Hardware costs about $1/W (for grid-tie PV, not a battery system.) Labor costs $1 to $3/W.
$20k in material and $40k in labor seems about the right proportion to me, considering the effort involved. But, too expensive for GT PV, might be reasonable for large battery system. Ratio was different back when panels cost $4/watt compare to $0.50/watt today (and minimum wage has doubled). If a battery system, battery is largest portion of cost, and I think labor should be a smaller percentage. For instance, $10k of PV with $20k to $30k of labor, plus $10k of battery with < $5k of labor.
Try amortizing cost over expected lifespan, i.e. divide by 10 or 20 to get annual cost. Divide that by 12 to get monthly. If answer is more than your utility bill, it obviously will cost money not save money, assuming present rates. It is possible for GT PV to save money (but not with expensive labor and cheap utility rates.) Battery based systems probably cost more than utility, unless a large cost to bring in transmission lines to a remote parcel.
To me, most of the effort is physical mounting of panels. If done half-@$$ed, with screws from feed through shingles, I guess it could be quick. I would want very good flashing, and standoffs attached to rafters not just sheathing. I assembled ground mounts of 2" steel conduit.
Grid-tie is easy, if net-metering gives you 100% of retail price for credit.
Web sites for "insolation" show effective hours of full sun per day, for your location and panel orientation (assuming no shade).
In my San Jose location, a 1kW array produces average 5.5 kWh/day throughout the year. Multiply by 365 for kWh/year and compare to utility bill.
For a battery system, use insolation on a summer day for summer loads, winter day for winter loads. Something like 7 kWh per day out of 7kW system in the summer, 2 kWh/day in the winter. Compare that to daily consumption, a utility bill divided by 30.
Battery needs to supply at least one night's consumption. Maybe more, depending on pattern of production and consumption. Traditionally, 3 days of use to get by when sun is hidden. Based on 50% depth of discharge for lead-acid, 80% or 90% for lithium.
Battery inverter needs to supply starting surge of A/C, which is either "LRA" locked rotor amps, or 5x operating current.
My system has way oversize PV, banking power with net metering for electric heat in the winter. (I also have gas available).
My battery is barely one night (old refrigerators are hogs.)
During the summer, PV runs A/C and charges battery at 0.2C
