How many solar cells would I need in order to provide all of the electricity that my house needs?


If you have read the HSW article entitled How Solar Yard Lights Work, then you can get a feeling for how much power a solar cell can produce. The solar panel shown in that article contains 4 cells, and each of them can produce 0.45 volts and 100 milliamps, or 45 milliwatts. Each cell measures 2 inches by 0.5 inches. In other words, with these solar cells you can generate 45 milliwatts in one square inch (6.45 square cm). For the sake of discussion, let's assume that a panel can generate 70 milliwatts per square inch.


To calculate how many square inches of solar panel you need for a house, you need to know:

How much power the house consumes on average.
Where the house is located (so you can calculate mean solar days, average rainfall, etc.). This question is impossible to answer unless you have a specific location in mind. We'll assume that on an average day the solar panels generate their maximum power for 5 hours.
The first question is actually pretty interesting, so let's work on it.
A "typical home" in America can use either electricity or gas to provide heat -- heat for the house, the hot water, the clothes dryer and the stove/oven. If you were to power a house with solar electricity, you would certainly use gas appliances because solar electricity is so expensive. This means that what you would be powering with solar electricity are things like the refrigerator, the lights, the computer, the TV, stereo equipment, motors in things like furnace fans and the washer, etc. Let's say that all of those things average out to 600 watts on average. Over the course of 24 hours, you need 600 watts * 24 hours = 14,400 watt-hours per day.

From our calculations and assumptions above, we know that a solar panel can generate 70 milliwatts per square inch * 5 hours = 350 milliwatt hours per day. Therefore you need about 41,000 square inches of solar panel for the house. That's a solar panel that measures about 285 square feet (about 26 square meters). That would cost around $16,000 right now. Then, because the sun only shines part of the time, you would need to purchase a battery bank, an inverter, etc., and that often doubles the cost of the installation.

If you want to have a small room air conditioner in your bedroom, double everything.

Because solar electricity is so expensive, you would normally go to great lengths to reduce your electricity consumption. Instead of a desktop computer and a monitor you would use a laptop computer. You would use fluorescent lights instead of incandescent. You would use a small B&W TV instead of a large color set. You would get a small, extremely efficient refrigerator­. By doing these things you might be able to reduce your average power consumption to 100 watts. This would cut the size of your solar panel and its cost by a factor of 6, and this might bring it into the realm of possibility.

earthrealm:

solar is just too expensive for the average nigerin!!!, its not that we don't know the value,

naija folks are still yet 2 appreciaate the invertr/batt system,

because thats the best combo 4 solar?,
do u know any cheap sources 4 solar cells?, am interested

eyimofe89:

first Nepa- never expect power always
then Phcn- power holding witholding company of Nigeria

I don tire

dave07:

The real issue here is not to talk about the problem but to find lasting solutions. I agree renewable energy source of power supply maybe too expensive for the average Nigerian. I agree we can just make do with generators and keep the whole neighborhood sick with co pollution and noise. I AGREE coal fired plants would be better than gas plants and hydro-plants, I agree with these and many more points, but I ask what do we really want as citizens of this great nation. Let's stop trading blames. The number of NEPA men who are facing serious jobs hazards daily and yet remain grossly underpaid far outweighs the little number interacting with the public and some of whose conduct has given the whole Organization a bad name. The rate at which we waste even the insufficient electrical energy available in the country and we are not made to pay for such wastages even surprises the people in neighboring Cotonou. The ease at which we run generators daily at very high operating cost and our reluctance to promptly and adequately settle our electricity bills will definitely baffle anyone from the west. MTN, VMOBILE, GLO and other telecommunication success stories were made because telecom can be achieved via radition, so you need no visible wire to connect people. but can you do that with electricity? In fact when the prepaid meters were introduced, the 1st questions Nigerian asked was 'how can we bypass this meter'. There are so many questions to ask, why is it that we have not been able to build or plan for power stations that will generate more than 1,000 MW to team up with Egbin thermal station which is presently the only station with the highest installed capacity of 1,320MW? or do we need a National conference, constitutional conference Sovereign or non sovereign to bail us out?


