Diode anti required return on small pv installation?

[Dune38]

Hello!

Okay, I'm going. I recovered small demonstration panels that I wish to mount in parallel, connected to a regulator and a small battery for ventilated and punctually lit my garden shed. The panels have different powers from 5 to 1w but do not have a non-return diode. I am divided between protecting the panels and using the diodes. In short, are the diodes compulsory? Are mofsets possible in place of Schottky?

Thank you in advance for your answers!

Ed

[izentrop]

Hello,
It is necessary indeed, otherwise the most enlightened risks to flow in the least enlightened.
The regulator must be equipped to prevent the battery from discharging at night in the panels and is not essential if you know the characteristics of the panels and the battery.
Mosfets could short-circuit the diodes on condition of being controlled by a control logic.

[Forhorse]

Do not confuse non-return diode and bypass diode

[izentrop]

Ok Forhose, I shouldn't have talked about shade, Mismatching concerns panels of more than 5W, all the same.

Dune38 should give us the characteristics of its panels to be able to advise it well.

[Dune38]

Ok Forhose, I shouldn't have talked about shade, Mismatching concerns panels of more than 5W, all the same.

Dune38 should give us the characteristics of its panels to be able to advise it well.

Hi Izentrop and thank you for your answer,

Well, that’s part of the problem. These are 6 transparent monocrystalline panels of 28x23cm, two other classic opaque. The opaque are at 5wp, a transparency is below about 1w 2 must be 2/3, two at 2 and the last is really faint. Not having the characteristics I expect a ray of sun these days to test them with the multimeter ...

This is where I am!

[izentrop]

Not having the characteristics I expect a ray of sun these days to test them with the multimeter ...

This is where I am!

It would be necessary to make an empty measurement and another with a resistance of 10 ohm at the terminals of each panel, with the same sunshine.
The voltage across the 10 ohm / 10 should indicate the rated current.

If the no-load voltages are identical, a Schottky in series with each panel, all this connected to the 10 ohm of sufficient power should provide information on the nominal current that can be drawn from the assembly.

[Forhorse]

A solar panel is already a diode.

[chatelot16]

when you put photovoltaic panels in parallel there is no need for a diode ... the currents add up ... a panel that does not produce a kidney because it is in the shade will not take the current from those who are in the sun

each photovoltaic cell is a diode which limits the maximum voltage by wasting the current produced ... below the maximum voltage the diode no longer wastes anything

so when you put in parallel panels of the same nominal voltage and connect them to a battery of the right voltage no panel wastes current even if the lighting is different

it is in series that the problem arises ... if one panel is less lit than another it opposes the current passge: a diaode of bypass is essential

parallel mounting is better for good photovoltaic use, but alas we prefer serial mounting which saves copper but poses many problems

[izentrop]

each photovoltaic cell is a diode which limits the maximum voltage by wasting the current produced ...

That is to say ? And at night, only one schottky then?

[chatelot16]

the photovoltaic effect produces current, and the voltage rises until the diode conducts! the photovoltaic cell is a diode which determines the maximum voltage by wasting all the current if we leave this maximum voltage ... fortunately we operate the photovoltaics at a voltage a little lower than the maximum so that this waste does not happen

to really seek the maximum there are the mppt ... but simply using photovoltaic panel with the right number of cell to connect to a 12V battery gives a result quite honorable

without sun and without anti-return diode the photovoltaic panel consumes a negligible current: the danger is rather the overload! without regulator a photovoltaic can boil a battery by overcharging

other utility of the solar regulator, limiting the discharge does not cut the circuit use when the battery voltage is too low