solar panels

hi can any one tell me if you can convert a 24 volt solar panel back 2 a 12 volt panel


thanks mick
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Reply By: Alloy c/t - Thursday, Feb 18, 2010 at 15:27

Thursday, Feb 18, 2010 at 15:27
Short answer is yes , long answer is solar panel regulator ,you will find that most panels put out more than 24v and a regulator is used to drop the voltage to something more usefull in a 12v system.
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Follow Up By: Member - Mike DID - Thursday, Feb 18, 2010 at 16:40

Thursday, Feb 18, 2010 at 16:40
No.

Panels designed to charge 12 volt batteries have an open-circuit voltage of 21 volts in bright sunlight.

You don't need a regulator to charge a 12 volt or 6 volt battery or a 2 volt battery from a "12" volt solar panel - a 100 watt panel will put about 5 amps into all of them when connected directly.

A Regulator is used to stop the current flow when the battery is fully charged
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Follow Up By: Member - John and Val - Thursday, Feb 18, 2010 at 16:40

Thursday, Feb 18, 2010 at 16:40
Not absolutely correct Alloy. Most solar regulators don't change the voltage. They simply stop excessive voltage reaching the battery by disconnecting the panel from the battery when the battery voltage is at a safe maximum. As Peter says below, an MPPT (maximum power point tracking) solar panel controller WILL change the voltage to suit the 12V battery. This improves the efficiency of the system, as a panel intended for charging a 12V battery actually has its peak power output at about 17-18 volts. The 24V panel will have its maximim power output at about 36V. A suitable MPPT controller will allow the panel to operate at its optimum voltage and will convert the voltage to suit the battery. Only recently have they become available at sensible prices.

John
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Follow Up By: Member - Mike DID - Thursday, Feb 18, 2010 at 16:42

Thursday, Feb 18, 2010 at 16:42
Peter's answer below is the most correct answer -

"as a temporary measure you can hook up your 24V panel to the 12V system - you'll lose half its output power though"
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Follow Up By: Member - michael (BOXHD) r (VI - Thursday, Feb 18, 2010 at 16:45

Thursday, Feb 18, 2010 at 16:45
thanks for that john and val as iam still learning about all this iam glad that i have joined exploroz all the members have been helpfull in every thing i have asked.

cheers mick
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Follow Up By: Alloy c/t - Thursday, Feb 18, 2010 at 16:52

Thursday, Feb 18, 2010 at 16:52
John ,twas only giving a short answer , ,, as for your statement that a 12v panel has a peak output at about 17-18 v that is not absolutly correct either , open circuit voltage can be upto 27.5 v from a 120w Kycera .
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Follow Up By: Member - John and Val - Thursday, Feb 18, 2010 at 16:55

Thursday, Feb 18, 2010 at 16:55
Mick,

You may find our blog Electricity for Camping useful. There are also other very informative articles on this site relating to solar panels and electrical setups generally. Look behind the "Articles" tab at the top of the screen.

Cheers

John
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Follow Up By: Member - John and Val - Thursday, Feb 18, 2010 at 16:59

Thursday, Feb 18, 2010 at 16:59
Alloy - Yes the peak power point does vary a bit, but is usually around 17-18 volts. The unloaded (open circuit) voltage may be considerable higher than this as you say, but then the power drops to zero when open circuit!!!

Cheers

John
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Reply By: Battery Value Pty Ltd - Thursday, Feb 18, 2010 at 15:28

Thursday, Feb 18, 2010 at 15:28
Mick,

A maximum power point tracker with built in DC/DC converter can do this most efficiently for you.

Or, as a temporary measure you can hook up your 24V panel to the 12V system - you'll lose half its output power though.

Best regards, Peter
AnswerID: 404761

Follow Up By: Member - michael (BOXHD) r (VI - Thursday, Feb 18, 2010 at 15:45

Thursday, Feb 18, 2010 at 15:45
thanks for that peter do u sell them or were can i buy 1 what cost are the y around about

thanks mick
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Follow Up By: Battery Value Pty Ltd - Thursday, Feb 18, 2010 at 16:06

Thursday, Feb 18, 2010 at 16:06
no worries Mick,

sorry, we don't stock these, but other business members might.

