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Solar Panel Electric Power Tutorial

Updated on August 07, 2014
Glenn Stok profile image

Glenn Stok has a Master of Science degree and applies his professional insight to analyze products and share reviews with tips and advice.

Proper installation of Solar Panels requires correct angle to the Sun and avoidance of trees. Trees may block sunlight from reaching your solar panels as shown here.
Proper installation of Solar Panels requires correct angle to the Sun and avoidance of trees. Trees may block sunlight from reaching your solar panels as shown here. | Source

This tutorial is a review of all the most common questions people have about solar panel electric power.

The scientific name for solar panels is Photovoltaic Material, or PV.

There are three different kinds of PV. They can be made from Single-crystalline Silicon, Polycrystalline Silicon, or Thin Film Copper Indium Diselenide.

Silicon is an element that becomes electrically charged when sun light rays hit it.

The solar panel business is having stumbling blocks:

  • China makes solar panels cheaper than they can be made in the U.S.
  • U.S. Solar Panel manufacturers are finding it difficult to survive.
  • The Obama administration gave over a $500 million loan guarantee to Solyndra [1], a U.S. solar panel developer, just before they declared bankruptcy.
  • Various state and government tax credits and rebates for solar installations are expiring.

Yet, considering the installation of solar panels on your home to save on your electric bills, or to go off the grid entirely, is still something to be considered.

You may still find affordable programs such as loans with rebates and tax credits, bringing your investment to break-even in just a few years.

Besides all that, it adds resale value to your home. And that is a big plus to consider.

In this article I will give a quick tutorial of Solar Electric Power and how it may completely eliminate your electric bill. I’ll explain what the rebates and credits are (while you can still get them), and how they affect your final cost.

I’ll also be talking about the proper method of installation, so you can determine if your situation is favorable to using solar panels. And finally, I’ll describe how to read your electric bill and compare the cost savings when using solar power.

Can solar panels give you a negative electric bill?

Some people think that solar panels will only slightly reduce your electric bill. But when installed correctly, as I'll explain below, it can completely eliminate your electric bill.

For that matter, many times your own solar panels will be creating more electricity than you use and that will feed backwards into the power grid making your meter run backwards. This is perfectly legal.

They want it that way because it saves the power companies the extra cost of generating more power.The cost of maintenance of the infrastructure is an important consideration that motivates power companies to offer huge credits for solar installations.

Do excess units of power from solar pay you back?

Good question. As I mentioned, you could have a negative electric bill. This is known as Net Metering. However the power company will not send you a check for the power you feed them. Most states require the electric company to credit you on your bill.

That credit remains on your bill until such time when your solar panels are not generating enough power due to clouds or leaves covering the panels. That is when you draw from the utility and that credit your built up helps towards your bill, possibly eliminating any charges. Even on bad days.

If you are not in the best location for efficient solar power generation you still will be able to take advantage of the sunniest days and draw on the reserve you accumulated on those dreary cloudy days. And of course at night as well.

By the way, solar panels work more efficiently the colder they are. So they actually perform fairly well in the winter months even though the sun is lower in the horizon. But this is true only if your panels are installed facing south, which is the only recommended method for proper installation.

Do you have to pay a delivery charge for solar?

At night or on cloudy days when your solar panels are not functioning, you will be drawing power from the electric grid and, in essence, using up your credits. So you can think of the grid as your storage unit for excess power that you can use later on. Technically it’s different from using batteries for storage. They don’t actually store it for you. They supply it to your neighbors who pay for the excess power that you generate. Then when you need it, you get it from the grid.

For this reason you are still connected to the grid even when you have solar equipment installed. The power utility will charge you their customary meter charge. Look at your bill and you will see that there is a charge for your meter and another charge for being connected to the grid. These charges continue to exist and there is no way to avoid them.

When you are generating more power than you use and your meter runs backwards, adding up credits on your bill, you still will be charges a small amount for the meter and connection charges. But the credits go towards future use of the utility's power when you need it.

What is the efficiency of solar panels?

Up Close View of Solar Photovoltaic Panels ~ Image Creative Commons Licensing
Up Close View of Solar Photovoltaic Panels ~ Image Creative Commons Licensing

Solar panels are only 15% efficient but don’t let that number confuse you. This is already taken into account when planning a total installation on your house that will provide 100% of your electric needs.

Not long ago, the technology was good enough to convert only 8% from the rays of the Sun. So the technology has already doubled in capacity. And new technology is coming along all the time.

That Copper Indium Diselenide that I mentioned earlier actually has an efficiency rating of 17.7%, according to the U.S. Department of Energy Photovoltaics Program.

