Powmr 3kw off grid inverter questions- Cant get over 1kw production- Weird/

[first class coatings]

Hi Forum:::

A forum member posted this, which sparked me to think of a few factors...

Based on this comment: - In general I get at most about 1400 watts out of the panels at peak (they are not an ideal facing but it's the best I can do on my property).

MY QUESTION: I have a powmr brand mppt hybrid inverter 3kw - 24 volt lead acid batttery set up...
I have 8 - 310 rec 310 watt panels connected .. I can never see my inverter going over 945 watts of production..

Rec panel open circuit voltage 36.3
amps 9
max pv on mppt inverter is 105
average showing on my inverter when nothing is running is 75


What seems interesting , is that i can pull 1.25 kw out to charge a EV on a 110v charger, ( I have a transformer BTW)
And the pv watts produced will never go higher than 950 watts on the inverter.. (Hovers between 745- and 950 watts max)
But the charger light blinks and it appears to balance out the battery to some level but while the sun is up and mostly at its peak approx 1 pm, , and as directive as possible, I live in Arizona, my panels are on a flat roof, not aimed south, but generally flat.. Appear to get quite good exposure.. Not sure if this contributes to that much power loss.. Nothing is shaded... It is weird that I cant seem to produce more than 950 watts??? Any thoughts on this with similar units like mpp or others you guys use.. Or any thoughts of what may be dragging down production.. Also, I have 2 panels in series/ connected to 2 panels in series then paralleled... 2 strings all together --fused then wired directly to the inverter -with no connection box.

Thank you for your thoughts.
SOLAR PANEL DISTANCE TO INVERTER IS LESS THAN 25 FEET - ALL PANELS.
HYBRID INVERTER STYLE
NO LOADS AFTER 5PM.



So a few members asked :
Here are the inverter specs.
pow-3km-24
rated power 3000 w
24 volt input
operating voltage range 30-80 vdc
max solar voltage 102v

However, the web site states 145 volt max pv, which may be false..

the web site states this however, :

Model: POW-3KM-24

• 3000W 24V-230Vac Pure sine wave inverter
• Built-in 40Amps MPPT solar charge controller
• Max Solar Input 145Vdc - THIS VALUE MAY NOT BE CORRECT- IT MAY BE ONLY 105 VOLTS, AS SHOWN ON MY STICKER ON MY UNIT AND THE INFO ABOVE..
• AC+Solar Charging : 60Amps
• Can connect to AGM and User-Defined

 

[The New JC777]

A Link to your inverter with specs would help us help you.

 

[Mcgivor]

Open circuit voltage is without any load check the voltage when it's charging, could there could be voltage drop, what distance and wire gauge from the combiner to MPPT.?

The input power will be restricted if the battery is in a higher state of charge, what is the battery voltage during charging?

What sort of loads are there overnight and is this off or on grid?

Being flat mounted shouldn't have much of an effect during summer, winter is where reduction of output would be noticed.

Is the Power inverter charger the plus version ?

 

[first class coatings]

A Link to your inverter with specs would help us help you.

updated the post, thank you for asking.

 

[first class coatings]

Open circuit voltage is without any load check the voltage when it's charging, could there could be voltage drop, what distance and wire gauge from the combiner to MPPT.?

The input power will be restricted if the battery is in a higher state of charge, what is the battery voltage during charging?

What sort of loads are there overnight and is this off or on grid?

Being flat mounted shouldn't have much of an effect during summer, winter is where reduction of output would be noticed.

Is the Power inverter charger the plus version ?

Hi, I just updated the post with the info,, I hope that helps Battery voltage during charging is 26.8 volts

 

[Mcgivor]

At 26.8V a lead acid battery is close to being fully charged, hense the reduced current, or wattage, discharge the battery to a lower voltage and see what happens, more than likely it will increase, but this isn't necessarily the case if the conductors are sized on the smaller end of the spectrum, a question unanswered in previous text.

 

[first class coatings]

Open circuit voltage is without any load check the voltage when it's charging, could there could be voltage drop, what distance and wire gauge from the combiner to MPPT.?

The input power will be restricted if the battery is in a higher state of charge, what is the battery voltage during charging?

What sort of loads are there overnight and is this off or on grid?

Being flat mounted shouldn't have much of an effect during summer, winter is where reduction of output would be noticed.

