charge controllers takes a long time to charge batteries

[mark dix]

i have (8) 225 watt solar panels and it seems to take 6 or 7 hours or more to charge my battery bank of (8) 6 volt battery and my charge controller is a xantrex c40 charge controller,should i get a another charge controller will that help speed up the battery charge?

[RussN9ZP]

i have (8) 225 watt solar panels and it seems to take 6 or 7 hours or more to charge my battery bank of (8) 6 volt battery and my charge controller is a xantrex c40 charge controller,should i get a another charge controller will that help speed up the battery charge?

Probably going to need more specifics. Batteries,panels,your location, etc.

[Sunking]

i have (8) 225 watt solar panels and it seems to take 6 or 7 hours or more to charge my battery bank of (8) 6 volt battery and my charge controller is a xantrex c40 charge controller,should i get a another charge controller will that help speed up the battery charge?

What battery voltage are you running, and how are the panels configured.

Here is what I am driving at. I suspect your CC is not rated to handle that much panel wattage.

With that said with as much panel wattage (1800 watts) you should NOT be using a PWM controller. as you are throwing away 30% of your panel wattage.

But to answer your question I would guess your system is not designed to do what you are demanding of it. Sounds like you are just using way too much power from the batteries, and your panels and CC are not able to keep up.

[epsgunner]

My TS45 controller (45 amp) will handle just about 850 watts with 12v panels.. its 48 amps going in at that point.. which is the MAX..

You've got 1800 watts and I'm guessing the 225w panels are 24v (30-36 or so) and about 7 amps each..

Your running a 24V bank or 48v bank correct..???

At a 24v system your pumping 56 amps (7 IMP * 8 panels) into the 40 amp controller.. (which is wasting ALOT as anything over 40 will be just lost).. and your bank will get less than 10% charge rate (see below)

At a 48V system your pumping 28 amps (7 IMP * 4 parallel strings of 2 panels).. which is fine..

Your battery bank is (6v 220ah batteries as example)

24v 440ah (4*220ah * 2 in parallel)

48v 220ah (8*220ah)

At 24v system you would be at 9% charge rate.. (do to clipping to 40 amps)

At 48v system you would be at a 12% charge rate.. which is fine..

How low are you taking the battery bank is the obvious question???

You should not be going less than 50% if you are.. that would explain a lot..

[mark dix]

i am running a 48 volt system an the panels are 2 strings of 4 panels in parallel ,and i live in phoenix az.

[mark dix]

What battery voltage are you running, and how are the panels configured.

Here is what I am driving at. I suspect your CC is not rated to handle that much panel wattage.

With that said with as much panel wattage (1800 watts) you should NOT be using a PWM controller. as you are throwing away 30% of your panel wattage.

But to answer your question I would guess your system is not designed to do what you are demanding of it. Sounds like you are just using way too much power from the batteries, and your panels and CC are not able to keep up.

should i get a second cc same as the one i have which is economical for my buget at 140.00 or get another brand cc and would i be able to yous them together if there not the same brand?

[mark dix]

My TS45 controller (45 amp) will handle just about 850 watts with 12v panels.. its 48 amps going in at that point.. which is the MAX..

You've got 1800 watts and I'm guessing the 225w panels are 24v (30-36 or so) and about 7 amps each..

Your running a 24V bank or 48v bank correct..???

At a 24v system your pumping 56 amps (7 IMP * 8 panels) into the 40 amp controller.. (which is wasting ALOT as anything over 40 will be just lost).. and your bank will get less than 10% charge rate (see below)

At a 48V system your pumping 28 amps (7 IMP * 4 parallel strings of 2 panels).. which is fine..

Your battery bank is (6v 220ah batteries as example)

24v 440ah (4*220ah * 2 in parallel)

48v 220ah (8*220ah)

At 24v system you would be at 9% charge rate.. (do to clipping to 40 amps)

At 48v system you would be at a 12% charge rate.. which is fine..

How low are you taking the battery bank is the obvious question???

