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Solar PV vs Solar Thermal: Comparing which is the better investment. Solar pv thermal

Solar PV vs Solar Thermal: Comparing which is the better investment. Solar pv thermal

    Solar PV vs Solar Thermal: Comparing which is the better investment

    What is the difference when it comes to solar PV vs solar thermal?

    Both solar photovoltaic (PV) panels and solar thermal panels use the same source of energy – the sun. However, there is a distinct difference between solar PV and solar thermal technologies in that they are used for different purposes. Solar PV converts raw energy from the sun into electricity for use in the home, whereas solar thermal converts this energy into heat for heating hot water in your home.

    solar, thermal, comparing, which, better

    So, which option is the better investment for the Irish consumer?

    The Answer to Solar PV vs Solar Thermal

    The answer to this question all depends on what energy needs you are looking to cover – home heating or general electricity. Solar thermal power is generally used for water heating; however, it can also be used to provide heat for the home. It is a simple system wherein the panels that have been installed on your roof collect the sunlight. This in turn heats up the liquid in the tubes within the panels, which is then transported into your hot water tank. It is stored here until you are ready to use it.

    Advantages of Solar Thermal

    • Solar thermal technology is more space efficient than solar PV. The panels tend to take up less space on your roof, making it ideal for those with less roof space.
    • The technology of solar thermal is significantly less complex than solar PV.
    • Solar thermal has a high efficiency rate. It can be up to 70% more efficient when it comes to collecting heat from the sun’s rays than solar PV.
    • Solar thermal is less sensitive than solar PV to light, therefore works better on a cloudy day.
    • It is the ideal environmentally friendly solution for heating water if you already have a hot water cylinder installed in your home.

    Solar Thermal Issues

    The main reason to opt for solar thermal energy rather than solar PV is for the space that it saves. Solar PV panels could take up to 2-3x more space on your roof than a solar thermal system for water heating. This is due to the higher efficiency rate of solar thermal as mentioned above. However, solar thermal takes up more space in your home due to the need for a hot water cylinder. There is also the potential for leaks with solar thermal as there are many pipes linking the system components, this issue is not associated with solar PV.

    Advantages of Solar PV

    • They have a long lifespan and can provide you with clean energy for roughly 30 years.
    • They can cover up to 80% of your household’s electricity needs, sometimes even more.
    • They are incredibly efficient in summer time and can’t freeze in winter time (solar thermal can freeze).
    • They are suitable for households with high-energy consumption.
    • Grants are available from the SEAI to help subsidise the initial upfront cost of the investment.

    Can Solar PV heat your water?

    A major reason to opt for solar PV rather than solar thermal is that it is considered to be more flexible. Solar thermal is limited to heating just your hot water, whereas solar PV can cover both your electricity and hot water needs. A diverter within the solar PV system will monitor when you are generating excess electricity. Instead of sending this electricity back to the grid, the diverter will re-route this electricity to your immersion to heat up your water.

    Why Solar PV is the Winner

    The cost of energy on the grid is rising annually by roughly 3.5%, whereas the technologies as well as the pricing of solar PV systems are only improving. This ensures that a solar PV system can only be seen as a sound investment when it comes to saving money and reducing your carbon output. The chart below illustrates the advantages that solar PV has over solar thermal in relation to the amount of energy produced by each system.

    Solar PV has the edge over solar thermal in that it generates electricity, which as explained above can also be used to heat your water. Whereas solar thermal is a system that is exclusively dedicated to heating water or air. Furthermore, the initial upfront costs of solar PV can be subsidised by the government SEAI grant scheme. Solar PV owners will soon also be able to sell excess electricity that they generate throughout the year back to the grid and generate further savings on their home energy costs.

    If you are interested on saving money on your energy needs then check out our website to see how you can save. Contact us today for a free quote and let us help you start your journey to zero carbon living!

