You are thinking about getting a solar PV system for your home, and in your research have come to understand what the major considerations are: your electricity demand and how to save energy, what types of panels are on the market, where to put your array so that it doesn’t suffer from the effects of shading, the performance of your system over time, the proper tilt-angle for your panels, how much an installation will cost, and what the pay-back period is likely to be. You now know most of what you don’t know (and therefore need to investigate!), but the biggest unknown is still the speed of technology. Would it be wise to wait for the efficiency of panels to improve before making the investment?
Nominal solar panel efficiency is not the be-all end-all of solar power
When considering your finances, the short answer to the above question is a fairly firm ‘no’. One of the main reasons for this is that the value of incentives for solar power and other renewable energy sources is set to steadily decline in the coming years–most notably the federal government’s solar rebate Renewable Energy Certificate (REC) multiplier is already scheduled to decrease annually over the next 5 years. (As we have mentioned in this previous entry, 1 July 2011 is the installation deadline if you want to take advantage of the 5x multiplier!) Likewise, Feed-in Tariffs (FiTs) have seen significant reductions (in NSW and Germany in particular) as the predominant, tried-and-true technologies (poly-crystalline and mono-crystalline panels) become more common and widespread and reach economies of scale. The point is that, although government incentives certainly do increase the affordability of solar power, even without these incentives there may still be sound economic justification for having a solar array installed.
While it is true that PV technology is constantly making strides, affordability does not keep pace with those strides. Research into new PV materials and technologies is constantly being undertaken. A quick look at my Google Alerts emails for ‘solar’ or ‘photovoltaics’ turns up a plethora of up-and-coming technologies (a couple quick examples: solar with nano-technology, nearly 18% efficiency on new polycrystalline technology; we’ve even written about future technologies in blog entries like this one), but the fact is that the technologies already in operation and commonly available are the ones that solar power installers know well. The bugs have been worked out of most of them, and those who have experience working with them know what to look out for if something goes wrong.
Solar Panel Efficiency vs Durability and Reliability
Here is a rundown on the efficiencies available for solar power: If you’re dealing with poly- or mono-crystalline panels, you can expect a solar conversion efficiency (essentially the percent of the sun’s energy captured and turned into electricity) of 10-12%. Amorphous (film) PV comes in at around 5-7%. The most efficient panels that you can find on the market get up to 17 or 18%. Compare this to photosynthesis in many plants, which can be less than 5%.
Which brings us to the next point. Something that many people forget about when considering a solar power purchase is that efficiency doesn’t matter nearly as much as cost per Watt or kiloWatt of installed capacity. You more than likely have ample space on your roof to provide for the energy demand of your home, and there won’t be a huge difference between the space taken up by a 10% efficient panel and, say, a 12% efficient one. If it looks like your system might not provide enough, it’s usually not a financial stretch to add another panel. Doing so may actually benefit you: you sell the excess into the grid. But getting an entire set of an equal number of similarly sized panels that have a greater efficiency could potentially break the bank: they often utilise rare materials or technologies that are not easy to come by and therefore pricey.
In any case, if you are a typical solar panel customer, it’s likely that you’ll be retrofitting your house with a roof-mounted array, in which case efficiency is not the most important factor. Instead, considerations regarding durability and reliability will probably take precedence for you. Unless you feel that you absolutely must have the latest technology (i.e. you are a bit of a techie/nerd), there’s really no reason to be too fussy about it, provided you have enough roof space. Or, if for example you’re dropping a huge load of money on a brand new house that you’ve just had designed specifically for you and have no compunctions or budget, then you might consider installing some flash technology. Otherwise it’s probably best to just stick with convention.
Written by James Martin
Solar Choice Analyst
© 2010 Solar Choice Pty Ltd
He is now the communications manager for energy technology startup SwitchDin, but remains an occasional contributor to the Solar Choice blog.
James lives in Newcastle in a house with a weird solar system.
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