Do the Math

Do the Math

To determine if investing in rooftop solar makes sense for you, be informed.

A consumer considering going solar typically wants to know the following things:

  1. What size solar system they need to cover their utility bill
  2. What size solar system can fit on their roof;
  3. How much do the solar panels they need cost;
  4. What would be their return on investment if they were to buy such a solar power system; 
  5. The solar incentives, solar rebates, tax credits and feed-in tariff they are likely to receive; and
  6. Whether they are eligible for a zero-down lease or finance product and, if so, will the power bill savings cover the cost of the monthly solar lease repayment

The cost to purchase and install a complete grid-tied solar photovoltaic (PV) system on a home will vary widely depending on factors such as the cost of options you may select--battery backup power storage, or the costs of building preparation, such as new shingles. Costs can also be higher if you add other features or have special installation needs (such as application over tile roofing) or you choose to use special mounting systems (such as sun tracking systems). Other factors may also affect price, including, but not limited to, your location, the building condition, type and location, its wiring and warrantees offered.

Sizing your system correctly so that it provides the optimum return on your investment requires a closer look at:

  • Your patterns of electricity use
  • How much power the panels will generate when they are placed in the orientation of your home.

A system that is oversized for your house could cause you to send a larger amount of excess energy to the grid. Payment or credit for this exported electricity is determined by your cooperative’s rates and policies. But, a system that is undersized could be unwise; too, if paying a bit more would significantly increase the benefits.

Once installed, how much money will you save?
The amount you save, if any, depends on many factors:

  • What size solar system does your home require? The bigger the system, the more expensive your upfront costs.
  • How much the solar panels cost. PV panels with high efficiency ratings are more expensive than lower rated panels.
  • What commercial rebates are available? State and local tax credits can also defray the costs.
  • What’s the solar rating of your home? The solar rating is a measure of the average solar energy (also called "Solar Irradiance") available at a location in an average year. The higher the rating, the more potential energy savings.

To determine your payback period, click here.

Financing and Tax Incentive Considerations
You may be paying for your own system at the time of installation, and looking to be paid back in savings on your electric bill. There are other financing options, such as leasing the system or borrowing the money to pay for the project. There are also incentives available, such as tax credits, which can make the project more favorable to you. You will want to look at both South Carolina and federal incentives.