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5. Since there are several different types of solar water heating systems, how can I compare their performance?
A solar water heater uses the sun's energy rather than electricity or gas to heat water, thus reducing your monthly utility bill. When installed properly, solar water heaters are more economical over the life of the system than heating water with electricity, dedicated heat pumps, heat recovery units or propane.
As sunshine strikes the collector, the water inside it is heated. If the circulating pump is regulated by a PV panel, the pump starts turning as the PV panel is activated by the same sunshine. This direct current (DC) motor pump moves water from the tank through the collector and back to the tank. As the sunís intensity changes throughout the day, the circulating pump also changes its speed accordingly. By the end of the day, the water in the tank has been circulated many times through the collector and has been heated to usable hot water temperatures. If the circulating pump is regulated by an electronic differential controller, a sensor at the outlet of the collector and a sensor at the bottom of the tank activate the circulating pump when the water in the collector is about 15-200 F warmer than the water at the bottom of the tank. The pump then circulates water from the collector and the tank. This process continues as long as the water temperature at the collector outlet is about 50 F higher than that in the bottom of the tank. If the temperature difference decreases further, the controller automatically shuts off the pump. Common appliance timers also may control system operation. The timer is set to operate during a period of the day when solar radiation is available to heat the potable water. It is important that the timers used in these systems incorporate battery back-up in the event of power failures. In order to avoid loss of energy from the tank during overcast days, the collector feed and return lines are both connected at the bottom of the storage tank. During normal operation, natural stratification allows the warmer water to rise to the top part of the tank. During periods of insufficient sunshine or high hot water demand, a backup electrical element in the storage tank heats the water. The check valve prevents heat loss when the circulating pump is off. The circulating pump consumes only a small amount of electricity ?around $5 to $10 worth per year, or in the case of PV ?none.
Your monthly savings will depend on the amount of hot water you use, storage tank size and type and price of fuel used for backup water heating. For a family of four, the typical hot water usage is 70- gallons per day, thus using 3990-kilowatt-hours per year to heat the water electrically, or $399 per year worth of electricity at 10?per kilowatt hour.
No. Solar water heaters are always installed with a backup heating system in the storage tank to ensure that hot water is available at all times. However, to maximize solar utilization and your savings, you should attempt to use the most hot water in the late morning and early afternoon when the solar system is operating at its peak due to the available sunshine. Also, your solar system will be more effective if your use of hot water is spread more evenly over the week. For example, if you use hot water for laundry, instead of washing seven loads of clothes in a single day, wash one load each day. This will reduce the amount of backup energy required for your solar system.
5. Since there are several different types of solar water heating systems, how can I compare their performance?
FSEC conducts a state-mandated standards program for solar domestic hot water and solar swimming pool heating systems. The same solar collector can perform differently when installed in different system types. In addition, the other components (tank, pump, controller, etc.) selected for a particular system can have a large effect on the overall performance of a solar system. To allow comparison of complete systems.
When comparing peak efficiency levels it may seem that there is little difference between flat plate and vacuum tubes, in fact flat plate may actually be higher, but this is during minimal heat loss conditions. When averaged over a year vacuum tube collector have a clear advantage. The key points are:
Rather than looking at just peak efficiency levels when comparing solar collectors, cost per unit of energy produced is much more logical. For example: Although collector A may be 20% more efficient than collector B, if collector A is 30% more expensive, then in fact collector B may be a better choice, as per kWh of energy produced per day it is cheaper. When payback time is of concern, not only price per kWh of the product is important, but also of the end system. In this regard Interma solar collectors provides a further vantage as Interma solar collectors are very easy to install, and that can make a huge difference in terms of total install costs.
Collectors should be mounted on an unshaded area of a south-facing roof. They can face up to 45 degrees east or west of south without a significant decrease in performance.
For all shingle and tile roofs in Florida that generally have pitches greater than 3 in 12 (i.e., 14 degrees), collectors should be mounted parallel to the roof. Collectors mounted in this manner are more aesthetically pleasing. However, for flat or very low-sloping roofs, collectors should be tilted at an angle (to the horizontal) that is approximately equal in degrees to the local latitude. Florida latitudes range between 25 degrees (in the Florida Keys) to 31 degrees (northern border). Since the sun is lower on the horizon during the winter months, tilting the collector at an angle up to 15 degrees greater than latitude will increase winter performance, which is desirable in most cases.
