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How likely would I be to smoke a eg4 Mppt -48 100 charge controller if the total isc is one amp more than the max rating on the data sheet?

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Joe_

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How likely would I be to smoke a eg4 Mppt -48 charge controller if the total isc is one amp more than the max rating on the data sheet?
Is the 22 amps max on the data sheet a hard stopping point or is it a firm suggestion.
In the desert outside of Phoenix. See 116 days in summer. 19 F at times in winter.


New to solar here.
Looks like the panels I was going to use are unavailable. Curious if I can substitute some others.
 
You're aren't likely to see full Isc except under ideal conditions.

Will this be multiple PV strings in parallel? If so, bring system up with just one string. That way if you did connect backwards, the reverse polarity diodes won't have to carry full array current, just one string.

Check voltage and polarity before closing switch or otherwise making final connection between PV and inverter.

Most inverters/SCC won't draw more current than they want. But no guarantees.
I think MPPT input is a buck converter, won't ever pull PV string lower than battery voltage. Could pull more than Imp but probably less than Isc. Only time I expect it to see Isc is if PV connected backwards.
 
Thank you for your answers.
Here is what I have for now. I have two EG4 48/100 500v mppt charge controllers says max is 22 amps. and 1 tracker per controller

On each charge controller I was hoping to have 7 series 2 parallel (total of 14panels) these have a Isc of10.19 voc of48.74 and rated at 395 watts.
But unfortunately those panels are out of stock and might be unavailable.

The replacements I am looking at are 455 watt 49.35 Voc and a Isc 11.44
I have space considerations because these are mounting to the top of a few shipping containers. The length of the panel has to be very close to 80 inches which limits my choices.

If I use them the Isc of the parallel strings would be 22.88 amps or almost a full amp more than the max on the spec sheet.
If you could explain why or why not this is or is not a deal breaker I'd be grateful, I do need to know if it will work or if I am going to shortly have to replace the charge controllers because I went too far out of the spec.
 
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Ellcon123 said:
Input voltage is critical, not amps. The amps listed are the max the SCC will output to batteries. Solar panels do not push power.
Click to expand...
I don't understand push power. Can you explain further?
This is what the spec sheet says in the Solar Specifications section.
Max Solar Current Draw 18A
Max PV String Current 22A
 
Hedges said:
You're aren't likely to see full Isc except under ideal conditions.

Will this be multiple PV strings in parallel? If so, bring system up with just one string. That way if you did connect backwards, the reverse polarity diodes won't have to carry full array current, just one string.
Click to expand...
Thanks I will do that.
Hedges said:
Check voltage and polarity before closing switch or otherwise making final connection between PV and inverter.
Click to expand...
This too.
Hedges said:
Most inverters/SCC won't draw more current than they want. But no guarantees.
Click to expand...

Hedges said:
I think MPPT input is a buck converter, won't ever pull PV string lower than battery voltage. Could pull more than Imp but probably less than Isc. Only time I expect it to see Isc is if PV connected backwards.
Click to expand...
the IMP on these is 11.03 so two p string would be ~22 amps which is right at the max acceptable power for the SSC. I would guess it can only actually use 18 of those amps from the spec sheet. OR am I screwed up in my thinking?

What would be ideal conditions. Are they actually achievable outside of a lab in your opinion?
 
The specs are also indicating something directly connected to the panels. When you add obviously required wiring to go from the panels to the charge controller that will drop the voltage and amps it is exposed to depending on the gauge and length of wire.
 
I wouldn't worry much about 5% over Isc.

If your two parallel strings have different orientation, they will never both be max current at the same time.
To the first order, consider the area they present to the sun. If two panels were touching in an inverted "V' shape, how wide would the base be? Ratio of that to what it is with both flat should be ratio of current.

I like two orientations to spread production out over more hours. One field trial showed about 2% less total power than if each had its own MPPT. But you get more kWh out of the MPPT by operating more hours.

I see full Isc on rare occasions. Cool clear day.
 
Joe_ said:
I don't understand push power. Can you explain further?
This is what the spec sheet says in the Solar Specifications section.
Max Solar Current Draw 18A
Max PV String Current 22A
Click to expand...
Those amps are what the panel can supply if required to. The panel is not forcing the power into the SCC. It's the load that draws power from the panels. A 200W panel doesn't supply 200W unless the load requires it.

