PV Gap

Bernard Said:

how long would a solar cell have to work to re-coup the energy used to make it?

We Answered:

I'm taking a class at UCLA about climate change and we had a speaker that made and installed solar cells. He said there were different types, some more efficient, but some more appropriate and style friendly. He said that they last on average about 30-40 years. As you know their manufacture is extremely energy intensive, and he said that they took about 4-7 years (depending on model) to save the energy that were used to make them. In the end though you have to take into accout that these solar cells could be made by other renewable energy sources at least in part, so this figure might be a little less, and their usage is still very important.

Lorraine Said:

Electricity Questions?

We Answered:

Much of the useful electrical energy is wasted as heat in our appliances.

Our electrical system in most homes is grounded, and in wet areas, our electric codes require ground fault circuit interrupters. These are a couple of the ways we are protected.

Electricity costs different amounts depending on where you live. It is sold in Kilo watts per hour. Some localities are set up to allow the electric company to charge different rates depending on the time of day, charging more during peak usage times.

There are three main types of solar cells. They are distinguished by the type of crystal used in them. They are Monocrystalline, polycrystalline, and amorphous.

Norma Said:

methods of generating electricity (not what you think)?

We Answered:

* Static electricity, from the physical separation and transport of charge (examples: triboelectric effect and lightning)
* Electromagnetic induction, where an electrical generator, dynamo or alternator transforms kinetic energy (energy of motion) into electricity
* Electrochemistry, the direct transformation of chemical energy into electricity, as in a battery, fuel cell or nerve impulse
* Photoelectric effect, the transformation of light into electrical energy, as in solar cells
* Thermoelectric effect, direct conversion of temperature differences to electricity, as in thermocouples and thermopiles
* Piezoelectric effect, from the mechanical strain of electrically anisotropic molecules or crystals
* Nuclear transformation, the creation and acceleration of charged particles (examples: betavoltaics or alpha particle emission)

Your should check out this site (yes, I know it's Wikipedia):
http://en.wikipedia.org/wiki/Electricity…

Nancy Said:

Help for my science fair project, Reply ASAP!?

We Answered:

The first step in the process occurs when rays of light from the sun strike the cells within PV modules (modules are commonly called “panels”). As the light energy hits the photovoltaic cells, electrons are excited and begin to flow. Multiple cells are connected in one module, and several modules are connected together to form an array, all harnessing and summing the flow of this electric power.

The current produced in the PV modules is Direct Current (DC). However, most of the lights, appliances, and other electrical equipment in our homes operate on Alternating Current (AC). Next in the chain of energy flow is a device called an inverter, which gathers the DC produced by the array and converts it to AC which can be used in the home. The inverter regulates the AC power it outputs, so it can be safely used by even sensitive electronic devices such as televisions, computers, and audio equipment.

The AC output of the inverter is connected to the home’s main service panel, where it intermingles with the AC power supplied by the local electric utility. Net Metering refers to the physical (and financial) ability of a home’s electric meter to “run in both directions”. We are accustomed to power only flowing from the utility to the loads in our house. However, with the house now acting like a mini utility producing its own electricity, there will likely be times when electricity actually flows out of the house and to the utility.

Many people think that solar power is a new concept. That couldn’t be farther from the truth. Harnessing power from the sun has been dated back to ancient civilizations.

Please see the below links for more information on most of your questions.

Margaret Said:

I need help something!!! (not homework question)?

We Answered:

The first is to purchase a ready made unit, the second is how to build one.

http://www.ecogeekliving.com/universalso…
http://www.instructables.com/id/How-to-m…

I Googled, what do think a Search Engine is for????

Cheers

GIMP

EDIT: Sorry, I screwed up both links, I think they are OK now.

Evelyn Said:

How Does A Photo-Cell Work?

We Answered:

http://www.howstuffworks.com/solar-cell.htm

see that its good.

A photocell is a relatively simple device that measures the presence of light. Photocells fall into two main categories: highly evolved versions that work with complicated equipment to help scientists find detailed readings of the amount and types of light produced by natural (such as stars) or synthetic (such as light bulbs) sources, and the consumer-oriented, photocells that generally just detect light and are unreliable when it comes to measuring it. Neither of these should be confused with photovoltaic cells, which absorb incoming light and turn it into electricity.
The average photocell works like a resistor. It contains a simple circuit that lets electricity flow through the cell at a certain rate. When the sensor part of the cell, usually on top, receives the light, it lessens the resistance of the device. This received light causes the electricity to flow through easier, at a faster rate. Another simple sensor measures the change in resistance and usually sends a signal to the primary part of the device, turning it on or off. Resistors can be calibrated, as the electric force is measured based on the effect the light sources have on the cell. This leads to a change in how or when the cell sends signals to another part of the device.
Manufacturers make photocells in many different sizes. The cheapest are made with simple plastic coverings and a ceramic structure. Two electrodes are set on either side of the cell, connected to wire terminals through which the electric charge passes. The light sensor is placed between these two electrodes, made from a photoconductive material that turns the light into electric energy. This is covered by a clear protective shell.

These type of cells are also called CdS (Cadmium-Sulfide) cells, light-dependent resistors (LDRs) and photoresistors. They are usually sold separately in categories based on resistance range, or what range they can measure, from light to darkness. Most cells measure light between violet and orange rays on the spectrum. They usually aren't larger than 1/2 inch in diameter and are usually only about 1/5 inch.

Photocells are also used in a variety of applications. Simple, uncomplicated versions are used in toys that may be activated by extra light or sound. More complicated versions may be used in motion-activated lights or alarms. The photocell senses an incoming amount of light and sends a signal when that light source is changed or disrupted. These are different versions from the scientific photocells used to measure more precise properties of light.

this one is better i guess!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!…