Safe to use NMOT ? vs sct

[JUMPSTART]

QUESTION: Can I go with the NMOT (Real World Conditions) as opposed to the SCT (Optimal Conditions) or is it too risky or do I definitely risk over voltage (Damage to my Solar Generator) at colder temperatures when the panel generates more?
.... Is there a max stated on the panel that it will "never" generate more?,... or will any panel always generate more below 77 degrees?
.... In Other Words: I want to max out my 2,100 Watt Input, (Many of these panels might be over my max voltage), Realize people say you will never see these optimal ratings. Am I chancing it?

.... We know this SCT test is done at 77 degrees (25 Celcius) but also at optimal light conditions

Solar Generator (has its own MPPT) Solar Input Max: 0-150 V / 2,100 W / 15 A

Looking to buy panels now. (probably 4 in series as I FEAR EXCEEDING AMPS) (Series: Voltage Increases / Amps Stay Same)
... I would like to reach my 2,100 W Input Max. All the nice panels I have found would exceed my Amps Max of 15 Amps.... SCT RATING.
IS IT SAFE TO USE THE (MNOT) DATA INSTEAD? Looks like I am limited to around 550 W etc panels as each panel voltage stays around 49.0 Volts (but 49 X 4 = 196... Exceeding my 150 V). Amps seem to be the hard one here as it's very easy to exceed this 15 Amp Max.

SCT CALCULATIONS SAY: EX: ( To not exceed my max )
VOLTAGE - 4 Panels (series) 37.5 V each Xs 4 = 150 V
WATTAGE - 4 Panels Xs 525 W each = 2,100 W
.... Parrallel (Voltage stays same / Amps Increase) is out of the question (15 Amps Max) = 4 Panels Xs 3.75 Amps each = 15 Amps Max ...(pretty whimpy panel)

AMPS ,... It only "pulls" in porportion to Volts / Watts? (So amps are not an issue?)

Solar Generator is pretty nice so I'm wondering if it has built in protection.

We all know the panels will (Never?) generate their SCT rating.... I just don't want to ($1,000) then find out I'm not doing anything and should have "chanced" bigger.

TWO MPPT CHARGE CONTROLLERS CONFLICT ? - (One from panel & the generator has one built in) ...Also tried researching CURRENT REGULATORS? / VOLTAGE REGULATORS.... I think this 'is" a charge controller. Not sure how my generator would like it,... not to mention finding the perfect one.


This is an OUPES (new company) Generator (and they want to get out there so very inexpensive") Much like the Delta Pros for MUCH LESS. I was surprised to see such high voltage input capability.

 

[OzSolar]

Welcome to the forum!

I'm not sure I'm getting all of your questions but I can offer the following:

For sizing wire and choosing components use STC - Standard Test Conditions. That's Imp x 1.25 and Voc on the coldest day on record in your area.

For estimating energy I use NOCT - Normal operating cell temps. I'm not familiar with MNOT but perhaps it's the same as NOC?

Many MMPT's can tolerate 1.25% or more amperage than their rating, in fact it's a common practice to "overpanel". No MPPT's can tolerate seeing a Voc higher than their rating. Actually there's one MPPT that can but that's not what we're talking about here.

 

[JUMPSTART]

Welcome to the forum!

I'm not sure I'm getting all of your questions but I can offer the following:

For sizing wire and choosing components use STC - Standard Test Conditions. That's Imp x 1.25 and Voc on the coldest day on record in your area.

For estimating energy I use NOCT - Normal operating cell temps. I'm not familiar with MNOT but perhaps it's the same as NOC?

Many MMPT's can tolerate 1.25% or more of thier rating, in fact it's a common practice to "overpanel". No MPPT's can tolerate seeing a Voc higher than their rating. Actually there's one MPPT that can but that's not what we're talking about here.NMOT - Nominal Module "OPERATING TEMPERATURE". Seems to be the new thing. ...Like a surrounding ambient temp? or panel temp might be more understandable. ...Unless one can measure the cell?

,... No, I really wasn't asking if my Solar Generator's MPPT could handle but thanks,... good to know! I was really asking if it is too risky to "assume" the "real world" panel output wouldn't go higher...... Silly question.
Yes, I could understand the famous 1.25 (like overdoing for safety as far as conductor insulation goes)(.....BELIEVE IT OR NOT: #14 AWG THHN IS RATED FOR 25 AMPS... SAFELY!). I guess my question was "Could I safely go with the "real world data" .... being that all the panels I am interested in 550, 600, + Watts etc exceed my voltage / amps. One problem is I am trying to achieve my 2,100 W Max...lol?

