Hybrid system fault

[Shaikh Emmad]

I have got 1 its showing 25A dc most of the time and theres 1 more thing that on 1st day pv volt was 36V now it is almost fixed at 24V but the panels are showing 28V and 30V i have installed them in pairs of 2 back to back not in a row

[SunEagle]

It is starting to sound like your charge controller is not working properly. It is possible that you exceed the maximum DC input voltage but the way you say you wired the 4 panels would only get you about 80v DC.

I would start with just 2 panels and see if they are wired correctly to the CC and then see if you get the proper voltage and current output to your batteries.

I also presume that you connected the CC to your batteries first and then connected the panels to the CC. If you did it the other way around the CC is either confused what the battery voltage is supposed to be or it is broken.

[littleharbor]

The op says he is using 4 300 watt panels and the 36 volts was what he expected to see so must assume parallel wiring. The numbers you are giving don't make sense you just said the clamp meter shows 25 amps most of the time but in another comment you say 0 amps to 5 amps. 28 to 30 volts would be normal as your batteries will pull down the panels voltage while charging.36 volts is the no load open circuit voltage of your solar panels. Kind of sounds like you are using too much power for your battery bank size so when the sun is shining you are staying in bulk charging trying to get the bank back to fully charged, full amperage, bulk charge mode. you haven't said anything about what you are powering. Are you drawing power 24 hours a day? If so, how much. What are you powering?

[Shaikh Emmad]

The op says he is using 4 300 watt panels and the 36 volts was what he expected to see so must assume parallel wiring. The numbers you are giving don't make sense you just said the clamp meter shows 25 amps most of the time but in another comment you say 0 amps to 5 amps. 28 to 30 volts would be normal as your batteries will pull down the panels voltage while charging.36 volts is the no load open circuit voltage of your solar panels. Kind of sounds like you are using too much power for your battery bank size so when the sun is shining you are staying in bulk charging trying to get the bank back to fully charged, full amperage, bulk charge mode. you haven't said anything about what you are powering. Are you drawing power 24 hours a day? If so, how much. What are you powering?

The current reading from pv to inverter wire is 25A and pv current that is shown in inverter is 0 to 5A.
im using it to power a small server room max 600w load.
My batteries are 2 in series 1 is 100ah 2nd is 132ah both 12V.

[SunEagle]

The current reading from pv to inverter wire is 25A and pv current that is shown in inverter is 0 to 5A.
im using it to power a small server room max 600w load.
My batteries are 2 in series 1 is 100ah 2nd is 132ah both 12V.

Again if the "output" of the inverter only shows 0 to 5A and your load is 600watts at 120 volt then it is working (600w / 120v = 5A).

But if your batteries need charging and the output is less then the 25A input I would say your charger has failed.

One thing I learned a long time ago was not to rely on the internal meter of a piece of equipment. I end up using my own volt meter and clamp on amp meter to verify what is going through the wires.

[littleharbor]

If you are putting 25 amps into a 100 amp battery you are WAY under battery'd (is that a word? lol). Your 4 300 watt panels are capable of putting out more than 25 amps in favorable conditions. You need at least twice the battery capacity. Can you get 6 volt golf cart batteries? If so get 4 and series wire them That will give you about 220 amps at 24 volts which is a better ratio of charging amps to capacity. Your two mismatched 12 volt batteries may be damaged or tired from uneven charging.

[SunEagle]

If you are putting 25 amps into a 100 amp battery you are WAY under battery'd (is that a word? lol). Your 4 300 watt panels are capable of putting out more than 25 amps in favorable conditions. You need at least twice the battery capacity. Can you get 6 volt golf cart batteries? If so get 4 and series wire them That will give you about 220 amps at 24 volts which is a better ratio of charging amps to capacity. Your two mismatched 12 volt batteries may be damaged or tired from uneven charging.

Good point. I never even though about the batteries being undersized for the pv system.

If they got charged too fast on the first day (which could have been about C/4) then it is very possible that one is no longer able to accept the charge.

Using equipment for a solar / battery system requires a little knowledge to properly design it. That is why most DIY systems fail soon after going into use.

[Shaikh Emmad]

But 2 12V 100Ah batteries make 2400W doesnt it? How am i under batteried?:P

[Shaikh Emmad]

Actually 2 batteries are in series so doesnt it make it 24 V?

[SunEagle]

Actually 2 batteries are in series so doesnt it make it 24 V?

Yes. Wiring those two 12v 100Ah batteries in series yields a 24volt 100Ah battery system with the rating of 100% ~ 2400Wh.

But the system is still rated 100Ah, which should not get a charge of more than C/8 which is 12.5amps. Even if those batteries were AGM type the max charging rate would be around a C/6 or ~ 17amps.

Hitting them with 25 amps is too much and too fast which can cause one or both to be charged too quickly and possibly fail.

[Shaikh Emmad]

So should i wire them in parallel to increase to 200Ah?

[Shaikh Emmad]

Also please tell me that the300w panel has 30V and 7.76A rating so doesnt it make it a 30x7.76~230 w panel?

[SunEagle]

Also please tell me that the300w panel has 30V and 7.76A rating so doesnt it make it a 30x7.76~230 w panel?

Chances are that if it is a 300 watt panel with an Imp = 7.76A then the Vmp ~ 300w / 7.76a = 38.65V and not 30volt.

[Shaikh Emmad]

Also can u tell me that i have an mppt inverter which says" PV array mppt voltage range is 120~460 Vdc" so do i have to provide it with least 120V from my panels?

[jflorey2]

Also can u tell me that i have an mppt inverter which says" PV array mppt voltage range is 120~460 Vdc" so do i have to provide it with least 120V from my panels?

Yes - if you want rated power from your inverter. Often inverters have an operating range, an MPPT tracking range and an absolute maximum. Within the tracking range you will get maximum possible power. Within the operating range it will start up and work. As long as it's under the absolute max it won't be damaged but may not work.