Commercial Solar FAQ

The size of your company’s solar energy system depends on several factors – your building’s energy usage, available rooftop or ground space and any capacity limits set by the utility. These factors, along with your company’s budget, will determine how many solar panels will go on your roof.

If you just want to know the maximum number of panels that can fit on your rooftop, you can fit approximately 10 watts of solar per square foot on a flat unobstructed rooftop. For instance, 100,000 square feet x 10 watts per square foot = 1,000,000 watts or 1MW. This is equivalent to (2,000) 500-watt solar panels.


Pitched rooftops can fit approximately 14-16 watts per square foot. For instance, 100,000 square feet x 15 watts per square foot = 1,500,000 watts or 1.5MW. This is equivalent to (3,000) 500-watt solar panels.

Almost all buildings are compatible with solar. The key is to start with a feasibility study that includes a detailed structural analysis of your building before getting to far in the development process.


This analysis will confirm that your facility’s rooftop framing can hold the weight of the proposed solar project based on the region’s dead and live loading requirements. See our blog Is Your Rooftop Ready for Solar? for more information.

Solar panels come with power production warranties of anywhere from 25-30 years and are designed to last for 40+ years. That’s a long time and solar is a long-term investment. That’s why it’s critical to know how old your roof is before installing a solar energy system. See the following FAQ, ‘Do I need to replace my roof before installing solar?’ for more details on the relationship between your rooftop and the solar installation. 

That depends. As noted in the previous FAQ, solar installations have power production warranties of anywhere from 25-30 years. Prior to installing a solar system, it’s critical to make sure that the life of your rooftop and the expected life of the solar array are in relative alignment.


One mistake we see made too often is putting solar on an old roof. In that situation, the panels will outlast the roof, leading to a costly removal and reinstallation of the solar panels during the re-roofing process.


Among other things, conducting a feasibility study for the proposed solar project gives you an opportunity to compare the current age of the rooftop to the expected life of a solar installation and determine next steps. Generally, if your rooftop top is due to be replaced in the next 5-10 years, we recommend an early replacement. This allows you to avoid doing the above mentioned removal and reinstallation. See our blog Is Your Rooftop Ready for Solar? for more information.

Not all solar panels are created equal. To be safe, we always recommend market-leading manufacturers with a proven track record of performance.


Solar is a long-term investment and, while most panels carry similar warranties, it’s a good idea to go with a solar panel manufacturer that will be around long-term in the rare event that there is a product failure.

Most commercial solar arrays are grid-tied systems which means when the grid is down, your building will experience a power outage. However, it is now common, and increasingly affordable, to add a battery that can provide power during an outage. Battery based systems can also provide additional benefits for your facility beyond providing backup for critical equipment.

The policy and incentive landscape for solar and energy storage is subject to change. For current federal, state and local policies and incentives in all 50 states, visit the Database of State Incentives for Renewables and Efficiency. Don’t want to sift through all the data? We’re happy to discuss what’s available based on your company’s specific location, utility and eligibility.

Typically, there are three financing options for both private and public sector companies. The option you choose depends on several factors, including any budget limitations, debt capacity or other restrictions your company has in place for such projects.

  • Cash Purchase or Capital Expense (CAPEX) – requires budget and money. The owner of the system can monetize the incentives such as tax credits and depreciation while paying a levelized cost of energy of 2-5 cents/kwh of solar generation.
  • Debt-Financed (AKA – capital lease) – This is a typical loan from a financial institution that is financed over a fixed term length. For debt-financed systems, the lessee can still monetize the tax credit and depreciation incentives that are typically monetized under a Capital Purchase, however the projects can achieve positive cash flow in the first year while using internal capital for other operational needs such as production. The owner of the solar energy system is a lessee to the lessor (bank or other financier), the owner still gets the incentives without the upfront investment and the system can achieve positive cash flow in year one.
  • Operational Leases/PPA’s/EaaS –Operational Leases/ PPA’s (Power Purchase Agreements)/ EaaS all have a similar transactional structure and allow for a 3rd party owner to own and operate the system while monetizing the incentives. The facility owner leasing the system still gets to enjoy the energy reduction benefits from solar while keeping the asset off of the company books since the lease/PPA payment is considered an operating expense. This type of financing is ideal for agencies and businesses that can’t use the incentives, don’t have a CAPEX budget, or have reached their debt capacity and can’t take on a loan.

We get this question all the time and, the truth is, compared to what you’re doing now, solar will always come out on top.


Better question: What’s the Levelized Cost of Energy (LCOE) or what’s the true cost of paying for solar right now versus paying for conventional electricity?


Even BETTER question: What’s the ROI for your current utility bill?


That being said, CAPEX projects generally have a 5–10 year simple payback. You can think of a CAPEX solar project as paying for 30 years of electricity upfront. Financed projects can get into positive cash flow in year one if energy savings are greater than the loan payment.

Great question! Call Pisgah Energy today at 1-828-615-6056 to discuss your energy needs and goals. Our management staff has 50+ years of experience in the solar industry and will guide you through the entire process – from concept through construction.