If you have a system that is operating in areas with subzero temperatures then freeze protection must be implemented. The easiest means of preventing freezing is to use a controller with a low temperatures setting, so when the manifold temperature drops below a certain pre-set temperature (50C/400F), the pump will circulate, warming the collector with water from the bottom of the storage tank. The pump will not run continually, just periodically, the frequency of which will depend on the outside temperature. In extremely cold areas, a closed loop using a glycol/water mix may be appropriate.
Yes.Interma collectors can be used in temperatures as low as -300 C, although performance is greatly reduced in such extreme conditions. Good heat output is still achieved in mild sub-zero conditions.
Yes. Although the heat output of the solar collector is reduced on overcast days it will still be able to provide heating. If it is a heavily clouded day or raining, then more gas or electric boosting may be required to maintain water at the required temperature. This system will be automated so you don't have to worry about running out of hot water on a rainy day.
Besides simply using less hot water, and timing solar-heated water use to peak when the solar exposure is at its peak, the following strategies are suggested:
Finally, in a one-tank solar system, it's a good idea to have the back-up element controlled by a timer or manual on/off switch to keep it from coming on during the day. This strategy allows the solar system to produce all the hot water without the back-up heater being activated.
Timers may become very attractive if peak-load pricing of electricity is introduced. In that event, electricity would be priced at a much lower rate during certain hours of the day than at other times. Peak-load pricing is being evaluated by many electric power companies.
The potential savings on water heating bills are affected the most by the type of fuel you are using to heat that water and the number of people in the home. If you are heating hot water for two or more people and you heat water with electricity or with bottled or natural gas, then you owe it to yourself to look at solar water heating, it could be a great investment for you.
Properly designed and installed systems with glass-covered collectors should perform well for more than 20 years. Controllers, like other electronic devices, may require servicing during the life of the system, and the pump and hot water tank may have to be replaced after 10 years. Since conventional water heaters have the same expected lifetime, water tank replacement costs are not regarded as unique to solar energy systems.
No. The Interma solar collector's components are all high temperature rated and non-flammable so even during strong sunlight with the circulation pump turned off (stagnation), the system will not catch alight or give off any sparks. The majority of the solar collector's components are stainless steel, aluminium, glass or glass wool. The manifold outlet should be fitted with a temperature relief valve, which will prevent the manifold temperature from exceeding 990C / 2120F.
It is ironic that you, if you are an individual using LP gas or electricity to heat water, will pay for a solar hot water system over the next 4 to 8 years whether you get one or not!! You can invest today in a solar hot water heating system and have monthly savings and increased equity value in your home, or you can pay the local utility company every month. Your solar system savings will offset your payments, so you will actually own your solar water heating system at the end of five years. Remember that all solar savings are in non-taxable income, so a dollar saved on your water heating expense is equivalent to $1.30 or more of your taxable income.
With confidence of our quality and our quality control, we give our guarantee for 5 years of our products sold to oversea and relative guarantee for the accessories with limited liability:
Any time you use solar energy to offset the amount of fossil fuels that are burned, you contribute to everyone's health and welfare. Operating one solar water heater instead of an electric water heater saves the equivalent of nine barrels of oil every year and reduces carbon dioxide emissions (a greenhouse gas) by 1600 pounds and sulfur dioxide (contributes to acid rain) emissions by 12 pounds. Multiply those emissions per household by all the homes in your neighborhood, town, county, or state, and the benefits -- and the air and water -- become even more clear. Environmental Consciousness is a state that induces action through your belief in leaving a better world for yourself and future generations. We are all free to believe what we choose and what we each do, attests to what we believe.
The existing thunder arrester on the roof should be increased at least 50cm higher than the top of solar water heater before installing. Meanwhile the distance between the solar water heater and thunder arrester should be kept as 10cm at least. It is not allowed to connect the solar water heater with thunder arrester directly. The insulation protection should be added around the solar water heater when necessary.
After the installation, there will be a shadow at the back of the solar water heater, and the furthest distance of the shadow is called covering distance. The distance is usually 1.25 times of the height of solar water heater. The best distance between two solar water heaters in a line is 1.5 times of the solar water heater's height.