2000 watt solar system avg output?


We've recently got a system installed, here's what it looks like.

2x 5kva Axpert inverters

2x banks of 4 batteries each

2x banks of 8x250w solar panels (16 solar panels )

each pair is for separate floors in the house for load management

now, we installed it a few days ago when we had a lot of rains and every day was cloudy. So we couldn't really load test the system.

Today was the very first day when we had clear blue skies (Lahore) and we found out that the solar panels are producing only 1000watts maximum- we took the reading at around 1:30 PM ( when I say the panels are producing 1000 watts, remember that 8x250w panels are connected to each single inverter, so that's 2000 watts per inverter ).

the installer told us that we can expect max 75% output from the panels, but as you can see they are only producing 50% (both inverters Were showing 1000watts each) . We are not sure if this is due to line losses, config issues, bad hardware or the installer simply lying.

We have the solar panels on the roof (obviously ) and facing more or less true South , with an angle of 27. No dirt or some such on the panels. No shadows, we even ensured there are no shadows from the front row of panels on the ones at the back as they are sufficiently apart. Very large roof.

the other issue with the inverters is that we can't seem to connect with the usb or serial port connectors no matter what. We called up the main vendor (it's voltronic/Axpert but it's from inverx) in Karachi and one of the tech support guys said they have blocked the ports on purpose so that people wouldn't mess around with them, and that the function is available on infini models (wont the vendors mess around with them then ? Genius logic ! Pay more money for premium features ) .

Has anyone got some ideas about what the issue would be ?


First thing to check is the line loss.

If you have a digital voltmeter, check the voltages both at panel and inverter ends. The difference should not be more than 2-3%.

What is the length of the cable run from the panels to the inverters. Do you know what size cable has been used?


Maybe tufail can tell better about axpert units and the low power production...


  1. I wouldn't be surprised if it turns out to be the limitation of the charge controller. 1000/55=19 amps. Although specs show 50 amps max, but I would suspect it would really be capable of about 25 amps.
  2. tufail should be able to advise.


In off-grid systems, less load on inverter will ask for less energy from panels.

Around noon time, try to put around 2000 watts of load on the inverter. And see what is the maximum that the panels are able to provide.

Ok thanks for the replies guys. Don't have a volt meter but will get to it in a few days.

The inverters are placed on the ground floor and a cable runs from the roof/solar panels down through the atrium, and it's about 30 feet long. The diameter of the cable (saw two cables inside the piping, positive and negative?) is one centimetre, brand is gm. I heard the electrician say to the installer 'pa ji can you afford this' to which the installer replied that he's getting good money. Not sure if that was for show or if the cables are genuinely good.

at noon, took the reading again and it was still 1000w input. Load was hovering around 950w . Asked someone to put more load and they turned on the clothes iron. Load went up to ~2000w , but the solar input didn't increase . Definitely something wrong . Losing at least 25% power somewhere (if I generalise the rule that a solar panel can output on the average 75% when we have lots of sunshine ) .

Asked the installer and he said 50% is the max I can expect . This is bs seriously . A 4000w system is only producing 2000w at noon with lots of sunshine, not hazy, no clouds etc .

what are my options? Is it due to the wire length ?


[quote=", post:, topic:"]Dont tell anyone.. it is the axpert`s very poor charge controller ;)[/quote]


Wire length does decrease VOLTAGE, depending on the input voltage and length of wire, but this isnt as much a problem, my lengths are almost 30+ feet and voltage loss is around 2-3V overall..not much of a problem.

GM and Pakistan cable are good enough quality brand, and very expensive too. so if it is original GM, you are good to go.

Problem is, and always will remain your charge controller inside your inverter. when a reasonably good 3 lac inverter produces 95% efficiency, do you expect a 50k inverter to perform at that level? your installer is right, you wont ever get more than 50% out of that setup.. We know that. majority people know that, even the INSTALLERS knows that, so if someone else may still try to live in denial, good wishes to them :D

however your problem solution isnt that big or that expensive. you can easily get a separate charge controller and install all the power input from panels into it, a good new CC will be able to provide 70-80% power on normal days and upto 90% on good after rain days with high irridiance. however your new CC MUST be a good one, if you skimp on it like the inverter, you will again get no results.

by looking at you config , can u tell whether your panels are series or parallel , to decrease line loss make sure you have setup the panel in series with rated of MPPT charge controller max voltage ......

download the User Manual from Voltronic Power website.

On page 22, there is details regarding parameter 31.
With the help of manual check your inverter, what is the setting for parameter 31.

Ok here is the make/model of the panels:





open circuit voltage 37.1v

short circuit current 8.52a

max power voltage 30.3v

max power current 7.92 a

max system voltage 1000v

i am not sure if the panels are in series, but I think they are. How do I confirm ?

@ farhan

when you say CC , is that the controller for sunlight charging ? How will it bypass the built in charger of the inverter ? How will it communicate wit the inverters ? Would I need one each for the 2 inverters ?

