Bringing Solar Energy to Colorado
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Bringing Solar Energy to Colorado |
Answers:
1. What is the difference between Solar Heating and solar electric systems? Solar Heating systems collect heat from the sun that is then used to heat water for in-house use (usually referred to as a domestic hot water [DHW] system, to heat the space in which you live (usually referred to as space heating), to heat a hot tub or spa, or to heat a swimming pool. A solar electric system collects the sun's energy and converts it to electricity. Depending upon the type of system, the electricity may be stored in batteries (similar to automobile batteries) for later use or may be used by an electrical device immediately, or in some cases fed directly into the power company power grid.
2. What is the difference between domestic hot water (DHW) and space heating? Domestic hot water, or DHW systems are used to heat the water that comes from your hot water faucet. The system may or may not use a separate storage tank as a pre heater in series with you standard water heater. A space heating system is used to heat the space in which you live. It may be as simple as a single collector panel that collects heat when the sun shines upon it with the heat then being pushed into the room. Or the system could be more complex with heat being collected and stored in a storage vessel of some type and be delivered to the room at a later time, as needed. For more details on both of these systems, click on the green "Solar Heating" menu box below.
3. What is meant when the solar heating guy talks about liquid and air systems? There are two basic means of collecting heat from a Solar Heating collector. These methods are to heat air and to heat a liquid. First, air can be passed over the heat absorption surface of the collector. The air, pushed by a fan, can then be delivered to the room that needs to be heated or it may be blown into a heat storage bin. Such a bin usually contains rocks which are heated by the warm air. The warm rocks are then able to give the heat back up to the air, say at night when the sun isn't shining. Cool room air is drawn over the heated rocks. This heats the air which is then delivered to the room. The second method of collecting heat is to use a liquid as the heat absorption medium. There are numerous liquids used as heat collection fluids, from water to glycol-water antifreeze mixtures, to silicone oils. Their functions are all the same, to collect heat from the heat absorption surface of the collector and deliver that heat to either a storage tank of some type or to some type of heat exchange surface where the heat is given up to a room for space heating or to a liquid such as water to heat a pool or spa. For more details on both of these systems, click on the green "Solar Heating" menu box below.
4. What are warm air collectors? Warm air collectors collect heat by forcing air over the heat absorption surface of the collector. The air can then either be directed into a room for space heating or into a heat storage bin for use at a later time.
5. How long will a storage tank last? This is a question that has a wide range of answers, simply because it depends primarily upon the quality of water and type of tank that you have to deal with. In some cases, a solar domestic hot water tank may last only five years. Such tank lives may be extended by periodic replacement of the tank anode. But the needed replacement of the anode rod probably wouldn't be known until the tank has failed unless the homeowner already knew there was a water problem. Other tanks where there isn't aggressive water may last over 20 years, even without periodic anode rod replacements. Space heating tank replacement depends upon the tank materials and possibly on how high a temperature the water within the tank is allowed to reach. Tanks made of stainless steel, although the most expensive, will usually last the longest (20 years or longer). Tanks made with a supporting frame and lined with an EPDM liner may last 10 - 20 years before the liner need replacing. If the supporting structure is wood, it may need replacing also in 10 years. Tanks made if fiberglass or polypropylene may last 5 - 15 years before a leak develops. These tanks are sensitive to maximum temperatures and the water within them should be kept below 150 - 160 °F.
6. How long will it take for a DHW solar system to pay for itself? This is another difficult question to answer, simply because of all the variables involved. The main variables include where you live, how much hot water you use, the size of your system, the cost of the fuel you presently use to heat your water, how well the system is installed, how difficult the installation is, how much maintenance is required, whether all equipment is new or some of it is used/refurbished, and how much you paid for your system (factoring in any incentives/rebates you may receive). So as you might expect, there will be a large range for expected payback time. But, for a two panel, 64 square foot system that cost $3500, there can most likely be cases where the payback times can range from 4 to 16 years. The bottom line is that each case needs to be evaluated individually.
7. Are there any tax credits or rebates available? Yes, but it depends where you live as to what may be available to you. Click to the "Solar Rebates" brown menu box below for the solar incentives offered by the different states.
