• Because Solartwin is far simpler than traditional solar water heating.
• Designing out complexity from solar heating systems means designing away from problems.
• Minimising hassle and disruption, Solartwin solar water heating usually takes about half a day to fit.

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• No mains electric bills, thanks to Solartwin’s 100% solar powered (photovoltaically pumped) and therefore zero carbon operation pump. Solartwin=heat+electricity.
• Solartwin often needs less top-up heating than traditional solar thermal technology, thanks to more hot and less tepid water due to the way hot water is stratified (floated) over cold
• Rapid fitting, less top-up heating & solar powered pumping = real value, not just to you but also to the environment.

• Double glazing in front of the solar panel’s absorber surface lets the sun’s heat and light in. The incident solar energy makes it very hot.
• Daylight runs an “intelligent” and efficient variable speed solar electric PV (photovoltaic) pump.
• It pumps cold water, via a narrow pipe, from the bottom of your existing hot water cylinder into the solar hot water panel. Here, the water heats up.
• Thanks to the solar powered pump, your solar hot water, and the free energy it contains, then delivers itself, direct, to the top of the hot water cylinder. That’s it.

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• Solartwin solar panels are a reliable, proven, robust, safe, low maintenance, type of solar water heating.
• Because Solartwin has a water filled solar panel, it does not need to have antifreeze, so it doees not need an engineer to come to replace the antifreeze every 2-3 years. Regular replacement is a requirement of many solar antifreeze suppliers.
• Solartwin solar water heating systems come with a 5 year system performance warranty in UK / Ireland. You may need to use appropriate hardness contril such as an ion exchange water softener on your water supply, to validate this warranty.
  
• Our solar thermal system contains very few parts and made in UK under ISO 9002 quality management, Solartwin is an intrinsically reliable solar water heating system. Having had the problems of conventional solar heating designed out, Solartwin uses no antifreeze chemicals and frees you from safety concerns about highly pressurised piping, mains voltages and large smashable glass panels or tubes.
• The solar hot water pipes are robust yet flexible. Made from silicone rubber the deliver bacteriological safety to BS 6920, and take high solar water temperatures too.
• With Solartwin solar panels for water heating installed, you are not dependent on the mains electricity supply working. Electric power cuts do not make Solartwin solar hot water systems need repressurisation by an engineer since it is a low pressure, off grid technology.
  
• The Solartwin solar panel is inherently self-regulating. Going on holiday? You don’t need to invite neighbours in for baths. You can even turn off the main water stopcock if you want.
• Moving house with your solar panel? No problem. Simply un-install and re-install your solar panel: your warranty is portable!

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• Because solar water heating is (potentially) a profoundly environmental product, and we want to make it that way.
• Because our 100% solar electric pumping system eliminates the typical 20% environmental penalty associated with using mains electricity to run solar heating pumps and controls.

The Solartwin solar water heating system is a sustainable and safe solar thermal technology because of an exceptionally safe combination of:

• Zero carbon operation
• Light-weight panels
• Non-boiling in normal operation
• Low voltage
• Low pressure
• Low Legionella risk

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• A recent UK government-funded study of eight solar water heating systems confirmed what has long been suspected: that the environmental benefits of solar can be substantially improved by eliminating mains electricity by using PV pumping. (Side by side testing of eight solar water heating systems 2001 DTI/Pub URN 01/1292 (PDF) )
• In this study, flat plate solar hot water systems negated an average of 17% of their potential global warming benefits (i.e. CO2 savings) by using mains electricity.
• For partial-vacuum tubes (“solar tubes” “evacuated tubes” or “vacuum tubes”), their loss averaged even higher, at 23%.
• In other words, if you run mains-powered solar water heating systems for ten years, its electricity consumption deletes its CO2 saving by about two years.

Solartwin’s environment-centred solar water heating design brief specifies a solar electric (PV) pump. So your CO2 savings won’t retreat two steps after advancing ten. Rather than focus on making the most efficient solar panels, at all costs, since we reckon that these would require lots of resources to make and too much electricity to operate we are deliberately seeking to make the most eco-efficent solar panels as part of our “big picture approach to design”.

• Per year, a Solartwin solar water heating system will save about a quarter of a tonne of CO2 if mains gas is the guel which you displace. The figure will be higher if bottled gas, oil, coal or electricity are saved instead by your using solar.
  
• Solartwin’s “carbon breakeven” (ie manufacture carbon budget against savings from running the solar panel) is around 18 months according to detailed analyses carried out by Bath University. Again this timeframe assumes that mains gas is displaced by solar panels. It would be even shorter for other fuels listed above.

