what happened to 10KW??? (under-utilized solar panel)

Say, 30Kw solar PV is designed to feed a 30kW load system. IF the load is reduced to 20kw what will happen to that 10kw of solar pv.

the solar pv is a standalone system :bang::bang::bang:

I think this power remain as heat on the collectors or reflected. Not converted to electic power.

Just not used at all. Think of it like a power supply rated at 30A, it can supply any load up to 30A, if you only draw 20A it doesn't mean the remainder went somewhere else. Typically an underloaded PV just produces a higher voltage.

A good system would use MPPT and load balancing to make best use of the overcapacity. In some instances, such as battery charging, it is necessary to use a dump to lose the excess power deliberately as heat.

Brian.

A lighter load is the same as increasing the resistance seen by the PV panel. Less current flows. Voltage rises. We can suppose that fewer electrons are knocked out of their atom, due to increased threshold voltage. Somewhere there should be an article which goes into depth about what happens, because I could be wrong.

Hi,

a while ago I sked this myself.
I don´t know the answer.

If the power remains as heat, then an unloaded collector should become hotter than a loaded collector. (I never tested this, nor have I heared about such a behaviour)
Or the optical situation changes and the heat is reflected. This means the solar panel does not change temperature (much).
Or is it something inbetween.

Klaus

Hi! I think 10KW is reflected as any radiation or converted to heat on collector element. The collector elements not convert this power to electic, because the output is limited at 20KW. The energy must not lost.
But I don't know the right answer...

To eeefreakians: Try to measure temperature of collectors at 20 and 30KW.

Sorry for my english. I very interested in this question.

I have never conformed this so I could be completely wrong: The maximum volatage specified for a PV panel depends on the number of individual cells in series. Looking at the ones I have here, the maximum voltage seems to be the number of cells multiplied by about 0.6, this could be implying that the cell works in a similar fashion to a PN junction and beyong that threshold, the cell starts to clamp it's own voltage by becoming conductive. If that is the case, under-utilizing the panel may increase the voltage and make it convert it's generated current directly into heat.

Brian.

You can run a 10Kw panel with no load at all, the voltage just goes up to the full rated open circuit voltage.
Just like a battery with nothing connected to it.

As you apply more and more load, the voltage slowly falls, and continues to fall as the load is further increased. Power in the load increases too, just as you would expect.

But at some point, the voltage really takes a dive as more load still is added, and the voltage drops much faster than the current increases. If you measure the actual power in the load, it will have dropped. The panels are now overloaded, and working very inefficiently, a situation that should be avoided.

That is the reason for adding a circuit that prevents overloading the panels, and only permits the panel voltage to be drawn down to the maximum power point (MPP), and no lower.

Under a really dull grey sky, with total cloud cover, your 10Kw panel may only be able to produce 500 watts, so the MPP circuit only allows you to get those 500 watts and not overload the panel any further than that.

When the sun again shines, the available power increases, and the MPP circuit allows whatever power is available to be drawn from the panels which may be anything from zero (at night) to the full 10Kw in perfect conditions.