8. How do I know if a solar heating system is working? Unfortunately, many of the solar heating systems that have been installed are lacking adequate instrumentation to answer this question. So, it is necessary for you to listen, smell, and feel your system from time to time. If it is operating, you will be able to hear a pump or pumps running when the sun is shining brightly, especially early in the day. Towards the end of the day, it might be possible that the system has heated up to its maximum temperature and shut down. You can also, near the end of a sunny day, carefully place your hand on the temperature - pressure (T&P) relief valve on the storage tank of a DHW system. It should be warm to very hot. Be careful as you could burn yourself if it is very hot. The T&P valve is usually screwed into either the top or the side at the top of the solar storage tank and should have a pipe coming out that leads to, and ends about 6" above the floor. As with a solar DHW system, the heat collection pump should be running when the sun is shining brightly, especially early in the day. Additionally, when the house thermostat first calls for heat, if you have had a sunny day, the heat delivery pump should be running and the pipes leading to and from it should feel warm to hot. There should not be any unusual smells associated with the solar system. If you detect a sweet smell or other unusual smell near the system, there may be a heat collection fluid leak. This should be checked by a qualified solar technician.
9. How do I know if a solar electric system is working? Fortunately, most of the solar electric (photovoltaic, or PV) systems that have been installed include adequate instrumentation to answer this question. Usually, there will be a voltmeter, ammeter, and sometimes an amp-hour and or a watt-hour meter. A volt meter will tell you at the voltage at which the system is operating at. This varies during the day and is dependant upon the type of system you have. An ammeter will tell you the rate at which batteries are being charger or discharged and in the case of grid-tied systems, the rate at which current is either being fed into or taken from the grid. Of course, if the system is a stand alone system and not tied into the grid and the lights go out, you have a problem. But it is prudent for an owner of a stand alone system to monitor the status his/her system daily.
10. What kind of anti-freeze is used in a solar heating system and is it safe? Several different fluids are used as heat collection fluids in solar heating systems. Probably the most common is a mixture of propylene glycol and water. This mixture is safe. If fact, propylene glycol is a common additive in numerous food products. Some heating systems will contain a mixture of ethylene glycol and water. This is a toxic mixture and should not be used with DHW systems. In some cases it may be used (with caution) with space heating systems, but only when there isn't any chance of contaminating the household potable water supply. There are also several oil based fluids used as heat collection fluids in solar heating systems. A synthetic oil used widely during the 1980s is called Bray oil and is non-toxic. Many solar technicians, when called upon to repair a Bray oil system are replacing the oil with a propylene glycol water mixture since the Bray oil costs are so high. Another oil that was used is mineral oil. Mineral oils can cause aspiration pneumonia when inhaled as vapor or particulates and are recognized skin carcinogens. So, this should handled with caution. Finally, silicone oil is used as a heat collection fluid with some systems. This type of oil has a very low toxicity, has good thermal stability, and won't freeze or cause corrosion. Silicone oil, in general, is more expensive than the other heat transfer fluids.
11. How much hot water will a solar water heater provide? This, of course, is dependent upon the size of the system. However, studies have determined that a system designed to provide about 70% of your hot water needs is about optimum.
12. How long will a solar heating system last? If all components of your system are new when installed, the system should last at least 20 - 30 years. You will undoubtedly need to replace or have repaired some of the system components along the way, such as a storage tank, a pump(s), a controller, and maybe a valve or two. But the collectors, if protected adequately from freezing and corrosion, should last for the entire 20 - 30 year period.
13. How often do I have to do routine maintenance on a solar heating system and what needs to be done? Although very little maintenance is required of a solar heating system, a homeowner should be aware of its operation and be familiar with its characteristic sounds. First, you should periodically check and make sure the system is operating (see #8 above). Spend a few minutes to become familiar with how it sounds when it is running under full sun light conditions. Every few weeks check that these sounds are the same. A change in its sound might indicate a problem that should be checked by a solar technician. If you have a liquid heat collection system with a propylene glycol water mixture as the collection fluid, the fluid should be checked at least once a year for pH (acidity) and its freeze protection level. If you have agressive water (this might be the case if you have needed to replace your water heater and it was less than 10 years old) you might consider having the solar pre heater anode rod replaced every five years, or at least have it inspected. Outdoors, look at the collector panels and make sure the glass covers are not broken. Notice whether there appears to be clouding (water condensation) on the inside of the glass. If water condensation persists, it could indicate a leaking collector which would need to be repaired. Solar Heating collectors, in general, do not need cleaning since normal rainfall will keep them clean. If you are maintaining a solar space heating system, you will probably need to add water to the heat storage tank several times each year. Ask your solar technician how to do this since no single description will cover possible configurations.
