How long will the three recently installed solar hot water systems take to pay for themselves?
Solar hot water can be a very effective tool in harnessing free energy and reducing our fossil fuel needs. This research will give a time in years, that the money saved from fuel use, will offset the cost of installation and maintenance of a solar hot water system. The data should show a five-year payoff of initial cost, and as fossil fuel prices continue to rise, an ever bigger savings on the gas bill. Ten years is the average time major replacement of parts would be required. The gas saved can’t totally be reduced as the system is only preheating the incoming cold potable water. The reduction in gas for the hot water heater is what will give us a fuel reduction data.
The data will be collected twice a week and posted on a blog at first opportunity. The data collection will go from summer solstice June 21, to winter solstice December 21. Thompson River University will be requested for data on the following: cost rebates from the government that would apply to solar hot water, Cost spent on the installation and maintenance, gas bills for the duration of the research and previous gas bills for base line comparison, Working documents for three buildings that the solar hot water systems have been installed on. Prices per unit will be obtained from a local company for a base line comparison of any unknown prices.
In all solar hot water systems you can use water, or a glycol water mix as a heat transfer medium. Glycol has higher freezing tolerance and is more suited to colder climates. If you are using glycol, the system must be a closed loop to stop transmission of the glycol into the potable water system. Water has a better heat transfer capability than glycol. All fluid piping would need to be insulated in order to retain as much heat as possible in the fluid transfer. The insulation also helps protect the pipes it from freezing.
The heat exchanger is a key component in the whole solar hot water system. The theory is that the more surface area that contacts between solar heated water pipe, and the incoming water pipe, the more heat that will be transferred. Once water has left the heat exchanger it returns to the collector in the closed loop system to be heated again.
There are three types of solar hot water collectors. Solar plate hot water system has “lower installation cost, simple construction, minimum maintenance requirements”. (applied solar energy pg 47) The solar plate works by thermal mass heating in two parts. Part one is the large plate itself, and two is the liquid being directed through the plate. (picture M-2) “Among the most efficient solar collectors is the evacuated tube collector.” (low energy buildings pg 454) The evacuated tube works by heating the fluid in a vacuum to try to minimalize any possible heat loss. There are two types of evacuated tubes; heat pipe evaporators, and an all glass tubes. The heat pipe evaporators uses the phase change of liquid and steam to give a high yield heat transfer. “A temperature rise of up to 150® Kelvin can be achieved.” (low energy buildings pg 454). The all glass tube uses passive circulation of the heat through the vacuum tube to a storage tank above. (picture M-1) A parabolic collector is a concave mirror or reflective surface that focuses the heat at the target tube of water. This tube could be evacuated for higher efficiency.
The research will compare the different types of systems; plate, evacuated tube, and parabolic collector. In order to determine the amount of time in years, each of the solar hot water systems, will pay for themselves. Other points of comparison: environmental conditions surrounding the units, amount of water supply fixture units (wsfu) the heating system required, the number of plate/tube collectors, global position, maintenance and installation cost, and the Heat transfer liquid. A table will be made for easy comparison.
A separate table will be made comparing the three solar hot water systems we are recording data from, and four solar hot water systems from different countries. These solar hot water systems are in Australia, Greece, the United Kingdom, and Turkey. Data from these four solar hot water systems are from peer reviewed journals. This table will contain :The angle the systems are situated at and the amount of annual sun they receive, with the help of a local company I will compare prices of evacuated tubes and labor cost of installation, examining the building plans for the three buildings, I will calculate the required wsfu’s each system requires, with the wsfu’s we can calculate the water heater needed and the amount of fossil fuels required to run the system, I will compare the transfer medium used on all systems in the research.
Once all data is recorded and tabled, it should show the cost effectiveness of the three solar hot water systems installed at TRU. as well as give some direct comparisons to other solar hot water systems.
