Hay River Solar Thermal Domestic Hot Water System

Posted 2015-02-05
Written by
Category Taking Action

Written by Tom Gross, Arctic Energy Alliance's South Slave Regional Energy Project Coordinator.

I received a call the other day from my friend and neighbor Art Barnes who lives just down the road from me out in Delancey Estates. Art, who I have known for many years, and who just recently retired, had told me in passing one day that he was installing a Solar Thermal hot water heating system on his home. I had been meaning to see what Art had been up to so when I got the call I decided to go out for a visit. It was a beautiful clear day, great for Solar - aside that we were still in January with the outside temperature holding at -27C.

When we talk about Solar panels or collectors we have two categories: Solar photovoltaic (PV) or Solar Thermal. Solar PV produces electricity while the Solar Thermal makes hot water. Solar Thermal collectors are either flat plates or evacuated tubes that can be installed in a closed or drain down type system. Art chose to “experiment” (as he called it) with the evacuated tubes using the closed system that he purchased at a very reasonable cost. He then designed and pieced the rest of the system together himself.

Solar Vacuum tubes have been around for about 100 years but using them for heating is fairly new. Today we have a vast selection of vacuum tubes on the market with each type having its own unique design offering different advantages. The system Art purchased is manufactured in China by Jiangsu Sunrain Solar Energy. These tubes, unlike some others, have an absorbing film inside an enclosed vacuum glass tube that is separated from the heat conductor and heat pipe. The advantage to this design is that should the glass tube get broken it can then be replaced reusing the internal transfer fin and heat pipe condenser.

Another advantage is that the absorbtion layer within the tube is installed all around the glass which in turn allows the tubes to absorb the sun’s energy from all angles, including from behind, which we midnight sun people can take advantage of.

The South Slave Region currently does have a number of operational plate and vacuum systems installed on residential homes and a senior’s facility but none of which come close in size to the 200 tube array that Art has placed in his back yard. The system did come with mounting hardware but Art opted to construct his own solar rack in an area he cleared along the river bank, which gives the system great solar exposure while also allowing it to be neatly piped together in series where each string of the four - twenty five tube manifolds join together. Manufacturers will recommend, based on the performance of their product, the number of tubes that can be connected together continuously or in parallel to avoid overheating. Art has arranged his system to ensure the piping is balanced providing equal flow rates from both upper and lower arrays. The solar piping that carries the supply and return heating fluid are made of flexible ¾ inch stainless steel and wrapped in high temperature Ethylene Propylene Diene Monomer (EPDM) foam that minimizes heat loss to just a few degrees over the 200 foot run made from the collectors to the control panel inside the house.

Art’s system provides preheating for a domestic hot water storage tank which then feeds into an indirect fired hot water heater. The indirect water heater then completes heating of the domestic water to the desired temperature, if required, using the primary boiler heating system in winter and for efficiency switched over to a domestic oil fired hot water heater in summer.

Most interesting is that the system will also provide space heating whereas the collectors also heat a separate solar storage tank that Art constructed himself using a 350 gal water tank and two copper coils: one that heats the water in the tank coming from the solar collectors and the second that then transfers the heat to the in-floor heating lines in his basement’s concrete slab.

On the day that I was there the system was showing that it had kicked in at around 10:00 AM and was producing between 50C to 54C by 2:00 PM. The benefit, according to Art, was that this system continued to provide heat to his floor well into the evening.

With the overall size of this system at 31.6 Sq. Meters it may possibly be the largest solar thermal system operating in the NWT. It has tube efficiency of about 73.4% and the potential to produce (under normal conditions) over 16 thousand kilowatt hours which is the equivalent energy to 1500 liters of heating fuel.

Art has accomplished something that we solar thermal folks dream of doing. That is, building a system that is large enough to be able to provide space heating during the shoulder season; and to date, it has logged over 450 hours since it was commissioned early September 2014. On the down side, at peak solar in May to June, the system will over produce but Art has his experiment under control with a sizable heat dump and retractable blinds installed on the collectors that can be lowered to limit operation. In addition, Art being a long time Northerner, mounted the tubes at 90 degrees so that they get as much sun as possible in the winter months and less than maximum sun exposure in the summer.

Art’s not finished yet though. Having caught the solar bug, Art is now considering using the sun to create the electricity he needs for his solar hot water system. Enter Ken Baigent, Arctic Energy Alliance’s (AEA) Solar Energy Specialist. Ken was down in Hay River recently and took the opportunity to meet with Art to discuss his system and provide some expertise on how Art could add solar PV panels to complement the solar thermal system to create the electrical power needed to operate it. We at AEA are looking forward to seeing the results of Art’s experiment after a year in operation, but one thing is for sure, Art and Marilyn will not be running out of hot water anytime soon.

Special thanks to Art & Marilyn Barnes for their contribution to Northerner’s Taking Action.