Overpaneling generic questions

gfmucci

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There are several model specific questions discussed about "over-paneling", but I have several general questions:

First to lay out my limited understanding:

I understand over-paneling is when either the spec'd max. voltage or wattage of the panels is greater than the max. input voltage specified for the genny.

I also understand that some solar generators allow over-wattage of panels because they have a built in limiter that restricts wattage beyond their spec'd maximum, and they will continue to operate. There are also generators WITHOUT a wattage input limiter that will shut down if the wattage is exceeded.

My questions:

Since the typical maximum output of most panels is only 80 to 90% of their claimed output (depending on numerous factors), is it wise to use panels with total specified wattage around 10% higher than claimed which, in practice, will keep the actual wattage still below the input limit of the generator?

Is that considered "over-paneling" since actual output wattage is still less than the input limit?

One related model-specific question:

The EcoFlow Delta has a 400 watt solar input maximum. But I read that it is a bit forgiving above that before it shuts down. Is this true, and is it true that it does not have a built in limiter that would keep it running beyond the 400 watt panel output?
 

HRTKD

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I understand over-paneling is when either the spec'd max. voltage or wattage of the panels is greater than the max. input voltage specified for the genny.

This is incorrect. Never, ever exceed the max PV input voltage of the solar charge controller! Over-panelling is exceeding the nominal watts, while still staying under the max PV input voltage.
 

chrisski

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Your SCC manual will give you something on max input, I would not exceed that.

My Victron SCC won’t put out more than its rated for. The 100/50 is no more than 100 input volts ad no more than 50 output amps. So, if I overpanel, the SCC simply won’t draw more than its rated; however, in the user manual it does say “no more than 60 short circuit amp input.”

I found that my flat panels far underperformed what I thought I’d get, and I considered overpaneling to get the full possible input, but I did not have room for another string, so I put another set of panels connected to a different charge controller.

I guess the method I tried to use was calculate something, if it was not max input, add more panels until it is. The reason I did not get max input like I thought, was flat panels and different strings getting shaded at different times, so I was about 30% under.
 

squowse

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As above - never exceed the maximum input voltage. Also allow 10-20% over the VoC for exceptionally cold bright days.
You can think of the MPPT as a valve that opens to let current flow. As it opens the voltage drops until the "maximum Power Point" is reached.
If it's an off grid setup and the battery is full, and there is no load then the valve will stay closed. If the output current gets to the maximum value it will not open the valve any more. In this way they can be safely overpanelled (surplus watts, not excess volts).
 

gfmucci

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Ok, good. Only exceeding watts input is involved in overpaneling, and its "actual" watts, and not just "spec'd" watts that is called "overpaneling", right?

Your term "valve." My term "limiter" that keeps excess panel watts from coming in.

Does anyone know which major brands/models have a limiter/valve to allow overpaneling without concern for exceeding the input limit that would orherwise cause the system to shut down so as to require a reset: Jackery, Bluetti, EchoFlow, etc.? I would prefer that the passing clouds don't reduce my input wattage to less than 50% of my units solar input capacity.
 

JAndle

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Caution on MPPT - it is not limiting instantaneous current but is pulse width modulating it to look like an average current. The panels and the batteries are fooled by this, but the max short circuit current of the controller MUST be honored or you risk melting bond wires or damaging the channel in the power FETS... Also note if you are tropical, the short circuit current can be quite a bit higher than the STC datasheet value.
 

gfmucci

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Caution on MPPT - it is not limiting instantaneous current but is pulse width modulating it to look like an average current. The panels and the batteries are fooled by this, but the max short circuit current of the controller MUST be honored or you risk melting bond wires or damaging the channel in the power FETS... Also note if you are tropical, the short circuit current can be quite a bit higher than the STC datasheet value.
So what is the practical application of that technical blurb when applied to units like the Ecoflow Delta or Bluetti eb240 using panel inputs? Can I exceed panel watt generation without unit shutting down? KISS.
 

JAndle

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You cannot exceed max PV power after adjusting from STC to your local insolation. Belize is +35% in May-July.
You cannot exceed max open circuit voltage at coldest temps.
You cannot exceed max short circuit current after adjusting from STC to your local insolation.