PS: NEVER THOUGHT ABOUT Higher Watt Panels but (instead of 4 panels) only 3 panels. 2S1P.

I like the idea of the coldest temp here in PA .... right around 32 or (1 Celcius) ...... Of course SCT Tests are at 77 (or 25 Celcius)... Good point.
... It seems the panel could generate more in cold.

One question might be: Is there a "maximum" figure it could "ever" generate listed on the panel? ...or can "any" panel generate more (below this 25 Celcius test)

 

[ricardocello]

like the idea of the coldest temp here in PA .... right around 32 or (1 Celcius)

 

[Hedges]

Most decent MPPT, SCC or inverter, can handle PV capable of delivering excessive current.

They will declare an Isc limit. That typically matters if array connected backwards, because the have a clamping diode. So connect the array with not all PV strings attached. Or when sun is off-angle. And make sure system is operating (correctly wired) before letting it produce full current.

Voc, use adjusted for record cold as Ricardo shows.

Wires and fuses, use 1.56x Isc.

Imp and power, NMOT is reasonable to design around, or over-panel if you like.

Obtaining permits or going through software, you may find they assume STC not NMOT.

PS: NEVER THOUGHT ABOUT Higher Watt Panels but (instead of 4 panels) only 3 panels. 2S1P.

3 panels "2S1P" isn't a thing. Maybe you mean 2S || 1 or something like that (whatever the syntax should be), but don't connect different length strings in parallel unless panel voltages are different such that string voltages are similar.

Consider 2s2p, with 2s of one orientation in parallel with 2s of another, 2s || 2s.

 

[Ampster]

One problem is I am trying to achieve my 2,100 W Max..

It is not a problem. The only issue is combining the panels in such a way that voltage does not exceed the maximum as mentioned earlier. That leaves current as the variable and that explains why many are over paneled by 25%.or more.

 

[JUMPSTART]

Most decent MPPT, SCC or inverter, can handle PV capable of delivering excessive current.

They will declare an Isc limit. That typically matters if array connected backwards, because the have a clamping diode. So connect the array with not all PV strings attached. Or when sun is off-angle. And make sure system is operating (correctly wired) before letting it produce full current.

Voc, use adjusted for record cold as Ricardo shows.

Wires and fuses, use 1.56x Isc.

Imp and power, NMOT is reasonable to design around, or over-panel if you like.

Obtaining permits or going through software, you may find they assume STC not NMOT.



3 panels "2S1P" isn't a thing. Maybe you mean 2S || 1 or something like that (whatever the syntax should be), but don't connect different length strings in parallel unless panel voltages are different such that string voltages are similar.

Consider 2s2p, with 2s of one orientation in parallel with 2s of another, 2s || 2s.

I'm new to this and 2S1P meant 2 Panels Series / 1 Panel Parallel = (EXAMPLE: 15 Amp Panels) ...The 2 in series would not increase amps 15 A .... But would the last panel "ADD" 15 A more? ( + & - would be connected to + to + / - to - )... Would think my 15 amps will then add 15 amps.

 

[Hedges]

That's what doesn't work well. The 1 panel will pull down voltage of 2 panels series. You'll end up with output similar to 2P.

You will get 15 + 15 = 30A, but not at much higher voltage (maybe 5% higher.)

 

[MisterSandals]

This is an OUPES (new company) Generator

Looks like they have 3 series and a few models in each series. Which one are you asking about?

 

[JUMPSTART]

Looks like they have 3 series and a few models in each series. Which one are you asking about?

I bought the OUPES MEGA 3 ($1,800) - 3,600 W / 7,000 W Surge - 3072 wh -- (Solar Input: 0-150 V / 2,100 W / 15 A)

 

[MisterSandals]

I want to max out my 2,100 Watt Input,

I agreed with others that recommend 2S2P. I will add that even 3S2P would work with just about any ~40V panel.

 

[JUMPSTART]

That's what doesn't work well. The 1 panel will pull down voltage of 2 panels series. You'll end up with output similar to 2P.

You will get 15 + 15 = 30A, but not at much higher voltage (maybe 5% higher.)

Oh,... OK, Thanks. Why would 1 panel in parallel pull the system down? (like batteries) ... Would 2 after in parallel be better? (I was reccomended by a company to do 2S 2P. (575 Watters)

Pretty much my plan was to just stick to series. (and mindful of partial shade) .... I never thought of 3 bigger panels in series BUT,... When you hit the panels (like 600W and bigger) the Amps per panel go up past (my 15A Max) ...Can't do much about that but it still exceeds and if a
"any" panel goes past,... guess I can't use it. I can work with Voltage though. (150V Max)

(150 V)
37.5 V Xs 4 Panels = 150
50 V Xs 3 Panels = 150 .... These 50 V panels (580, 600 W +) is where the amps go too high. Guess I'm trying for the impossible. (Unless I Can Find.... AMP REGULATOR?

