Solar Thermal is Dead Green. Building. Advisor. In the northern half of the U. S. and even much of the South installing a residential solar hot water system doesnt make any sense. Its time to rethink traditional advice about installing a solar hot water system, because its now cheaper to heat water with a photovoltaic PV array than solar thermal collectors. In short, unless youre building a laundromat or college dorm, solar thermal is dead. The idea has been percolating for six years. Justmoney looks at how a borehole, rainwater tank or well point can be integrated into your home and what the cost would be. Frequently Asked Questions. QUESTION Can anyone tell me about the Titan Tankless Water Heater I want to switch my old tank water heater to a new tankless unit. What fuels are available for heating What domestic fuel is most commonly used in the UK Where does natural gas come from What about my bills, is gas a cost. Installing a solar water heating system is your best bet. Itll likely pay for itself in as little as seven years, and. OilTankhalfburiedDF.jpg' alt='Cost Of Installing Domestic Oil Tank' title='Cost Of Installing Domestic Oil Tank' />In the early days of PV, when PV equipment was much more expensive than it is now, homeowners with PV systems especially off grid homeowners were instructed not to use electricity for heating. After all, since electricity is precious and expensive, and since PV power usually costs even more than grid power, it made sense to save electricity for uses like refrigeration, lighting, and home entertainment. For decades, we all assumed that the greenest way to heat domestic hot water was to use a solar thermal system. But then two things happened PV equipment got cheaper, and heat pump water heaters became widely available. The logic of using a PV system to heat water was first explained to me in early 2. Charlie Stephens, a policy analyst for the Oregon Department of Energy. I reported the details of that conversation in an article, Heating Water With PV, published in the May 2. Energy Design Update. If you want to do solar water heating and solar space heating, solar thermal remains too expensive, Stephens told me. Its not as cost effective as using an air source heat pump. Heat pump that relies on outside air as the heat source and heat sink not as effective in cold climates as ground source heat pumps. PV array. In our climate, a properly sized solar thermal system can provide 1. So you paid 4,0. Musing with the idea of installing a wood burner of some sort Understand whats involved before you set about installing a wood burning stove. Large Horizontally Oriented Water Heating Collector with a Unique Heat Storage System. Deciding what type of heating fuel to use in your home can seem overwhelming. The reality is most fuels cost about the same to heat your home. Read on to learn more. Accounting Software For Small Architectural Firms List. We love to hear from our customers and we have received so many emails and reviews, we decided to open this forum to share them with others. If instead, using the same money, you just add an extra kilowatt of PV to the roof, you could heat all of your hot water year round with an air source heat pump. You can quibble with the details used in Stephens argument it may take more than a kilowatt of PV to meet your hot water needs, for example, and his 2. Some solar heated water goes to waste. Solar thermal proponents know how to calculate the number of gallons of hot water produced by a typical 4 by 8 solar collector in a variety of climates. Good%20%20Bad%20Tank%20Posters%205-3-2013.jpg' alt='Cost Of Installing Domestic Oil Tank' title='Cost Of Installing Domestic Oil Tank' />After calculating the thermal energy that this represents, they usually concluded before PV prices dropped, anyway that solar thermal collectors were a better bargain than a PV array. But the number of gallons of hot water produced by a solar collector is always less than the number of gallons actually used by the homeowners. After all, if great quantities of hot water are produced on a day when it isnt needed, you cant really count the energy production in your annual tally. Solar thermal energy is inconsistent, and during the long sunny days of summer, most solar thermal systems make more hot water than the typical family can use. Although Charlie Stephens pessimistically estimated that a residential solar thermal system in the Pacific Northwest would only supply about 4. In a 2. 00. 6 study, researchers from Steven Winter Associates monitored two residential solar thermal systems for a year, one in Wisconsin and one in Massachusetts. Each house had two solar collectors. The solar fractions of these two systems were 6. Comparing solar thermal and PV systems. Compared to a PV system, a solar thermal system has several disadvantages Unlike a PV system, most solar thermal systems have moving parts pumps and solenoid valves. In freezing climates, solar thermal systems are sometimes subject to freeze damage. Solar thermal systems require regular maintenance, including antifreeze replacement. Unlike owners of a grid connected PV system, who can be credited for their excess electricity production during the summer, owners of a solar thermal system cant sell the excess summer production of their hot water systems. While a pole mounted PV array can include a tracking mechanism to follow the suns path across the sky, its virtually impossible to install solar thermal collectors on a tracker. On average, PV systems probably last longer than solar thermal systems. There are far more stories of troublesome solar thermal systems than there are stories of troublesome PV systems. Solar thermal systems sometimes develop air bubbles that interfere with the circulation of fluid, suffer from leaking pipes, or experience problems from summertime overheating. PV systems, which suffer none of these headaches, look attractive in comparison. Lets do the math. Since 2. 00. 6, when Stephens first proposed that it was cheaper to heat water with a PV array than a solar thermal system, two factors have emerged that greatly strengthen his case more reliable heat pump water heaters have become widely available, and PV modules have gotten dramatically cheaper. During the same time period, sales of solar thermal systems have also been hurt by a third factor dropping natural gas prices. But thats a topic for another article. Although its always difficult to predict future price trends, there are reasons to believe that the price of PV modules will continue to drop, while the price of the copper tubing used to make solar collectors will continue to rise. In northern states, a typical residential solar thermal system includes two 4 by 8 collectors and a 1. Instead of spending 1. W PV array The 1. W PV system would produce 2,1. Wh per year in Boston or 2,0. Wh per year in Madison, Wisconsin. Lets be conservative and use 2,0. Wh for our example. Assuming that the average COP of the heat pump water heater is 2. Wh to raise the temperature of a gallon of 5. F water to 1. 20F. So 2,0. 00 k. Wh can produce 2. U. S. Department of Energy assumes is used by the average American family. So, once youve paid for the system, you get free hot water. Thats a much better deal than a solar thermal system that produces only 6. Trust me if you have a solar hot water system, youll have to invest in maintenance and replace a few parts over time, too. Of course, if your family uses less than 6. COP than 2. 0, or you live in a state with more sunny days per year than Massachusetts or Wisconsin, or the average temperature of your incoming cold water is higher than 5. F, then your new PV system will be producing extra electricity that you can use for other purposes. In fact, many families use significantly less than 6. A Canadian researcher, Martin Thomas, monitored hot water use in 3. Canadian homes in 2. If your family uses 4. W photovoltaic array costing about 5,0. PV array rather than the 1. W array proposed for northern families using 6. What if you use an electric resistance water heaterLets do the math for those who prefer to use an electric resistance water heater. If you invest 1. PV system, youll get a 2. W system assuming a PV equipment cost of 4. The PV system will produce 2,7. Wh a year in Boston. Using electric resistance heat, it takes 0. Wh to raise a gallon of 5. U. S. and Canadian families, according to two recent studies. If the family with the hypothetical 1. The PV option produces 3. To make 2. 8 gallons a day an amount equal to the average output of the solar thermal system with an electric resistance heater, all you would need in Boston is a 1. W PV system costing about 6,3.