PV Gap

Anthony Said:

solar cells capacity?

We Answered:

That cost does seem high.

Here in San Jose, California in the United States I have several colleagues that have purchased solar photovoltaic systems for their homes.

The systems are advertised as capable of producing up to 3,000 watts under ideal conditions. However they actually produce substantially less than that.

My colleagues experience is that annual production has been running approximately 4,000 kilowatt hours per year.

That is not enough electricity to run a home.

The system is designed to feed electricity back into the grid if the system is producing more electricity than the home is using, which seems to be a rather rare occasion.

The cost of these systems installed in San Jose, California is approximately $30,000 dollars U.S.

If you finance the installation with a 6% loan, the annual interest cost of the system is $1,800 dollars U.S.

At 4,000 kilowatt hours of electricity per year that is a cost of 45 cents per kilowatt hour which is rather expensive for electricity.

If you purchase one of these systems to provide electricity for off the grid applications, then you also need to buy a large number of batteries to store the electical energy which is an additional cost.

Solar photovoltaic cells are fascinating the way they produce electricity from sunlight. Unfortunatelly they are a very expensive way to produce electricity.

Randall Said:

what is solar energy?give some brief notes?

We Answered:

Solar Energy, radiant energy produced in the sun as a result of nuclear fusion reactions It is transmitted to the earth through space in quanta of energy called photons, which interact with the earth's atmosphere and surface. The strength of solar radiation at the outer edge of the earth's atmosphere when the earth is taken to be at its average distance from the sun is called the solar constant, the mean value of which is 1.37 × 106 ergs per sec per cm2, or about 2 calories per min per cm2.

The intensity is not constant, however; it appears to vary by about 0.2 percent in 30 years.

The intensity of energy actually available at the earth's surface is less than the solar constant because of absorption and scattering of radiant energy as photons interact with the atmosphere.

The strength of the solar energy available at any point on the earth depends, in a complicated but predictable way, on the day
of the year, the time of day, and the latitude of the collection point. Furthermore, the amount of solar energy that can be collected depends on the orientation of the collecting object

Billy Said:

I want to work in the fied of solar energy. SO:?

We Answered:

I took a normal physics degree, and in the last year took all my optionals in thermal & condensed matter physics, which is what you need for solar power.

Physics will give you the fundamental quantum mechanics needed to understand solar cells and work on fundamental design and the effects of that design*.

Chemists can work on the production of solar cells; a fair bit on the processes to make traditional 'crystal' cells, but a lot more on things like upcoming dye-sensitized solar cells and organic solar cells.


Engineers will work further downstream, partly overlapping with the physicists' designs, but mainly on how to put a whole solar power system together and install it. This will likely be more 'real world' experience, and you can help make big cost savings there (most of the drop in silicon installations is from this), but you likely won't be working on improving fundamental designs.


I prefer understanding how things work fundamentally, so physics is best for me. If you'd rather be involved in more real world stuff, then engineering would be my preference.