If you obey all of those, you can use more panel wattage than the inverter output rating and the MPPT will just operate at higher voltage and lower current than the optimum.

I cannot definitively address the inverters that you asked about because I have not researched them. Sigineer 5000W unit allows 5500W max PV and 450V max PV but has no max short circuit current listed. In Belize I can only use 4074W as rates at STC on the panel specs, which limits me to 7s using 560W panels.
 

gfmucci

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Here are two examples I just researched:

Bluetti AC2000P - blurb from a review by Ben Gillmore. Even though the input limit from solar is 700 watts, this unit can apparently be "over-paneled" without the unit shutting down:

The AC200 MPPT charge controller has a solar input rating of 35-150v and 12a. It is rated to let up to 700w of solar go through it. The beauty of having such a large charge parameter is that it is capable of “over-paneling.” That means that I can install more than 700w of solar panels on the system to ensure I am getting the full 700w charge and that I can lengthen how many peak solar hours I get each day.
He can double the panel wattage to 1,400 watts, and get the full 700 watts into the generator for several more hours per day.

EcoFlow Delta - As I understand from various reviews of this unit, if the 400 watt max is exceeded by very much, say up to 420 watts, the system does not simply not allow more than 400 from entering the system, but the whole system kicks off and needs to be manually reset. So if you have 460 watts of panels so that you get around 390 watts during the best 4 hours of the day and the input happens to spike much beyond 400 watts, the unit will trip off and has to be manually reset.

Is the 700 vs. 400 watt max solar input, plus the over-paneling feature of the Bluetti plus a tripling of the number/cost of panels worth the extra $500 cost of the unit over the EcoFlow Delta. For my proposed use, probably not.

Thinking out loud, I would probably resort to Chrisski's method and see how close to maximum wattage input I can achieve with my initial panel array. If I'm still far short, I guess I could add another panel if I stay under the 65 volt and 400 watt max.

Can different wattage panels be placed in series?

Another downside of the EcoFlow Delta is that the User Manual states that if non-EcoFlow panels are used, the warranty is void. And EcoFlow has only 110 and 160 watt panels. But they mention that 4, 110 watt panels can be attached in parallel for 440 specified watts, but likely high 300's in practice.

Technical Specifications for 110 watt panel:

110W Solar PanelRated Power: 110W(+/-5W)
*Open Circuit Voltage: 21.7V(Vmp 18.5V)
Short Circuit Current: 6.3A(Imp 6.0A)
Efficiency:21%-22%
Cell Type: Monocrystalline silicon
Connector type: MC4
Operating & Storage Temperature: -4° F to 185° F (-20° C to 85° C

With the 3, 110 watt panels that come with the EcoFlow system (rated total of 330 watts) I would probably get 300 watts, max., during the best 3 or 4 hours, and less than a 150 watts during the rest of daylight - not considering the potential for "partly cloudy." Not good. So 4 in parallel is the way to go.

Is there such a thing as an external panel wattage input limiter that can be plugged in-between the panels and the generator?
 
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gfmucci

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Then I just read this about over-paneling on the Delta from the Ecoflow User Group on Facebook:

The Delta specs are maximum 65 V at 10A, 65v x 10a = 650 watts. Just feed the delta as close to 65 V at 10 A that you can.
Your only concern is not to go over 65 V, too many amps is OK but it's wasted power.
The controller will lower the amount the Delta takes to 400 W, and when there's less sun you should still have a lot of power.

This implies that we CAN over-panel the Delta as long as the voltage is not exceeded, does it not?

This leads to more questions:

Can parallel wired panels be in a 3 series/2 series configuration, or do they need to be 2/2 or 3/3, etc.? Can series panels be at different wattages, say 110 and 160 watts in series, or do they need to be the same wattage?
 

chrisski

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Can different wattage panels be placed in series?
There’s some math involved, but try this: https://solarpanelsvenue.com/mixing-solar-panels/

There are my thoughts on overpaneling a SCC. I have a Victron 100/50 which is $265, buy I am not willing to try this and fry it.

