Is there a 'standard' PV panel output voltage?

[Vortex2]

I have found a source of cheapish PV panels.
IIRC these have 72 cells wired in series so give out a high output voltage.

Is there a standard voltage expected from PV panels?

Or can controllers etc accept almost any input voltage?

[clv101]

Any half decent MPPT controller can take lots of DC voltage, 150V and 250V is common. Individual panel voltage is not important as you'd always want to hook them up in strings of 3-6 panels in series anyway. Get the voltage as high a possible for less voltage drop in the cables or to allow thinner, cheaper cables.

[adam2]

As above, an MPPT charge controller will accept a very wide range of input voltage. Any common type requires that the input voltage be greater than the battery voltage.

The voltage of a PV module varies according to the number of cells in series, each cell contributes about half a volt. No great accuracy can be expected as the voltage varies a bit.

For charging a 12 volt nominal lead acid battery, about 14.5 volts is needed for a fast or equalising charge. Allowing one volt for losses in the charge controller, and another volt for losses in the connecting cables, that suggests a minimum of 16.5 volts from the PV module. Most modules intended for charging a 12 volt battery have 36 cells in series to give about 18 volts. This works well with an older type NON MPPT controller.

Larger modules often have 72 cells in series, to give about 36 volts on load, these larger modules are used for charging 24 volt batteries, or a number of modules in series to give hundreds of volts into a grid tie inverter. A 72 cell/36 volt module can be used to charge a 12 volt battery PROVIDED THAT A MPPT controller is used.

Small modules built into consumer grade goods may have only a very few cells in series, perhaps to charge a single cell.

All PV modules produce a lot more than the nominal voltage if unloaded. A 72 cell/36 volt module if open circuited can give 60 volts or more, which is into borderline dangerous voltage. Several such modules in series and on open circuit will produce a definitely lethal voltage. Take care.

[BritDownUnder]

I would have thought most MPPT also have some form of DC-DC converter as well as the MPPT logic to allow charging 12V or 24V batteries from ''strings'' of several 24V solar panels in series. It is even possible for DC-DC converters to raise the voltage - a ''Boost'' converter - but could be inefficient.

Solar cells seem to be relatively good current sources supplying a constant current regardless of terminal voltage until quite high voltages when the current output drops precipitously. I recall the solar installers of my first installation short circuiting the panels to measure the current flow with a clamp meter and the panels did not seem to mind it at all.

[adam2]

Yes, most MPPT charge controllers do have the ability to charge a 12 volt battery or a 24 volt battery from any higher voltage, up to a limit.
My remarks about a 36 cell/18 volt module being for charging a 12 volt battery, and for 72 cell/36 volt modules being used for charging a 24 volt battery refer to the older type of non MPPT charge controller.

MPPT controllers used to be very expensive and only justified for large systems, but they are now more affordable and therefore used in all but very small systems.