One thing to look out for is the type of solar panel. Industry is coming out with better more efficient models.
The formula is (price of solar panel system) compared to electricity cost compared to the life cycle of solar panels. This info is not usually given. for eg. do the panels last 20 year (and how is the efficiency after 5, 10, 15, and 20 years. When do you have to replace the solar panels and at what cost. Will you get a solar hot water heater?
Another key thing is storage space and how much electricity you can store with current technology. There are different types of storage systems (hydro, deep cycle batteries, Lithium-ion batteries. All have advantages and disadvantages.
Keep in mind that for your house: Normal house hold items: Fridge, stove, washer, dryer, dishwasher, heat (electric), floor warming devices (water or electrical), heat pumps, air conditioning, thermal well (used with certain heat pumps), lights (today 24 Volt systems using LEDs might be better than 120 volt system (current tech-), electrical outlets separate from lighting circuits, hot water heater (gas or electric).
Additional circuits: Workshop equipment 120V or 240 v. Most houses have 200 amp service, but how much of that will be in the workshop?
Additional electrical requirements: Car charger for electric cars X (how many e cars).
So you need to take in your future electrical load into account, if you plan on a workshop and electric car plus normal household load.
Also if installing solar, will it be on the house roof or off to side. How its installed on house roof. The latitude you are at determines the proper angle the solar panel have to be installed at. This is usually different from roof angles. roof angle depend on climate and weather conditions.
Solar panels should not be installed on the north side of roofs... eg look at a tree, moss grows on the north side of trees, usually meaning no sunlight....South side preferred, because the sun travels thru the south from east to west....sun exposure.
Another thing to look at is hydrogen making. Say e car are not going electric, but are going to hydrogen instead. Could you produce your own hydrogen for you hydrogen fuel cell on your car/truck.
Try looking on utube for people that live off grid and use solar power. (take into account alot are US programs and hence the money is in US).