The two methods are
- focusing sunlight onto a liquid that is heated and used to turn water into steam to drive the turbines
- photovoltaic cell (layers of silicon to generate electricity)
I am sure that the photovoltaic panels are more efficient in converting solar energy to electricity as there isn’t much loss in the process.
Has NASA developed any such aerobot for missions in Space or other planets?
yes,solar energy can be harness in a space mission but the photoradiation about which are talking
is very weak so it is can become as main fuel but we can use it as alternative source
In a sunny location, sunlight has a power density of about 1 kW/m2. Photovoltaic solar cells can convert this power into electricity with 15% efficiency.
If a typical home uses 390 kWh of electricity per month, how many square meters of solar cells would be required to meet its energy requirements? Assume that electricity can be generated from the sunlight for 8 hours per day.
Michelle, John is quite correct in his math. The only problem with the problem as it’s stated is that the average solar panel is closer to 11% efficient. There are some leading edge ones that claim to have reached as high as 18%, I don’t know if they have been independently tested yet, but most run between 10 and 13 %. So about 11 square meters should do it based on your weather forecast.
We actually live in a solar powered home. Our panels are advertised at 12% efficiency, they are multicrystaline. Our entire array takes up 155 square feet, or about 15 square meters. Our home uses about 300 kwh per month, and in the summer, we usually have a little excess, meaning by 2 pm on sunny days, our batteries are full and can’t hold any more charge, so for an hour or two, the panels only power the small loads in the house, and the rest is wasted. This is necessary though, so that after a few cloudy days, when the sun comes out, there is extra to bring the batteries back up as well as run the home.
Are you working on a homework assignment, or just doing research? There are some better places to get info on this subject than asking hacks like me online. Solar Energy International would be my first pick, and some of the renewable energy associations too. I will put some names and links below for you. Also, there is a great periodical that covers this stuff right down to the nuts and bolts, Home Power Magazine. It is actually where we got started 11 years ago, now we have made it here. Check out some of the websites and do some of your own research, you’ll be well informed in the end. Good luck, and take care, Rudydoo
If there were many reflecting mirrors to double and triple the light received by photovoltaic cells, would that increase their efficiency?
This question is worth a look because while it’s true that solar cell panels have a relatively low photovoltaic efficiency, why not keep bouncing the same beam of light on it, sort kind of like redepositing the same bad check at the bank until it goes through? Assuming that unabsorbed light reflects from the solar panels (it’s a different problem if the reflection is diffuse), we can create a well between a solar panel and a mirror set at an angle to it, so that light infall reflects repeatedly inside it. It’s an interesting problem, because I can see that there’s a lot of design tradeoffs involved here, and it would depend on how light is scattered from the solar panels. Enough usable light has to be scattered from the solar panels to make it worthwhile, it’s no good if the scattered light is at a different wavelength that’s not absorbed by the panels.
I’m SURE solar panel engineers have already thought of this angle, pun fully intended.
Addendum: For those that think that efficiency of solar cells is "very high", check out the link to a chart showing that most solar cell technologies are from 12% to 24% efficient in converting sunlight.
why don’t we put huge solar panal up in space and send the energy back down to earth . may be everything could be powered from that
no more ned for oil, coal etc
It’s called space-based solar power, and a lot of people are taking it seriously.
The most commonly suggested transmission technology would be a beam of microwave radiation, from the satellite to Earth.
Looking for web-sites or mail order companies (within the U.S. or Canada) that supply Photovoltaic Modules (Solar Panels), Wind Turbines, Battery Banks to store the energy, and inverters to convert the energy for home use.
Also if anyone has any experience with living "off the power grid" are there any web-sites or books that can teach me more about setting up off grid systems?
I designed and installed my own grid-tied solar system on my house, which was built in 1973. I have a degree in engineering though and would not recommend such a project unless you have similar training. Even so I used a licensed electrician to do the final wiring for me. Therefore you should be looking for a reputable solar installer.
I installed my system about 4 years ago and to date have generated about 22.5 megawatt hours of electricity, which has saved about 19 tones of CO2 emissions. My system saves my about $1200 per year on my electrical bill and generates about 75% of my electrical needs.
I have included a very good website that can both help you estimate the costs of a solar installation and can help you find an installer if you decide to go forward with your project. I also inclued the site where I bought my solar panels and inverter (the third link below).
I can give you a bit of background about solar systems to help you get an idea of what to expect. Solar electric systems come it two types: grid-tied or battery backed. My system is grid-tied. That is the most popular type because it is much less expensive and requires less maintenance than the battery backed type. However, during a power outage the grid-tied system will go out too. So if you want continuous power you would have to have batteries.
Most systems for home use run from 2 to 4 kilowatts in size, which is a measure of the peak power output of the system. That will provide between 50% and 75% of a typical home. A system in that size range will cost between $18,000 and $36,000 to install. Depending upon incentives offered by your state or local government or utility you can expect to receive tax breaks or rebates of between about $2000 and as much as $15,000 leaving you with a net out-of-pocket cost of between $10,000 and $30,000.
