I am building an ADU in Pacific Grove and solar panels came up as an option. Here is some information that you should consider when researching solar.
1. Roof and house orientation. How much surface solar modules cover on a roof or how big the installation is on the ground makes a difference in the amount of energy produced. Generally, they are placed facing south or west to be exposed to the most sunlight, optimizing power. In Pacific Grove, we have a lot of foggy days and many neighborhoods have tree cover so it might not make sense. Get a solar energy expert to come out and evaluate your property before proceeding.
2. Weight on the roof. Make sure your structure is able to handle the weight of the panels and equipment. Roof replacement or fortification may be in order which would add cost to your project. Also make sure your installer clearly explains how the installation will be done.
3. Panels. In recent years, panels have become more efficient, thinner, and better looking so educate yourself on products and companies before making a decision.
4. Number of panels: The number of panels installed is generally based on the amount of electricity occupants use, which is why an installer often asks for 12 months of electric bills. If an owner of a solar powered house uses more electricity, they might request a larger array,
5. Lease of buy? A typical panel system might run between $15,000 and $25,000.
If someone pays upfront, it may take 7 to 10 years for a payback, but if someone leases the system, the savings will be less per month, but the homeowner has no upfront investment. You'll need to do the numbers for your particular situation.
6. Local and community rules: Cities and planned developments may have specific rules about exterior features of a home so always check with your local jurisdiction and home owners association so you understand the do's and don'ts
Keep in mind that you will still pay a fee to be connected to the grid so getting solar might be more of an ethical consideration versus a true cost saving measure.
Source: Realtor Magazine, September 30, 2021. What Home Owners Should Know About Solar Panels