Bypassing a built in MPPT charge controller

[Keith85]

Hello all
I am new here and also new to solar, my name is Keith i live in southern Africa, Zimbabwe to be specific.
i am planing on setting up a small solar system for my two bedroom house, Our Grid power has become very limited, we only get it from 10pm to approximately 4am.
I have done some research and watched the beginner videos on the DIY SOLAR CHANNEL. anyway i have calculated my consumption at 246watts this comprises of
1} 47inch TV @75watts
2) Modem 20watts
3) 8 LED House lights 7watts each Total 56 watts (these will only be on from 5:30pm to 10pm)
4} 1 laptop @95watts ( this will not be on all the time)

Because of the limited access to solar products here and my limited budget i could only afford to get a 1500watt hybrid inverter by a company in India, its a 24volt inverter with a built in 25amp MPPT charge controller the lable on the inverter specifies 600watts max of solar panels and i have secure four 150watt 12volt panels, it also specifies maximum VOC 50 and VMP 30-36.

The manufacture recommends using flooded lead acid batteries which are easily accessible here, i am planing on buying two 200ah flooded lead acid batteries.
We usually a good 6 solar hours, i need help, with two issues i have told by the company selling the batteries that the built in charge controller might not be able to charge charge the batteries sufficiently?

If that is true would someone be able to advise me if it will be possible to bypass the built in charge controller with one of the 40amp units that are recommended on the DIY Solar channel.

Thank you in advance

[neweclipse]

With the correct skill-set I imagine this could be sorted out.

[Mike90250]

In most cases, connecting several battery chargers directly to the batteries (via the appropriate safety fuse) is just fine. I have the following charging sources connected to my batteries, sometimes 3 of them are charging all at the same time.
Inverter/Charger 90A charger
Morningstar MPPT 60A Charger
Midnight Classic 70A Charger
Iota 15A charger

[Keith85]

Thank you so much for your responses i really appreciate the advice,
i am considering two options,

1) this is more of a question, is it possible to over panel this inverter to 1200watts of solar panels? i have seen this mentioned on some sites.

2) buying an EP Ever 40amp MPPT charge controller and increasing my solar array to 1200watts then using that to charge the batteries, will this work as there will no-longer be power going into the inverter from the panels. will the inverter still work optimally?

Thanks again

[Mike90250]

With your 24V inverter, your 2 batteries will be in series (I suspect they are each 12V, 200A ?) yielding a 24V 200ah battery. They batteries will want to be charged with at least 20 amps .
your 4, 150w 12V panels will need to be wired in series (only if your controller will accept about 90V of PV input) . With de-ratings and such, I only expect your 4 panels to be able to supply 18 amps under the best conditions. So your existing controller is likely to work, if it's input voltage is safe at 90V.

But your batteries will really want more power.

If you could obtain 2 more of the same PV panels, and wire them in 3Series, 2 parallel, that yields 720W of harvest, and 27 amps to the batteries.
Any of the modern MPPT controller from Midnight, Morningstar, Victron, or Outback, can easily handle a moderate amount of "overpanel" and can limit the power to internally safe levels. Your controller is unknown to me, and I cannot advise about it.

[Keith85]

WhatsApp Image 2019-10-04 at 23.24.56.jpeg

Thank you Mike90250, i have attached a picture with the specs of the inverter from the box it came in hopefully it helps in outlining the PV input voltage.

[Mike90250]

Wow, <50V to use with PV.

So, what are the specs on the back of the PV panels.

Vmp ____
Voc ____

[Keith85]

WhatsApp Image 2019-10-05 at 19.05.13 (2).jpegWhatsApp Image 2019-10-05 at 19.05.13 (1).jpeg

That's the spec sheet that was in the box with the panels.
i am now very worried Mike90250, please help i need to find a way to make salvage this system, hopefully without spending a lot more money.
i have a friend who is considering upgrading his system and he said he could sell me his 60amp MPPT he currently has six 150watt solar panels, the exact same ones as mine and he says his charge controller is indicating 19-27amps during at peak production, his system is 24volts

[littleharbor]

You can series wire those panels, two at a time, to make 24 volt nominal output, which is what your inverter seems to be limited to. Questionable as to whether you have a true MPPT controller with that inverter. Personally I would pass on connecting your panels to that inverter and use it strictly for it's inverter function and get a real MPPT controller .

[Keith85]

Thank you Littleharbor, that was my initial line of thought as well, This would mean the cables coming from the separate charge controller would go directly to the battery and the inverter will only be connected to the battery and grid power.

Will this harm the inverter in any way or it will still function normally?

[littleharbor]

I don't know the exact circuitry of your inverter but I cant imagine there'd be a problem, and yes connections as you have mentioned. Don't forget the fusing at the battery, or as close as practical, for the inverter. Also DC rated circuit breakers into and out of the charge controller make for convenient maintenance to the system.

[Mike90250]

With those 18V panels, you can use 2 in series, with a simple PWM controller. That will give you about 7A @ 24V. Add 2 more panels and another PWM controller, and you are up to 14A
if you have a 15-20A PWM controller, you can use 4 panels, 2S,2P frankly, with just 2 panels in series, an expensive MPPT controller will not help very much.

To get a MPPT function, you need 3 of those panels in series, and your inverters MPPT input of <50V prohibits that. ( 3 panels in series Voc = 66V )

[Keith85]

Thank you Mike 90250, So should i definitely bypass the built in 25amp mppt? if so shall i go with the 60amp mppt that my friend wants to sell me second hand for $150 or the 2 PWMs as you mentioned? i can get 30 amp PWMs for $30 each or a 50amp PWM for $60. I have grid power every night for 6hours the inverter has a 15APM fuse on the input so i take it that's maximum it will take. So im hopping the grid power will help

I just want to be sure my batteries will charge fully every day so that i can get the best life span out of them

[Mike90250]

Well, I've lost count of how many panels you have.. But the PWM should be fine, you don't need a MPPT till you graduate to a high voltage (2x battery voltage) array

[Keith85]

I have four of those 150watt panels and two 12 volt 200AH tall tubular, flooded lead acid batteries