Efficiency Of Solar Panels Is Based On Your Latitude

Latitude is the angular position north or south of the Equator.

If the Sun were directly overhead then its rays would be at a right angle (90º) and this will produce the best charge from solar panels. If the sun’s rays fall on a panel at an angle less than 90º, the voltage will be reduced significantly.

The sun’s rays will be coming from the south during the winter months in the Northern Hemisphere since the Earth’s axis is at a 23.5º angle. For this reason, it is recommended that panels be placed on roofs that are facing south.

However, the further you are from the Equator, the more the angle of the Sun’s rays will be from overhead. Therefore solar panels have less and less efficiency for homes further North in the Northern Hemisphere and further south in the Southern Hemisphere.

How do solar panels actually work?

One solar panel creates 6 to 24 volts DC, depending on the angle of the Sun and interference such as clouds or shade from trees and buildings. It is best to avoid the possibility of these disturbances. A competent installer will indicate if your situation will benefit enough by using solar panels on your roof.

In order to get 120 volts, solar panels are wired in series. Voltage adds up serially. There is an inherent problem with this arrangement, but there is no other solution. If one panel is blocked by shade, it will considerably reduce the total output. Just like a flashlight that has one dead battery.

Even if the others are good, the current doesn’t flow as well. Another analogy is with Christmas tree lights wired in series. If one bulb is dead, the whole string of lights goes out.

Batteries in a series add up their voltage. That's how four 1.2-volt batteries in a flashlight will power a 6-volt bulb. Solar panels add up the same way. But then the Direct Current needs to be converted to AC. We use 60 cycles AC in the US. The unit that does that is called an inverter.

The final component that you need for a complete system is a battery. The battery holds the charge to provide consistent voltage to the inverter. The inverter not only changes it to AC, but also steps up the voltage to 120 volts. Two inverters in series are used to produce 240 volts. Alternatively, a transformer can be used to step up 120 volts to 240 volts.

The inverters have a 10-year warranty and the solar panels have a 25-year warranty. You need to check with your own supplier for the exact terms they may give you.

Thin-film Photovoltaic Laminates

An alternative to solar panels is the thin-film photovoltaic (PV) laminate, invented by Stan Ovshinsky.

Mr. Ovshinsky was the same inventor who was involved with designing flat screen liquid crystal displays (LCD), which is commonly used for television, laptop and computer monitors, in addition to displays on smartphones and handheld computer devices such as the Apple iPad.

The PV laminate can be bonded directly to any surface. The video at the right shows how it is attached to metal roofing.

Is there a way to determine how well solar panels will work?

There is a device called the Solar Pathfinder that can be used to determine how well solar panels will work for you. The Solar Pathfinder analyzes shading from trees and adjacent buildings throughout each day year-round.

Why do the Government and the local electric utilities want you to get independent of the grid? Creating electric power by present means adds CO2 to the atmosphere. This may be contributing to global warming. Power plants are increasingly adding to air pollution. Solar power does not create air pollution.

Video - The Solar Pathfinder

What's the cost of solar equipment?

Snow on solar panels can severely reduce electric power output.
Snow on solar panels can severely reduce electric power output. | Source

You thought I’d never get to this. I’ll give an example of the costs of a typical solar panel installation for your home, using the figures from the provider who gave the seminar I had attended.

If you live in the Northeast United States, these prices will be accurate. Otherwise they are still useful as a guide.

Prices vary across the country from various solar panel companies. And some panel manufacturers offer rebates as well. It's important to check with your local suppliers and compare.

Say you have a 500 square foot roof area that faces south and is sunny all day with no interference that can cause shade. Thirty solar panels will cover this area and will produce 5700 Watts of power.

The annual output will be 7125 kilowatt hours (KwH). If your electricity is costing you 22 cents per KwH then this is a savings of $1,603 per year. If your Electric Bill averages out to $133 per month, then you are free of the grid.

Take a look at your electric bill. There are basically three charges you need to add together to find your total cost per KwH…

  1. The Power Supply Charge. This is the cost of the electricity.

  2. The Delivery Charge. This can be close to the cost of the power, doubling what you thought you were paying.

  3. Taxes, don’t forget taxes.

There are no delivery charges for Solar Power that you create with you own equipment. There are no taxes either. It’s your own power!

Once thing to understand is that you should stay on the grid so that your excess power feeds backwards into the grid. Therefore you will always have power when your solar panels can’t produce.

Remember what I said before, you will be simply using your own credit that you got when you fed the excess power into the grid. So if you have enough panels, you may very well never pay your electric utility again.