You should not be going less than 50% if you are.. that would explain a lot..

i am running two strings of 4 panels i have a 48 volt system?should i break them up into 4 strings of 2 panels each?

[epsgunner]

Again, How low are you running the 48v battery bank??

Less than 50% or ???

If you run it down to say 20% it will get shot REALLY fast..

ETA.. 2 strings of 4 panels?? or 4 strings of 2 panel each??

2 panels (24v each) would be 48 volts..

You should be 2 panels per string and then those 4 in parallel.. 48v x 4

The other way is 96 x 2 and would be WAYYYYY wrong..

[Sunking]

i am running a 48 volt system an the panels are 2 strings of 4 panels in parallel ,and i live in phoenix az.

Sure you do not mean 2 strings of 4 panels in series? Only way it could work.

What are your panel specs. Need the Vmp and Imp. With 225 watt panels tells me they are panels made for Grid Tied systems. If my assumption is correct you have two problems:

1st problem is if those are grid tied panels arranged in a 2 x 4 configuration the Vmp of the four panels in series is way too high for a PWM controller meaning you could be loosing as much as 50% of your power. For example lets say your panel is rated Vmp = 26 volts and Imp = 8.6 amps. Each string would be 104 volts @ 8.6 amps. With 2 parallel strings 104 volts @ 17.2 amps into the controller. Output of th econtroller at 100% duty cycle = 50 volts 17.2 amps = 860 watts. So what is the spec of your panels?

2nd problem is likely you are draining your batteries more than 20 to 30% each day, and your panels cannot get them fully recharged in a day. You did not mention th ebattery specs other than they were 6 volts and you have 8 of them. I assume you made the mistake of using golf cart batteries and they are rated 6 volts @ 225 AH. That gives you a total reserve capacity of 8 x 6 volts x 225 AH = 10,800 watt hours. That only gives you about 2 Kwh per day usage. Do you know how many Kwh per day you use?

In Phoenix with your panels if you used a MPPT charge controller you can generate up to 6 Kwh per day. But and it is a big but your batteries are way undersized like 66% undersized. You have 10.8 Kwh capacity now and you need 30 Kwh.

Assuming your panels are GTI with a Vmp of 26 volts just by changing out your PWM controller with a quality MPPT controller will give you 100% more power. Yes I did say 100% more power. The charge current would go from 17.2 amps to 34.3 amps.

So from the sounds of things making a couple of assumptions your system is improperly designed and nothing is matched up to work with each other. Sounds like you need to replace your charge controller and add 200% more battery capacity.

[Naptown]

That is a PWM charge controller
Junk it and get an MPPT controller such as the Morningstar MPPT series.
Set the controller to Bulk= absorb to get the most charging capacity out of it.
Depending on battery type disable the equalize function.

[mark dix]

Sure you do not mean 2 strings of 4 panels in series? Only way it could work.

What are your panel specs. Need the Vmp and Imp. With 225 watt panels tells me they are panels made for Grid Tied systems. If my assumption is correct you have two problems:

1st problem is if those are grid tied panels arranged in a 2 x 4 configuration the Vmp of the four panels in series is way too high for a PWM controller meaning you could be loosing as much as 50% of your power. For example lets say your panel is rated Vmp = 26 volts and Imp = 8.6 amps. Each string would be 104 volts @ 8.6 amps. With 2 parallel strings 104 volts @ 17.2 amps into the controller. Output of th econtroller at 100% duty cycle = 50 volts 17.2 amps = 860 watts. So what is the spec of your panels?

2nd problem is likely you are draining your batteries more than 20 to 30% each day, and your panels cannot get them fully recharged in a day. You did not mention th ebattery specs other than they were 6 volts and you have 8 of them. I assume you made the mistake of using golf cart batteries and they are rated 6 volts @ 225 AH. That gives you a total reserve capacity of 8 x 6 volts x 225 AH = 10,800 watt hours. That only gives you about 2 Kwh per day usage. Do you know how many Kwh per day you use?

