The Solar Powered Home
This past week we reached one full year of powering our household purely off of solar power.
We are an on-grid power system, so instead of relying on a battery system to store our energy on site, our solar panels feed the energy that they produce directly into the public electric grid to be used. We did this for a few reasons;
- It was more cost effective for us to tap directly into the electrical lines that run right by our property line, rather than invest in a battery storage system.
- Batteries on site would require space. Considering that our home is just 1,206 square feet, real estate is prime, and we didn’t want to sacrifice any to that infrastructure.
- Being hooked to the grid ensures that on days the panels are buried under snow and ice, or weeks that we don’t see a bit of sun, we still have power. It also ensures that the most energy possible is being utilized on those days the sun is making more than we are personally using. The electric company “banks” our excess generated energy on those sunny days that we generate more energy than we use, then subtracts our used energy on those days that we use more than we produce. The kilowatt-hours (kWh) of energy that our array produces minus the kilowatt-hours that our household uses determines over a designated period of time if we produce more energy than we use, or if we use more energy than we produce.
During this first year using solar energy we successfully generated more energy than we used. We used 2,930 kWh for the year, an average of 244 kWh per month. And during this time we generated approximately 3,900 kWh.
This is pretty exciting stuff all around! To put this perspective, according to U.S. Energy Information Administration, in 2016, the average annual electricity consumption for a U.S. residential utility customer was 10,766 kWh, an average of 897 kWh per month.
You may be wondering how in the world our energy usage is so low?
When designing and building our home we used a construction manager who specializes in Green Homes. Our house is Energy Star Certified which means it is constructed with materials that guarantee the efficiency of minimal cold/hot air transfer, and is wired and outfitted with all low energy use appliances and fixtures. Also, the house is a passive solar design. This deliberate design allows us to use minimal cooling due to the awnings shielding the summer sun light from reaching our windows, and a cupola for heat release. It also means minimal heating is needed beyond the warmth of natural light that hits our windows by the angle of the house and placement of the winter sun. And our polished concrete floor acts as thermal mass to store and distribute that warmth. I’ll share more about our home design in another post soon.
Now for the good stuff of what a practical difference that annual production of clean energy makes!
This 3,900 kWh has offset ~ 2.7 Metric Tons of Carbon Dioxide.
That is equivalent to the CO2 emissions of ~ 2,883 pounds of coal burned.
And equivalent to greenhouse gas emissions of almost an entire ton of waste sent to the landfill (or) 6,393 miles driven by a utility passenger vehicle.
We often get asked what we paid for a system like this. And the answer is two fold. We paid $14,8xx for this system in December of 2016. However, over the past two years we have received almost 50% of that back in federal and NY state tax incentives. So ultimately this system has cost us $8,000.
It is indeed an investment. But, I consider it a worthwhile one.