Before investing in the cc, I must ensure it is definitely a fault of the controller / inverter ? How expensive is the external cc going to be ? Do you have some models in mind ?

Also someone told me the 5k inverters are overkill until I add more panels, is that right ?


1 - you simply connect all the input of the panels into the charge controller instead of the axpert.. leave the rest of the wiring as it is.
.. CC = Solar charge controller will convert all solar power and charge batteries as well as excess power will be passed to inverter which will provide house with solar power and wapda chaging at night, as it is already set to do.

2 - EP Solar have some of the better CC in market. their PWM and MPPT both work over 70-90% efficiency depending on sunlight... their E-tracer series in MPPT is very high grade, but around 52k for a 60 Amp model.. PWM are almost half the price, and almost 80% as capable as MPPT, as MPPT is newer tech and charges premium..outback and Schnieder are other good options.. outback is ok, but Schnieder is better, comes with local 3 years warranty and costs 90k :P

buying a slightly less expensive 40A model would also be enough but will prevent you from adding more panels in future.. 40A will max out at 2200W panels, 60A model will allow you to add upto 3500W panels in future.

3 - in power, nothing is overkill. 5kva means around 3700W power, which is decent enough for each floor.. your units are ok for the inverter purpose and you probably dont need anything else.. axpert work fine in inverter mode.. it is their CC which sucks so bad, and that is the most vital component of the whole solar system..

[quote=“neo_x, post:10, topic:22182”]

i am not sure if the panels are in series, but I think they are. How do I confirm ?


You can confirm by looking at the LCD panel and reading the value of PV Voltage.

In your case I would wager that the PV voltage is 120 volts dc. This would mean that each array of 8 panels has been configured as 4 in series and two sub-arrays in parallel. If these were all in series as you say, the voltage would exceed the inverters max. PV input rating which according to the datasheet is 145 volts.

Please check the voltage and current at around mid day and post here.


Ok ppl thank you v much for replies ones again, very helpful.


I saw this too late , and only managed to take readings at 2:30 today.

here is what I saw:

PV BATT ampere 11A, with load of 300w

input ac voltage 229v

input PV batt voltage 69v (with 300w load) / 54v with 2k load

other strange settings

U1 72 40

U2 01 24

I am not sure I saw current readings Anywhere on the display

@ farhan

so the external cc will take connections from solar (and am I right in saying I just need to buy one for all panels , what if I add more panels in future ) and then connect to batteries. The inverter(s) is also connected to batteries. So both external cc and inverter Wapda charger are charging the batteries at same time. Would they not conflict with each other ? More drain on batteries ? I still don't understand how the cc will communicate with inverter (you said the inverter will still use solar as well as Wapda)? Is the external cc to be connected to the inverter somehow ? Would want to run 2 inverter acs (1.5 tonne) in the future so will probably get 2000/3000w more panels (in addition to 4000w now )

I still can't believe Axpert is so crap. These were the new models and are advertised as having MPpt controller (also the installer said so) .

[quote=“aurangzebhaque, post:12, topic:22182”]

You can confirm by looking at the LCD panel and reading the value of PV Voltage.

In your case I would wager that the PV voltage is 120 volts dc. This would mean that each array of 8 panels has been configured as 4 in series and two sub-arrays in parallel.


I guess I was wrong here. Infact to me it seems that the installer has divided the 8 panel array into, 4 parallel sub-arrays of 2 panels in series. I wonder why he has done that because this looks a bit in-efficient.

Maybe tufail can advise.


If I am not mistaken, axpert(5kva w/mppt, atleast) while on inversion mode(using only Solar-panels and Battery to power loads) will show input ac voltage as 0. As it disconnect it-self from Wapda(even if available), if the settings are done so.

May be, your inverter is set so that it charges the batteries from solar panels as first source. And your loads are set to be powered with utility/wapda as first source(assumption based on your information that increasing loads at noon time did not increase the power from panels).

Turning Off the Wapda input to the inverter, will shift all the loads to be powered with solar-panels and batteries. See if you get better wattage from solar-panels when there is no ac input to the inverter, around noon time.

[quote=“enlightened, post:15, topic:22182”]

If I am not mistaken, axpert(5kva w/mppt, atleast) while on inversion mode(using only Solar-panels and Battery to power loads) will show input ac voltage as 0. As it disconnect it-self from Wapda(even if available)…


I just re-read the opening page of the manual and found that I was approaching the matter wrongly. AXPERT IS NOT A HYBRID INVERTER. I have been looking at it with that in my mind. By rereading the manual it is clear. This is simply an inverter with a battery charger.


^ Exactly.. same thing inverex is doing these days..

A minimum proper hybrid inverter is the Infini solar model// which costs 1lac 30k for a 3kva, while axpert costs 50k for same capacity.. and they are by the SAME company.. even infini isnt that good , but atleast it a a proper hybrid with ability to feed the grid as well.. baseline inverter to use is infini.