14. How often do I have to do routine maintenance on a solar electric system and what needs to be done? Although these systems are very reliable, they do need periodic maintenance. The systems that contain flooded batteries (those non-sealed batteries that have caps on the tops of the individual cells) need to have distilled water added every so often. How often depends upon the condition of the batteries and how they have been used. They should be inspected at least once per month and distilled water added when the electrolyte level appears to be about 1/4" below the split well leading into the cell. Add enough distilled water to bring the level up to the bottom of the split well. You will soon get a feeling as to how often this procedure should be done. Do this maintenance when the system is not being charged and not providing much power to the electrical system. Also, do not perform an equalization immediately after filling the cells as it will probably result in some of the cells spilling a little acid onto the top of the battery. Wear eye protection and have baking soda close at hand in case of an acid spill. This is a potentially hazardous job so approach it carefully. While inspecting the batteries, check to see that all of the electrical connections are tight and free of corrosion. Once or twice each year the following added checks should be performed. If the PV array is accessible check and verify the bolts holding the PV modules to the mounting rack are still tight and there is no sign of movement. If you have a multi meter and are familiar with electrical hazards, you might want to check for continuity through any fuses within the systems. Be sure power is removed from the fused circuit before attempting this check. Make sure all circuit breakers are in the proper position. Finally, watch your PV modules and anytime they appear dusty or splattered with bird droppings, hose them off. The importance of being familiar with your system operation cannot be over emphasized. By seeing, hearing, or smelling something different, you may be able to prevent a minor inconvenience from becoming a major problem. If you are concerned but hesitant to attempt any troubleshooting, call your solar PV technician as soon as possible.
15. Does solar heating and solar electric work in the winter? Yes, in fact some solar heating collectors and PV modules are tilted to perform better in the winter than in summer.
16. How does heating work in the winter if water is used in the collectors, won't it freeze? Water is used in certain solar heating collectors as the heat collection fluid and is very effective in both summer and winter. The trick is to make sure the water leaves the collector when heat is not being collected. Drain back systems are designed to accomplish this and when installed properly, are very good systems. Drain down systems will also accomplish this collector draining but are dependant upon proper operation of a component called a drain down valve. These valves have been shown to be prone to failure in the Colorado area with catastrophic results (collector freeze ups in the winter). Consequently, there are very few drain down systems left in operation in the Colorado area. For more details on the operation of both these systems, click on the green "Solar Heating" menu box below.
17. I don't like the looks of solar collectors standing up on roofs. Does it have to be this way? No, in fact some installers are installing collectors flush on the roof. In this position, they resemble sky lights. Although mounting collectors flush on the roof may improve the "looks", such mounting may result in decreased wintertime performance if the roof is at a shallow pitch such as 4/12 or 5/12. Although performance is decreased at these angles, some installers are compensating for the decreased performance by adding one or two additional panels. This will compensate for reduced winter performance but greatly add to un-needed summer time heat gain (unless it can be used to heat a pool or spa/hot tub). This added heat needs to be considered when installing additional panels to compensate for shallow roof angles.
18. Won't solar collectors blow off the roof in strong winds? Yes, this can and has happened. However, if properly installed with the collector supports anchored into the rafter/truss roof structure, the chances of the collectors being blown off is very small. The installer must verify the soundness of the rafter/truss roof structure and make sure the hardware connections are indeed tied securely to this structure. Many solar collectors in the Boulder, Colorado have survived winds in the 75 to 100 mph range. Scary but true.
