New solar panel voltages?

[hour]

I've been out of the panel purchasing game for a while, so I'm cruising all of the consumer grade retailers I've known over the years and finding something curious.

Some are offering "9V" panels, 18v Voc. Or "15v" panels, 27v Voc.

Can anyone theorize on why this is a thing? Seems a little far fetched to think they're doing it so people can redesign their entire systems at the panel level and not have to upgrade their charge controller to hit some very narrow voltage tolerance number, for instance... or work within the bounds of some crummier "solar generator" units.

And actually, in looking at clown shoes Jackery, two 9v panels in series wouldn't work, and the 15v alone wouldn't work either. So who are they trying to please by rattling the standard?

 

[LakeHouse]

I would just ignore those nominal voltages. Years ago when people where using PWM controllers, 'matching' panels to battery voltages made sense. But MPPT controllers are cheap enough now that there's really not much reason to use PWMs. What that's done is made it so that panels don't have to fit into a narrow range to be useful.
For example, with a 12V system and a Victron 150/35 SCC, you could string together anywhere from 1 single panel (Vmp greater than the about 19V you need to start charging), to as many as 5 (Voc = 27.28 * 5 = 136.4V, which is less than the 150V max for the SCC, even with temperature correction), and it would work fine.

 

[hour]

I would just ignore those nominal voltages. Years ago when people where using PWM controllers, 'matching' panels to battery voltages made sense. But MPPT controllers are cheap enough now that there's really not much reason to use PWMs. What that's done is made it so that panels don't have to fit into a narrow range to be useful.
For example, with a 12V system and a Victron 150/35 SCC, you could string together anywhere from 1 single panel (Vmp greater than the about 19V you need to start charging), to as many as 5 (Voc = 27.28 * 5 = 136.4V, which is less than the 150V max for the SCC, even with temperature correction), and it would work fine.

Well, doesn't that make this even more peculiar if there's even less reason to fit in to narrow voltage margins now? What's the point of deviating from the standard?

 

[Mattb4]

The panel you posted an image of has a Voc of 27.28 and a Vmp of 23.83. This makes it unable to charge a 24v nom. battery by itself. It however is within specs to charge a 15v battery (I imagine there is some setups in the weird world of power packs) that may run 5S LifePO4. (17 volts full) As to ones for a 9v battery I suppose that a 3S setup could be theorized. Or it may be some other battery chemistry this is designed for.

 

[LakeHouse]

Well, doesn't that make this even more peculiar if there's even less reason to fit in to narrow voltage margins now? What's the point of deviating from the standard?

My point was that it currently makes sense for manufacturers to ignore the old ‘standard’ entirely. Because other than maybe for some RV applications, there’s no reason to make nominally ‘12V’ panels anymore.
As for why stop following a standard that isn’t useful, that seems to me the wrong question. Why not stop following it?

 

[KnobCountry]

A 15v panel is perfect for a lifepo4 12v battery which charges at 14.4 or whatever.

They are just letting you know you can't use it for 24v systems without 2 in series.

Once the mppt pulls down 27 voc it is not quite enough to kick off charging a 24v system which needs 28v or so.

They are letting you know with clear numbers what it can do.

 

[MattiFin]

Well, doesn't that make this even more peculiar if there's even less reason to fit in to narrow voltage margins now? What's the point of deviating from the standard?

There is not any standard. Manufacturers make whatever people(companies) seem to be buying and what the manufacturers can gobble up.
And invidual cell sizes have been going up as production is moving to larger silicon ingots. There is limited number of voltage options you can build from a number of cells in size x*y

”12v” and ”24v” panels are dying variety, most of the production is nowadays in 30-50V range. Low voltage panels are mostly small sizes for rv use or something like that. You pay typicall considerable premium for the small panels as they are novelty item today.

 

[zanydroid]

Utility and residential panels are pretty darn standardized within a “node” (ie cell size vs wattage. Not a firm rule though as half cut and asymmetric sub modules IE 5 column are a thing).

At the risk of being an a—hole I don’t think the target demographic for 12V and 24V panels is going to be able to exert market pressure to standardize it, or on average be sophisticated enough.

You even see a handful of stories here of installers that oof the voltage transition between two module generations.