Solar FAQs

MTE is committed to helping our members go solar. That's why we work to help members learn and understand emerging energy technology like solar, electric vehicles, and battery storage. If you have questions about solar, contact MTE and our in-house team of certified solar experts. The information is free and the advice can save you thousands on your solar installation.

Check out these frequently asked solar questions. For more information, go to to view our workshops, whitepapers, and learn about our no-cost ProSolar consultations.

Energy Production Questions

Photovoltaic (PV) systems generate solar energy using semiconductor cells to convert sunlight into electricity. PV systems contain solar panels to absorb and convert sunlight and inverters to change direct current (DC) into alternating current (AC). AC is the standard electrical power that we use in our homes and businesses. PV cells connect into solar panels mounted in an orientation to take the most advantage of the sun. That can be on rooftops, canopies, the ground, or integrated into roofing shingles or other building materials.

No. Depending on the season, a PV system typically generates power from 8 a.m. to 6 p.m., reaching its maximum output between noon and 1 p.m. when the sun is at its peak. When PV systems are not producing power, Middle Tennessee Electric and TVA provide other resources to deliver reliable electricity to homes and businesses.

Yes. However, a PV system generates less electricity when the weather is cloudy. A PV system might receive only 5 to 10 percent of the usual amount of sunlight on an overcast day, so the power output decreases proportionately.

Solar panels vary in size, wattage, and technology. A typical solar panel produces 250 watts of electricity and measures 3.25 ft x 5.4 ft, or about 17.5 sq ft. A 5-kW solar system requires around 400 sq. ft. of usable south/south-west facing roof area by applying typical solar panel specifications. This includes additional space to comply with fire safety standards.

PV systems generate more power at lower temperatures. Like most electronic devices, they operate more efficiently when it’s cooler. PV systems generate less energy in the winter than in the summer, but that’s due to the combination of fewer daylight hours and lower angles of the sun, not to cooler temperatures.

Many factors can affect the efficiency of your solar panels. These include:

  • The shading on your house
  • The orientation and tilt of your solar panels
  • How many sunlight hours your house receives during the day
  • The quality of your inverter
  • The temperature

Any combination of these factors can significantly impact the amount of solar energy your panels generate.

Financial Questions

ITC is the Federal Investment Tax Credit (ITC) Program issued by the government to support solar energy development in the United States. The ITC is a tax credit and not a tax rebate — before buying a solar PV system, check with your tax professionals about the implications ITC has on your finances.

Currently, the ITC allows residential and commercial members to claim a 26% tax credit towards the total investment of their system. This tax incentive as of today will end on December 31st, 2023 when it ceases to exist for residential members.

In addition to the ITC and accelerated depreciation (for commercial members), there are varying rebate and incentive offers, depending on the state where you live. Contact MTE’s distributed energy resource coordinator to get the latest information on solar rebates and incentives.

The time to recover the cost of your solar system installation can vary significantly based on several factors. With the current rate structures and incentives provided, an average residential solar system in the Tennessee Valley is about 10 kW and requires at least 26 years to pay off even with the ITC applied. Some members may not break even on their installation depending on their energy usage, PV system size, and maintenance costs.

The Modified Accelerated Cost Recovery System (MACRS) is a tax advantage mechanism that allows commercial members to accelerate depreciation of their solar investment over 5 years and thereby reduce their tax burden. This can result in a quicker return on investment for applicable commercial members.

Yes. You can set up personal financing for your solar system installation through your bank or preferred loan company. Your interest rate and loan terms impact your return on investment. If you decide to finance your solar PV system, we recommend shopping around to find the best interest rate and loan terms for your situation.

Maintenance & Ownership Questions

A typical solar system has a useful lifespan of 25 to 30 years, depending on the local environment and the system's durability. After this period, your solar panels will continue to generate electricity but at a lower efficiency.

Solar inverters have a typical lifespan of around 10-12 years, and you can expect to replace them at least once over the lifespan of a solar system.


PV systems typically have two types of warranties provided by panel manufacturers: a product warranty and a performance warranty. The product warranty usually covers 10-12 years of manufacturing defects, wear and tear, and environmental issues of the panels. Since panels become less efficient over time, the performance warranty guarantees a certain amount of solar production for up to 25 years. You can expect to get 90% of the advertised production for the first 10 years and 80% production until the system is 25 years old.

A solar inverter warranty should be a significant consideration when purchasing a system. Warranties may vary widely by manufacturer, so please contact your solar installer for specific warranty details.

Solar panels generally don’t require much ongoing maintenance throughout the system's lifespan, as there are no moving parts like tracking systems. However, inverters and other connected components may require periodic maintenance or inspection. MTE recommends annual routine inspections and maintenance to ensure your system functions properly and efficiently.

More about MTE Solar Programs

Yes. MTE offers free solar advice from our in-house NABCEP certified solar expert through the ProSolar program. This program allows members interested in solar to get a consultation over the phone or through email. If you’re thinking about purchasing a solar PV system, check out our ProSolar program to learn how MTE can help you make the most of your investment.

Through the Dispersed Power Production (DPP) program, TVA may allow a qualified solar PV system to sell excess generated power. Members can sign a contract with TVA to sell excess solar generation to TVA for roughly 2 cents per kilowatt-hour. The contract process can take 2-3 months, so we recommend starting this process before you have finished installing your system. Additional costs, hardware, and construction might be required before your solar PV system can safely connect to the MTE electric grid.

To find out the current details of the DPP program and how to set up your PV system to participate in this program, contact our distributed energy resources coordinator.

There are several ways members can offset their carbon footprint and invest in solar or green technology without having to buy or install a PV system at their home or business

You can learn more about MTE’s renewable programs at

Talk to an expert in solar. Find the right thing for you. 

We’ve got solar expertise on staff. Before joining MTE, Tim Suddoth spent over 6 years in the Solar Industry learning the ins and outs of sales, design estimating, permitting, commissioning, and installing solar systems. He holds certifications from NABCEP — the North America Board of Certified Energy Practitioners — the gold standard for solar. If you have any questions, Tim is available to talk to at no charge.