Five checks to make before investing in rooftop solar

Before installing solar panels, homeowners should weigh their electricity use, roof orientation, financing and the size of the system, DR reports. SolarSim director Erik Olsen recommends comparing offers from several suppliers before making a decision.

1. Your electricity use

Generally, the more electricity a household uses, the more it can save with solar panels. The biggest savings come from using the electricity generated at home, Olsen says, because households receive a lower price for power they send to the grid.

Olsen does not set a minimum level of electricity use at which a system becomes too expensive. Homeowners who want to know whether solar could pay off should obtain specific offers.

2. The roof’s orientation and condition

A south-facing roof produces the most electricity, usually around midday, when households may need less power. East- or west-facing panels produce less overall but generate electricity in the morning or evening, when it may be more useful. A battery can also store power for later use.

Homeowners should consider whether they will need a new roof soon. Moving the panels to a replacement roof within, for example, five to 10 years would add a cost.

3. Whether you have an electric car

An electric car does not necessarily make solar panels a better investment. If the car is usually plugged in after its owner gets home in the evening, it will typically charge overnight, when the panels are not generating electricity, Olsen says.

4. How you will finance the system

A down payment may be required when taking out a bank loan, but having savings is not essential. Many banks offer lower-cost green loans for energy improvements. Olsen says the savings from a solar system can exceed the loan costs when borrowers qualify for a low interest rate.

5. Compare offers from several suppliers

For the investment to make financial sense, the system should not be larger than needed. Olsen recommends asking several suppliers for quotes so their calculations can be compared rather than relying on one company’s estimate.

Example for an average household

A household with an electric car typically uses 7,900 kilowatt-hours of electricity a year. SolarSim’s example recommends a system rated at 8.8 kilowatts peak, equivalent to about 22 panels.

The system would cost between 50,000 and 100,000, depending on whether a battery is included. A battery adds to the initial cost but can store electricity generated during sunny hours for use when power is more expensive, typically in the evening and morning.

The system could cover between 32 and 64 percent of household electricity use, depending on whether it has a battery. In the example, 32 percent would repay the loan in less than eight years, while 46 percent would take between eight and 10 years.

SolarSim says the figures are an example based on prices in 2025 and 2026, not a guarantee. Electricity prices vary from year to year: higher prices can shorten the payback period, while lower prices can lengthen it.