PV Gap

Jennie Said:

How much do solar panel roofs save on your electricity bill?

We Answered:

The savings would depend on a variety of factors. If you live in the Southwestern U.S. you can actually MAKE money by selling surplus power back to the power company, i.e.: your meter will run backwards.

The initial cost is what often stops most people from installing them, it can be upwards of $10,000 or more. For most other areas you'll probably break even with the power company.

They're great on hot sunny days in that you can keep your house very cool during the day and it won't cost you anything in electricity. At night however do remember that you'll be getting power off the grid.

Miguel Said:

How many watts of electricity will a single 120 watt solar panel produce in 24 hours?

We Answered:

First an electrical Watt is an instaneous unit and is Voltage times Amperage (P = E * I).

So your solar pane will produce 120 watts for any of the following conditions

12V * 10A = 120W
24V * 5A = 120W
48V * 2.5A = 120

Notice that all of the above voltage and current combinations equal 120 watts.

Lets assume that your panel produces 12Volts

If you do not connect anything to the panel you will have zero current flow, and as a result you will have zero watts.

12V * 0A = 0 Watts

Now you connect a device like a radio which draws a single amp when its turned on. The radio only takes the amount of current it needs to operate.

12V * 1 A= 12W THe radio only needs to draw twelve watts of electrical power. Even though its connected to a 120W panel you are only using 12W and you have 108W of un used generatingcapacity (120 -12) available to connect other things to like lights or other devices.

So in order to use the full wattage of the panel you have to draw enough current at a given voltage to equal the panel rating. This 120W rating for your panel is most likely for a bright sunny day. A couldy day it will produce less voltage and ove couse it won't work at night

Now remember I said watts are an instaneous unit. You can measure the voltage and current with a meter at any given time, and compute the watts being consumed at the time you measured the voltage and current.


If you notice that your electric bill is using KW-Hrs (Kilowatt Hours). Kilo is a prefix that means 1000 so 1000W = 1KW.

Watt Hours or Kilowatt Hours are a cumulative reading. They provide a means to equate how much wattage has been used over a period of time. Watts times Hours = WattHours

100W used for 1 hour = 100 W-Hrs
50W used for 2 hours = 100 W-Hrs
200W used for 1/2 hour = 100 W-Hrs

Watt hours measure the average amount of energy used of a period of time. So if I turn on a 100 W light for 15minutes every hour for 4 hours I will use 100 W-hrs of energy
100W * four 15 minute intervals (15 min * 4 = 1 hr) so 100W * 1 Hr = 100 W-hrs. I used the same amount of power over a four hour period. I just used power in 15 minute intervals and used no power for periods of 45 minutes.


So to answer your question about how many watt it can produce in 1 hour the answer is 120 W-Hrs provided that you connect devices that will consume enough current at the generated voltage to equal 120Watts and that these devices consume that power for the entire hour.

Claire Said:

How much electricity does an average solar panel generate?

We Answered:

maybe 150 watts, enough for a few light bulbs, possibly a small TV. Add up the wattage numbers of the items you want to run and see if it's less than 150.

You will also need a battery, a charge controller, and an inverter.

Remember that the wattage number is only in direct sunlight, with the sun perpendicular to the panel. If just one small part of the panel is in shade, you get no output.

As soon as the sun moves away from perpendicular, the power output starts to drop.

Judy Said:

How many dollars would 1 kilowatt make, concerning electricity made by a solar panel?

We Answered:

My electric rates are 8.52 cents ($0.0852) per kilowatt hour. That is 1,000 watt hours. It means the I can use 1 watt for 1,000 hours for 8.52 cents, or 1 watt for 1 hour for 8.52/1,000 cents = $0.0000852. So for every hour you sent 1 watt back to the power company you get $0.0000852. It would probably take 3 or 4 years to make $1 worth, taking into account night and clouds.
But that is what I pay for electricity. Usually they pay you less than that to buy electricity back from you.

Ivan Said:

How does a solar panel turn sunlight into electricity?

We Answered:

Sunlight is composed of photons of light.
These photons can be caught by anything. The result is a bit of heat and it lights up. When you go outside and the sun is shining, it is "Bright" out as a result of the items around you absorbing these photons or reflecting them.

Solar panels are made up of hyper pure silicon. This material, when exposed to sunlight photons doesn't just become visible to the eye, it absorbs the photons, and their energy. This energy kicks loose a few electrons in the silicon and creates a magnetic field at the same time. The size of this magnetic field defines the voltage (Volts) of the cell, and directs the electrons.

As these free electrons are loose, they want to leave, and are directed by the magnetic fields to the poles. By putting a bit of solder on the cell at these poles you can remove the DC power (positive and negative). This flow of electrons is the current, or amperage.

The more electrons that flow from the cell, the more current you have.

To get power in sizable amounts, you need lots of these cells. You string them together in two types of circuits. One adds voltage, the other circuit type adds amperage. You can only add 1 at a time, but you can add many circuits of cells together.

To Bring up the Voltage:
String lots of cells together, connecting positive to negative, so you only have 2 connections out the ends. This is called a serial electrical connection. A string of 10 cells, at 40 watts (4 volts & 10 amps) strung together with 9 negative to positive connections, and single wires out the ends results in a 40 volt 10amp system.

To Bring up the Amperage:
String lots of cells together, connecting all positive connections. Then connect all negatives together. Again, you only have 2 connections out the ends. This is called a parallel electrical connection. A string of 10 cells, at 40 watts (4 volts & 10 amps) strung together with 9 negative to negative, and 9 positive to positive connections, and single wires out the ends results in a 4 volt 100 amp system.

At certain limits (voltage and amperage), the panels short circuit and will no longer generate power. This limits the number you can string together. To create large arrays, you evacuate the electrons and combine them later via combiner boxes and diodes.

Blocking diodes (one way doors for electricity) get the power off the circuit and into a charger controller (for batteries), an inverter (to make AC power like the wall outlet) or a combiner box (to further jump the voltage and amperage with serial and parallel circuitry before a charge controller or inverter).

For better definitions of Solar Panels, Solar Cells, and Solar Arrays, go here. http://www.bdbatteries.com/solar.php


To see how to make the power for your power bill go here.
http://www.bdbatteries.com/panelcalculat…

Ana Said:

what is the size of solar panel needed to supply electricity for a house?

We Answered:

You normally run the household off batteries and an inverter. Then you size how many batteries you need and the power you are going to use. Then you calculate the minimum amount of sunlight per day and how much energy it has to replace for the usage in the house from the batteries over a day or even two days and that should give you the solar panel capacity. To work out the amount of power you need, you switch on everything and measure the current. Then you can calculate the VA rating by multiplying that to the voltage.