PV Gap

Laurie Said:

Does Grid Tied Solar Photovoltaic on your roof qualify as, owning your power, to power your own Home or Biz?

We Answered:

I don't think so.. I think you still lease the lines that attach to your home from the utility pole. But you could always detach from that.. you just need enough PV, or wind, whatever to meet your own personal demand. Maybe a backup generator for cloudy days or eclipses?

Tamara Said:

solar power question?

We Answered:

If they directly generate electricity with the solar panels, then it would be "Photovoltaic".

If they are heating water, then I'd put it in the category "Solar Thermal Heat".

Claude Said:

solar power?

We Answered:

You have 6.7 cm^2 of cells.

from wikipedia:
A solar cell of 12% efficiency with a 100 cm2 surface area can be expected to produce approximately 1.2 watts of power.

6.7/100 = 6.7%
6.7% of 1.2w = 80 µwatts
(this is at optimal conditions)

I have no idea what AM1.5 is.

Leona Said:

If I am designing a power plant, a Concnetrated Solar Power (CSP) or Photovoltaic would be better? and why?

We Answered:

A CSP would be more complicated because you need to keep your concentrator (mirror, lens) aimed at the sun. Then you need some sort of plumbing to transfer the heat energy to something like a steam engine or turbine which is connected to your generator. Parts of your system have to withstand very high temperatures. On cloudy days it doesn't work at all.

A PV system generates electricity directly without all those steps. The panels will work best if they track the sun but they don't have to. They also will generate a little electricity on overcast days.

The wattage is directly proportional to the area of the panels so a high megawatt system will cover a lot of ground but it doesn't have to be all in one place. You could use the roofs of several buildings.

Leslie Said:

solar power explanation? photovoltaic cell?

We Answered:

Photovoltaic cells generate DC at a fixed voltage (determined by the materials the photo-cell is made from). The voltage does not depend on the amount of light.

The current available does depend on the amount of light. So you want the battery to hold any extra power the photovoltaic cells generate so that when you need power but there isn't enough light, there will still be enough power available to you.

Different batteries have different behaviors, but it is very common for battery voltage to vary with the charge and for batteries to be damaged if there is too much charging current.

So the charge controller is there to make sure the battery likes what it sees - the right voltage, not too much current, etc. (In a car, this is called the voltage regulator and is generally simpler.)

But house power is typically 120 Volts A.C., not the lower D.C. voltage that the battery likes from the controller or that it puts out itself.

The inverter takes in D.C. and puts out A.C.

As for the most widespread and tested application of solar power, it is heating water. Solar water heaters have been used by many people all over the world for over 100 years:
http://www.toolbase.org/Technology-Inven…
http://apps1.eere.energy.gov/consumer/yo…

Photovoltaics are far more recent. Their most widespread application was for powering small calculators.

As for the best way to use solar power on a large scale, no one really knows, but some still think that is, and are putting their money into, heating water:
http://news.bbc.co.uk/2/hi/science/natur…

Billie Said:

How efficient/cost-effective would it be for solar power generation to be used on a massive scale?

We Answered:

Photo voltaic cells are an ecological disaster, costing (read using lots of resources to manufacture) a lot, and they have a limited life. They are uneconomic which is why solar farms use mirrors reflecting light to a central tower or to water pipes, where the high temperatures generated heat water to drive a turbine.
In a hostile environment like the sahara, photovoltaic cells or mirrors would be sand blasted into oblivion.

Ben Said:

Do u think it is wrong to use nuclear power plant?

We Answered:

Its a lie that solar power and wind turbines are good for the environment. The compounds used to build either create huge amounts of pollution, as does disposal of them when they are worn out. The foot print of a high energy solar installation is massive and kills everything that lives there. Wind turbines kill birds by the thousands. Neither technology can be self sustaining without huge injections of taxpayer money. I used to do some engineering work in both fields and studied them in depth.

Nuclear power is not all that dangerous. The navy has been using it for many years without accident and the technology just keeps getting better. It is easier on the environment than any other technology you can come up with, including hydroelectric. Hydroelectric destroys huge tracts of land and causes droughts as well as killing off species that rely on the free flow of water. In addition, the US has tapped out almost all viable rivers, there is just no place to put more hydroelectric generators.

While nuclear waste is an issue that needs to be resolved, it is clearly the path to future energy resources.