But the thing to understand is that they will still charge you for the meter connection to the grid. That is a small daily fee. Here on Long Island, LIPA charges just .18 per day, so nothing to be concerned about.

Solar panels lie close to the roof on mounts, which are installed by drilling holes through to the rafters. Consider putting a new roof on before installing solar panels so you don't have to remove the panels so soon for another roof replacement.
Solar panels lie close to the roof on mounts, which are installed by drilling holes through to the rafters. Consider putting a new roof on before installing solar panels so you don't have to remove the panels so soon for another roof replacement. | Source

Getting back to our example. If we are installing 30 panels to cover a 500 square foot area to produce 7126 KwH per year, that costs $45,030.

Now for the good news, LOOK at these CREDITS (I am using the data for Long Island, NY, but you may have similar credits and rebates)…

  1. NYS Energy Income Credit: $5,000

  2. Federal Investment Tax Credit: $7,524

  3. LIPA rebate: $19,950

How did these work out?

  1. The NYS Energy Income Credit is 25% of the contract price, but it is capped at $5,000. Unlike a deduction, the credit comes off your amount you owe in April, dollar for dollar. Your own state may very well be offering a similar credit.

  2. The Federal Investment Tax Credit is 30% of the contract price and it has NO cap on installations through December 31, 2016.

  3. I’m not done yet. Your local Power Utility may give you a rebate. The Long Island Power Authority (LIPA) is the local power utility on Long Island. I included that as an example. If you live on Long Island, these numbers are accurate for you. If you live elsewhere, check with your utility for any rebates they may be offering. For example, on Long Island, LIPA is giving a huge financial assistance to effect a 40% reduction in the retail price.

After all these credits and rebates,

the net cost is only $12,556.

That includes parts and labor!

Who installs solar panels?

Solar panels are hooked up to your present electric system with interfaces as shown here. The reason for a direct hookup is that you will want excess energy produced from your solar panels to flow out to the network, turning your meter backwards.
Solar panels are hooked up to your present electric system with interfaces as shown here. The reason for a direct hookup is that you will want excess energy produced from your solar panels to flow out to the network, turning your meter backwards. | Source

Licensed contractors install solar Electric Systems. You can find providers near you by searching for “Solar Products Dealers and Services” on the Internet on in the Yellow Pages.

Solar Panel contractors will evaluate your home and determine if Solar Power is right for you.

The provider who gave the seminar I had attended, actually uses Google Earth to do a preliminary study of one’s home to determine if their roof is slanted to the south (as is required) and to see if any trees or other buildings are creating too much shade.

But then they need to come out to the home in order to do a thorough investigation. At that time you can go over your questions and discuss your concerns about trees, shade, etc.

I even asked if they would run a new electric line from one side of the house to the other, since my south slanting roof is on the other side, far a way from where the electric line comes in. They said that there were cases where they included that in the published price quotes. But an on-site review will be required for a final commitment.

Is Solar Power worth it?

If you plan to stay in your home for at least six more years you will break even by then. But even if you sell sooner, the cost of a Solar Electric System may be recovered with the added value of your home when you sell.

Another way to look at it is to compare the investment in solar power to that of buying CD’s or other investments.

Since the break even period is six years, that is equivalent to earning 12% on your investment. Where else can you safely get a return like that?

Adding Solar Power to your home also increases it's value. When shopping for a new home, buyers will take the lower cost of electricity into account when they figure the amount they are willing to pay for your house.

In a neighborhood with high electric utility costs, having solar panels on your roof can make a big difference with selling a house and with how much you get for it.

It's easy to learn everything you need to know before buying. Go to your nearby home improvement store and ask if they will be having any seminars hosted by local Solar Electric Providers. This will give you a chance meet local installers face to face without the need to make any commitments. You’ll come out of it with a wealth of knowledge.

© 2009 Glenn Stok

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    • richtwf profile image

      richtwf 6 years ago

      Thanks for that Hub. I've learnt a few useful things.

      The British government is now encouraging the same approach here. You've mentioned the positives but are there any negative aspects that might need to be borne in mind for those considering solar installation?

    • Glenn Stok profile image

      Glenn Stok 6 years ago from Long Island, NY

      Rich, thanks for your comments. To answer your question, yes, there are a couple of negative things to to consider. If you have a North facing roof, you may not get enough power from your solar panels. Also if you have a lot of trees covering your house, you will need to trim them or remove them so that the sun hits the panels as much as possible. A reputable installation firm will do the proper analysis and provide you with their report. I know one firm locally who uses Google Satellite view to check out the trees around a house before even coming out to to a full investigation.

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