12 point checklist to buying a solar geyser

Posted by: Yes Solar Cape (Cape Town, South Africa) – 29 October 2010

When purchasing a solar water heating system consider the following 12 points, and evaluate each one before committing to a system.

Yes Solar installation - evacuated tubes

1. Certification – what kind of certification does the system have? First prize is SABS Mark Approval. This is a higher form of certification than just an SABS Test Report. Mark Approval means that the entire supply chain of the product has been inspected and that SABS are confident that the product will consistently meet their standards.

2. Also look out for Solar Keymark certification (EU), and the German TUV standard.

3. Direct versus Indirect systems – basically, if you live near the coast you can install a direct system (no intermediate heat transfer fluid), but if you live somewhere that is prone to frost (i.e. temperatures drop below 4 deg), then you have to go for an indirect system. Where possible, go for a direct system, the heat loss between panel and geyser is lower.

4. Evacuated Tube versus Flat Plate collector – the respective suppliers / manufacturers of these systems place too much emphasis on this question. Rather look at the build quality, efficiency and durability of the collector, regardless of the type of technology it employs. Pay special attention to corrosion resistance – low quality stainless steel and shoddily galvanized metals will start to rust after a couple of years.

5. A quick way to measure efficiency is to look at the rebate a system enjoys. The rebate is simply a multiple of the Q factor of the system (which is a measure of its efficiency). But be careful to compare systems of the same size, e.g. a 200 litre system with a 200 litre system. Continue reading

Moon has water cycle

Posted by: Yes Solar Cape (Cape Town, South Africa) – 25 October 2010

Nearly a year after announcing the discovery of water molecules on the moon, scientists revealed new data uncovered by NASA’s Lunar CRater Observation and Sensing Satellite, or LCROSS, and Lunar Reconnaissance Orbiter, or LRO.

The Moons Cabeus Crater. Credit: NASA

The missions found evidence that the lunar soil within shadowy craters is rich in useful materials, and the moon is chemically active and has a water cycle. Scientists also confirmed that the water was in the form of mostly pure ice crystals in some places. The results are featured in six papers published in the Oct issue of Science.

Michael Wargo, chief lunar scientist at NASA Headquarters in Washington said that NASA has convincingly confirmed the presence of water ice and characterized its patchy distribution in permanently shadowed regions of the moon, this major undertaking is the one of many steps NASA has taken to better understand our solar system, its resources, its origin, evolution, and future.”

In a media release NASA explains that the twin impacts of LCROSS and a companion rocket stage in the moon’s Cabeus crater in October last year lifted a plume of material that might not have seen direct sunlight for billions of years. As the plume traveled nearly 10 miles above the rim of Cabeus, instruments aboard LCROSS and LRO made observations of the crater and debris and vapor clouds. After the impacts, grains of mostly pure water ice were lofted into the sunlight in the vacuum of space.

Anthony Colaprete, LCROSS project scientist and principal investigator at NASA’s Ames Research Center said “Seeing mostly pure water ice grains in the plume means water ice was somehow delivered to the moon in the past, or chemical processes have been causing ice to accumulate in large quantities, also, the diversity and abundance of certain materials called volatiles in the plume, suggest a variety of sources, like comets and asteroids, and an active water cycle within the lunar shadows.” Continue reading

Solar fences make good neighbours

Posted by: Yes Solar Cape (Cape Town, South Africa) – 16 October 2010

For Narad Mani Poudel, a 45-year-old farmer living in the Madi valley of Chitwan, Nepal, life used to be in a constant state of terror. Recalling an incident three years ago, he said, “Wild elephants ransacked my house and consumed almost all of the rice that I had stored for the coming season. My family and I could do nothing but watch, thankful that we got away with our lives.”

Tiger at Valmiki Tiger Reserve

Situated in the southern part of Chitwan, the Madi valley is surrounded on all the sides by protected areas; the southern border is shared with India, through the Valmiki Tiger Reserve. However, this unique geography has led to human-wildlife conflict, resulting in severe crop damage, attacks on livestock, destruction of property and human injuries and casualties. Traditional methods of defending crops from wildlife – torches, drums, trenches and thorn bushes – proved futile. Already poor and struggling to make ends meet, the communities of Chitwan took a dim view of the parks and the animals that inhabited them; some retaliated with violence.