Do we even know what to expect in electric power supply, our rights and responsibilities as regards the supply we get from PHCN or whatever. We all have a stake in the power sector because whether we like it or not it affect us all. Why can we not task our electrical engineers and fresh graduates to design and construct locally made renewable modules such as inverters and also brainstorm on how we can tap into the rich solar resources to provide community electricity projects adapting foreign technology to local needs. If today in Nigeria, foreigners are making use of our "scraps" as raw materials for product which they end up producing in Nigeria and export to other countries, I believe it is time to sit up and refuse to accept the status quo. Abeg Seun, you go 4give me for this, but I am making am appeal here to all who are electrically inclined in local fabrications to please get in touch with me. I believe we can all do something together with God on our side. I rest my case for now

ameristu:

Nuclear is actually the cheapest and most stable way of generating electricity. The problem is if people are aware of the dangers of nuclear power plants would they allow them build nuclear power plants close to them. The world has not built a new nuclear power plant since the 8 mile incident in the United States when the reactors heated, which lead to explosion of the reactor which wiped out a whole city, also the radioactive waste from nuclear plants is still a problem. The radioactive wastes are being stored in containers and they have not found any means of didposing them properly without affecting the environment.
The solar option which seems by far to be the most realistic way of generating electricity still has to be massively funded by the government, as a result cause the amount of solar panels needed to generate sufficient electricity for the basic needs like lighting,television,airconditioners,charging cell phones all at the same time is very expensive compared to the other ways of generating electricity also we all have to remember that electricity cannot be stored and the amount that can be stored usually discharges very fast when put to use, there is no sunlight at night but people still need electricity supply even at night.
We need to generate electricity that is cheap and can meet the demand of the citizens of Nigeria. Thank you.

ameristu:

I totally agree with you my friend Mr.kobojunkie. Let us look at it from another point.
The cost per KWh from Coal costs about =N=7.01
The cost per KWh from your generator is =N=8.01 (This actually depends on the generator size, this is a for a single family)
The cost per KWh from solar would cost about =N=50.03

Over time the cost of generating power from solar would go down after companies recover half of the money they invested in putting the equipmen in place. From my calculations which could take as much as 15 years. Calculate how much money one would have saved during that 15 years and by then there might have been a new technology in generating electricity then.

Calculate how much money one would have saved during that 15 years and by then there might have been a new technology in generating electricity then.

Innovative financing


“With all their advantages, solar systems are not cheap to install,” says Mr. Jem Porcaro, an analyst for the Energy and Environment Group at UNDP. “A typical home system in sub-Saharan Africa costs anywhere between $500 and $1,000 and such systems typically provide enough power to light three to six rooms and power a black-and-white TV each night. But the cost is well beyond the means of most African households.”



The use of innovative financing schemes, like fee-for-service arrangements, is one way to overcome these high up-front costs, notes Mr. Porcaro. Installing solar panels to power multiple houses at once can also cut down on costs. More households could afford solar power, argues the World Bank, if governments were to remove barriers, such as high import duties, that increase the cost of the panels. Regional cooperation to facilitate trade is another major NEPAD goal.


African leaders are demonstrating commitment to bring solar power to rural homes. For example, a UNDP-GEF report on solar financing and delivery models notes that private sales, through dealers, initially dominated the market in South Africa, but that the government, a leading NEPAD proponent, later initiated a massive off-grid effort that is now fully active. Botswana, Namibia, Swaziland, Zambia and most countries in the region have developed solar markets, in many cases with special funds to support consumer credit.

Boost to businesses

Besides domestic use, people are harnessing solar power to run small businesses. Entrepreneur Abina Lungu operates a maize-grinding mill in Nyimba, eastern Zambia. With reliable solar energy, he can work well into the night to meet all his customers’ orders. His house, close to the mill, is also lit by solar power. Mr. Lungu is one of the many villagers serviced by the Nyimba Energy Service Company (NESCO), an enterprise funded by the Swedish International Development Agency. To get power into a home or shop, NESCO installs a system that includes a panel, battery, charge controller and power points. The cost is $33.33, including the contract fee. Thereafter, consumers pay a monthly rental fee.

“I pay 30,000 kwacha [about $6.25] as a rental charge every month to NESCO,” Mr. Lungu told the Integrated Regional Information Networks (IRIN), a humanitarian news agency. “For me, it works out cheaper to use solar because paraffin is more expensive, and even if electricity comes to Nyimba, not all the people will get connected.”

No major marketing is needed to convince African citizens to turn to solar. The demand is high. NESCO says it has about 360 people on its waiting list. “We are struggling to satisfy demand,” confesses Mr. Stanislas Sankhani, the company’s project manager.

