In many (most?) areas, solar systems are considered "overimprovements" from the perspective of appraisals.
This generally means that any increase in home value (increasing appeal to the buyer directly) won't translate to a higher loan amount from the bank (which will only loan out the on-paper valuation), restricting the ability of the buyer to actually pay the higher price they would otherwise be willing to pay.
This could change as solar systems proliferate, making them almost a "standard" feature of most houses. It also wouldn't affect sales to cash-paying investors, which in some markets are the main buyers, since they don't need to qualify for loans anyway (and therefore can ignore appraisals).
Either way, I wouldn't bet on it increasing the home's value more than ~40% of the cost, if that.
This generally means that any increase in home value (increasing appeal to the buyer directly) won't translate to a higher loan amount from the bank (which will only loan out the on-paper valuation), restricting the ability of the buyer to actually pay the higher price they would otherwise be willing to pay.
This could change as solar systems proliferate, making them almost a "standard" feature of most houses. It also wouldn't affect sales to cash-paying investors, which in some markets are the main buyers, since they don't need to qualify for loans anyway (and therefore can ignore appraisals).
Either way, I wouldn't bet on it increasing the home's value more than ~40% of the cost, if that.