To be straight with you, the movement for solar power for homes is still in its infancy. Currently the growth of photovoltaics and solar power for homes in general are still majorly dependent upon subsidies and tax credits. In truth, right now, conservation probably holds the most pay back for your dollar.

Photovoltaic solar power for homes systems in the lab are now around 40% efficient with projections up to around 60%. You can find photovoltaiscs operating at around 14% efficient. While this is not a fueled system where operating costs are the primary consideration, it does have an impact on how much of a system you will have to buy.

Solar thermal, while being slightly different from solar power for homes, is a lot further down the road to solving its efficiency issues because solar water heaters depend on a different principal. Solar thermal collectors are from 60 to 80% efficient these days. Vacuum tube collectors that help to run the system are also effective in cloudy weather and in cold environments.

Getting heat from the sun  using solar thermal technology and water heaters goes back thousands of years to the time of the Romans and beyond. There were solar thermal panels and water heaters in California in the early part of the 20th century. So this is a much older technology.

A lot of potential energy is lost with a photovoltaic cell. Much of the reflected energy and energy that is transformed to heat goes wasted and is therefore inefficient. A solar hot water system, on the other hand can capture roughly 80% of the required domestic hot water. Consquently, it has a realistic pay back period of just 2 to 3 years. Of course, after the costs are paid back, you can keep the savings and do what you want with them. So, you can see that solar hot water systems are genuinely cost effective in today’s competitive marketplace.

Solar thermal applications are going large scale to produce electricity. Pilot plants have three main designs:

Solar power towers where heliostats reflect sunlight onto a target. This system seems to work well as a hybrid with a gas fired power plant to take over when needed. We talked about this in an article on this blog a few days ago.

A hyperbolic dish reflector eliminates the need for much of the moving hardware of the above needed to track the sun. A trough collector system eliminates even more of the tracking hardware.

However, without subsidies these facilities are struggling to become competitive against nuclear, petrochemicals or coal power.

The main problem with solar power for homes and indeed any renewable source right now regardless of its efficiency or cost effectiveness, is that it will only work with some kind of a back up system. In the U.S. this is known as ‘the grid’. A big question here is, do we seek to move away from reliance on state organized power facilities? Setting things up on a national scale will always have its efficiencies. However, we are leaving the decisions in other peoples hands, which is how we have arrived here, in the epicenter of a genuine climate crisis.

Americans like the idea of  solar because it is produced internally. The fear of being held to ransom from other nations for their energy is a real one. Currently the US imports large quantities of both nuclear fuel and petrochemicals. Protecting the supplies is already becoming very expensive, requiring military might.

Meanwhile, India and China are massive sprawling burgeoning nations moving more and more into industrialization. The speed of their success will depend largely on their ability to obtain energy sources at viable prices. As competition makes one country’s supplies dwindle, the need for military involvement could increase. This aspect of energy policy needs to be looked at very closely.

Coal is still the driving energy source for nearly 50% of the U.S. electrical grid. We are only beginning to wake up to the total costs for using this energy form. The expression ‘clean coal’ is largely a smokescreen (excuse the pun!) The health and environmental issues are unacceptable over time. Even George W Bush was coming round to seeing that thee is a major problem with his much cherished fossil fuel policies.

We must keep looking, keep innovating, keep being optimistic. Breakthroughs are happening in all areas. Depending on where you take your information from, the future for solar power for homes would appear to be rosy, albeit with some serious challenges ahead. We must now step up to these challenges, for the sake of future generations, and for the sake of the planet.

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