Solar Electricity is here for the longterm.   But one of the more difficult aspects of understanding solar, is determining the costs of a solar system vs. the benefits a homeowner gains when purchasing a system.

In this article, we will explain how you can produce $100 worth of electricity from your own home solar system.  And we will give details on how much the solar electric system would cost to produce that same amount of electricity.

To start, we need to choose a location in the United States to be working with.  This is important, because nearly every location has a unique amount of sunlight hours per year, and different locations also have different prices for electricity.  Another varialbe that should be taken into consideration are the current solar rebates that may or may not exist as this will affect the systems costs.(For this example, we will not take into consideration any rebates or tax incentives for solar)

Solar Example:

• Location:  San Francisco, California
• Average sunlight hours per day per year = 5.2
• Average cost per kilo watt hour of electricity = $.23

So, first we need to determine how many kilo watt hours equal $100

• $100/.23= 435 kwh equals $100

Next, we need to figure out what size solar electric system is necessary

• 435 kwh would equal 435/30= 14.5 kwh per day
• 14.5 kwh/day  divided by the average sun hours per day of 5.2 (14.5/5.2)=2.79kwh

So, 2.79 kwh AC need to be produced during each of the 5.2 average sunlight hours

Next, all we need to do is bring the 2.79 which is an Alternating Current number to DC and then we are finished. Since there is an energy loss going from DC to AC, the actual DC number will be about 18% larger than the AC number.

• 2.79DC(1.18)= 3.29 kW solar system

So, in review, it looks like a 3.29 kW DC solar electric system would be able to produce about $100 of electricity per month for someone in San Francisco, CA.

That would be about a 20 panel solar system and would be roughly 300 sq. feet of solar panels.

Solar panels come in a whole bunch of sizes or you might say they come in different wattages or watts.  One really common size/wattage is a 200 watt solar panel.  The physical size for one of these panels is roughly 5  feet long by 3 feet wide, and usually about 3 inches thick.  So, think of one of these panels being about 15 square feet.

What does a 1kw (1000 watt) system take up in square feet?  Well, that’s roughly 5 solar panels that are 200 watts each.  So, the math would be 5 x 15 square feet or about 75 square feet total for a 1kw solar system.

The Energy Production of one 200 watt solar panel:

This again will depend on the sunlight hours of the location that you are going to place the solar panels.  If for example you have 5 sunlight hours per day per year in your location, you could expect each panel to produce about 1 kilo watt hour per day in direct current.  And of course if you had 5 panels, that would equal about 5kwh/day in direct current.  There is going to be a slight energy loss when the energy is converted into alternating current(AC) so after that factor, you would have about 85% of what you started with give or take a little either way.

Here are some pictures of what these solar panels might look like.  They are examples of 200 watt panels:

GE 200 Watt

Sanyo 200 watt

One of the first questions that you will ask is: how many kilowatt hours (kwh) of electricity will my solar system produce where I live? That’s a great question, and one which everyone should ask themselves when you buy a solar system.

Las Vegas Solar Cells

There are several ways to figure this out. This post will explain the easiest way to determine the electric production for a solar system.

-The size of the solar system that we will evaluate is going to be for a 2.0 kw PV solar system. That is equal to a 2000 watt solar system because there are 1000 watts in a kw.
-The location that we will use to come up with an average sunlight hour number is Las Vegas Nevada. The average number of sunlight hours there is approximately 6.4 hours per day.
-We will use an energy loss amount of approximately 15% when the current goes from DC to AC

So, here is the equation:
2000 wattsDC X 6.4 hours/day = 12,800 watt hoursDC/day = 12.8 kwh/day on average in DC

Next, we will factor in the energy loss of 15%:
12.8kwh X .15= 1.92kwh of lost energy in the conversion to Alternating Current

Next we will figure out how much AC current is left to use:
12.8kwhDC-1.92kwh(lost)= 10.88kwh AC produced per day

Next, we will figure out how many kilo watt hours are produced each month on average:
10.88kwhAC/day X 30(days in the average month) = 326 kwhAC produced on average per month

Next, we will figure out how many kilo watt hours are produced on average per year:
326 kwh AC per month X 12(moths in the year) = 3,912 kwh per year

SO, in Las Vegas, Nevada, you could expect a 2.0 kwh solar system to produce approximately 3,912 kilo watt hours of electricity per year.

One of the assumptions is that there would be no shade hitting the solar panels as that would adversely affect the electricity production.

When you are buying a solar system in Las Vegas, be sure to ask the solar professional to explain the expected sunlight hours to you.  This is quite possibly the most important bit of data you need to know before writting any checks.