punish it. Simply calling any form of taxation "dumb" is not constructive.
Also, it's not just the simple "Jimmy has a solar panel on his roof" scenario we're talking about here. Collective solar energy initiatives on residential properties are becoming a real industry.