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
I am bad at math so I hope someone else double checks this I just really wanted to see if I could solve it
so you have 1kw/m2 * 8 hours a day
so 8kwh/m2 * 15% efficiency
1.2kwh/m2 per day with 30 days in a month
36 kwh/m2 per month
so 390 kWh / 36 kwh/m2 = 10.8333
I’m not sure if the month is a part of it or not, if not I got 325 m2 which seems awfully high but maybe? I really hope someone with a talent for math does this.
So let me get this straight BillRussell I say that I’m not good at math, I ask someone else to double check this, and even though I did this correctly, you still give me a thumbs down? Wow man you must have a serious hard on for YA! points. I even gave you a thumbs up, because this is clearly your subject.
References :
First of all, 390 kW-hour / month x 1 month/30 days x 1 day/24 hours = 540 watts average
That is quite a bit below average which is about twice that.
1 kW/m² x 0.15 = 150 watts/m²
540 watts / 150 watts/m² = 3.6 m²
but that is for 24 hours of sun a day. Multiply by 3 (24/8) to correct for that and you get
10.8 m²
.
References :
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
References :
Solar Energy International SEI.org?
Midwest Renewable Energy Association MREA.org
Great Lakes Renewable Energy Association GLREA.org
Homepower.com