How much energy can solar panels make?

Question

I read an article that said the avg. U.S. home uses 25kw of power a day. How many panels would be needed to make that much power and how would you store the energy made? Also, if anyone knows, how do you sell power back to the utility companies?

Answer 1

The amount of energy you can create depends on where you live and the orientation to the sun. I'm in the process of getting panels now. I will produce more electricity during the summer months and less in the winter. My system will provide at least 1/3 of my energy and up to 1/2 averaged over the year.

Usually you chose to store your extra energy or sell it back to your utility. Storing it involves a bank of batteries. Not all utilities allow you to run your meter backwards. If they do, then you may have credits for electricity on certain months and pay on others.

Answer 2

The amount of peak sunlight a house receives over a year depends on location.  In Arizona it might be 7 hours.  In Southern California it may be 6.  In some places it may be less than 4.  Also, it's affected by trees shading the house, and which way the roof points, but let's say for figuring that a house gets 5 hours peak sun a day.

To get 25 kW - hours of energy, you need 5 kW of panels for 5 hours.  Realistically, with losses and the way manufacturers rate their panels liberally, that's around 6 kW of panels.  Panel sizes vary, but they're in the ballpark of 200 watts each, so that would be 30 panels.

Let's say each panel is 5 x 2.5 feet (12.5 square feet).  Then, in total, that's 375 square feet of roof space, which would fit in a square 20 x 20 feet.  This would fit on an "average" house easily.  The problem for most people would be the cost, likely $40,000 or so.  Ironically, if a family of 4 lives in each house, this works out to be about the cost of the Iraq war.  But I digress.

How does one sell power back to the utility?  Most, but not all, utilities allow this sort of arrangment by contract.  When your solar panels produce more electricity than you use, the electric meter is driven backwards (it counts DOWN).  When the panels are contributing less than you use, or nothing, the meter moves forward like it does today.  At the end of the month, or year, the power company checks the meter, and you settle up what you still owe.  If the power company owes you, they might issue a small check, or more likely, just say thanks for your donation to the power grid.  In this way, for most installations today, no batteries are involved.

In some places, there are special rates, sometimes above market price, for the electricity you produce.  In such situations, there is special equipment connected to monitor your production.

Answer 3

even though you might not have a home depot in your area, if you read the post it will give you most of the answers that you need.

http://www.treehugger.com/files/2006/10/...

Answer 4

depends on how much and how strong the sunlight a panel gets.  A well made solar wafer will convert 19% of the energy it receives.  A poor one might convert as low as 7%.  Over the 25-30 year life of a solar wafer, the conversion factor lowers.  Currently the only way to store solar energy is in an electric battery.  Not very effective.

A local solar comapny could tell you what you need in terms of panels.  Current baybacl for a homeowner is 15-20 years.