Besides being a leading solar thermal technology on the issue of zero carbon clawback in operation, we also aim to lead the global solar thermal industry in tems of carbon breakeven time because our technology, as a whole, is lightweight and it is designed as sustainably as possible and with the lowest carbon footpriint as we can reasonably achieve.

• goodbye to antifreeze chemicals in the solar pipes
  
• you usually keep your cylinder: waste less when you install solar heating
  
• uses “green” hydro-aluminium for the solar panels
  
• lightweight = less embodied energy in your solar panel
  
• hotter solar water = less top up heat
• energy-efficient microbore solar hot water pipes
• phone, not car surveys save CO2 when you buy solar thermal.

• Eliminating most of the gadgetry, plumbing, antifreeze, unreliability & maintenance inherent in traditional solar water heating systems. (Antifreeze is four to six tmes as stiicky (viscous) as water so it needs more energy to pump it (which is why we can use a 5 watt solar electric panel to power our pump. Conventional solar needs a much larger, say 25 watt pump to pump antifreeze if it were to use PV pumping at all.)
• Usually delivering hotter water whether it is sunny or overcast, and earlier in the day.
• This helps towards the solar panel creating your zero carbon house.

1. Flexible pipes lead to Solartwin’s water-filled (not antifreeze-filled) solar panels. With Solartwin, this water may need to have its hardness controlled properly or the panels may scale up. Domestic limescale controi is an established and proven technology so preventing scaling is not a problem. While our silicone rubber pipe is not as fast a conductor of heat as metal in old solar panels, the wall of our pipes is only two millimetres thick, plus ithas a large surface area, so it offers very little thermal resistance in practice, even at high sinlight levels.
2. On the other hand of the design tradeoff, antifreeze in conventional solar panels usually needs replacing every few years. It can degrade over time. Replacement can be expensive and it is a hassle to organise. We view antifreeze as an avoidable burden of maintenance upon solar panels.
3. Some chemical solar panel antifreezes can also coagulate and block conventional panels at high (stagnation) temperatures.
4. And if solar heating antifreeze degrades or leaks or boils out, and is then replaced with water, as sometimes happens, the unprotected metal solar panels may crack in cold weather when they freeze, requiring them to be replaced with new solar panels. Sometimes even a compete new solar water heating system. In our experience, this tends to be Solartwin, because our solar panels are freeze tolerant
5. As a major plus, once it has collected the solar energy as heat contained in water, Solartwin’s solar panel carries and conducts heat rather better than antifreeze can. The fact that water is about six times less sticky (viscous) also helps. For example, it means that concentional solar hot water heating systems can have problems if air bubbles do not get expelled from their solar panel circuits, to the extent that special new solar cyclone devices for spinning these bubbles out have now been developed to prevent them from reducing conventional solar pumps from cavitating – which causes them to work at reduced or even zero capacity.
6. Besides getting rid of freezing problems in metal solar panels, one major benefif of having water-filled solar panels is that they allow you to use less energy on pumping. The Solartwin approach of using not antifreeze but (much less sticky) water in our solar panels means that conventional solar water heating’s energy burning 20-50 Watt pumps can be dispensed with. They can replaced with Solartwin’s miniature, well engineered, 5 Watt solar water pump based on a brushelss DC motor and a diaphragm pump head. This is always run on solar photovoltaic electrricity, solar power that is generated on site. That’s the “zero carbon” solar panel operation innovation.

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Hotter solar water, how?

• Variable speed solar PV pumping is more accurate than traditional on-off control. Solartwin measures and adjusts to daylight as dull as 10-20%, so water stays longer in the panel, heating up better.
• Our solar panel coatings maximise heat gain up to around 70C, while usually giving boil-protection when you are away. Harvesting 95% (+/- 3%) of ordinary daylight plus non-visible infrared, our coatings don’t need hot days nor bright days to catch energy effectively.
• No heat exchangers. Indirect solar heats water via a heat exchanger at the bottom of a costly new cylinder. But solar heat exchangers impose system inefficiencies: they rely on cooling in order to operate. Some partially evacuated tube (solar tube / evacuated tube) systems have second heat exchangers on the roof.
• Stratification = Top down heat. Solartwin delivers solar heated water direct to the top your existing cylinder, maximising temperature by floating (stratifying) it, unmixed, on cooler water below. So when you open your tap, Solartwin solar hot water arrives, first. And it gets hot earlier in the day.