Is the Power inverter charger the plus version ?

not the plus version...
If I place a draw from the inverter and pull 1.25 kw, or even 2.9 kw , the pv produced will not travel over 950 watts... It doesn't show that I am producing power at that step, but the charge light blinks.. but the inverter is now pulling 20-30 amps from the battery..

 

[Bud Martin]

OP: " I have 2 panels in series/ connected to 2 panels in series then paralleled... 2 strings all together"
Please clarify your panels wiring, your description does not make sense.
You have 2 panels connected in series connected that to the other two panels in series, that means one string has 4 panels in series, so total Voc = 36.3 x 4 = 144.8V.

 

[Mcgivor]

not the plus version...
If I place a draw from the inverter and pull 1.25 kw, or even 2.9 kw , the pv produced will not travel over 950 watts... It doesn't show that I am producing power at that step, but the charge light blinks.. but the inverter is now pulling 20-30 amps from the battery..

Looking at the specs the Plus version has a 60A MPPT charger, the regular is 40A, if this is correct then the nominal output would be 960W, this would be consistent with your observations, the MPPT charger would be over paneled but cannot exceed it's maximum capacity. This is benificial during winter months especially with flat mounted panels.

The specifications are what I found, therefore may be incorrect due to various model options, if they are correct, taking into consideration the fact wattage output is dynamic and will vary depending on battery state of charge, the system may well be working normally.

 

[schmism]

you didnt say were you were but this time of year I only make about 1.5kw out of 2.5 kw of panels due to amount of sun.

 

[first class coatings]

OP: " I have 2 panels in series/ connected to 2 panels in series then paralleled... 2 strings all together"
Please clarify your panels wiring, your description does not make sense.
You have 2 panels connected in series connected that to the other two panels in series, that means one string has 4 panels in series, so total Voc = 36.3 x 4 = 144.8V.

Hi,

Ok, Here is my set up...
I have 2 panels in series- x 2 then i combined them in parallel. When testing voltage on that string with my multi meter, the reading is 75 volts for the 4 total panels (Series / parallel) ..
Total output voltage on that string is 75 volts and suspect of 24 amps...

Did the same thing for the other 4 panels.. voltages were the same, but ran the 2 positives from both strings to the inverter, which is a run of less than 20 feet, and connected the negatives to the inverter.. No combiner box, just 2 fuses of 20 amps on each string combined together..

So in clarification- 8 total panels, pv input voltage reading on my inverter is 75 ,, with 8 panels of 310 watts series 2 x2 then placed in parallel.
All panels are eastward facing with nice sun exposure from 9 am till 3pm,, then the fade..
on my panel , nominal power voltage vmpp states 37.2 , open circuit voltage 45.5 v , current 8.34

hope this makes things a bit more clear..

I'm concerned this powmr inverter is fully under rated or not properly preforming...

 

[Bud Martin]

on my panel , nominal power voltage vmpp states 37.2 , open circuit voltage 45.5 v , current 8.34.
I have 2 panels in series- x 2 then i combined them in parallel. When testing voltage on that string with my multi meter, the reading is 75 volts for the 4 total panels (Series / parallel) ..
Total output voltage on that string is 75 volts and suspect of 24 amps.

2S2P string
The Voc of this string is 45.5Voc x 2 = 91V, +15% for cold weather = 105V.
Current for the string of 2 panels in series is 8.34A (I am assuming Isc)
Current of 2 strings in parallel is 8.34A x 2 = 16.68A

So you combine the 2S2P with another 2S2P in parallel = 2S4P, the results are
Voc will be 91V (105V worst case cold condition) to the PV input.
Total current to the SCC = 16.68A x 2 = 33.36A

 

[first class coatings]

you didnt say were you were but this time of year I only make about 1.5kw out of 2.5 kw of panels due to amount of sun.

I am located in Phoenix AZ

 

[first class coatings]

Looking at the specs the Plus version has a 60A MPPT charger, the regular is 40A, if this is correct then the nominal output would be 960W, this would be consistent with your observations, the MPPT charger would be over paneled but cannot exceed it's maximum capacity. This is benificial during winter months especially with flat mounted panels.

The specifications are what I found, therefore may be incorrect due to various model options, if they are correct, taking into consideration the fact wattage output is dynamic and will vary depending on battery state of charge, the system may well be working normally.