Purna Bahadur Kunwar, Co-manager for WWF-Nepal’s Terai Arc Landscape Protected Areas and Buffer Zone project, remembers back to 2007, when he began discussions about biodiversity conservation with community groups. “They repeated a local adage, saying they are trapped in a ‘natural jail.’ They were not paying any attention to us at that moment.”

But over the course of several months, the community groups and WWF found common ground. Residents wanted to live in peace, and WWF wanted to safeguard endangered tiger, rhino and elephant populations. Both agreed that the solution might lie in another adage: Good fences make good neighbors.

“We worked together on a detailed plan for solar-powered electric fencing. The proposal included total cost, community contribution, the possibility to leverage other funds and a management and maintenance plan for the wooden fence posts. With this plan, we called a joint meeting of four Buffer Zone User Committees of Madi,” said Kunwar. Continue reading

The age of cheap electricity is at an end

Posted by: Yes Solar Cape (Cape Town, South Africa) – 10 October 2010

The age of cheap electricity in South Africa is at an end. It may pay to consider alternative and renewable energy sources – or to invest in methods of increasing energy efficiency.

Soar water heating - evacuated tubes on frame

Unfortunately, there are several factors working against an easy transition from the Eskom grid to your own little energy island.

Sustainable and renewable energy engineer Frank Spencer, CEO of Emergent Energy, said the immediate problem is that we are in a transition period from cheap to more expensive electricity.

“Our electricity is still too inexpensive to drive behaviour change, but that will change. In addition, our houses are built so poorly that we use a lot of energy to run them, such as poor insulation on geysers, pipes and ceilings, and energy-inefficient appliances,” Spencer said.

“Houses are optimised for upfront costs, not running costs. As with almost every industry, life-cycle costs are seldom considered.”

Getting the best advice on investments in alternative energy sources is not easy, said Spencer. “Most companies are looking to sell some product, which makes it very difficult to get independent advice. Further, there is no reputable accreditation body that I am aware of.” Continue reading

Greenhouse gases take more blame for rising temperatures

Posted by: Yes Solar Cape (Cape Town, South Africa) – 07 October 2010

Scientists found that a decline in the Sun’s activity did not lead as expected to a cooling of the Earth – a surprise finding that could have repercussions for computer models on climate change.

Study showed that during a waning phase solar radiation increased

The Sun’s activity is known to wax and wane over 11-year cycles, which means that in theory the amount of radiation reaching Earth declines during the “waning” phase.

The new study was carried out between 2004 and 2007 during a solar waning phase.

The amount of energy in the ultraviolet part of the energy spectrum fell, the researchers found.

But, contrary to expectation, radiation in the visible part of the energy spectrum increased, rather than declined, which caused a warming effect.

The investigation, based mainly on satellite data, is important because of a debate over how far global warming is attributable to Man or to natural causes.

Climatologists say that warming is overwhelmingly due to man-made greenhouse gases – invisible carbon emissions from coal, gas and coal that linger in the atmosphere and trap solar heat.

But a vocal lobby of sceptics say that this is flawed or alarmist, and point out that Earth has known periods of cooling and warming that are due to variations in the Sun’s output.

“These results are challenging what we thought we knew about the Sun’s effect on our climate,” said lead author Joanna Haigh, a professor at Imperial College London where she is also a member of the Grantham Institute for Climate change.

“However, they only show us a snapshot of the Sun’s activity and its behaviour over the three years of our study could be an anomaly.”

Insisting on caution, Haigh said that if the Sun turned out to have a warming effect during the “waning” part of the cycle, it might also turn out to have a cooling effect during the “waxing” part of the cycle.

In that case, greenhouse gases would be more to blame than thought for the perceptible rise in global temperatures over the past century.

“We cannot jump to any conclusions based on what we have found during this comparatively short period,” Haigh said. “We need to carry out further studies to explore the Sun’s activity, and the patterns that we have uncovered, on longer time scales.”

The study is published in Nature, the weekly British science journal.

– Sapa-AFP