    Solar Thermal Systems

    Different from solar PV, which generates electricity, solar thermal systems generate heat. Solar thermal or solar heating system can be used quite effectively for your home or business.

    solar, thermal, comparing, which, better

    Solar thermal systems work by absorbing sunlight and converting it into heat – you might call it a solar water heater for your home. For mid to higher level temperature applications, a dark surface on the solar thermal collector is used to absorb the sunlight. Technological developments in evacuated tube solar collectors over the past 20 years have resulted in surfaces that can absorb as much as 93% of available sunlight and only reflect a very small amount. The round shape of the evacuated tubes allows for “passive tracking” and improves performance over flat plate solar collectors. This means that solar collector systems can reach efficiency levels in excess of 75%! The task of the solar collector is then to efficiently transfer the absorbed heat to water which is circulated through the panel. Solar thermal collectors are ideal for both domestic hot water and commercial applications where hot water, heating, and even cooling is required.

    If you are considering a solar thermal system for your home or business, the experts at Sun-Wind can help you determine what your best options are. Contact us today and we will answer any questions you have. With just a few simple questions we’ll be able to determine whether your site is a good candidate for a Solar hot water array. If conditions appear to be favorable, a Sun-Wind Solutions representative can come to your location to perform a no-cost, no-obligation solar site assessment.

    Contact us today to see if Solar Thermal is right for you.

    solar, thermal, comparing, which, better

    Free Solar Heating System Site Evaluation

    Sun-Wind Solutions will visit your location for a solar thermal systems site evaluation with a solmetric sun eye. The criteria in planning a solar water heater array depends on the following:

    • Orientation – An array that faces south is the best, however, west and east-facing arrays are viable, but with slightly diminished efficiency.
    • Shading – Simply put, the longer you have direct sunlight shining on your array, the more production you will achieve.
    • Roof slope – A slope between 30 and 40 degrees is most efficient but not critical, We can suggest a solution that works very well with your given your site conditions.
    • Aesthetics – Clients, especially on residential projects, want a balance between efficiency and aesthetics. They take pride in their homes and want a solution that works and also looks good.
    • Panel Location – Based on clients wishes and the weight of the criteria above.

    We want you to be completely satisfied with you purchase. We’ll listen to you and provide options to help you achieve the best balance of all the factors above.

    Economic Analysis for Solar Water Heaters

    Investing in a solar water heater system will allow you to reduce your carbon footprint while saving you money. The federal Renewable Energy Tax Credit can allow you to save 30% on the cost of your system. We will provide details of the features and benefits of the system including cost-of-system, expected savings and expected ROI (return on your investment). Each system will vary depending on site conditions but, in general, a system can pay for itself within 3-5 years.

    Engineering / Design of Solar Thermal System or Solar Water Heaters

    Sun-Wind Solutions will develop a plan and handle all of the details for your solar heating system including:

    • Comprehensive site survey for home solar water heaters
    • Engineering review of solar thermal systems
    • Evaluation of site logistics for a solar heating system
    • Evaluation current infrastructure as it relates to proposed solar thermal installation
    • Coordination of structural and mechanical engineering for a solar water heater
    • Apply for, and secure all required permits and applications for home solar heating system

    Service-and-Support for Solar Water Heaters

    Service for solar hot water systems will require changing the biodegradable polypropylene glycol fluid every 2-3 years for good system life. This fluid prevents freezing in the winter months.

    Solar Heating System Installation

    Our team of solar professionals will work with you and your family to ensure smooth and timely completion.

    The following items are part of a typical installation:

    • Final solar site prep as needed
    • Installation of Solar Thermal hardware components
    • Integrate new system into existing infrastructure

    Solar Thermal Systems Testing and Commissioning

    • System check and test
    • Coordinate inspections
    • Commission the new system
    • Owner overview and training session
    • Transfer of system documents to owner
    solar, thermal, comparing, which, better

    Solar Water Heaters

    Solar water heaters.- sometimes called solar domestic hot water systems.- can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use.- sunshine.- is free.

    How They Work

    Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don’t.

    Active Solar Water Heating Systems

    There are two types of active solar water heating systems:

    • Direct circulation systemsPumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.
    • Indirect circulation systemsPumps circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.

    Passive Solar Water Heating Systems

    Passive solar water heating systems are typically less expensive than active systems, but they’re usually not as efficient. However, passive systems can be more reliable and may last longer. There are two basic types of passive systems:

    • Integral collector-storage passive systemsThese consist of a storage tank covered with a transparent material to allow the sun to heat the water. Water from the tank then flows into the plumbing system. These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.
    • Thermosyphon systemsWater is heated in a collector on the roof and then flows through the plumbing system when a hot water faucet is opened. The majority of these systems have a 40 gallon capacity.

