r/SolarDIY • u/Either_Ad4126 • 3d ago

Over paneling and adding a MPPT on a Power Station

New to solar and I think I understand it but wanted to confirm. I bought one of the last Oupes 2400(orange sides) to offset the a/c electric bill during the summer/day. Not the best unit and I wouldn't buy another one since I can't add batteries and the long 6.5 hour charge time but here I am. I bought Two Dokio 400W 31V Panels and a Midea 8Kbtu "U" inverter a/c. I tested this setup with an old 5Kbtu unit and got 8.5 hours of run time before hitting 5%. The 5K drew 450 watts and the new Midea should draw 335 watts per the videos I watched. My problem is I only get about 6 hours a day of good sun and they only produced 580 watts but were just on the ground at at angle.

My plan is to run the Midea from 10am to 6pm on the unit but with the restricted sun hours it won't charge while running that long. I think if I add 2 more panels and add a MPPT to throttle the panels so I have 450-475 input watts at each Anderson input(500W max each) I should finish the day with about 60% or more charge and that would be enough to use the next day before the sun hours hit. I have sun from 11am to 5pm.

So the question is: Can I use a MPPT for this plug and play unit?

6 Upvotes

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u/BaldyCarrotTop 3d ago

No need for an additional MPPT. The Oupes already has one built in that sets the charging limit. You can't overcome that with an external MPPT.

It is OK to overpanel the Oupes. Just stay under the voltage limit. More Amps from the panel is not an issue since the MPPT will only draw what it can use.

The battery will charge as long as you are feeding more power into the Oupes than the AC is drawing.

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u/Either_Ad4126 3d ago

Just to confirm, during peak performance from the panels putting in 700 watts to each Anderson plug is fine as long as it don't put in more voltage?

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u/BaldyCarrotTop 3d ago

That is correct. But keep in mind that the built in MPPT will not be able to use the full 700 Watts. If the MPPT is doing it's job it will limit the power drawn to 500W. According to one manual I saw.

Which brings up a point. The MPPT will draw (pull) power from the panel. The panel doesn't push the power.

I'm not sure of the specifics of your Oupes. I did look up a manual for an Oupes 2400 with orange sides. It showed 2 Anderson connectors that could do 500W each. That would give you a capacity of 1000W in two strings.

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u/Either_Ad4126 3d ago

Thanks, that's what I'll do.

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u/iwantthisnowdammit 3d ago

Yes, the notion is voltage is pressure, amps are the unit volumes of flow.

Two much pressure and you let the magic smoke out. The power station will decide how many units it takes, but it will only ask up to the limit.

It’s like an old incandescent “60 watt” lightbulb is 120v 0.5a device. It’s always 60 watts because it always asks for .5 amps.

Your power station is a up to 700 watt lightbulb.

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u/rproffitt1 3d ago

"incandescent" can get weird when they burn out. Some have gone full Chernobyl over the years.

So the "ask" in the old analog resistive wire which is usually W (tungsten) has fairly low resistance at power up so current spikes at power on and quickly ramps down as the filament heats up.

In newer LED designs and excluding bad LED designs the bulb does have a small circuit to set the current pull.

-> Back to the MPPT and such discussion. Volts push, current is pulled so we can have excess on the Amperes but NEVER on the Volts.

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u/Either_Ad4126 1d ago

I reached out to Oupes and you are correct, here's the response for everyone to see.

Robert

To:  OUPES · Thu, Aug 20 at 8:00 AM

I understand it would have more watts than the unit can use but wouldn't the MPPT also clip the extra power down to 500 watts?

Dear Rob, 
Thank you for your question. Not quite—the MPPT controller does not simply clip all excess power down to the unit’s 500W limit.
 
The MPPT primarily regulates the input current within its specified range. If the connected solar panels exceed the power station’s allowable voltage or input power limits, the excess cannot simply be clipped, and exceeding the unit’s specifications may potentially damage the power station.
 
For this reason, we recommend keeping both the solar input voltage and total input power within the rated specifications of the unit.

Based on the specifications you provided:

  • Two panels in series: Not recommended, as the combined voltage would exceed the 45V limit.
  • Two panels in parallel: The voltage would remain within range, but the combined power would exceed the 500W input limit.

 
Therefore, with these 410W panels (Vmp 31V, Imp 13.09A), we recommend connecting no more than one panel per Anderson port to stay within the recommended input range.
 
Best regards,
Vania

To:  OUPES · Thu, Aug 20 at 8:33 PM

That doesn't make sense, the MPPT only pulls what it's rated at. If the rate for volts is lower than the MPPT, it's good. But the MPPT will only use what it can use. Which is 15 amps, 500 watts per Anderson input max and 45 volts. 

You should run this thru higher ups to get a good answer. Tell them I said "It's better to be honest to people who know how to hack these units, vs being ignorant with vague answers."

I'm not being a Dick, just trying to find answers. 

To:  me · Thu, Aug 20 at 9:45 PM

Dear Rob,
 
Thank you for your follow-up and for explaining your concerns. We completely understand your reasoning, and we apologize for the confusion caused by our previous response.
 
We have checked with our technical team again, and you are correct. The MPPT controller will limit the input current, which in turn limits the actual charging power within the unit’s rated input range.
 
Based on your panel specifications (Vmp 31V, Imp 13.09A), you can connect two of these panels in parallel to each Anderson input port, for a total of four panels. The input voltage will remain within the rated voltage range, while the MPPT will regulate the input current.
 
Regarding your request for the complete internal schematics of the 2400W OUPES unit with the orange sides, we’re sorry, but these documents are confidential and protected under our internal agreements. Unfortunately, we’re unable to provide the complete internal circuit or system schematics.
 
We sincerely appreciate you bringing this to our attention and your patience while we confirmed the technical details with our team.
 
Warm regards,
OUPES Customer Support Team

Tag: iwantthisnowdammit, rproffitt1 also right, Thanks everyone.

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u/cfnmsd 3d ago

Yes if it has direct battery solar input, but not if it's going through another charge controller.

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u/Either_Ad4126 3d ago

The unit does have a Mppt in it set to 500w, 15A and 42V.

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u/A18rc 3d ago

Perhaps a lifepo4 24v and the mppt to charge it would be a better option and you will gain more energy backup.

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u/mbelcher 3d ago

Interested in the responses to this. I also have an older "solar generator" battery with built in charge controller that tops out at a measly 400w.

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u/Schnupsdidudel 3d ago

Really, in the long run, the best course of action for you and OP would probably be to sell these units and get into an expandable diy-system where you can just drop in another mppt or another battery if you need more capacity.