 

[JUMPSTART]

It is not a problem. The only issue is combining the panels in such a way that voltage does not exceed the maximum as mentioned earlier. That leaves current as the variable and that explains why many are over paneled by 25%.or more.

I have 15A Max I can go. (you said amps variable?) (or "The" Variable) (if parralell). ... Looks like Im stuck with series connected only via my limited amps so. --- Thanks,... Good to know I might not get into trouble.... if some "SCT" is 25% high.

 

[Hedges]

If 2s and 2s were wired in parallel but oriented differently with a 60 degree angle between them, they would never present more area to the sun that just a single 2s. More hours, no higher peak current.

 

[JUMPSTART]

Welcome to the forum!

I'm not sure I'm getting all of your questions but I can offer the following:

For sizing wire and choosing components use STC - Standard Test Conditions. That's Imp x 1.25 and Voc on the coldest day on record in your area.

For estimating energy I use NOCT - Normal operating cell temps. I'm not familiar with MNOT but perhaps it's the same as NOC?

Many MMPT's can tolerate 1.25% or more amperage than their rating, in fact it's a common practice to "overpanel". No MPPT's can tolerate seeing a Voc higher than their rating. Actually there's one MPPT that can but that's not what we're talking about here.

Thanks. Imp = Max Amps Possible? ....Voc (Voltage Open Circuit) ... I don't I ever saw a chart for various "Temperatures" but I'll look. Thank you.

 

[JUMPSTART]

I agreed with others that recommend 2S2P. I will add that even 3S2P would work with just about any ~40V panel.

One problem about parallel is my 15A Max. (Am I wrong?) 2 Panels in series = 15 Amps .... As soon as I connect "another" panel(s) in parallel I will then start "adding" amps to this 15.
An actual company recommended this 2S2P with 575W...

This is why I assumed I'm stuck with series (voltage adds) but make sure I don't exceed 150V

 

[MisterSandals]

I don't I ever saw a chart for various "Temperatures" but I'll look.

Look for the temp coefficient. It is the voltage change per degree C above or below 25C (77F).

Usually around .35%.

 

[JUMPSTART]

Look for the temp coefficient. It is the voltage change per degree C above or below 25C (77F).

Usually around .35%.

Oh! Now I can calculate precisely! Thank you.

 

[Ampster]

I have 15A Max I can go. (you said amps variable?) (or "The" Variable)

The fixed limit is Voltage and you need to calculatate what that is based on temperatures mentioned earlier in the thread. Then to get to the Watts you want, calculate the Amps using Ohms law (Watts =Volts X Amps). As most people have commented the current is not typically a limit since your device will only pull the current it can process and that is why I described it as a variable. You should double check your device to confirm but typically Wattage is the oveerall constraint which is driven by the maximum voltage leaving current as the variable in the equation. Once you have those parameters you can decide which combination of parallel or series panels does not exceed the voltage limit.

One problem about parallel is my 15A Max. (Am I wrong?)

I will let @OzSolar respond but I tried to answer that question above. You may be making a wrong assumption about maximum Amps. The panels only put out the Amps that the inverter or charge controller pulls from them based on Ohms Law.

 

[JUMPSTART]

The fixed limit is Voltage and you need to calculatate what that is based on temperatures mentioned earlier in the thread. Then to get to the Watts you want, calculate the Amps using Ohms law (Watts =Volts X Amps). As most people have commented the current is not typically a limit since your device will only pull the current it can process and that is why I described it as a variable. You should double check your device to confirm but typically Wattage is the oveerall constraint which is driven by the maximum voltage leaving current as the variable in the equation. Once you have those parameters you can decide which combination of parallel or series panels does not exceed the voltage limit.

I will let @OzSolar respond but I tried to answer that question above. You may be making a wrong assumption about maximum Amps. The panels only put out the Amps that the inverter or charge controller pulls from them based on Ohms Law.

Awesome. The one thing I was wondering was "amps", as amps are not necessarily a "thing" but rather a flow that happens. Thanks to all I now know what to look for (temp coefficients) to further calculate as well. A harder question to answer is the NMOT business (as these panels are tested SCT in a super controlled environment,... including the light source and wind.) Assume I stick with SCT.... and get a feel for the NMOT thing. ...Quite possibly subtracting 25% from the SCT rating? ...(I hate asking all these questions but) I suppose at least I know I won't burn things up. ////// Thanks Everyone!