RANT for no reason..(not directed at any one specifically)

Thats why i dont ask for people to understand what i suggest, cz having just ONE inverter at your house doesnot make you the expert at anything, especially when you havent screwed a single screw in the process or peeled a single wire, or when you havent even SEEN the box of any other model.. reading manuals and specs online, or reading forum posts from internet from different sources doesnot give you Hands on experience.. and further arguing against those who have used or are dealing in power commercially, with your incomplete information makes you a douche..

PS: I neither am an expert in any such matters, nor do i claim to be, nor i need to be quoted like so

/ Rant

back to topic

neo, you are confusing 2 things together

1 - a hybrid invert has built in 3 things, 1 charge controller, 1 inverter, 1 AC battery charger.. they work together... solar power comes to charge controller 1st of all, this then sends the power to either the battery or the inverter directly to run appliances.. when solar is low, inverter takes power directly from battery as well as the remaining solar power...

in both cases, solar power wires are going to the battery terminals directly, where solar is coming to charge as well as excess power for home.. inverter takes power from the battery terminals, 1st excess power then from battery when excess solar is less than required..

2 - external charge controller does exactly the same..just it is outside the inverter itself.. it takes all the power from solar, and charge battery, and the excess power as well.. in this case, the inverter will also be connected to battery same way.. it will 1st take the excess power, and then from battery itself..if required..so basically it is exactly what was happening before, just the cc is outside the inverter casing..

3 - at night, there will be no solar, so batteries will drain to a certain point which value is set in the inverter, at which level, the wapda ac charging will start by the inverter itslef, andthere will be no double charging as there is no solar.. even if you forcefully do double charing, nothing will happen, cz the external cc is alone the price of the whole axpert unit,and much more costly than even the charging unit of a APC ups. it is extremely advance and intelligent charging sysem which will stp charging battery if it finds excess current coming to the system.. so there is absolutely nothing to worry about over charging.. besides, newbatteries donot overcharge.. the Solar CC are one of the most advanced charging devices for home and commercial use available.. they extend battery life a lot.

4 - for one battery bank, 1 extrenal charge controller needed.. for 2 banks, 2 needed.

Sorry guys, went away for a few days.

I will try out suggestions next week.


I've attached a picture of how the inverter is wired/connections.

sorry for being thick, but how will the inverter utilise solar power, battery and / or wapda at the same time when the cc is external?

Right now, here is how it works.

under 1000watts load , it will not use battery or wapda (if solar is indeed generating that much)

the moment load goes over 1000w, it starts using SURPLUS POWER from battery IF battery is over 90%.

if battery is under 90% it will start taking SURPLUS power from wapda instead .

with the setup you have proposed (not saying with finality however, I may have misunderstood, so apologies in advance), it will just use wapda or battery (because solar will be invisible to it), and solar is just being used to charge battery ?

In the attached pic, where will I connect the cc and appliances ? Will the appliances be connected to both the cc and

And if you're saying, yes, solar can indeed be directly used as a power supply for connected appliances, then are you also saying it is either/or (use solar or use inverter - manually switch).

In in the picture , where will I connect the cc? 2vsemb7.jpg

consider the solar power as a big tidal wave of water..

you have constructed a dam in front of it..all water/power is stopped before the dam. ahead of a dam is a river to supply water to irrigation areas and wherever needed in villages for consumption.

now make one bore and install a tap in the dam. water will flow through the tap according to need and charge your batteries./ run a turbine.

now here is the external internal factor.. if you make another bore in dam, water will flow into the river, as well as being used in turbine since both have surplus water behind from one same source. so an external drill hole will serve both functions..

or make one internal hole big enough to run turbine and let surplus flow into river. same amount of water, serving same both purposes. just bores location are different.

lets say, you have 2000W power coming, you connect wires from panels to CC, and CC to battery terminal, where the inverter wires are also connected.. so when battery needs 500W power, it will only draw 500W power from the incoming CC, and the rest of the 1500W will flow to the inverter and run home. in case home needs 1900W power, it will take all 1900W power and battery will get only 100W power, which means it is still being charged, and not drained at all.. if home needs 2500 w power, it will take all the power from the cc coming to terminal of battery and battery will provide additional 500W to fulfil home needs... since everything is connected at the battery terminal, all thats going on is the sergeant controlling traffic on a Chowk signal.

I see - so from what you are saying, solar cc is only there to charge the batteries.

Solar cc is not connected directly to the inverter, and the inverter knows nothing about it. Nor is it connected to any other appliances...

House/appliances will never run directly off of solar power alone (just indirectly)

Which also means battery is in constant usage and the life will reduce considerably. It will be constantly charged and discharged. This seems very inefficient.

Unless my assumption is SERIOUSLY wrong, lack of education etc... and what happens (even now) instead is, even though solar is being shown as a power source in the diagram , which I am assuming means appliances are DIRECTLY running off solar through inverter with NO battery usage whatsover (if solar is providing enough power), power from solar is actually going into the battery FIRST AND THEN inverter takes power from battery to run everything? So even NOW battery is constantly being used even though there is enough solar power ?