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New Record For Solar Cell Power Efficiency
mdsolar writes "Renewable Energy Access is reporting that a consortium led by researchers at the University of Delaware has achieved 42.8% efficiency with a silicon solar cell. The method uses lower concentration (factor of 20 magnification) than the previous record holder (40.7% efficiency) so that it may have a broader range of applications, since tolerances for pointing the device will be larger. They are now partnering with DuPont to build engineering and manufacturing prototypes. They expect to be in production in 2010. On a roof, such cells would require less than half the surface area to produce the same amount of power as today's standard solar panels, which have an efficiency of about 17%."
I'm interested in solar power as a means of lowering the fossil dependency - but there are other, better means of doing so. The CE manufacturers need to meet them half way and mandate more efficient devices that consume less power and bring back the humble ON/OFF switch that actually did turn off the power. Is it that hard to walk to the TV? And, of course, wind and tidal need to be followed up.
The main problem is the general public. Everybody wants wind power (but not in their back yard) you have to actually change the law and rubbish collection to get them to recycle, and everybody needs to buy the latest and most powerful gadget on the market.
Making a more efficient solar cell is an excellent step, but I'd be more interested in a more *cheap* one so they can be taken up on a mass scale.
The most efficient use of solar power is the water heating system. Solar panels are a distant second for now - as they are very costly for the power they can produce (we assume your house needs heating or hot water). Depending on conditions, wind power might be a cheaper overall choice than solar panels.
But in places like California, solar panels indeed pay for themselves
Peak solar power is around 750W per square meter of installation. With those new panels, you could get - let's say - 1000W per 4 square meters (40 square feet).
Assuming you are going at work using 10kW (14 HP) average for two hours (both ways), and assuming 6 hours a day peak power, and your losses are zero, you need less than 15 square meters (160 square feet).
Now, if you add 50% losses in the recharge system (car and house), you need to double that - 30 square meters, or some 300+ square feet of solar installation, inclined to an angle equal to your location's latitude (equator- flat roof top, Alaska - sharp roof)
Assuming your car has 20 square meters of surface, all of it oriented towards the sun. In Ecuador. With 100% efficient solar panels.
You can get at most 20 HP of power from that. In your real situation, with maybe 5 square meters of surface available in the morning, and lower solar power, and the 40% efficiency solar cells, you get 2HP (or 1.5KW). Does it help? A bit, yes. If your car can load itself all day with energy, and know when she will reach destination, she could bleed the electricity storage battery (and reload it later). This way, you could get 10 square meters of max power, 8 hours a day, and with perfect efficiency in rest (charge, discharge, motor) you get 80 HP hours - or two hours at 40HP. Good enough for a commute... but...
Now, you could buy solar panels at $5000 per kW (and 20 pounds). Assuming double efficiency is treble the price - you need $15,000 per square meter, so you'll pay $150,000 for solar on your car. Is it worth to drop your fuel consumption 50%? Or completely?
It probably takes a lot more than three years to pay back the investment. A three year payback would be astounding. If that were the case, you could shut down all the existing power plants and run the country just on solar. OK, that's a bit exagerated because solar doesn't make power all the time. Even so, a three year payback would see a dramatic increase in solar use.
The calculation that produces a three year period says that you start saving money after three years. It assumes that you borrow money to buy the panels. After three years, the money you save on electricity is greater than the loan payments. The link below has a graph. You will notice that the savings take a big jump after twenty years. That's when the loan is paid back and you aren't making payments any more. So, using the link's assumptions, the payback on the investment is about twenty years.
http://www.ongrid.net/PVPayback.html
The point of the link is that, even if it takes a long time to pay for the system, you can still save money by going solar.
That is why the two should be combined... Water-cooled Photovoltaic panels give the best of both worlds: cooler PV panels which are more effective PLUS warm/hot water for heating, hot water or - indirectly - cooling. The technology is out there. It is simple. It works. As to why is is not used that much yet? Good question.
A search on 'water cooled pv' gives some interesting documents about experiments done with this combination. Read them and then go and build something like that. My 2 puny 11 watt panels are somewhat to small for this application but anyone who has (plans for) panels on the roof AND a need of warm water does him/herself a disservice by not looking in to this IMnsHO...
--frank[at]unternet.org
"The CE manufacturers need to meet them half way and mandate more efficient devices that consume less power and bring back the humble ON/OFF switch that actually did turn off the power."
I recently had a new lady move in with me... and she insisted on actually unplugging things like my stereo when we were not using it. I was skeptical about the benefits of this tactic to save electricity, but being a curious person I was willing to humor her.
By unplugging all of my electronic devices (there are many of them) when not in use we saved around $30 U.S. a month. Where was all that energy going? Not sure.
If you are the type of person that has electronics in every room give it a try for yourself. Even if you don't care about being 'green' you will likely see a difference in your energy bill. Either way you win.
Regards.
Comment removed based on user account deletion
I looked into this recently. Installing a ground based heat pump instead of a regular air conditioner would have been around $6K (instead of $2K for the AC). Note that this was for an old style 12 SEER AC unit that's no longer available against a 25+ SEER heat pump (get added bonus of generating heat). AC units have almost doubled in cost, and now are about $4500 installed (new US regulations require higher SEER units).
Why didn't I get the ground based system? Because when it's over 100 F and your main AC unit dies, I couldn't wait for the ground based unit installation taking over a week. I will plan for one at my next house though.
The cesspool just got a check and balance.
Hi,
I will try to put a summary to the interested folks around:
A photovoltaic system is composed today by:
- Module
- Inverter DC/AC
- Mounting system
- Cabling
- Measuring/Protection electrical stuff
Most of the cost today is the module. Systems go (net) for 4-5$/Watt.
More efficient cells (and modules) mean less installation costs. For the future, it will be important since cell and module prices will go down.
Today, in California, if you take a system lifetime of 25 years, the kWh equivalent "price" is about 25-30cent.
System price decrease is expected to be 5-10% yearly for the next 5-10 years at least. This means that very soon the PV power will be cheaper than the one sold by the utility.
PV systems are perfect for distributed energy: a centralized power plant is not really cheaper or more efficient than a 5kW roof installation. And the energy transport kills the small margin that you had in favour of the big thing. That is why most utilities are not hot about PV: it is against their business model.
For the moment, it is not cheap to get "disconnected" from the grid. Therefore, a mix of PV and other electricity is necessary. PV has a nice peak at max. consumption peak. However, the evening consumption must be covered otherwise. Wind, biomass, ocean waves, geothermal, whatever.
PV in order to charge e-cars is OK today already. A car that uses 10 liter to do 100km, at a 20kW mean power, is using 20kWh energy for 10 liter gas, at 1$/liter it would be 50 cent/kWh. Make the calculation with your local gas price/gallon and you see that, even today, it is competitive. And cleaner. Only e-cars are not yet developed/deployed as they need to be.
About Solar-thermal energy for cold- it works for mid-big sized equipments, it is cheaper and especially more reliable than electricity... PV supporting electrical AC is still a bit more expensive but both run a nice race.
Ah, the typical guy asks about energy payback times: depending on technology, after 1-4 years your system has produced the energy needed to make it. Longer times belong to PV prehistory and to right-wing-thinktank analysis.
Cheers!