Solar FAQ

  • 1. Is solar water heating another feasible choice compared with gas or electricity?

    Solar should not be seen as an alternative to gas or electricity, but actually a complement. Solar cannot totally replace gas or electric heating since there are some days when there is little sunlight. On average, during a year, a suitable sized solar system can meet 60%-70% of a household's hot water needs. Producing more heat is unadvisable since too much heat will be produced in the summer. The hot water system can automatically heat water, which ensures enough hot water regardless of sunlight levels.


  • 2. How long will it take to offset my investment?

    Sunflower solar collectors are much more economical than many other ones. For a family of four, the price of a full system may not be too much than a new electric or gas system. The annual electricity or gas saving vary with you location (solar levels) and current hot water usage. However, in a average family that spends 25% of its electricity bill on hot water heating, the full cost of the purchase may be offsetted as quickly as 4-5 years in reduced bills. You will indeed make considerable savings during the use of the solar hot water heater.


  • 3. Can Sunflower solar collectors work normally in cold surroundings?

    Yes. Although performance is greatly reduced in extreme conditions, Sunflower collectors can still work normally in temperatures as low as -30oC. Good heat output is still achieved in mild sub-zero conditions.


  • 4. What will happen if one of the tubes is broken?

    Firstly, the tubes of Sunflower solar collectors are very strong and not fragile. However, if the worst situation should happen, solar tubes can be replaced very easily. They are relatively cheap and available through your local Sunflower distributor. Anyway, Sunflower solar collectors can operate with several broken tubes, although the efficiency will be reduce. Under such circumstance, it is recommended that the broken tubes should be replaced immediately.


  • 5. Will the solar collector provide heat for the water on a cloudy day?

    Yes. Although the heat output of the solar collector reduces on cloudy days, it is still able to provide heat. If it is a heavily cloudy or rainy day, more gas or electric pressure may be required to maintain water at the required temperature. This system will be automatic, so please don't worry about running out of hot water on a rainy day.


  • 6. Can the solar collector be used with my available water heating system?

    Normally yes. Simple renewal valves can often be used to allow solar to be connected to your existing cold water inlet. If your tank cannot accept the solar input directly, an additional storage tank can be set up to pre-heat the cold water before entering into the existing tank.


  • 7. Are the solar collectors conspicuous on the roof?

    As long as the collector is mounted on the roof, it will be blended into the roof quite well. Sunflower solar collectors are very thin and can be easily mounted on a roof. To some degree they look somewhat like a skylight. You have to confirm the building restrictions with your local council when installing your solar collector. Click here to view installation photos. 


  • 8. Can Sunflower solar collector be installed on a flat surface?

    Yes. They can be mounted on a flat roof, or on the ground by using a stainless steel Flat Roof Frame. The collector should be installed at a minimum of 20o angle to ensure optimal heat pipe operation.


  • 9. How do I protect my solar system when the temperatures are under zero?

    If a system operates in areas at subzero temperatures, then freeze protection must be implemented. The easiest way of antifreeze is to use a controller with a low temperatures setting. So when the manifold temperature drops below a certain pre-set temperature (5oC/40oF), the pump will circulate and then warm the water in the collector from the bottom of the storage tank. The pump will not run continuously, just periodically, the frequency of which depends on the outside temperature. In extremely cold areas, a closed loop with a glycol/water mix may be appropriate.


  • 10. Will the solar collector be a fire danger when the weather is hot and dry?

    No. The components of Sunflower solar collectors are all high temperature rated and non-flammable, that is, even in 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 collectors' components are stainless steel, aluminium, glass or glass wool. The manifold outlet should be operated with a temperature relief valve, which will prevent the manifold temperature from exceeding 99°C / 212°F. 


  • 11. Can the water be heated to a high enough temperature?

    Yes. In good weather, the Sunflower solar collector can heat the water to boiling point. Although this is not so necessary, the system should be designed to provide a daily temperature rise of around 25-30°C (45-54°F) in the summer. Sizing a domestic system that can bring the cold water up to 60°C/141oF in a day is not logical, because if hot water is not used up for one day, the system will be boiling and dumping hot water by the temperature relief valve in the following day, which is a waste of both energy and water! Please size solar water heating system reasonally to ensure optimal performance and minimal wastage of water.


