PV Gap

Anne Said:

Whats the annual energy output of the average solar panel.?

We Answered:

The energy output is highly dependent on the location. For a specific area, you can look up the equivalent peak sun hours per day here:

http://rredc.nrel.gov/solar/old_data/nsr…

Let's say that it says the peak sun is 5 hours / day in your location. Then a typical 200-watt panel would have 5 x 200 = 1000 wH = 1.0 kWh per day, or 365 kWh annually. The tables above already take into account average cloudy days, and seasons.

A typical size installation would have perhaps 16 of these panels, but it could be less, or much more.

Misty Said:

how does the output of a solar panel vary with the angle of the light?

We Answered:

By the sine of the angle. If you haven't taken trig yet, I'll just mention that the sine of an angle is the ration of the length of the adjacent side of a right triangle to its hypotenuse and refer you to wikipedia for more detail.

What you need to do is set up a light source such as a 100 watt light bulb perhaps about 1/2 meter over a table. Hot glue the straight sides of 2 protractors to the bottom of your solar cell. Then you can use little props like maybe a couple of erasers so that you can angle the solar cell any way you like, reading the angle indicated by the protractors where they touche the table top.

Then you need a voltmeter and a load. A good load for an average solar cell might be a 100 ohm resistor from Radio Shack. Connect the resistor across the output of the solar cell via a pair of wires, hook the voltmeter across the resistor, and take readings of the voltmeter at say every 10 degrees from 90 to 0 degrees. Make a graph.

I don't know how sophisticated you intend to get with this, or your grade level. The above setup will give you a very basic experiment. The voltage output will increase with angle up to a peak at 90 degrees. But it is the power output of the solar cell that will be proportional to the sine of the angle of incidence, and power equals voltage times current. Email me if you want more information or have questions.

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Arnold Said:

What is the average voltage output for a solar panel?

We Answered:

Individual cells are about 1/2 volt each. How they are interconnected and how many cells there are determine the total voltage and current.

Larger ones are configured usually for 12 or 24 volts.

It's like a bunch of 1.5 volt batteries. You can connect them all in parallel, all in series, or any of many series parallel combinations.

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Irene Said:

Does damage to a solar panel affect their voltage output?

We Answered:

it depends on if the photovoltaic cell itself is damaged. if it's just the glass then there will be a slight voltage drop.

if it drops in current, it'll also drop in voltage, because of ohm's law. as long as the resistance remains constant the voltage and amperage will drop and increase at the same time. if your charging batteries, it would be better to monitor voltage, because amperage controls how fast your battery charges. if the voltage drops too low, (under 1.5 of the voltage of the battery your charging) it could damage it.

hope this helps

Tom Said:

What does solar panel output refer to?

We Answered:

Solar panels are rated under standard test conditions (STC), a certain amount of light at a certain distance, at a certain temperature, etc. A kW, or kilo watt, is 1000 watts. So for the amount of time that the sun meets those conditions, the rate of output is 1500 watts. An average location has an average of 5 sun hours a day, the total time that you produce the rated output.

Watts is a rate, like miles per hour (mph), how fast it is going. Watt hours, or kilo watt hours (kwh) is a quantity, like miles. So if you drive 50 mph for 5 hours, you went 250 miles (50 mph x 5 hours). If you produce 1.5kw for 5 hours, you have the potential to produce 7.5kwh a day. Multiply that by 30 days in a month, you get 225kwh a month. In reality you will lose about 30% of the rated power from less than ideal weather, system losses, etc., so it's more like 150kwh a month. You can look at your electric bill to see how many kwh you use a month, maybe around 1000kwh, and see what percentage of your usage a system like that can power.