Step 4: Powered by the Sun!

By Mark Adams

This is the final blog in the series on the stairway to Net Zero housing. Net Zero houses produce more energy than they consume. Most homes, regardless of their age, can be upgraded to become Net Zero. But even taking just a few of these steps will enable homeowners to reduce their carbon output as well as save on their monthly utility bills.



Adding rooftop solar is the subject of this blog. If you’ve taken the steps to weatherize and electrify your house, then powering it by the sun is the last step to achieving a Net Zero house. Rooftop solar a proven technology that’s been in use for decades.



Advantages of rooftop solar

  • Lowers your electric bill and protects you from future price increases

  • Net metering allows you to use grid power after sundown at no charge (up to the amount of excess generated by your panels during during daylight hours)

  • Increases the resale value of your home

  • Reduces your carbon output

How to find installers

Energy Sage offers a free online service for finding solar panel installers. Based on your individual situation and needs, they will provide you with up to three competitive quotes from pre-screened providers. You can compare the quotes online and then schedule a consultation appointment with your chosen installers. Here is the website to get started: www.energysage.com.


Note that some of the larger installers, such as Tesla/Solar City and Sun Power, do not contract with evaluation services like Energy Sage. As a result, homeowners may want to conduct an additional and wider search for installers.


Other considerations

  • Work with installer to estimate your kilowatt hour sizing requirements. This will determine the number of panels required and the price of the system. The estimates should be based on the last 24 months of your consumption history.

  • Include estimated consumption from future needs for large energy consumers such as heat pumps, electric cars, or electric water heaters.

  • Use Google's Project Sunroof (https://sunroof.withgoogle.com/) or tool from National Renewable Energy Lab (https://pvwatts.nrel.gov/) to estimate your solar potential, solar system size requirements, annual savings, and payback period.

  • Make sure installer is willing to work with a muni electric company and willing to come to Marblehead.

  • Never sign a contract with a door-to-door sales rep without researching the company first.

  • Monitoring services – the ability to do an online check of the performance of the entire system as well as individual panels is necessary to keep the system running at an optimal level. Some installers bundle a monitoring service with their offering while others partner with another provider which will offer the service separately at an additional cost.

  • New England weather should not be a concern. Any snow that falls onto the panels will melt rapidly and, on cloudy days, the panels will still provide quite a bit of power.

Financial rebates and tax credits

There are incentives offered by the Federal and Massachusetts state governments that will offset the cost of the installation of rooftop solar panels.

Federal tax credits

Homeowners are eligible to take a credit off their income tax liability in the amount of 30% of the cost of installing solar panels. Consult your tax advisor to ensure that you can take this maximum benefit.


Massachusetts tax credits

State residents can take 15% off their state income tax liability up to the maximum of $1000 per year.


Here’s an example. A family spends $30,000 to install solar on their roof, they are eligible for a federal tax credit of $9,000 and a state tax credit of $1,000. The net cost of their installation is $20,000.