For overpaneling a SCC, even though it limits output, I have noticed my SCC’s do not instantly react to power needs. Perhaps the panels really can deliver the power instantaneously, but the SCC has some algorithm to ample and deliver power based off what the PV can deliver and how much the System needs, and the SCC is a middle man. The more I think about it, that’s when an over paneled PV system might send too much power out to try to send too much power within its own circuits and fry itself.

My 100/50 says no more than 60 amps short circuit amperage. So I guess if panels could send 70 amps to it, then the SCC algorithm may not work and may fry it.

What I would do, is if I never see the max amps year round, I would add panels until I hit max output amps. I would be sure my measurements were not just done in the winter when the sun reaches 45 degrees overhead, because in the summer with the sun straight up would deliver a whole lot more amperage.
 

Forbisher

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This implies that we CAN over-panel the Delta as long as the voltage is not exceeded, does it not?

This leads to more questions:

Can parallel wired panels be in a 3 series/2 series configuration, or do they need to be 2/2 or 3/3, etc.? Can series panels be at different wattages, say 110 and 160 watts in series, or do they need to be the same wattage?
Yes of course you can over panel the Delta and any other solar generator or SCC.

Dunno where you got the idea that you could not.
Glad you are getting it as almost everything in your first post was incorrect.

12V panels are about 20Voc to 22Voc so 3 in Series is very close to 65V.
Cold temps increase Voc but the great feature of Solar Generators is that they have a safety cut off with an error code so that you can not fry them like the usual SCC.
 

Bud Martin

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The load decides how much power it will draw from the power source up to the power source max capacity.
The Victron max shorted current is for how much it can handle in case the PV polarity is connected in reverse to the input of the SCC.

MPPT250-100.PNG
 

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gfmucci

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Yes of course you can over panel the Delta and any other solar generator or SCC.

Dunno where you got the idea that you could not.
Glad you are getting it as almost everything in your first post was incorrect.

12V panels are about 20Voc to 22Voc so 3 in Series is very close to 65V.
Cold temps increase Voc but the great feature of Solar Generators is that they have a safety cut off with an error code so that you can not fry them like the usual SCC.
"Dunno where you got the idea that you could not."

I probably made it up after misinterpreting someones review.

And after reading corrections to statements reflecting my initial understanding, I actially got most things right and a couple things wrong. Thanks for correcting and clarifying. Tough crowd!
 

Substrate

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@gfmucci Seems like your level of interest and understanding puts you out of the marketing demographic the Eco-Flow and the like are aimed at.

It might be easier and less frustrating to DIY your own bank according to your own needs, rather than trying to engineer a system around other commercial offerings, where we can spend all day long bench-racing specifications.

Save time and frustration - DIY it!
 
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gfmucci

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Thanks for your confidence in my interest and abilities. But I prefer the more mainstream and predictable. My quest is to learn what to expect of the equipment I acquire relative to understanding my needs with the outages we may experience in central Florida.
 

Substrate

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Well their mainstream marketing shows ground-mounted solar panels sitting right on the grass where shading is a problem.

Surely I'd buy it to brew up a cup of coffee while I fly my drone. Having an immersive experience with my popcorn maker during an outage and taking shots of it with my 35mm camera.

So.. yeah, at this forum, we're not really the target. :)
 

Stiffmeister

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My max voltage is 150v. When I plug three panels in series I get 105-108v so it's three panels per string max. (not sure your term overpaneling). 300 watt panels x24 is what I spec'd at (7200 watt inverter and 80 amps on a 48v setup). It sounds all perfect right? But those panels never make 300 watts even in Cabo San Lucas at noon in June. I added an additional 6 panels per solar charger to compensate for the deficiency. The charger FM80 will protect itself limiting to 80 amps so no problem increasing from 24 to 36. Panels were cheap, they don't make near what they are rated but the 7200 Outback Inverter was big bucks and I need AC. Oh I had to get an MNVP12 or something so I could have 12 strings...no biggie.
 

gfmucci

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Overpaneling. I used the term but it's not "my term." A lot of people use that term to describe when they provide panel watts above the max the controller will absorb. If my panels generated 1000 watts and my controller processed only 800, I am over-panelled, but benefiiting from closer to the 800 watt controller capacity during more hours of the day or when it is overcast or partly cloudy, or if as substrate mocked, if my panels were laying in the grass.
 
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