I started with one 400W panel to try this year. It's those panels that you can simply put in your garden, plug in a regular outlet, and it will inject directly in the house. Nothing goes back to the network as long as it is consumed locally first, so no need to have a specific contract to sell it, you will just lose the occasional extra watts that are reinjected in the network bt not paid. You just declare them to the enrgy distribution company. Those panels will however only work if you are connected to the network (for example, to avoid injecting power on the network while there is an outage and risking the life of the people working on the power lines)

That panel should produce about 500kWh per year where i live, for an estimated 100$/year at my current energy prices, and should be ROId in 7 years.

On a few sunny days where nothing is running at home, there will occasionally be more production than the house consume at noon.

For the next panel, there should be more energy that is not consumed at peak sun time of sunny days, so i considered buying the model with an integrated battery. But After calculations for my cases, the 'not wasted' extra enrgy would cost more than the current energy prices on the network. So either i'll buy a second one without battery and mine something with the extra power, or i'll just keep only one and just buy 1% of bitcoin with the money, i have not yet decided.

One small detail to know with those panels. They give you a 'smart plug' that will measure how much is produced, and connect to your wifi so yu can see the data in an app. That thing consumes at least 5W consistently. My single pannel should produce on a yearly average 50W. So by simply using it on a single panel setup, you are already losing 10% of your production! I keep it because it is a cheap way to know from wherever i am if there is still power and internet at home, for me this is an important information because i run things at home. But some people might have an interest to not use it and trade the loss of production monitoring for more 'usefull' power production