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A few years ago, I began writing regularly about electric cars and the batteries that power them – technologies that will help humanity stop relying on fossil fuels. And as the bad news about the damage caused by climate change continued to mount, I began to worry about my own carbon footprint.
Last year my wife and I got solar panels for our roof. Then we replaced our air conditioning system and received a model with a heat pump function. Shortly afterwards, our boiler leaked and we got a new high-performance boiler. Then we bought a battery electric car.
We haven't reached a carbon-free lifestyle yet. The new boiler burns natural gas and we keep our old gasoline-powered car. We also have a stove and fireplace that run on natural gas. Still, our CO2 emissions will be far lower in 2021 than in 2019. And we are on the way to radically reducing our CO2 emissions over the next ten years.
Government policy has been of great help here. The federal government offers generous incentives for the purchase of solar panels and electric vehicles. The District of Columbia we live in offers additional incentives for both. These have not only lowered our expenses directly, but also helped manufacturers achieve economies of scale that made these technologies affordable in the first place.
So I thought walking through the experience might inform – and perhaps inspire – others who might consider a similar jump.
Solar on the roof
Enlarge /. There are 8.5 kW solar panels on my roof. In the background you can see our converted chimney and the condensation unit for the heat pump.
Timothy B. Lee / Ars Technica
My green energy odyssey started with solar panels. My wife and I live in a row house in Washington DC with a gently sloping roof facing south. With no tall trees behind the house, it is ideal for generating electricity all day.
In spring 2019 I received offers from two solar companies. One company wanted $ 35,538 for an 8.5 kW system with 26 panels. The other company quoted us $ 33,372 for an 8.64 kW system with 24 panels. Either way, we will receive a 30 percent tax credit worth more than $ 10,000, which will keep the net cost below $ 25,000.
We decided on the more expensive provider. The cheaper bidder wanted to anchor the solar panels directly on the roof, while the more expensive proposal would hang the modules on beams attached to the parapet walls on either side. The first company assured me they could seal the roof like new, but the idea of cutting into the roof made me nervous.
Later, the winner told us that our roof was near the end of its life and would cost more to replace after installing solar panels. So we decided to have them replace our roof. Our chimney was also in bad shape, so we had another company remodel it. This increased the project cost by $ 17,482. We financed all of this – and the HVAC upgrades that I'll discuss shortly – with a home equity loan.
The roof was installed in early August. The solar panels arrived in October. Then waited a month for Pepco to connect the system to the mains. Our system was finally active in November 2019.
Solar panels only generate electricity during the day. So if we wanted to build a self-contained system, we would have had to buy batteries to store excess electricity during the day and use it at night. Fortunately, the DC law requires our electricity supplier Pepco to perform what is known as the grid measurement. When we have excess electricity, Pepco credits us with retail prices, effectively providing us with free energy storage.
Our solar modules pay for themselves in five years
In 13 months of operation, our system generated more than 11 MWh of electricity, which is estimated to have saved us $ 1,250 on our solar system website. Our electricity bills reflect this. For the year prior to installing the solar panels, our electricity bills totaled $ 1,254. The following year we only paid $ 72.
Nevertheless, it would have taken more than 20 years for the solar modules to pay for themselves simply because of these electricity savings. Fortunately, free electricity wasn't the main benefit for us.
According to the DC law, Pepco has to obtain an increasing proportion of its electricity from renewable sources. Pepco can either generate its own renewable electricity or purchase Renewable Solar Energy Credits (SRECs) from third parties like us.
Thanks to DC's strict green energy needs, SRECs in the district sell for more than $ 400. Each SREC represents 1 MWh of electricity, so our solar modules generate around 10 SRECs per year. Therefore, we can expect SREC revenues of up to $ 4,000 per year. So far, we've received three quarterly payments totaling $ 3,647.
When you combine the SREC revenue with our electricity savings, the solar panels will likely pay for themselves in about five years.
Americans outside of DC probably won't get that much. Many states do not have an SREC program and those that have lower SREC rates.
When we installed our solar modules in 2019, they received a federal loan of 30 percent. That number dropped to 26 percent for 2020. It should drop to 22 percent in 2021 and to zero in 2022. However, Congress was just passing legislation to extend these deadlines by two years. The 26 percent credit will now be available until the end of 2022. After that, it will drop to 22 percent in 2023 and then to zero after that.
On the other hand, the cost of solar panels continues to decrease. And some parts of the country get more sun than Washington DC. So, if you live in one of the sunnier states in America, solar panels might be a good investment even with little or no government assistance. And yet it's good for the environment.
Enlarge /. The condenser for our heat pump. It dissipates heat in summer and dissipates cold air in winter.
Timothy B. Lee / Ars Technica
When we decided to replace our air conditioning in early 2020, we didn't think about reducing our carbon footprint. The condenser for our old air conditioner was noisy and took up space in our tiny back yard. When we were planning to put solar panels on our roof, we wondered if we could put the capacitor on the roof too.
Our original plan to do both at the same time didn't work out. A few months after installing the solar panels, I hired a company to install a new system on the roof as the old one was near the end of its life.
We decided to pay an additional $ 1,000 for a version that doubles as a heat pump and can both heat and cool our home. The total cost of the air conditioning – including heat pump power and crane rental – was $ 12,666. With the purchase of the heat pump, we will likely get a $ 300 tax credit and a discount from the District of Columbia.
Weeks after installing the new air conditioning, the oil boiler that feeds our radiators leaked, creating a puddle of water in the basement. I've wanted to get rid of this old kettle – and the huge oil tank in our basement – for years. The leak accelerated our schedule. Instead of trying to save our aging cauldron, we decided to replace it. It was July so we had plenty of time to get a new one.
After examining the options, we decided on a highly efficient condensation model. We have a "combi" unit that doubles as a flow heater. It hangs on the wall and takes up dramatically less space than our separate boiler and water heater before. It cost $ 10,500. I received a $ 825 discount from the District of Columbia and may be eligible for a $ 150 tax credit.
Traditional boilers waste heat by sending a lot of steam down the chimney. In contrast, a condensing boiler cools the flue gases to convert most of the steam back into water, with a few additional percentage points of heat being extracted from the process. These cooler, more humid exhaust gases cannot reach a conventional chimney. Instead, condensing boilers use a plastic exhaust pipe that protrudes from the side of the house and is angled slightly down so that the condensed water flows outside.