Thank you.. This is quite interesting.. You may be dead on!.. I have another unit with 48 volts 5kw system with 4500 watt of pv, but the highest i can produce is 2.8 kw no matter what.. Must be limited by the charge controller amps. (48 volts x 60 amps =2,880 watts- Consistent with the 24 volt system and 40 amp charger= 960 watts.. the same equation...

So Here is the most important question....???
The inverter is rated for 3kw... But if i am only able to produce 1 kw lets say , and i over panel 1 kw, I suspect I can produce more battery charging current?, so will more panels just put more current to the battery to help offset the draw load?? is that how this seems to work???

 

[Mcgivor]

To get around the problem I would remove one array string and use a separate charge controller set to the same parameters as the inverter MPPT, or use a separate SCC with a higher capacity as the sole controller.

The thing to remember is any loads will subtract from the charging current, if you had a 10A draw on the battery, Yorr charger is effectively a 30A charger not 40A. There's no free lunch unfortunately

 

[Bud Martin]

BTW, do you have clamp on meter to check the battery charging current and compare it ti what is shown on the PowMr display?
PowMr SCC are known to show more charging current than it really is.

 

[first class coatings]

To get around the problem I would remove one array string and use a separate charge controller set to the same parameters as the inverter MPPT, or use a separate SCC with a higher capacity as the sole controller.

The thing to remember is any loads will subtract from the charging current, if you had a 10A draw on the battery, Yorr charger is effectively a 30A charger not 40A. There's no free lunch unfortunately

So in essence... A rated 3kw inverter will not really be able to supply 3 kw free and clear by solar power / by adding solar panels or extra panels to be greater, and or equal the load.. ?
in this equation,, after 950 watts, it will draw from the battery to be able to put out up to 3kw, but no way to balance out solar pv, and kw draw over 950 kw, with out using the battery to buffer on a smaller inverter I take it..

So if this is the case, one should seek a higher mppt built in charge controller with higher amps, to get higher pv output?

 

[Mcgivor]

So in essence... A rated 3kw inverter will not really be able to supply 3 kw free and clear by solar power / by adding solar panels or extra panels to be greater, and or equal the load.. ?
in this equation,, after 950 watts, it will draw from the battery to be able to put out up to 3kw, but no way to balance out solar pv, and kw draw over 950 kw, with out using the battery to buffer on a smaller inverter I take it..

So if this is the case, one should seek a higher mppt built in charge controller with higher amps, to get higher pv output?

The inverters ability to support loads directly from PV is limited to its on board MPPT's capacity, in your situation around 900W, any more is taken from the battery, the problem is the battery will never get charged if output exceeds input.

Having a separate higher capacity SCC also providing input will allow the inverter to output a higher wattage but again limited to its current capacity. Always focus on the battery charging as a priority then loads, exprienced offgrid operators usually have sufficient PV to cover both loads and charging, along with equipment sized to utilize the PV.

The inexpensive all in one units are best suited as a UPS standby with grid priority, where multiple days allow the battery to recover, they can be used offgrid if extra charging capacity is added to the system, there is no need to buy another all in one.

 

[first class coatings]

The inverters ability to support loads directly from PV is limited to its on board MPPT's capacity, in your situation around 900W, any more is taken from the battery, the problem is the battery will never get charged if output exceeds input.

Having a separate higher capacity SCC also providing input will allow the inverter to output a higher wattage but again limited to its current capacity. Always focus on the battery charging as a priority then loads, exprienced offgrid operators usually have sufficient PV to cover both loads and charging, along with equipment sized to utilize the PV.

The inexpensive all in one units are best suited as a UPS standby with grid priority, where multiple days allow the battery to recover, they can be used offgrid if extra charging capacity is added to the system, there is no need to buy another all in one.

Thank you so much, This was driving me crazy to figure out why the deficit... (YOU ROCK MCGIVOR) SO MUCH APPRECIATE THE GREAT FEED BACK.. should I run the 4 panels to cover the 900 estimated load watts, and get a small mppt charge controller and add the other 4 panels to it to offset my draw during the day? or just keep the 8 panels in the all in one?

 

[Mcgivor]

Having a single SCC rated to handle all the charging is the best approach but also more expensive, having 2 charging sources is possible if the settings of both chargers of are identical, not always possible though, if not customizable.

This is why many serious operators generally stay away from all in one units and use professional grade equipment, it allows for flexibility.