  • 12. What are the necessary maintenance of the solar collectors?

    Under normal circumstances, no maintenance of the system is required. Due to the shape of the tubes, regular rainfall and wind will keep the tubes very clean. Should a tube even be broken it must be replaced immediately. This is an cheap and easy job. Any "handy" person can install a new tube (while adhering to local normal and safety regulations). Although Sunflower solar collectors can operate with several broken tubes, the efficiency will reduce obviously.


  • 13. Can Sunflower solar collectors be used to heat a large number of hot water?

    Yes. Sunflower solar collectors can be connected in series or parallel to provide large amount of hot water for a commercial settings such as schools, hotels or office buildings. There is actually no limit to the size of the system. However, collectors must be setted up in banks of no more than 150 tubes (in series), otherwise the water may boil.


  • 14. Can I heat my swimming pool by a Sunflower solar collector?

    Sunflower collectors are heat-resistant ones, which are therefore ideal for spas, since the volume of water is small and the temperature requirements are high. But for swimming pools, the volume of water is large and the required temperature-rise is only several degrees. The cost of heating a pool by solar tube collectors (for domestic purposes) may be considerably high. For large scale swimming pools, however, Sunflower collectors may be an extremely feasible supplement to gas or electricity.


  • 15. Is the efficiency of solar tube collectors higher than that of flat plate collectors?

    When comparing peak efficiency levels it seems that there is little difference between flat plate and evacuated tubes. In fact, the efficiency of flat plate may actually be higher, only when it is during minimal heat loss conditions. But in long terms use, generally a year, evacuated tube collectors have a clear advantage. The key points are:

    1. Owing to the cylindrical shape of the evacuated tubes, they are able to passively track the sun throughout the day. Flat plate collectors can only provide peak energy output at mid-day when the sun is perpendicular to the collector's surface. To know more about IAM and its performance click here.
    2. Air is evacuated in the solar tube to form a vacuum condition. This greatly reduces the conductive and convective heat loss from the inner of the tube. Then wind and cold temperatures have less effect on the efficiency of the evacuated tube collector.
    3. Sunflower solar collectors can operate in subzero temperatures without the system sustaining damage. Flat plate systems often require expensive and complicated "antifreeze" systems to be installed with.
    4. Evacuated tubes are strong, long-lasting. And if one were broken, it is inexpensive and easy to replace. However, if a flat plate collector panel is damaged the whole panel must be replaced.
    5. Owing to the high-efficient absorption of solar radiation even during couldy weathers, combined with excellent insulative properties of the solar tube, solar tube collectors can warm the water all year round (backup from gas and electricity is still required).
    6. With the several advantages of evacuated tube collector over flat plate collectors, a smaller collector can be used to perform the same heating. For example, a standard family of 4-5 people would usually require a 250-300L water storage tank. According to your location, only 30 evacuated tubes would be enough to meet all summer hot water needs and a large percentage in other seasons.
    7. Flat plate solar collectors can produce similar heat output to evacuated tube collectors only during hot and sunny conditions. Generally over an entire year, evacuated tube collector heat output per net m2 of absorber area, is between 25% to 40% greater than that of a flat plate collector.
  • 16. Which collector is of greatest value?

    Rather than looking at just peak efficiency levels when comparing with 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 actually collector B may be a better choice. Because per kWh of energy produced per day in 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 Sunflower solar collectors provides a further advantage since Sunflower Solar collectors are very easy to install, and that can make a big difference in terms of total install costs. 

    For more information concerning collector performance please click here.


  • 17. What is the solar radiation (Insolation) level in my area ?

    Click here to learn more about Insolation and the values for your region.


  • 18. How do I calculate what size of collector should I need?

    Please click here to visit the collector sizing page.


  • 19. Can Sunflower solar collectors be used in a drainback configuration?

    Yes. The end port version of the Sunflower solar collector is well suited to drainback use. The question is often asked if the solar collector will be damanged when the pump turns off and the system stagnates in good sunlight - no, it won't, as the collectors are designed to bear stagnation. What must be considered through is the insulation used on the pipe close to the collectors, as this must be able to withstand stagnation tempertures.