With a concerted NEPAD effort Africans will, hopefully, not languish in line for much longer. Solar electricity, states the World Bank, is as good as an electricity grid for rural households since they do not consume much power. In a modest Nyimba office, 320 kilometres away from the Zambian capital’s grid, a sign confidently announces that the office is up to date: “Solar is good ,  even in thatched houses; it will reach you wherever you are.”

ameristu:

You have said it. Solar is no doubt the best way to generate electricity. Some facts about solar energy generation
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Solar generation cannot meet the electricity demand of any country
Solar power generation is expensive, right now it is only for the rich my grandmother in the village cannot afford it.
Solar power is not 100% reliable as in that there are many days in the years when it rains and we have very little sunlight
There has to be a back up if anyone is planning of using solar to generate electricity, most of the time people use generation as back up
Solar panels are easily scratched, which reduces their productivity greatly, the scratched parts or damaged parts have to be replaces and they are costly
solar panel have to be motorized because the sun constantly changes direction during the day, the solar panels would have to be constantly moved to face the direct rays of the sunlight
again no country can totally depend on solar power generation as the only source of generation
There is no sunlight at night that would mean you would always be in black out nightly
The size of solar panels to power one's house to be ale to operate all the appliances in the house at the same time is about the size of a football field. imagine solar panels the size of a foot ball field on top of your house of if you want a smaller size you would have to turn off some equipments in order to be able to use the other.
[li][/li]
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With coal you don't have all this problems
You create jobs for miners, create jobs for drivers, people to maintain the power stations e.t.c
generating power from coal would only create more jobs, be stable and boost our economy.

salinco:

Quite educating stories, I presumed strongly that if our government is up to the task there should be no problem of energy. If a grassroots’ government decides to eradicate the problem of energy, they can source funds from the financial institution, and on the long run all the expenses will be spread on the houses in a local and it could be cheaper. A very good local government will subsidize the expenses and surely it will in turn increase the local generated revenue.

To me it is not expensive is like investing money to get money. The have wasted billion of naira on NEPA/ NPHC. So let the generation, distribution, financing and management of energy start from the Local government or the State government and supported by the government at the center to allow individual contribution.

February 20, 2006


South Africa Claims Breakthorough in PV Solar
According to an article on the IOL, South Africa website, scientist Professor Vivan Alberts and his colleagues at the University of Johannesburg (formerly Rand Afrikaans University) have achieved a breakthrough in developing a "revolutionary, new highly efficient solar power technology" after 10 years of research.  Panels will be available within a year.  The technology has been patented throughout the world. It is claimed to be "much more efficient than the costly old silicon solar panels."

The article goes on to say:

A German company IFE Solar Systems, has invested more than R500-million (US $83-million) in the South African invention and is set to manufacture 500,000 of the panels before the end of the year at a new plant in Germany. Production will start next month and the factory will run 24 hours a day, producing more than 1,000 panels a day to meet expected demand. ,

The South African solar panels consist of a thin layer of a unique metal alloy that converts light into energy. The photo-responsive alloy can operate on virtually all flexible surfaces, which means it could in future find a host of other applications.

Alberts said the new panels are approximately five microns thick (a human hair is 20 microns thick) while the older silicon panels are 350 microns thick. the cost of the South African technology is a fraction of the less effective silicone solar panels.

According to this  November 2004 article:

Prof Vivian Alberts of the Department of Physics at the Rand Afrikaans University in South Africa and team have developed and patented a novel manufacturing technique that finally makes it possible to construct CIGS solar panels at a very low cost. , Work done over the last two years indicates that panels can be produced in commercial volumes at a cost of about R 500 (US $83 or $1.66/W) for a 50 Watt panel. This is much cheaper than existing solar panels available on the market.

$1.66/W is much lower than anyone else is achieving right now but, if you believe their price, they could be on about the same pace as some other non-silicon thin film producers will be in a year, so I don't see their technology as "revolutionary."  Their installed price might be about $3.00-$3.50/W (at 2x panel price).  The key to low cost cells is the manufacturing methods and it is awful ambitious of anyone to assume they can reach that price in one year, even with a "novel" manufacturing process. 

Daystar and others are developing similar technology.  Daystar may be reaching $3.00-$3.50/W installed price in 2007 with their Gen II production if everything goes right.  They are achieving 20% efficiency in the laboratory which is much better than anyone most get with silicon.  Daystar plans on reducing its installed price to the range of $1.00/W when its Gen III production is tuned up in 2009, but I suspect they may have to go to a Gen IV process, producing wider width cell panels and a higher production rate before they reach that price.

NREL has said that industry needs to get its price down to about $0.52 per watt (cost $0.26) to achieve installed price of under a $1.00/W, (for 13% efficiency CIGS panels) the holy grail of pricing necessary to compete with utility power without any subsidies in the US. Electricity is much more expensive in South Africa than in the US, so maybe their price is competitive over there. Prices this low are for large multi-MW installations, not for household installations, so that is another factor to consider.  Supplies of Indium and Gallium become tight when you are talking about multi-GW production so yet another obstacle to overcome. And then could we have patent infringement lawsuits at some time?  Life is so complicated.