    Storage Tanks and Solar Collectors

    Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.

    Three types of solar collectors are used for residential applications:

    • Flat-plate collectorGlazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors.- typically used for solar pool heating.- have a dark absorber plate, made of metal or polymer, without a cover or enclosure.
    • Integral collector-storage systemsAlso known as ICS or batch systems, they feature one or more black tanks or tubes in an insulated, glazed box. Cold water first passes through the solar collector, which preheats the water. The water then continues on to the conventional backup water heater, providing a reliable source of hot water. They should be installed only in mild-freeze climates because the outdoor pipes could freeze in severe, cold weather.
    • Evacuated-tube solar collectorsThey feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin’s coating absorbs solar energy but inhibits radiative heat loss. These collectors are used more frequently for U.S. commercial applications.

    Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a tankless or demand-type water heater for backup.

    Selecting a Solar Water Heater

    Before you purchase and install a solar water heating system, you want to do the following:

    Also understand the various components needed for solar water heating systems, including the following:

    Installing and Maintaining the System

    The proper installation of solar water heaters depends on many factors. These factors include solar resource, climate, local building code requirements, and safety issues; therefore, it’s best to have a qualified solar thermal systems contractor install your system.

    After installation, properly maintaining your system will keep it running smoothly. Passive systems don’t require much maintenance. For active systems, discuss the maintenance requirements with your system provider, and consult the system’s owner’s manual. Plumbing and other conventional water heating components require the same maintenance as conventional systems. Glazing may need to be cleaned in dry climates where rainwater doesn’t provide a natural rinse.

    Regular maintenance on simple systems can be as infrequent as every 3–5 years, preferably by a solar contractor. Systems with electrical components usually require a replacement part or two after 10 years. Learn more about solar water heating system maintenance and repair.

    When screening potential contractors for installation and/or maintenance, ask the following questions:

    • Does your company have experience installing and maintaining solar water heating systems?Choose a company that has experience installing the type of system you want and servicing the applications you select.
    • How many years of experience does your company have with solar heating installation and maintenance?The more experience the better. Request a list of past customers who can provide references.
    • Is your company licensed or certified?Having a valid plumber’s and/or solar contractor’s license is required in some states. Contact your city and county for more information. Confirm licensing with your state’s contractor licensing board. The licensing board can also tell you about any complaints against state-licensed contractors.

    Improving Energy Efficiency

    After your water heater is properly installed and maintained, try some additional energy-saving strategies to help lower your water heating bills, especially if you require a back-up system. Some energy-saving devices and systems are more cost-effective to install with the water heater.

    What are Hybrid Solar Panels? What is solar PVT?

    As a past installer of both solar thermal and PV electric systems, I can say that they each have their pros and cons. Hot water solar systems are tricky to put together, they can leak, need pressurizing, antifreeze adding, etc. In short, installation is a hassle.

    Modern systems generally need a circulating pump and regular maintenance is essential. Saying that, they work really well. If the system is sized correctly, it will provided lots of hot water for years.

    On the other hand, solar PV panels are really easy to install. There are no moving parts, so once it’s all connected up there isn’t a lot of attention required to keep the system running smoothly. Wipe down the panels twice a year, keep them out of the shade and you’re good to.

    Hybrid solar panels are also known as PVT, or PhotoVoltaic Thermal Panels, a relatively new technology which combines two solar energy conversion principles into one unit. A solar hybrid PVT panel converts sunlight into electricity and also heat in the form of hot water.

    What is solar PVT?

    Discover your solar saving potential

    PVT stands for PhotoVoltaic Thermal, which indicates a device that combines two technologies – solar PV and solar thermal (hot water).

    Solar thermal panels were all the rage 10 years ago but lately haven’t been doing so well. This is surprising, because it’s a much more efficient process than solar PV. The only downside is that the energy can only be used as hot water and isn’t flexible like electricity.

    Hybrid solar thermal and solar PV is an interesting technology combination that improves the output from your solar PV from a mere 20 percent to over 80 percent energy conversion. Solar PV is a great technology that has grown leaps and bounds, particularly over the last two decades, but its efficiency remains around 20 percent, even in premium panels.

    How efficient are PV solar panels?

