2009 Vashon Solar Tour
Solar Hot Water - Flat Panel Collectors - (Lyons Residence) We partnered with Artisan Electric, Inc. to install this two panel Caleffi solar hot water system (foreground). A 75 gallon Caleffi storage tank with a single electric element back-up pre-heats the existing 50 gallon electric water heater. The electric back-up element in the solar storage tank means that on days without any solar, the element activates and heats the upper half of the solar tank. This insures that at all times there are 35+ gallons of hot water added to the existing 50 gallons. On solar harvesting days during the summer, the entire 75 gallon solar tank will be heated from the solar panels while the electric element remains off. This means that the existing electric water heater will not require electricity either, as it will be filled with hot water flowing from the solar heated tank. Solar Hot Water - Evacuated Tube Collectors
We partnered once again with Jason Williams of Artisan Electric Inc. to place this Thermomax evacuated tube solar collector on Jason and Jennifer's house on Vashon Island. Jason installed the solar photovoltaic array to the right and that's our 20-tube collector on the left. This dual PV/thermal system combines well adding solar generated electricity to the savings of solar generated hot water. Evacuated tubes work great for this geographical area and will heat water even on cold, clear days. We installed a 60 gallon solar storage tank in the basement to pre-heat the existing 35 gallon electric water heater. This means that during the winter the electric tank doesn't have to use very much electricity and during the summer, it doesn't have to use any at all. Meanwhile, Jason and Jennifer will have the great pleasure of watching their electricity flow backwards into the grid.
BEYOND THE TOUR: Solar Hot Water - Flat Panel Collectors This was an interesting and challenging installation. The two panels for this Caleffi system needed to be mounted above the garage , facing south on a roof that pitched west. This meant not only adding aluminum extensions to the standard Caleffi roof mounts in order to achieve pitch, but also adding cross bracing and an additional support on the downside to prevent lateral movement. We fabricated our own roof mount on the latter to accommodate the resulting compound angle. The owner wanted the panels to be hidden below the roof ridge and so a thirty degree pitch was our limit. If the aim is to harvest as much winter sun as possible the collector pitch should be latitude plus five degrees. On Vashon Island this would mean fifty two degrees. However, because there is limited solar gain in the winter months in the northwest, it often makes more sense (especially when it is a solar hot water system only, as opposed to solar heating) to pitch the panels at a lesser degree thereby harvesting as much solar as possible during the summer, when solar gain is highest. The result is more solar collected annually.
Solar Hot Water - Removing Existing Flat Panels Sometimes it's necessary to remove old solar panels. In this case we removed three flat plate panels which had been installed by the previous homeowner so the current owner can install a new roof. After inspecting the old panels we realized that the seals which keep atmospheric moisture out of the panels had deteriorated. The current owner will be gutting the house and remodeling so we are designing a new plumbing system for the new layout which will incorporate a new solar hot water system with new roof panels to augment the new hot water demand. This will include two Takagi natural gas on demand water heaters. The on demand heaters will be augmented by the solar storage tank. When there is not enough available hot water from the solar tank for normal hot water use, a diverter valve will automatically switch to the on demand heaters.