It has a 14.2 kW solar array on the roof.  The electricity from the panels powers the air-source heat pumps, runs all lights and appliances, and charges the electric car.  The house is still connected to the grid.  Any extra power that the panels produce during the day goes out to other electric customers.  At night, the house is powered by the grid.  But, over the course of a year, the panels produce as much power as the household consumes.  That makes our house a net-zero house.

 

In 2014, we participated in the Solarize program, which made it easy to install our tiny 1.5 kW (6 panels!) system.  At the time, we were using an average of 4 kilowatt hours (kWh) a day. The system was sized to our usage.

 

Fast forward to late 2018, when we decided to install a heat pump to heat our house, using the oil boiler as little as possible.  Again, through the Solarize program, we added 8 kW of solar generating capacity to cover the energy used by the heat pump.

 

In the spring of 2019, the boiler suffered an untimely death.  Rather than replace it, we added another heat pump to even out the temperature throughout the house, and, of course, more panels.  While we didn't have an electric car at the time, we were able to add enough capacity to cover the electricity needed to charge an EV.

 

We chose the "hyper-heat" heat pumps, which work better at lower temperatures, since they are our only source of heat.  Having grown up with oil boilers, it was a great leap of faith to rely on this new technology.  It's working out just fine, with the added benefit that they provide air conditioning as well.

 

Our house didn't become net-zero overnight.  We made changes over several years, having no idea in 2014 that "electrify everything"  was going to be how carbon emissions are eliminated.  An added bonus to the changes is having saved over $16,000 by not buying heating oil or gasoline.

 

Oh, and the electric car?  Fun to drive!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Image: Charging their electric car | Image credit: Sandy Tosi

 

If you are considering upgrading to solar and/or heat pumps, here are a couple of resources to guide you.  Check out your solar options through Energy Sage.  Find out about heat pumps and energy efficiency programs.

 

Sandy Tosi is a Sierra Club member.