PV Gap

Peter Said:

Why are solar panels effected by operating temperature?

We Answered:

Absolutely temperature matters. So what do higher temperatures do to solar photovoltaic panels? As temperatures rise, the efficiency of solar panels decreases. Heat causes electrical resistance to the flow of electrons. On days where the temperature is more than 75 degrees, the electrical resistance makes the voltage fall thereby producing less kilowatts per hour. Your roof is much hotter than temperatures on the ground. That’s why solar panels are not mounted flat to a roof. There’s usually a few inches of spaces between the panels and roof so air flow can easily pass through and cool the panels down.

There are some photovoltaic panels that are designed specifically to operate in hotter temperatures. These panels have a higher temperature coefficient. This is especially important in high heat climates like Arizona or New Mexico, but probably wouldn’t make too much of a difference in New England (except maybe this year). If someone lives in one of these areas, they should speak to a solar installer to make sure they are using they right equipment for their region.

Please note: Solar thermal panels used to heat water can withstand high temperatures without any degradation. In fact, hotter temperatures would actually be better for these types of modules.

Carolyn Said:

Mythbusters....Is it possible to make a nonpolluting self contained power source?

We Answered:

Your idea violates the first law of thermodynamics. You can never get more energy out of a system than what you put into it. In fact, you will aways get less energy out of a system because nothing is 100% efficient. (Except heaters, but heat is not usable energy.)

Colleen Said:

is florida too hot for in floor heating?

We Answered:

Florida has cooler days and nights. In floor heating is probably a little expensive for the amount of heating you require in florida. I think most people in southern florida get by with much cheaper heating systems and just pay the extra in electricity or gas.........you never know though in the future...they say global warming will actually cause some areas to get much colder.

Geothermal is good because it can be used to heat or cool so yeah go with that. You can use the heat from the earth to heat the fluid in the pipes under the floor. You would have to use forced air for cooling, but they make all kinds fo systems if you want to pay $20,000 now to save $1000 a year for the next 20. Of course by then you will be due for a new system.

Maria Said:

Looking into solar power (panels and such) but have a few questions..?

We Answered:

It sounds like a 2 or 3 kW system may be enough to power all of your needs. I wouldn't be able to give you an accurate guess unless I had your electricity information.

Since this is a small solar installation, I think the installed cost would be close to $7.00 per watt or depending on the complexity of the roof/electrical work. For a 2 kW system, that means $14,000, or, for a 3 kW system, that means $21,000.

Depending on where you live, there may be a state or municipal rebate which would pay for some of the upfront cost. You also would likely qualify for the 30% federal tax credit.

Below I linked to a page that shows residential incentives for Massachusetts, Connecticut, and Rhode Island in case that's where you are.

Most installers offer a complimentary evaluation and a free estimate. I would contact someone in your local area to do the analysis for you.

Albert Said:

What is the highest efficiency/best Light output 12v Bulb for a 12v Solar system and where can I buy them?

We Answered:

You could use four ultra brite 5-mm LED in series with a protective 12.7 volt Zener diode across a 12 volt battery. Use an SMPS charger to maintain the battery at 13.33 volts. Use a 1 ampere diode IN4001 series to drop the voltage by 0.7 volts to 12.62 volts and feed the 4-LED series. Use as many such series to get the desired light output. The power of each 4-LED series is 12 x 15 = 180 milliwatts. If you use ten such series, (with 40 LEDs), you could have the output of a 60 Watt bulb, but use only 1.8 Watts. The system if followed to the second decimal value will last 3 years without any maintenance. It is worth the cost. You could give the specifications to any SMPS manufacturer and get it made to suit your needs.