Posts Tagged‘photovoltaic’

Polymer Photovoltaic Cells See Efficiency Boost with Better Designs.

The solar cells you see on many roofs today are built out of silicon, the same stuff that powers your computer and smartphone. The reasons for this are many but it mostly comes down to silicon’s durability, semiconductor properties and ease at which we can mass produce them thanks to our investments in semiconductor manufacturing. However they’re not the only type of solar cell we can create, indeed there’s a different type that’s based on polymers (essentially plastic) that has the potential to be much cheaper to manufacture. However the technology is still very much in its infancy with the peak efficiency (the rate at which it can convert sunlight into electricity) being around 10%, far below even that available from commercial grade panels. New research however could change that dramatically.

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The current standard for organic polymer based solar cells utilizes two primary materials. The first is, predictably, an organic polymer that can accept photons and turn them into electronics. These polymers are then doped with a special structure of carbon called fullerene, more commonly known as buckyballs (which derive their name from their soccer ball like structure). However the structures that form with current manufacturing processes are somewhat random. This often means that when a photon produces a free electron it recombines before it can be used to generate electricity which is what leads to polymer cell’s woeful efficiency. New research however points to a way to give order to this chaos and, in the process, greatly improve the efficiency.

Researchers at the USA’s Department of Energy’s SLAC National Accelerator Laboratory have developed a method to precisely control the layout of the polymers and fullerene, rather than the jumbled mess that is currently standard. They then used this method to test various different arrangements to see which one produced the highest efficiency. Interestingly the best arrangement was one that mimicked the structure we see in plants when they photosynthesize. This meant that the charge created in the polymer by a photon wasn’t recombined instantly like it usually was and indeed the polymers were able to hold charge for weeks, providing a major step up in efficiency.

Whilst this research will go a long way to solving one of the major problems with polymer based solar cells there are still other issues that will need to be addressed before they become commercially viable. Whilst a typical silicon solar cell will last 20 years or more a polymer one will only last a fraction of that time, usually only 4 years or so with current technology. For most solar cells that amount of time is when they’ve just paid back their initial investments (both in terms of energy and revenue) so until they get past this roadblock they will remain an inferior product.

Still research like this shows there’s potential for other technologies to compete in the same space as silicon, even if there are still drawbacks to be overcome. Hopefully this research will provide further insights into increasing the longevity of these panels at the same time as increasing their efficiency. Then polymer panels could potentially become the low cost, mass produced option enabling a new wave of investment to come from consumers who were previously locked out by current photovoltaic pricing.

Would You Pay $10,000 to Never Pay an Electricity Bill Again?

Make no mistake; renewables are the future of energy generation. Fossil fuels have helped spur centuries of human innovation that would have otherwise been impossible but they are a finite resource, one that’s taking an incredible toll on our planet. Connecting renewable sources to the current energy distribution grid only solves part of the problem as many renewables simply don’t generate power at all times of the day. However thanks to some recent product innovations this problem can be wholly alleviated and, most interestingly, at a cost that I’m sure many would be able to stomach should they never have to pay a power bill again.

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Thanks to the various solar incentive schemes that have run both here in Australia and other countries around the world the cost of solar photovoltaic panels has dropped considerably over the past decade. Where you used to be paying on the order of tens of dollars per kilowatt today you can easily source panels for under $1 per kilowatt with the installation cost not being much more than that. Thus what used to cost tens of thousands of dollars can now be had for a much more reasonable cost, something which I’m sure many would include in a new build without breaking a sweat.

The secret sauce to this however comes to us via Tesla.

Back in the early days of many renewable energy incentive programs (and for some lucky countries where this continues) the feed in tariffs were extremely generous, usually multiple times the price of a kilowatt consumed off a grid. This meant that most arrays would completely negate the energy usage of a house, even with only a short period of energy duration. However most of these programs have been phased out or reduced significantly and, for Australia at least, it is now preferable to use energy generated rather than to offset your grid consumption. However the majority of people with solar arrays aren’t using energy during peak times, significantly reducing their ROI. The Tesla Powerwall however shifts that dynamic drastically, allowing them to use their generated power when they most need it.