    So only 20 percent of the energy intercepted by the solar panel is converted into electricity. The rest of the 80 percent is lost. Now this may not be important for people that have large roof areas for installing solar panels, but for people with limited roof space like in an urban setting, that 80 percent lost energy means a lot more.

    Even a cursory look at the solar PV technology tells us that it is approaching a point of maturity. Technology development is adding extra power to the panels but only in small increments. In recent years we have seen cut-cell, PERC and bi-facial solar technology has improved the gain of panels.

    We are now coming to a point where, in order to squeeze more out of the PV panels, we have to look either towards the prohibitively expensive multi-junction solar cells used in satellites or perovskite cells. Perovskite has the potential to go further than crystalline silicon cells but at present it remains unstable and degrades quickly.

    How to make solar panels more efficient?

    Is there a way to convert more energy out of solar irradiance?

    Yes, there is. It is by using a solar PVT panel, or in other words a photovoltaic thermal hybrid collector. As the name suggests, it is a combination of solar thermal collector and photovoltaic cells that maximize the solar gain with the simplest of methods.

    Video and transcript by kind permission Synergy Files

    It provides both electricity and heat as an output and the best thing about it is that the two technologies complement each other and work symbiotically. If we look at solar thermal collectors on their own, we find that they are very efficient devices. In fact, the evacuated tube collectors have been recorded with energy efficiency of over 90 percent, meaning they can convert nearly all of the incident sunlight into heat.

    Does heat affect solar panels?

    Solar PV, on the other hand, can only work with photons in the sunlight of particular energy levels and the rest of the photons simply pass through and get absorbed by the back layer. They end up producing heat in the cells which is undesirable. In fact, this generated heat reduces the output of the solar cells.

    The thermal coefficient of the PV panel, a value that is provided with its specification sheet, tells us precisely the drop in performance of the panel with rising temperature. In desert climates the PV panel temperatures are known to reach above 70 degree Centigrade. To cool the panels down options like cooling jackets are used.

    In solar PVT panels the photovoltaic cells are placed on top of a solar thermal collector. The excess heat that builds up is removed by water running through the thermal collector. It has been claimed that hybrid panels can have efficiency as high as 85 percent and can generate four times the energy produced from the same surface area for only 25 percent increase in cost.

    In cold climates biggest energy use is heat

    In Europe and many other cold climate countries over 52 percent of the total energy used goes into space and water heating. Heat remains the biggest energy and use studies have shown that active heat removal systems can improve the PV panel life from 30 years to 50 years.

    Heat removal not only improves the instantaneous performance of the solar PV cells but also adds longevity to their life. 20 percent higher annual output of electricity has been reported for PV alone in a PVT system, compared to a non-pvt system.

    Well, one may ask that if this is the case then what is the hitch? Why is this technology not so prevalent? Why is it that only a small number of companies are producing it?

    How to use solar hot water

    It turns out that PVT technology is not simple plug and play as PV technology is. Furthermore, in summer time one can end up with large quantities of water that is 35 to 40 degree centigrade in temperature and has nowhere to go. For this reason people with swimming pools are the ones that are opting to install them for now.

    There is a way around it. The excess heat can be dumped by passing the hot water through outdoor convectors when it’s not needed. The fact remains that when we are using both electric and thermal outputs of the PVT we are essentially saving double the amount of money.

    In many places electricity are three times the price of gas and this is exactly the ratio of output you get from a PVT solar panel, that is three units of heat with one unit of electricity, thus doubling your savings. If Tesla went this route of the PVT rather than for the solar roof tiles, it will be much more beneficial for people who don’t have the roof space enough to accommodate several kilowatts of PV panels.

    What does PERC mean in solar panels?

    PERC means Passivated Emitter and Rear Cell and is a variation on the standard architecture of crystalline silicon solar cells. An extra layer reflects light energy back into the cell structure where it can be converted into extra energy, bringing 1 to 2% extra efficiency.

    What are half cut solar panels?

    A typical industrial solar PV panels has 60 cells. Half-cut solar panels have their cells cut in half, so they have 120 cells per panel. Advantages include more electrical paths for supplying electricity to inverters and less reduction in power output due to shading.

    How do bifacial solar cells work?

    Bifacial solar cells work by allowing more light to pass onto the solar cell structure so more energy is converted. This is achieved by replacing the traditional back cover with glass or other transparent material.

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