The US Department of Energy has a great webpage on what to consider before going solar. If you decide you want rooftop solar panels then you can use this calculator.
Keep in mind that even for a residential solar system, there are economies of scale. You should install the largest system you can physically fit on your residential property. Also remember that everything is going electric. Induction cooktops, heat pump water heaters, heat pumps for home heating and air conditioning, electric cars, so you want to make sure you install enough capacity for the electrification of our world.
Consider that trees shade your house, keep it cooler in summer months, sequester carbon, are a key part of climate change mitigation and adaptation, and are a vital to our local ecosystems so consideration should be given to whether rooftop solar is the best option if it requires the removal of numerous trees. Check out this mass Audubon presentation in on balancing solar installations with habitat preservation.
Carlisle’s Community Choice Aggregation program allows residents to purchase 100% renewably sourced electricity for any electricity not coming from on-site solar.