The critical thing as far as the SCC is voltage. Even in low light a panel can still be at nominal voltage but amps will be low. The voltage has to be below the rating of the electronics in the SCC.
 
Joe_ said:
Thank you for your answers.
Here is what I have for now. I have two EG4 48/100 500v mppt charge controllers says max is 22 amps. and 1 tracker per controller

On each charge controller I was hoping to have 7 series 2 parallel (total of 14panels) these have a Isc of10.19 voc of48.74 and rated at 395 watts.
But unfortunately those panels are out of stock and might be unavailable.

The replacements I am looking at are 455 watt 49.35 Voc and a Isc 11.44
Click to expand...

This is severe over paneling of these SCC's. Input rating is 5500W. I caution pushing these SCC's to limits. One member here stated his unit failed but when I pressed him for information on his PV, he never responded. I'm pretty certain he severely over paneled the unit or some cold day the VOC went over.

I have a pair installed with 16 530W panels, I run 8S per unit, VOC is 49V, ISC is around 13A. I have seen as much as 5100W for extended periods run thru the MPPT on partly cloudy days. These seem to take the watts available from PV, very efficient unit. I will be releasing a video someday on my PV and have some footage of the SCC pulling more watts on a string than the panels are rated for.

In your case, I would purchase another SCC, use 9S without any parallel strings on a unit. This gets you to 27 panels and you get full output of available PV yield. For $400 per SCC, that really is a no brainer. Keep the volts high and amps low is way more efficient. 3 units spread the heat produced and the higher voltage lets the MPPT run cooler. Higher amps create heat, heat causes failures in electronics.

You will need to look at max VOC at your coldest temps for your area and determine if VOC at 9S will go over the 500V rating of these units. I suggest the Midnite calculator. https://www.midnitesolar.com/sizingTool/


Joe_ said:
I have space considerations because these are mounting to the top of a few shipping containers. The length of the panel has to be very close to 80 inches which limits my choices.

If I use them the Isc of the parallel strings would be 22.88 amps or almost a full amp more than the max on the spec sheet.
If you could explain why or why not this is or is not a deal breaker I'd be grateful, I do need to know if it will work or if I am going to shortly have to replace the charge controllers because I went too far out of the spec.
Click to expand...
If you want to over panel, clipping will occur and you lose that potential yield. As to whether these units are prone to failure with severe over paneling is undetermined at this point. It would have been helpful if the member with the failure had listed the PV input but some people sometimes realize their mistake and don't want to look bad in public.

If you do over panel and have a failure, please share the information, it helps anyone looking at the SCC's to determine if it fits their system.

One more thing is these units have a firmware update to correct the F01 code from setting. I did a video showing how to update firmware on these and the cable needed. https://diysolarforum.com/threads/e...-mppt100-48hv-sets-code-f01.68669/post-889561 If you do not have the RS485 to USB custom cable needed, contact EG4 and they will send the cable out free of charge.
 
Zwy said:
I have a pair installed with 16 530W panels, I run 8S per unit, VOC is 49V, ISC is around 13A. I have seen as much as 5100W for extended periods run thru the MPPT on partly cloudy days. These seem to take the watts available from PV, very efficient unit.
Click to expand...
How much noise does it make?
 
Thanks for the replies. I had extremely limited internet for the last few weeks while traveling and was not able to check the board .

I passed on the panels I was inquiring about in this thread when another source of the original panel I had hoped to use showed up unexpectedly. Turned out to be more local to me too so I can pick them up, no shipping. The company I purchased them from was willing to hold them till I get back, which should be shortly. I only need to pick 1600# of panels up now. What could go wrong? Lol.

I will review my calculations again to be sure that I don’t screw this up. Thanks for the link to the midnight calculator.

I‘ll be within the specifications this time amps wise with the 395 watt panels, and not on the bleeding edge which is a relief. I’m fairly certain I have room voltage wise. But will double check and re work that if necessary so I do..

There is definitely a lot to learn. I appreciate everyone’s assistance in getting this up and running.
 
Ellcon123 said:
Those amps are what the panel can supply if required to. The panel is not forcing the power into the SCC. It's the load that draws power from the panels. A 200W panel doesn't supply 200W unless the load requires it.

The critical thing as far as the SCC is voltage. Even in low light a panel can still be at nominal voltage but amps will be low. The voltage has to be below the rating of the electronics in the SCC.
Click to expand...
Thank you for that clarification. Makes total sense.
 
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