My Experiences With Solar Water Heating
Our Sun radiates an incredible amount of energy upon the surface of the Earth every day. This energy is powerful enough to drive our planet’s weather and support all of the life forms on Earth. It seems obvious that the Sun’s energy would be central to any home heating scheme yet this free energy source has been largely ignored by home designers opting for less permanent fossil fuel alternatives. If you are planning to free yourself from the gas or electricity grid then taking full advantage of solar energy is a must.
I am lucky to live in Saskatoon which is one of the sunniest places in Canada. We enjoy about 2400 hours of full sunlight here annually. Much of this comes during the summer months when we have long daylight hours due to our northern latitude. Our winters are also quite sunny from January on but our winter days are quite short with extremely cold temperatures so complete daily solar dependance throughout the winter is a challenge. I looked up the heating degree days statistics to give you an idea of our climate. Degree days are defined as follows by Environment Canada:
Degree-days for a given day represent the number of Celsius degrees that the mean temperature is above or below a given base. For example, heating degree-days are the number of degrees below 18° C. If the temperature is equal to or greater than 18, then the number will be zero. Values above or below the base of 18° C are used primarily to estimate the heating and cooling requirements of buildings. Values above 5° C are frequently called growing degree-days, and are used in agriculture as an index of crop growth. Values in the tables represent the average accumulation for a given month or year.1
January 1086
February 876
March 738
April 409
May 208
June 82
July 36
August 61
Septemeber 207
October 420
November 726
December 1002
Total 5852
These statistics were obtained from Environment Canada.
My planning for solar water heating began with a lot of research as usual. The factors I considered were system costs and efficiencies. I also took part in the home EnerGuide program and was therefore eligible to receive a grant of $1500 for the installation of a certified solar water heating system. This also had to be taken into account because it made purchasing a complete system more attractive than building my own from scratch.
The two systems I found to be the highest quality and locally available were produced by Thermo Dynamics Ltd. and Enerworks. Costs for complete 2 panel systems from these companies were around $5000-6000 to my door and my estimated cost for building the panels on my own and acquiring the other mechanical parts individually came to a total between 2000 and 3000 dollars. If I included the EnerGuide grant I would receive for the factory made systems then there was only a difference in cost of 1500 dollars. I decided the difference in cost wasn’t worth the effort and time of building a system from scratch.
The efficiency of the factory made systems was higher than what I thought I could achieve with a DIY system. My research showed me that with common materials I shouldn’t expect to achieve a panel efficiency much higher than 60% and factory made panels were typically rated from 70-80%. This higher efficiency was necessary for my application because I did not have much installation space for these panels. If I lived on a farm or at least had a large area of southern exposure then a DIY system may well have come out on top because the number one rule of thumb in solar collector design is that collector size is king. Why spend thousands on a high efficiency collector when you could just build one two or three times as big for half the price? You’ll end up collecting more energy with larger slightly less efficient collectors than you would with a small but pricey high efficiency model. Anyway, the factory made models won the efficiency contest due to my limited space available.
In the end, I decided to invest in the Thermo Dynamics Solar Boiler system. This system uses two 4 foot by 8 foot panels and includes a complete system control unit with a computer, heat exchanger and pump. I bought the system from Nexus Solar in Saskatoon who were very helpful with system design and installation questions. I chose to buy two panels in hopes of heating all of my hot water in the summer and also being able to contribute to space heating in the colder months with the use of a hydronic heating system. The cost of the system was about $5400 including shipping and I also needed to buy a large 270 litre water storage tank and other plumbing supplies. My total cost for everything involved in the system was about $4500 ($6000 minus the $1500 grant ).
Here are some pictures of the solar water heating system installed:
solar panels just installed
support cables
- rafter reinforcement
solar storage tank and pump
The installation of the panels was awkward to say the least. I was unlucky in owning a house with a east and west roof slope but lucky to have an engineer as a neighbor. He was nice enough to help with wind load calculations so these panels don’t blow away. Fishing the insulated copper piping through the wall cavity from the attic to the basement was also a challenge but relatively simple after I figured out a few tricks. The only additional component I needed was a storage tank. Many solar panel companies will sell super insulated solar storage tanks but it is just as effective and far cheaper to buy an electric water heater and add your own insulation to upgrade the R-value of its walls. Once the tank was connected to piping from the storage tank, the panel and the solar panel that powers the unit it began to function effortlessly.
The system has been working well now for two years. I have been pleasantly surprised at how much energy the panels can absorb in the middle of winter. It can be -17 degrees celsius outside but as long as it is still sunny the panels can still heat my water to 50 degrees celsius. Unfortunately, the panels sit behind a large elm tree and are partially shaded from late October to mid February so I can not enjoy the full solar gains that would be possible with this system. However, in the summer months, the panels generate far more hot water than I could ever use so I have got plans in the works for a summer hot tub and have even been considering some seasonal heat storage options. Overall, I have been happy with the performance of this system. It was definitely worth the initial investment. I now spend nothing on water heating from April to October and have cut my annual heating bill by 50% (with the help of some additional insulation) because the energy gained by these solar panels can contribute to my hydronic heating system. I save $500 annually on heating costs so this system will pay for itself in less than 10 years only save me more as fuel costs continue to rise in the future.
