What happens when a solar panel makes too many amps?

the panel doesn't "make" excess power. it will only deliver either the max power that it is capable of given the solar energy, or the max power that the controller can deliver to the load, whichever is smaller.

think of it this way. your honda generator can output 2000VA, BUT it ONLY does that when the load needs that many VA, otherwise it only delivers the power the load needs.

Very informative. Does the panel, then, actually become slightly cooler when the "valve" is open, that is, when the circuit closes? If this sounds stupid it's only because in the fundamentals of electricity I am stupid.

howardwheeler wrote:
I don't doubt what any of you are saying, but I guess I don't quite understand the analogies. I can get the idea of the plug having potential but nothing flowing and the shower head having the potential to blast water if it's ever turned on. But these examples seem more focused on the valves at the end of a chain of delivery, one electrical and the other water. But I guess it's electric generation that I don't understand, because with the sun hitting the solar panels we aren't dealing with the shower head but rather the main pumping station or not the plug but the hydroelectric turbines at the dam. We are at the source of generation. Does the panel just shut off? It seems like it will be generating electricity that disappears. Again, I don't doubt your statements I just want to have my understanding enlightened. I'm sure I just don't have the right perspective. But I'd like to get it.

Electricity is the flow of electrons. The sun knocks them loose from atoms and they subsequently flow down the wires, however if there is no demand for this flow it "backs up" in the wires. So in short, the panels only make as many electrons as can leave (and return) through the wires.

So going with the water analogy, the panels produce "pressure" but without an open valve there is no flow.

time2roll wrote:

howardwheeler wrote:
I know it's safe. I guess what I meant was where does the excess power go?

Same place the power goes when the panel is not connected to anything.
The excess electric power is not actually produced. As the amps are throttled back the voltage rises to approach Voc and efficiency drops off.

This is one way to look at it, but if the question is where does the power "from the solar cells" go the answer would be it is thermally dissipated in the cells if the power cannot flow to the controller. Actually that is dynamically true with the A.C. power grid too, but that is going to get way too complex fast so....

:o

howardwheeler wrote:
Does the panel just shut off?

yes, the controller disconnects it. During the time it is disconnected no power is generated since the circuit is OPEN.

The controller adjusts the ON/OFF times to provide the correct amount of power. If more is needed the ON time increases to 100% ON.
The frequency the controller turns ON/OFF is very fast!

Say a panel can make 4A but only 2 is needed, the ON/OFF time would both be 50%. If 1A is needed the ON time would be 25% and off 75%.

I envision as this, when OFF (open circuit) the panel has voltage but no amps, no power. When ON it has both.



Note the blue power curve below, at both ends there is no power, when the panel is shorted and when the circuit is open. (homemade IV/power curves from the sticker on the back of a 60w panel).



Back to water, consider opening and closing the faucet from full ON to full OFF to control how much water flows (not a choke or some sort of restriction). Open and close very fast, letting the ON/OFF times change to control the water flow.

Metaphor
Food on a plate uneaten.

A simple 60mm 24vdc .15A muffin fan would raise tolerance an eyebrow raising amount. Guess that's bad form.

I don't doubt what any of you are saying, but I guess I don't quite understand the analogies. I can get the idea of the plug having potential but nothing flowing and the shower head having the potential to blast water if it's ever turned on. But these examples seem more focused on the valves at the end of a chain of delivery, one electrical and the other water. But I guess it's electric generation that I don't understand, because with the sun hitting the solar panels we aren't dealing with the shower head but rather the main pumping station or not the plug but the hydroelectric turbines at the dam. We are at the source of generation. Does the panel just shut off? It seems like it will be generating electricity that disappears. Again, I don't doubt your statements I just want to have my understanding enlightened. I'm sure I just don't have the right perspective. But I'd like to get it.

It is a bit like the hole in the wall you plug your coffee pot into.. It likely is rated 15 amps but the coffee maker pulls perhaps 2 or3, So what happens to the other 12? Nothing, they do not exist..

An even better description:

Your shower.. Odds are if you take the head off and you are on "City water" you can push 5 or more GPM through that 1/2 inch pipe.. But with the head on you get perahsp 2 GPM,, Where do the rest go? No place, Same with the solar panel

The Controller is .. The shower head.

There is no power at Voc!