In Phoenix with your panels if you used a MPPT charge controller you can generate up to 6 Kwh per day. But and it is a big but your batteries are way undersized like 66% undersized. You have 10.8 Kwh capacity now and you need 30 Kwh.

Assuming your panels are GTI with a Vmp of 26 volts just by changing out your PWM controller with a quality MPPT controller will give you 100% more power. Yes I did say 100% more power. The charge current would go from 17.2 amps to 34.3 amps.

So from the sounds of things making a couple of assumptions your system is improperly designed and nothing is matched up to work with each other. Sounds like you need to replace your charge controller and add 200% more battery capacity.

yes i have 2 strings of 4 panels specs are vmpp 29.5 vdc an impp 7.97 amps VOC 36.9VDC ISC 8.47amps and my panels are siliken slk60p6l pmpp is 235 watts. should i connect 4 strings of 2 panels instead of 2 strings of 4 panels and i should get an mppt charge controler?

[Sunking]

OK let's make sure I fully understand because I think I know what the problem is. You have 2 parallel strings. Each string has 4 panels in series. You have a PWM controller connected to a 48 volt battery. If that is correct I can certainly understand why you are having problems.

With your panels in a 2 x 4 configuration the array output is on the order of 118 volts @ 15.9 (1880 watts) amps to the controller input. On the output of the controller you have 48 volts @ 15.9 amps 760 watts. You have now discovered the hidden flaw with PWM controllers. A PWM controller the input current = output current.

There are two fixes:

1. Reconfigure your panel 4 x 2. 4 parallel string with 2 panels in series in each string. this will give you a input to the PWM controller of 59 volts @ 31.8 amps (1880 watts), and output 48 volts @ 31.8 amps 1525 watts or a net loss of 20 %.

2. Best solution replace the controller you have now with a 40 amp MPPT controller, and leave the panels the way they are.That will leave with an input of 118 volts @ 15.9 amps (1880 watts) and an output of 48 volts @ 37.2 amps 1780 watts. That will speed up your charge time to some 200%

[mark dix]

OK let's make sure I fully understand because I think I know what the problem is. You have 2 parallel strings. Each string has 4 panels in series. You have a PWM controller connected to a 48 volt battery. If that is correct I can certainly understand why you are having problems.

With your panels in a 2 x 4 configuration the array output is on the order of 118 volts @ 15.9 (1880 watts) amps to the controller input. On the output of the controller you have 48 volts @ 15.9 amps 760 watts. You have now discovered the hidden flaw with PWM controllers. A PWM controller the input current = output current.

There are two fixes:

1. Reconfigure your panel 4 x 2. 4 parallel string with 2 panels in series in each string. this will give you a input to the PWM controller of 59 volts @ 31.8 amps (1880 watts), and output 48 volts @ 31.8 amps 1525 watts or a net loss of 20 %.

2. Best solution replace the controller you have now with a 40 amp MPPT controller, and leave the panels the way they are.That will leave with an input of 118 volts @ 15.9 amps (1880 watts) and an output of 48 volts @ 37.2 amps 1780 watts. That will speed up your charge time to some 200%

thank you for the info sunking do you know of a reasonable price 40 amp charge controller brand that i should buy for my panels an are my panels spec ok?

[Sunking]

thank you for the info sunking do you know of a reasonable price 40 amp charge controller brand that i should buy for my panels an are my panels spec ok?

Yeah a little overkill but that is a good thing as it allows you to grow a bit in panel wattage is a Chevy Morningstar 45 amp model. About $150 to $200. You can even go to the 60 amp model for a few bucks more and keep you running a few more years (3200 watts @ 48 volt battery) with panel upgrades.

If you want a BMW model opt to spend the bucks on a Midnight Solar Classic 150. Up to 5200 watts @ 48 volt battery. But we are talking $800 plus but top of the line features, bells, and whistles. You can also get a Cadillac Outback FM60.

Hope that helps

[Naptown]

That "Chevy" is about $400 wholesale probably closer to 450-500 retail.
That is if we are talking the tristar MPPT without the data module.