Success is about product market fit - solving a problem for a large enough body of customers that you can repeatedly reach & service.

That isn't industry specific, but you can see how tech makes that formula easier because it becomes easier to reach a large body of customers and to build a repeatable process.

As for your idea, lead gen businesses struggle to receive funding - but can be successful if you can self fund/launch. My advice is to try the process manually at first. Can you find a customer and then get their solar funded, doing all the steps manually while you document the process.

If you can pull that off and analyze how to repeat it, you're off to the races