There are some really handy databases with detailed insolation data available for sizing your solar projects. https://nsrdb.nrel.gov/ https://nsrdb.nrel.gov/ i

There are some really handy databases with detailed insolation data available for sizing your solar projects. https://nsrdb.nrel.gov/ https://nsrdb.nrel.gov/ is one place to find this stuff. Years ago I worked on environmental monitoring systems for snow and ice management. One of the things I did was help spec out solar systems for remote installations in Alaska and Canada. The basic issue was "How much sun will there be in a typical summer?" combined with "How much power can we store in our batteries?" and "How much power can we draw from the lead acid batteries without them freezing?" (who knew that a discharged battery freezes at a lower temperature than a charged one? I sure didn't). It's a pretty straightforward process, actually. The company I worked for had a pretty detailed spreadsheet to help with bids, but essentially you: 1. look up the insolation data for the install site in one of the databases with that info (like https://nsrdb.nrel.gov/ https://nsrdb.nrel.gov/) 2. compute rate of loss over time for your installation (power consumption +_self-discharge) 3. look at the battery datasheets to determine how much you can discharge the battery at any given time based on anticipated temperature ranges 4. work out what your tolerances are for temperature and insolation variability Usually there would be a couple of options that were in the cost sweet spot where you had a bit more solar and bit less battery or vice versa. Some of these sites were up around the arctic circle, so battery was pretty important in those cases, since you're looking at months without appreciable sun combined with low temperatures. This wasn't even the major part of my job, but it was a small company and I wore a lot of hats.