PV Gap

Casey Said:

Using a solar panel to make energy?

We Answered:

Small solar panels produce almost no power that matters to anything. A whole square meter may produce 80 Watts when facing the noon sun in Arizona. take that down to 28 Watts in Erie Pa.

The 80 Watts can charge a 12 volt battery at about 8 amps times 6 hours, or 48 Amp hours per day in Arizona or perhaps 15 amp hours/day in Erie.

The amount of energy you can save declines as the battery is more charged so you need to use up the power stored before you have more to save.

To do that charging you need a circuit that will carry 8 amps, including a voltage regulator. So, if your circuit can stand 20 amps the person in Arizona can run 2 square meters of panel. It may seem strange but the same is true for the person in Erie. The person in Erie has to allow for the maximum output of the panel, not the expected average. The person in Erie will occasionally have really clear skies and put out maximum rated amps.

The amperage that the batteries can put out at maximum should not be used. That will destroy the battery. One puts a breaker on each output circuit to protect the circuit and a breaker that limits battery output to 120 amps based on a battery rated at 800 amps. That 800 amps is surge capacity.

One or two panels does not really justify having this capacity for battery and circuitry. I can think of using it to provide an emergency LED lighting system.

Lewis Said:

Using a solar panel to charge a 6 V. electric childs car battery?

We Answered:

The battery is doing what good sealed lead acid batteries do; slow decline in voltage after being disconnected from the charger.. Battery sounds good.

There are several things you can do:

Use the 220v you have in your house wiring, just get the right plug adapter by asking at a GOOD hardware or electric store. I think things that are designed at 50 cycle work fine at 60 cycle.

BEST:Get a European to USA adapter rated at 25 watts or More.

Buy a second identical battery for the car, hook them in series and top off their charge using the solar charge on trickle after doing the bulk charge with the 6v charger.

Using the present 6v charger on a timer.

Buy a decent 6v smart SLA charger on-line or at Batteries Plus, which also might be a good resource for your situation.

Do not use the solar charger for two weeks without modification to the circuit, it could really shorten the lifetime of th battery depending on the solar's output.

Derrick Said:

(maths/physics/electricity) How much power is produced by a solar panel given the equation:?

We Answered:

"TO help interpret the graph: Sunrise is the first interception of the equation and positive x axis."

That's the key statement. They're trying to hint that the model is only valid between the two points where the equation intercepts the x-axis (i.e., sunrise and sunset).

The equation is for watts, and the time in minutes, so if you integrate it between the two x-intercepts, you will get watt-minutes. Since this is physics, multiply by 60 to get Joules. In real life, you would more likely divide by 60,000 to get kilowatt-hours.