Higher latitudes may be less favorable for solar due to needing more panels to generate a given amount of electricity.
Check out Project Sunroof. It is a project by Google. You enter your address and electric bill information. It calculates the amount of sunlight you receive, system size, etc. Then you can try various scenarios to see the approximate cost and payback time - lease/buy, large/minimal size. It is a good ballpark estimate.
In our state (and likely others) there are variations in the R rating of different communities which affect the # of panels needed as well. Our neighborhood has a high R rating but my brother’s neighborhood is higher and others are lower. The higher the R rating, the more electricity produced (on average) for the # of panels installed.
Yes, if it is cloudy more often, then you will need more solar panels to generate a given amount of electricity. Local features like trees, hills, other buildings, etc. can also affect a given building’s solar effectiveness. Or perhaps, as mentioned previously, if bird droppings accumulate faster than rain washes them off, that can be a local factor to consider.