from12v to 24v with same items ....

[Sunking]

sorry for bothering you all , and taking much of your time.

You are not bothering us. Now that I know English is not your first language changes things. There is a very simple solution for you. Does not require you to buy anything, just reconfigure your panels and batteries.

You said:

if I have 12v system ( 12v panels , going to mppt charge controller 60amps connected to 2x battery each 200amh connected parallel

How many of these 12 volt panels do you have, and how are they configure? Regardless of the battery voltage being 12 or 24 volts, last thing you want to do is wire the panels in parallel using an MPPT Controller. Doing so just defeats the whole purpose of the MPPT controller. You can charge a 12 volt battery with 120 volt panels assuming the Charge Controller Input Voc is 150 volts or higher. You want to run the panel voltage as high as the controller allows as this maximizes efficiency, keeps material cost as low as possible, and minimizes fire risk.

So answer me these two questions, and I can tell you how to get where you want to go at minimum cost and maximum efficiency.

1. How many panels do you have, and what are the specifications? Pmax, Voc, and Imp. The specs should be on the manufacture nameplate.
2. Make and Model Number of your Charge Controller?

Essentially what I am going to tell you is to wire all your panels in series, and wire your batteries in series. That's all that needs to be done. Nothing to buy or breakdown on you. Only catch maybe is if you have a Prime Number of panels greater than 3. Prime Numbers do not work like 5, 7, 11, 13, 17...... With a Prime Number you only have two configuration options of all in parallel the absolute last thing in the world you want to do, or all in Series is exactly what you want to do, but there is a catch. Depending on the Charge Controllers maximum Voc input voltage, and the panels Voc rating limit the number of panels you can wire in series. If your controller has a 150 Voc, and you really have 12 volt battery panels with a Voc = 22 volts you can get as many as 5 panels in series assuming you do no tlive in a cold climate.

One last comment. If you have not bought any panels yet, last thing you want is 12 volt battery panels. MPPT Controllers antiquated low voltage panels. 12 volt battery panels are a lot more expensive than higher voltage Grid Tied Panels. So if you have not bought panels yet you are in good shape. But we can make the 12 volt battery panels work if that is what you have already.

So answer my 2 questions and lets get you going OK?

[Mike90250]

thanks ampster for your post ,
....
I keep my system as it is and I step up the voltage to 24v by using that transformer putting it after batteries and before the inverter
( the load will deal with 24v not 12v and the storage is still as 400 amh not reduced to 200 amh .
I don't think I can make more clearly than that

Unless your 24v inverter is a very small inverter and has only small loads, it's not likely going to work well with any gadget between it and the batteries. Inverters consume wildly varying amps, 120 times a second, and would require a very robust converter AND a beefy capacitor if there was any power involved over 50 watts or so.

This is why we stress repeatedly the importance of robust cables between the battery and inverter, the current surges are enormous and will trip an inverter off-line from undervoltage faster than your voltmeter can read it.

[zolar]

hi mike,,,

This is my second peeve about under informed solar power enthusiasts.

DC transformers. The do not exist.
You can buy a DC - DC converter to increase or decrease DC voltage. it is an active electronic circuit. A transformer is AC only and passive.

may be yes , I didn't say the correct word ( I should had said converter instead of transformer ) or at least a ( device ) , sorry my bad English.
but after that and finally ,,, I said to install that device after the batteries and before the inverter .

anyway don't bother about it.
cuz I feel some members may don't like this discussion , , if any else said it I would replyed for him ,,,
but I won't reply for sunking (always I got benefit from his topics he wrote or replyed , I really learned a lot from him,,, he will always be a master for me and I am as you said just an enthusiast.

[Mike90250]

hi all again....
....... will it work if I use step up transformer from 12v to 24v fitted between panels and charge controller ??........

This is my second peeve about under informed solar power enthusiasts.

DC transformers. The do not exist.
You can buy a DC - DC converter to increase or decrease DC voltage. it is an active electronic circuit. A transformer is AC only and passive.


And my first peeve (dare I say the D word ? ) Diodes. Do I need a diode? do I need a bridge diode? my batteries wont charge, how do I install a diode?
Add on diodes in solar, went obsolete in the 70's when the Blocking function was incorporated into charge controllers with an active FET
Replacing Bypass Diodes in panels that were fried by shade, is a the only valid reason to purchase a diode.

[zolar]

thanks ampster , thanks sunking ,for your time to read my topic and reply
and thanks to all who took apar either reading or replying
I will wait for a day that I can put a pic
sorry for bothering you all , and taking much of your time.