You can google around a bit, you should find them under "MPPT controller".
But I have to warn you, just for the one panel, it'll be uneconomical because last time I checked, I didn't find them particularly cheap.
They're mainly for a complete array of panels, to get maximum solar power out of them.
You can select the output voltage on the MPPT (12, 24, 48), completely independetly from the solar array input voltage configuration.

Someone with more solar experience may be able to help finding what your want.

What's the application? Why this mismatch between panel voltage and rest of system?

Best regards, Peter
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Follow Up By: Member - michael (BOXHD) r (VI - Thursday, Feb 18, 2010 at 16:41

Thursday, Feb 18, 2010 at 16:41
thanks peter even if i buy a mppt for around say 700 it will still be cheaper than a 130 watt system at around 1300 i think it will work out about 900 all up and it will be a 175 watt system
thanks mick
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Follow Up By: Member - John and Val - Thursday, Feb 18, 2010 at 17:08

Thursday, Feb 18, 2010 at 17:08
Mick,

Your numbers are a bit worrying! Just what sort of system and what sized panels are you considering? The MPPT controller will help you get closer to 100% of the panel power into your battery instead of under 70% with a simple controller. It won't turn a 120W panel into a 170W one.

Cheers

John
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Reply By: Member - michael (BOXHD) r (VI - Thursday, Feb 18, 2010 at 15:29

Thursday, Feb 18, 2010 at 15:29
thanks for that alloy that is going to save me a lot of money

cheers mick
AnswerID: 404762

Reply By: Member - Allan B (QLD) - Thursday, Feb 18, 2010 at 17:02

Thursday, Feb 18, 2010 at 17:02
Michael, What is the configuration of your 24 volt solar panel. Is it a single panel or is it two panels hinged.

If two panels then they are probably each 12 volt and connected in series to provide a 24 volt output. If so they could be reconnected in parallel to become a 12 volt system.

Cheers
Allan

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Follow Up By: Member - michael (BOXHD) r (VI - Thursday, Feb 18, 2010 at 18:48

Thursday, Feb 18, 2010 at 18:48
hi allan it is just 1 panel a suntec 175 watt 1.5x880x35 mm 24 volt


thanks mick
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Reply By: Member - Trackker (QLD) - Thursday, Feb 18, 2010 at 18:56

Thursday, Feb 18, 2010 at 18:56
Hi Michael, in my experience some 24v panels are actually split in half running 2 x 12v sections that are wired in series. If you have a junction box as opposed to multi-connect leads and inside the junction box you have 4 or 6 terminals, you should be able to identify the two 12v circuits and wire them in parallel. This would also double the output amps at 12v. I have certainly used one 12v half of a damaged kyocera 24v panel to power a fridge. Sharp panels with junction boxes are the same. I have never tried paralleling the two 12v outputs but it is worth investigation. Also in the real world these two kinds of panels will give you 40v open circuit for a 24v panel and 20v for a 12v and will differ slightly up or down with temperature. Hopes this helps, cheers Dave
AnswerID: 404786

Reply By: Member - Ed C (QLD) - Thursday, Feb 18, 2010 at 20:29

Thursday, Feb 18, 2010 at 20:29
Your 24V (nominal) panel will be around 44Voc, and around 36Vmp (as previously stated), and is a perfect match-up for one of these >>

Morningstar Sunsaver MPPT
(this is what I'm using;-))

If purchased from the U S of A, they are considerably less expensive than if purchased locally..

About the best price I've on these lately is this one on ebay >>

Sunsaver MPPT on ebay


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AnswerID: 404806

Follow Up By: paulnsw - Thursday, Feb 18, 2010 at 21:47

Thursday, Feb 18, 2010 at 21:47
that is the link looked up to post the Sunsaver MPPT
will be ideal for your 175w panel
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Follow Up By: paulnsw - Thursday, Feb 18, 2010 at 21:49

Thursday, Feb 18, 2010 at 21:49
the postage at $US19 for the ebay one makes it super cheap
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Follow Up By: paulnsw - Thursday, Feb 18, 2010 at 21:51

Thursday, Feb 18, 2010 at 21:51
here is an Aus dollar listing for the same item

suggest buy the meter at same time
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Follow Up By: Member - michael (BOXHD) r (VI - Sunday, Feb 21, 2010 at 10:32

Sunday, Feb 21, 2010 at 10:32
thanks for that ed very helpful is a lot more cheaper thatn local


cheers mick
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