19. How long will a solar electric system last? Some PV module manufacturers are now warranting their modules to provide at least 80% of original output power for 25 years and at least 90% of original output power for 12 years. Other active components of a PV system such as inverters, controllers, and instrumentation are electrical components and at some point will fail. Typical warranties on inverters and charge controllers are running two years with optional extension plans offered by some manufacturers. Batteries, on the other hand, will wear out and depending upon the battery type and how they are treated and maintained, may need to be replaced every 5 - 10 years. There are some batteries, however, that will last longer. These are specialized batteries and harder to find.
20. What happens when I need a new roof? Most roofers will require the panels be removed before they can remove the old roofing material and install new roofing. Either Solar Heating panels or PV modules can be temporarily be removed to allow the roofers to do their work. It must be strongly emphasized to them however that the pipes leading to and from the solar panels must not be shoved into the attic area and covered over. The same holds true for any wiring/conduit for PV systems.
21. Are replacement parts hard to find? Most replacement or equivalent parts are available. Certain Solar Heating controllers contain parts that are obsolete and no longer available. However, most of the time when these controllers fail, the parts to repair them are available.
22. What is meant by a "closed loop system" and an "open loop system"? A closed loop system means that once a fluid, be it water or an antifreeze fluid, has been placed into a piping loop, the loop is sealed and nothing more is added. An open loop system will periodically have water added to make up for water that is either lost through draining, evaporation, or drawn from a faucet.
23. What amount of greenhouse gases is displaced by a nominal sized DHW system? A nominal size two panel, 64 square foot system that will supply 70% of the DHW heating needs for four people (assume each person needs 20 gallons of heated water per day) and the water is heated from 55° - 130 °F, will displace about 2.4 tons of global warming gases per year according to the http://www.miamidade.gov/derm/tips/globalwarming.asp web site. This site states that each 100 kw-hr of electrical energy production saved prevents the release of 130 pounds of global warming gases.
The Sustainable Media Network's 14 minute video"Clean Energy News: Buying a Solar Electric System" answers the most commonly asked questions posed by potential photovoltaic (PV) system buyers. The end result is a smarter customer whose questions become better focused and, therefore, more likely to invest in clean, renewable energy systems. Video clips can be viewed and the DVD purchased on-line at http://www.sustainablemedia.net.
For additional specific information please click on the subject of interest below.
Some Solar Energy Industry Association (SEIA) links
http://www.seia.org/learn/energytypes.asp Solar energy types
http://www.seia.org/learn/myths.asp Solar myths and facts
http://www.seia.org/buy_solar/manufacturers/ Manufacturers - a short list
Some Energy Efficiency and Renewable Energy Network (EERE) links
http://www.eere.energy.gov/solar/about.html About the Solar Technologies Program
http://www.eere.energy.gov/solar/mission_vision_goals.html Solar Program Mission, Vision, and Goals
http://www.eere.energy.gov/solar/financial_opportunities.html Solar Program Financial Opportunities
http://www.eere.energy.gov/solar/cfm/faqs/ Solar Program FAQs
http://www.eere.energy.gov/solar/info_resources.html Information Resources and Publications
http://www.eere.energy.gov/solar/sh_related_links.html Related Links and More Information
http://www.eere.energy.gov/informationcenter/ Ask an Energy Expert
http://www.fsec.ucf.edu/solar/links/links.htm#genfla Select Solar Energy Links. Listed on this page are a select number of solar energy sites that have been found to be very useful in providing general solar information, implementing solar energy programs and conducting basic solar research. Of course, this is only a very small sample of the innumerable solar energy related web sites that can be found on the internet, but in general, these have proved to be the most useful due to the specific information they provide.
http://energy.sourceguides.com/index.shtml The Source for Renewable Energy. This Web site has an easy-to-use directory of more than 2,500 renewable-energy-related businesses and organizations throughout the world.
www.solarbound.org The SolarBound website (the Million Solar Roofs Initiative for Northern Colorado)
Contact CoSEIA at any of the addresses below.
| Main office - 8745 W. 14th Ave., Lakewood, CO 80215 Denver metro phone: 303 333-7342 Non-metro phone: 1 866 633-9764 E-mail: info@coseia.org |
CoSEIA Records - PO Box 77, Como, CO 80432 Phone: 719 836-4804 E-mail: coseiarecords@hughes.net |
This page last updated on 5-21-07