[Sunking]

I keep my system as it is and I step up the voltage to 24v by using that transformer putting it after batteries and before the inverter ( the load will deal with 24v not 12v and the storage is still as 400 amh not reduced to 200 amh .
I don't think I can make more clearly than that

The only thing you are making crystal clear is you do not understand one word of what you are being told, and you have no idea what you are talking about or doing. You are trapped inside a 12 volt toy box.

Example say you have 4 x 12-volt 200 AH batteries. With those 4 batteries, they can be configured for a 12, 24, and 48 volt system. Given that you would opt for 48 volt system, or maybe 24 volts because it is the least expensive and highest efficiency.

As for power, all three configurations have the exact same capacity in Watt Hours:

1. 12 volts @ 800 AH = 9600 watt hours
2. 24 volts @ 400 AH = 9600 watt hours
3. 48 volts @ 200 AH = 9600 watt hours.

Lastly there is NO SUCH THING as a DC TRANSFORMER. They do not exist as it is IMPOSSIBLE. Get that through your head and quit wasting everyone time.

[Ampster]

You are trying to fool Ohms Law if you think you can double your power.
In your example you are correct that the storage remains at 400ah. What Ohms law tells us is if you put a 1 Amp 24v load on that device it will have to pull over 2 Amps out of that 12 volt source in order to provide 24 volts. You cannot fool the laws of physics. In other words your 400ah battery will drain twice as fast.

[zolar]

thanks ampster for your post ,
brother if you read the topic from beginning you will see that :
the rule you wrote , I said many times that i know it ,,,, suneagle explained it ,,,,, ,also pnw_steve said that more than once.
that's why I want some one who go with me step by step.
the only thing may stop me from trying to understand is what pnw_steve said that ( transformers do not work with dc ) .
anyway generally I will say it again trying my best explaining and I hope will be clear ( may be due to my bad English I couldn't deliver the idea ):

guys I am with you all and I am sure of what you all said that for a certain load wattage " higher voltage less amps consumption"
please say yes you agree for that .....
now I am saying while using 2x batteries of 200 amh each connected parallel as 12v to be total storage of 400amh ,
OK?
no need to reduce the storage to 200 amh when I connect them in parallel to use 24v.
I keep my system as it is and I step up the voltage to 24v by using that transformer putting it after batteries and before the inverter ( the load will deal with 24v not 12v and the storage is still as 400 amh not reduced to 200 amh .
I don't think I can make more clearly than that

[Ampster]

Here is where thinking in terms of Watts or Watthours may make it easier.
12x400 = 4800 Watthours
24x200 = 4800 Watthours

[zolar]

hi steve again ,,thanks again and sorry for bothering ....
brother lets say it step by step and its only 2 steps .,,,,
believe me I got your point but that point only equal if the load using12v with 400amh batteries or 24v with 200amh batteries.
IF YOU ARE WITH ME TILL HERE TELL ME ( OK ) please

[PNW_Steve]

And, again, transformers DO NOT work with DC.

[PNW_Steve]

Zolar,

I think that you are missing the point.

The storage capacity of a 12 volt 400 a/h battery bank is exactly the same as a 24 volt 200 amp/hour battery bank.

P=I x E.....

[zolar]

hi steve and thanks for your post ,
and what you said about amps consumption vary depend on voltage, its absolutely right and I know that ,,, HERE IS THE SPOT , and THATS WHY I am saying this
connecting the 2 batteries parallel as 400amps will be more storage than connecting them series as 200amps only .
BUT ,,, BUT ,,,,BUT,,, installing the stepup transformer between the batteries and inverter will give the voltage of 24v with more storage and the load will depend on voltage which is just before the inverter ( which means consumption is half than if it was 12V ) and the result ofcourse I gain more time running my load.
sorry guys may be I can't say my idea clearly . ( my bad English )

[PNW_Steve]

Another detail.....

You need to decide on whether you are going with a 12 volt or 24 volt battery bank and then buy a suitable inverter to match.

Transformers only work with AC. With a DC system there do exist "buck/boost" converters that will convert 12 volts DC to 24 volts. That would not be a practical solution in your application. Stick with an inverter specific to your batteries.

[PNW_Steve]

Zolar,

your batteries will yield the same amount of energy regardless of whether you connect them in series or parallel.

Series: 24 volts x 200 amp/hours = 4800watt/hours

Parallel: 12 volts x 400 amp/hours = 4800watt/hours.

The advantage to using the 24volt battery is that a given load draws half the current compared to a 12 volt system.

Example: a 480 watt load will draw 20 amps from a 24 volt battery and 40 amps from a 12 volt battery.

Lower current means lower voltage drop. This allows smaller conductors and $ savings.

I highly recommend the battery stickies in the forum. Especially the battery/inverter sizing sticky.