The website below has a very nice estimating program that will recommend a system sized for your needs and can calculate all the tax and rebates available to you based on your zip code. You will need to give it how much electricity your home uses. Look at your last 12 months of utility bills to calculate that.
The program also calculates your monthly, annual and lifetime savings as well as the break-even time for you system. It also estimates the increase in property value that a solar system will provide you with. I think you will be very pleasantly surprised to learn how fast a system can pay for itself. Including the added property value most systems will reach break-even in less than two years. See the second link, which is directly to the "My Solar Estimator" page. It is very easy to use.
Before you select your system’s final size you should consider replacing some of your appliances. This is especially true if they are the age of your home. Newer appliances are much more energy efficient. You can reduce your solar system size by purchasing a couple of thousand dollars worth of energy star appliances first. That will actually make your total system cost, including new appliances less – plus you get new appliances – nice!
Appliances to focus on are: electric stoves, dryers or ovens, consider replacing with gas; refrigerator, washing machine and dishwasher, consider replacing with a new energy star rated unit. If you have electric central heating consider replacing that with a heat pump or gas furnace. The solar estimating program can help you evaluate the economics of these changes. Also do not forget to replace all incandescent light bulbs that you can with compact fluorescent units – do that this weekend 
.
Note also that the My Solar Estimating program will calculate the cost of financing a solar installation. Most people finance the installation by refinancing their mortgage and the program will tell you how much additional your monthly mortgage will be to finance the system.
The Find Solar site is one of the best places to locate local reputable solar installers once you are ready to pursue the installation. Another very good source of general information about solar and other renewable energy options for homeowners is Home Power Magazine (third website). Good luck with your new system.
If we used only hydrelectric, wind, photovoltaic solar, geothermal, we could virtually eliminate burning the solar energy that was stored millions of years ago in the form of oil.
It would take some forward thinking and strong willed people to fight the powers in place now.
We could do it in a decade if we tried. It wouldn’t be hard, just expensive. Are you willing to give up your current transportion to save the world?
So I watched this video by Ray Kurzweil:
http://www.ted.com/talks/ray_kurzweil_announces_singularity_university.html
At 5:38 he shows a graph of Photovoltaic Production. The graph shows an approximate doubling of photovoltaic use every two years.
I thought this was interesting. I’m sure cost was a factor in this behavior. What would happen if you graphed the cost of solar power per kW. Perhaps the cost of solar power is also following some sort of exponential model, and we can see when the cost of solar could rival the cost of coal/oil/other forms of energy.
Does anyone know if this has already been done? Does anyone know where I could find historic prices (like cost of solar/kW)?
Although, I wasn’t able to find the average cost of solar per kW, I did find a site with a lot of solar data. Look under energy at www.swivel.com.
The present selling cost of solar Panel is about 3 US $ per watt.So per KW it is costing 3000 $. This cost of investment is very high in terms of return gain by using the solar energy compared with fuel used electricity. Unless we found some method to reduce the cost of production of solar Panel to one third of present cost it is not an alternative.
what countries around the world use solar power to create electricity ( e.i. photovoltaic, concentrating solar power) please leave a web site. thanks!
here’s section with some articles that could be helpful to you
http://renewableenergyarticles.blogspot.com/2009/11/solar-energy.html
So if you had sunlight passing through the atmosphere at the equator on the a solar panel perpendicular to the direction of the light waves, how much energy in watts would it produce? I want the answer so I can speculate as to how much energy we could get out of a dyson sphere.
At the equator, the Sun provides approximately 1000 watts per square meter on the Earth’s surface. 1 kW per m² converted to one km², provides 1,000,000 kW / km² or
1,000 MW / kW² of solar energy at the equator.
Now look at the efficiency of the photovoltaic cells.
Commercially available solar panels are about 20% efficient. Technology breakthroughs may move this to more than 30% in the near future. Below is a list of photovoltaic efficiencies of the various technologies.
Efficiency Report
11.1% Thin Films: Past, Present, Future
17% Sunpower Introduces High-Efficiency Photovoltaic Modules
19% HelioVolt: Thin Film Technology Efficiency Comparison
20.5% Samsung’s Solar Cell Breakthrough
32.3% Photovoltaics: Energy for the New Millennium
72%?? Full Solar Spectrum Photovoltaic Materials Identified
Applying the efficiencies availble today provides the following energy outputs:
1,000 MW / km² x 20% efficiency = 200 MW / km²
1,000 MW / km² x 32% efficiency = 320 MW / km²
You will lose a portion of this in the energy conversion to your utilization equipment. Check out the solarexpert link below for a detailed explanation. of the factors that affect solar performance.
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The answer depends on where you are located (latitude) and the number of days without clouds. You’ve defined the location as the equator, but it will also depend on how much time has perfect conditions. Solar panels that are track the sun improve performance. Dust and dirt on the panels will greatly reduce the power output.
In southern California, the daily sun profile provides an annual average of 5.5 hours per day of peak conditions. Morning and evening condtions have low sunlight intensity.