Question around PV Array MPPT VoltageRange in my PIP-LV2424-MSD

[frankypc]

Two weekends ago i installed my entry solar system, it is composed of

1) MPP Solar PIP-LV2424-MSD
2) 24v 220ah Flooded Battery Bank
3) 6 beamreach solar 280watt panels for a total of 1680watts

Panel Specs are as follow:

Pmax 280
Vmp 31.33
Rated Current: 8.95
Voc 39.04

My panels are connected in 2 strings of 3 panels each in series and then both are in parallel.

So far the max i have seen is 1200watts of PV Power, and in a perfect day i see it sustaining around 1054watts. I can say im happy with the setup but somehow i was expecting, living in a tropical island with some great sun to be hitting maybe around 1300 constantly around 12pm-1pm ?

So i have been questioning if i have something wrong .

The PIP-LV2424-MSD Spec say the following:

Max. PV Array Open Voltage: 145vdc
PV Array MPPT Voltage Range: 30~80Vdc

All this long post to ask, Is my setup going over the PV Array MPPT Voltage Range? Would that be affecting my total system output?

If 1054watts is the best im going to get on average i am a happy camper but i dont want to leave stones unturned if there is something i can do better to maximize my system output.

Thank you

 

[snoobler]

I don't see anything amiss.

You only ever have the potential to make max power when you're getting a true 1000W/m^2 irradiance, and your panels are perfectly perpendicular to the sun.

Use link #5 in my signature to determine your solar hours available for your location, panel orientation and tilt.

Take the October hours number, e.g., 3, and multiply it by your panel wattage: 3h * 1680W/1000W/Wh = 5.04kWh - you should be able to harvest this much energy even if you're not hitting peak.

 

[frankypc]

Snoobler

Thank you for the reply!!

I will do as you mention and track the harvest against the irradiance instead of just focusing on hitting max numbers

 

[snoobler]

You'll need to do your best to use as much power as the panels can supply in order to find that number. In most cases, batteries are fully charged pretty early in the day, and the panels are just providing load power during the day.

Gotta make sure you are asking for more than the panels can deliver. Battery charging may be the limiting factor. If you're in absorption mode at 12-1, your panel power is limited by what the batteries can take. Next time around noon, fire something(s) up that really put a load on the system and see what you get.

 

[frankypc]

Hi Snoobler,

In the previous 12pm-1pm test i have used a heat gun that puts 1600watts of power. Today we have scattered showers and very little sun so i will have to pick a further date that is super sunny and i will do sample tests maybe starting around 11am. In order for battery not to be limiting factor i will make sure they charge at night using AC power so they are not affecting the reading the next day.

Thank you so much for the guidance on this.

 

[snoobler]

Don't bother charging them. That ENSURES they're the limiting factor. There is no harm in the batteries charging during your test as they represent yet another load. I suggest a total load well in excess of your 1680W panel power. At least 2000W.

 

[Jim Burrow]

I have the same set up as you and layout as you. I live in sunny (although 3/4 of it on fire) California and crossing my figures I get 1200 watts from the PV. Although at a perfect angle to the sun, it should get around 1600 watts.

My problem that I will never get the perfect angle and my wires from the panels to the controller is a good 50 feet. So I have losses there.

However, I haven't got around to testing my panels as I haven't installed them yet anywhere.

 

[snoobler]

Don't bother charging them. That ENSURES they're the limiting factor. There is no harm in the batteries charging during your test as they represent yet another load. I suggest a total load well in excess of your 1680W panel power. At least 2000W.

To clarify, I'm essentially recommending you confirm your batteries aren't the limiting factor on your production. No need to consume over the course of the whole solar day - just hit the system with a 2000W load at peak solar and see what your panels produce.

 

[frankypc]

Hi Snoobler.

I followed your lead and I'm peaking around 1200,1300watts its just that my batteries are full all the time and loads are so loads that I'm not challenging the system enough because my loads are so low and i dont use the batteries at night.

 

[snoobler]

So even with a load in excess of 1700W, at high noon, your production peaks at 1300W?

That's about 77% of rated. That's reasonable, particularly if you're not perfectly perpendicular to the sun. I know in summer with year - round tilt (35° Lat, 29° tilt), I typically get about 90%. I suspect it's getting to be less as we march towards winter.

 

[frankypc]

Hi Snoobler,

That is correct, when i put loads over 1800 watts and with proper sun etc it peaks at around 1300watts PV. So yeah i guess its not a bad number and better than the 1054watts i had measured earlier.

So in short I'm not hitting my system hard enough in normal use but it seems that if i would put in higher loads more often i would harvest very close to what i should be getting for my system per the calculations on link #5 as instructed.

 

[snoobler]

Sounds good. When the sun gets around to being in the optimal position in the sky, I'd look to try again just for giggles.

Yes, the battery being in absorption charge phase is often the limiting factor on peak solar power. My 3kW array usually peaks around 1700W.

Today was almost 1900W because I hit the battery pretty hard last night (ran RV fridge on AC overnight).



The top chart is power peaking at 1855W, and the bottom chart is battery voltage (blue) and current (orange). The taper is the absorption phase where voltage his held at peak and current is tapered to prevent going over-voltage. Thus power is restricted.

Note that the blue line is decreasing - this is temperature compensation due to the battery heating:



System is in a shipping container in the high desert, and it experiences pretty substantial temperature swings.

 

[frankypc]

Hi Snoobler

I will definitely keep testing as you saw in the other thread about intermittent discharging due to higher loads. I'm looking to use the system more during the day to maximize the solar harvesting.

You have an awesome system , and in the middle of the desert those temps must get crazy

 

[snoobler]

"high desert" - we're at about 6800 ft elevation, so we rarely get over 100°F.

I still have another 3kW of panels to mount... kinda pointless as the batteries can't handle the 3kW...

Gotta get to work on the Lithium battery...

 

[frankypc]

This is my first system, after hurricane Maria i wanted something that would let me get my house going on solar with the basics and then at night run a couple of fans and the fridge. I was on a limited budget so i got one of those Reliance Control transfer switch and moved 10 120v cirtcuits to the Transfer and i feed the transfer with the MPP Power so i can manually pick and choose what breakers are in Utility or in "Gen"

So far im loving the setup, my goal is maybe 5 years from now do a larger system but for now this is awesome. Ive had already some outages and i have not needed my small honda eu2000i genny