Four (4' x 10') Solar Thermal Panels located on my Garage

The first renewable energy system we got was a Solar Thermal system. There are lots of ways to get energy from the sun. When people think of solar power for their homes, they typically think of two main types. One is solar thermal, which takes heat out of the sun’s rays and puts it into the house or heats the water directly. Solar thermal direct transfer is the most efficient type of solar energy to produce. It is done even better if it is designed into the architecture home, so you don’t need a separate system. The other method turns the suns energy into photovoltaic energy and creates electricity to power electronics. (I will do a separate post specifically on the Solar PV system shortly.)

Our solar thermal system is designed to heat our water for our domestic hot water supply and also has what is called a heat assist system that is designed to pre-heat the air prior to it going into our furnace, which is powered by natural gas. The system is over sized for the summer (as we only need hot water in the summer), but the extra capacity is designed for heating our home in the winter. It offsets about 70% of our hot water heating in spring, summer and fall and offsets about 70% of our home heating in the fall and spring and about 50% in the winter.

In addition, we changed out 2 two-zone HVAC systems for 1 four-zone high efficiency system that only heats and cools the floor we are on. So we have two of the floors we are rarely on to “off” and have the other two floors set to the specific times were are mostly on the floor. I wanted to make sure we were only conditioning (heating or cooling) the floors that we were on, when we were on them. It seemed to be wasteful to me to heat or cool the basement except for on the rarest of occasions.

Our system is:

• Four (4) 4′ x 10′ AET Solar Panels were installed on the garage.
• A 120 gallon storage tank to store the heat collected from the panels.

I frequently get asked what our return on investment (ROI) for our solar system/s will be. We didn’t do it for a ROI, we did it because we want to get off (climate destabilizing) carbon based energy and help motivate more people to move in this direction. However, there is a tremendous ROI on this and a hedge against future energy price increases.

Currently, we save about $900 to $1,000 a year (based on our usage this year vs. last), so our payback is ~12 years if natural gas stays at today’s rates. The systems should last at least 25 years, so the internal rate of return (IRR) on initial investment of about 8% and the net cash of $18,028 if the system lasts for 30 years (including the $10,472 system cost) and  assume that energy prices remain the same (which is highly unlikely in my opinion and doesn’t seem to be the long term trend.)

System Cost:                        $26,180
30% State Rebate:                -$7,854
30% Federal Rebate:           -$7,854
Our Cost:                              $10,472

Our system was installed by Solar Service Inc. and we think they did a great job. They are certainly pros in the area:

Solar Service Inc.
7312 N. Milwaukee Ave.
Niles, IL. 60714
Tel 847.647.9312
Fax 847.647.9360

Here is a copy of our Solar Service Thermal Contract