Sandy asks…

If a typical home uses 390 kWh of electricity per month, how many square meters of solar cells would be requir?

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.

Henry Dover answers:

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

Mark asks…

In a sunny location, sunlight has a power density of about 1 kW/m^2. Photovoltaic solar cells can convert this?

In a sunny location, sunlight has a power density of about 1 kW/m^2. Photovoltaic solar cells can convert this power into electricity with 14% efficiency. If a typical home uses 380 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.

Henry Dover answers:

Let’s say you have 1 square meter of panels. Then you get 8 hours x 1 kW/m^2 x .14 = 1.12 kWh of energy per day.

If you have 2 square meters, you get 2.24 kWh’s per day.

If you have N square meters, it’s 1.12N kWh’s per day.

Scale that up to a month (use 30 days for a month unless advised otherwise), and you should be able to solve for N.

Sanity check: the answer should be between 5 and 20 square meters.

William asks…

how many square meters of solar cells would be required to meet its energy requirements?

In a sunny location, sunlight has a power density of about 1 kW/m2 . Photovoltaic solar cells can convert this power into electricity with 16% efficiency.
If a typical home uses 385 kW/m2 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.

Henry Dover answers:

About a million

Susan asks…

energy use and environment (frustrating problem, been working on for over an hr) HELPPPP?

In a sunny location, sunlight has a power density of about 1 kW/m^2. Photovoltaic solar cells can convert this power into electricity with 16% efficiency. If a typical home uses 380 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.

Henry Dover answers:

If the sun shines for 8 hours a day and assuming there are 30 days in each month, then in a month the sun shines for 8×30 = 240 hours

If a typical family home uses 380kW-h per month, then the power they actually use per month = 380kW-h /240hr = 1.5833 kW

Sunlight has power density of 1 kW/m^2 & photovoltaic cells can convert this to electricity with 16% efficiency. This means that one actually gets 0.16 x 1 kW/m^2 = 0.16 kW/m^2 from the cells

so the square meters of cells needed to meet energy requirement of home = (1.5833 kW / 0.16 kW/m^2) = 9.896 m^2

Mary asks…

How can we recycle/reuse/reduce energy in our lives?

I heard braking force in cars can be used as energy rite back into the car.

How abt other ideas to reuse/reduce/recycle?
Like maybe installing solar panels on as many homes as possible and channeling excess energy back into the power grid?
Or Water collected in skyscrapers can be gushed down into a bigger pipe that moves a turbine to generate electricity for that building?

These are my ideas.

Let’s share them!

Henry Dover answers:

I have lots of info that I think you will find quite helpful and enlightening:

http://ecowellness.multiply.com/ for excellent inspirational info within my blog to help not only our world and its creatures, but to also open peoples hearts and minds to many amazing wonders that life has to offer. I also have lots of info in my blog to help fuel peoples imaginations to many possibilities that can be found only in the minds eye.

Along with lots of environmental info, amazing environmental pictures and videos (These videos show the beauty of this world and what life can be like if people take the time to appreciate life’s true beauty).

Let us all strive for a greener/brighter future by helping to create a solid foundation for future generations to build upon, so we can hand them a beautiful world, filled with never ending awe and wonders!!

Where peoples differences and uniqueness are accepted, where we all live as one, helping one another so that we can all play our own mysteriously beautiful melodies in the never ending, awe inspiring, song of life :-)

I truly have faith in humanity and believe that someday our lives and the world in which we live will truly be transformed for the better.

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