PV Gap

Julian Said:

Is this site nonsense - regarding DIY power generation?

We Answered:

All sorts of scams all over the world! No wind generator yet made is worth the money it costs to install it, maintain it and endure the overall ugliness and noisiness it brings.

Lester Said:

Solar strips on calculators to power other electronics?

We Answered:

You would need a LOT of them.

You need to read up on some basic principles like voltage and current. Measure the current needed by your proposed load (the thing you want to power), and measure the current produced when those solar cells are running a calculator.

The solar powered calculators were feasible because they didn't have backlights - hence they consume very little power. Consider that similar calculators without solar cells were powered from a few button or coin cells (357, 2032, that sort of thing), and could run for more than a year on such sources.

Now consider that no modern PDAs exist that run from such batteries... although some of the old primitive things like the Casio B.O.S.S. series could do so, they didn't have backlights either.

There *are* keychain LED lights that run from just one or three coin or button cells. However they don't run for nearly as long as a calculator would.

It is of course axiomatic that to power a lamp (any lamp, LED, CFL, any lamp) with solar cells will require far more light hitting the solar cells than the lamp is going to produce.

To power a PDA is possible... your best bet would be a very old Palm Pilot without a backlight; at least, do not try to turn the backlight on... but you'll need an area of cells at least as large as the PDA, if not quite a bit larger.

Esther Said:

"Natural Energy"- Solar Power vs. Windmills?

We Answered:

Well Ben a small wind mill would probably be easier to build but I don't know every thing about them. A solar one would probably get your more energy(depending on where you are).

Anne Said:

Good sources for DIY solar LED landscape lighting?

We Answered:

there is a solar rope light on the market now, Menard's , Carry's them or do a search on solar rope lights,

Virgil Said:

Can a solar charger work using a regular power supply?

We Answered:

Sounds like you have the power supply in parallel with the solar panels, feeding the charger, right?

If so, you're putting power into the solar cells and the charger at the same time. If those are 12V panels, you're putting 16 volts on them and probably back-biasing them. The solar panels are designed for direct connection only when they are a higher voltage than what they're feeding.

The simplest way to fix this is to use a power contactor (large relay) -- DPDT. One side to the solar cells, the other to the power supply. Have it pass the power supply to the charger when the grid is on and the solar cells to the charger when the grid is off. That's what you're trying to do any way, right? Since your electronics are running off of the batteries either way (right?), the momentary switch shouldn't cause any problems.

Here's one for 20A at 28VDC for $16 from digikey.com. The coil is energized with 100VAC, so it just hooks to the main (if you use 120). I'm sure there are similar relays with 240 VAC coils, if needed. You could put two in parallel if you need a higher rating than 20A.