Your average Australian household uses around 16KW/h worth of electricity every day something which a 4KW photovoltaic system would be able to cover. To ensure that you had that amount of energy on tap at any given moment you’d probably want to invest in both a 10KW and 7KW Powerwall which could both be fully charged during an average day. The cost of such a system, after government rebates, would likely end up in the $10,000 region. Whilst such a system would likely still require a grid connection in order to smooth out the power requirements a little bit (and to sell off any additional energy generated during good days) the monthly power bill would all but disappear. Just going off my current usage the payback time for such a system is just on 6 years, much shorter than the lives of both the panels and the accompanying batteries.

I don’t know about you but that outlay seems like a no-brainer, especially for any newly built house. The cost of such a system is only going to go down with time as more consumers and companies increase their demand for panels and, hopefully, products like the Tesla Powerwall. Going off grid like this used to be in the realms of fantasy and conspiracy theorists but now the technology has been consumerised to the point where it will be soon available to anyone who wants it. If I was running a power company I’d be extremely worried as their industry is about to be heavily disrupted.

Renewable Energy.

After my last foray into the controversial world of the environment and power generation (which generated some stimulating discussion and research for me) I thought it best to take a look at the renewable means of power generation and which of them have a future. I’ve had a bit of experience with most of the technology in the past with a few of my off site engineering lectures, a requirement for any engineering degree, being held on renewable energy technologies. My father also teaches renewable energy classes at the local TAFE here in Canberra, and I’ve seen quite a few interesting projects he’s been involved with over the years.

When we talk about renewable energy sources we’re looking for something that doesn’t rely on fossil fuels. The main candidates for renewable energy are:

Now not one of these solutions can provide meet all of the energy needs of the entire world and there’s many different factors to consider. The ideal solution will probably end up with a combination of many of these technologies (and some of the ones that are currently under development) just like the power generation we use today.

First the main consideration is base load power generation. Whilst this is usually trotted out as the argument to destroy the idea of using any form of renewable energy it does have raise a key points that need to be addressed. Many of the renewable energies I’ve mentioned (in fact just over half of them) can’t produce stable amounts of power. Solar, wind and oceanic technologies vary their power output significantly depending on their environment. To solve this issue base load generating stations like geothermal and biomass have to be used to supply that base level of power. The other alternative is to invest some storage technologies, like molten salt for solar thermal. For Australia I believe that geothermal and solar thermal are probably the way to go. This is because we have so much uninhabitable land that is very dry and sunny, something that these technologies thrive on. Photovoltaics are nice for smaller installations however they currently do not scale as well as the others, although that might all change when sliver cells take off¹.

Secondly load following plants are also required in order to accommodate variations in power requirements. Biomass and Hydroelectric are both options for this however I’m not entirely sure how well they can scale up. It may be more efficient to have more base load plants and just disconnect them from the grid. Whilst that may sound counter-intuitive it would be perfectly acceptable since the energy is usually not being harnessed anyway.

The last problem I’ve seen with the implementation of renewables is the lack of ideal locations for certain technologies. Geothermal requires geysers to be present or implementation of a hot rocks plant. Wind requires either high altitude or favourable wind environments such as offshore. Solar and solar thermal require a decent amount of sun and a nice flat area. You can see where I’m going with this, there’s a fair amount of work to be done to get these things in and working.

Having said all this, I’m still all for these technologies. All of the problems I’ve put forward are nothing short of solvable and eventually we’ll be forced into implementing these solutions. The great news is a lot of the supposedly big bag oil companies are in fact on board and supporting this kind of technology. The ones who aren’t will eventually fall by the wayside and we can only hope they come around before they pull an Enron and dissolve the company.

I still believe nuclear would be a great transition technology, but only time will tell.

¹I actually had the pleasure of meeting the developer of sliver technology, Andrew Blakers, back when I was a fledgling engineer. His technology does have the potential to change photovoltaics in a way that would make them highly viable. Origin Energy has some great pictures of the cells in development, and hopefully they’ll be commercially available soon.