Same as you Bill with ours.

Will wait with baited breath for any info.

-- Edited by Ma on Tuesday 4th of October 2011 03:09:33 PM

Ma wrote:

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Will wait with baited breath for any info.

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 baited breath???? I know Blue's a keen fisherman but baiting his wife's breath????

(I suspect you mean bated breath)

(only joking)

jimricho wrote:

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Ma wrote:

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Will wait with baited breath for any info.

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 baited breath???? I know Blue's a keen fisherman but baiting his wife's breath????

(I suspect you mean bated breath)

(only joking)

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 Have you ever kissed a fisherperson (note I didn't say man) after he/she/it has done a Rex Hunt.......................................I thought not.................

Darling Bill12 if you are going to spend money a wise investment is always the prudent way to go darling. Darling the Morningstar Prostar will meet your needs just perfectly dear. Darling have a little squizzie at the website http://www.morningstarcorp.com/en/pro-star

Darling the Prostar is temperature compensated precision regulator unlike Plasmatronics. Darling the Plasmatronics is like the T model Ford of the solar world, outdated, old tired positive regulation technology with no temp compensation as standard. Darling the other issue is having to push buttons on the Plasmatronics to get a readout. Darling another failure of Plasmatronics you need to change the charging settings all through the year as the seasons change to charge your battery correctly.

Mr Red wrote:

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Hi Guy`s,

While on the subject of solar,I would like to ask anyone who has a solar kit did you buy them already assembled or buy the parts and you assembled them yourself.

 

           Thanks   Mr Red.

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 I purchased seperate units, it pays to have the regulatop as close to the battery as possible to help eliminate voltage drop. When its mounted on the solar paneland is regulated back to 13.5 volts, it may be only 12.75 volts by the time it gets to the battery but if its mounted at the battery it may come to the regulator at 17.5 volts, go into the regulator and come out to the battery a 13.5 vplts (figures used as just fictitious)

cheers

blaze

I'm not a solar expert but it would seem to me that 13.5v would take "forever" to fully charge a wet or AGM battery regardless of how much sunshine there is, and that's before the voltage drop mentioned by Blaze. It would therefore also seem to me that a regulator with a few "smarts" would be a better option than just using larger (or more) panels to make up the deficiency. I'm a bit out of my league on solar so I'd be interested in any thoughts.

blaze wrote:

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My volt meter read 14.3 volts at 7.30am this morning, I am using 105amp/h battery, 190 watt 24 volt pannel fixed to the roof of my van, this runs into a 24 to 12volt regulator. My sola guy said to me this system was 30% more efficent than a 12 volt system. The cost of the panel and reg was just under $1000
cheers
blaze

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Darling Blaze your sola guy is telling whopping great big doodooos. Darling 12V panel is more efficient with a quality MPPT controller than 24V panel. Darling these people that are telling the whopping great doodooos on MPPT have no idea of the technology and must have issues understanding the technical writings. Darling in fact solar panel mounted on flat roof a quality PWM regulator compared to quality MPPT regulator is so marginal to say no difference. Darling spend the money on an extra solar panel rather than quality MPPT requlator. Darling an extra panel will give you real extra amps not fictional amps some doodooo telling sola guy tells you.

jimricho wrote:

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Solar is not my forte so I'll ask the question.....Is a 24volt panel(s) functionally equivalent to two 12 volt panels in series. If so what is the unregulated output voltage? Is it in the range 32 - 36 volts (ie twice that of a 12v panel).

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Darling Jim yes, equivalent to 2 x 12V panels at 17V each x 2 =34V ± a volt or two. Reducing the voltage to 14.3V from 34V uses more energy than 17V to 14.3V. Darling you cannot have higher voltage reduction without pain.

Jacko wrote:

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jimricho wrote:

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Solar is not my forte so I'll ask the question.....Is a 24volt panel(s) functionally equivalent to two 12 volt panels in series. If so what is the unregulated output voltage? Is it in the range 32 - 36 volts (ie twice that of a 12v panel).

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Darling Jim yes, equivalent to 2 x 12V panels at 17V each x 2 =34V ± a volt or two. Reducing the voltage to 14.3V from 34V uses more energy than 17V to 14.3V. Darling you cannot have higher voltage reduction without pain.

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 I thought that may have been the case, also confirms my thought that a 24v panel is a waste of volts and money when the end object is to charge a 12v battery

Peter_n_Margaret wrote:

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On the other hand, transmitting the power from the panels to the regulator at twice the voltage will incur considerably less losses due to voltage drop, so it is not a simple yes/no decision.

Cheers,
Peter

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Wouldn't a heavier gauge cable be a significantly less expensive way of doing that?

Would an appropriate regulator (MPPT?) be necessary to make use of this extra voltage.  It seems to me that a "common or garden" variety regulator would just dissipate this extra voltage.  Watt for watt you're only going to get half the current out of a 24v panel campared to a 12v panel.  (watts = volts X amps) If the regulator can't turn this extra voltage into current it seems an expensive waste.

Would voltage drop be a problem anyway in the smaller systems we've been discussing recently?   (Assuming the cable sizes are adequate and the controller is installed close to the battery)

Thanks for that link Peter. As I've said previously that although I have a career background in electronics I don't have "hands on" with solar so I'm on a learning curve. However the explanation in that thread does generally line up with my understanding of the various types of controllers. I still fail to see why 24v panels would be better than the much less expensive option of using adequate size cable in the first place, even with an MPPT.

Hi Jim

RE :"

[Quote]Would an appropriate regulator (MPPT?) be necessary to make use of this extra voltage.  It seems to me that a "common or garden" variety regulator would just dissipate this extra voltage.  Watt for watt you're only going to get half the current out of a 24v panel campared to a 12v panel.  (watts = volts X amps) If the regulator can't turn this extra voltage into current it seems an expensive waste.

Would voltage drop be a problem anyway in the smaller systems we've been discussing recently?   (Assuming the cable sizes are adequate and the controller is installed close to the batter""quote ]

A MPPT reg is designed to track the solar panel's peak power point

Basically it takes the available solar output & converts its to more current@  a lower voltage

It makes use of the Power lost in the PANELS with a standard PWM reg

eg  standard Pwm with a 100Wt 12v nominal [max power @ about 17v panel & the battery voltage @ 13v loss across the reg around 0.6v

Actual useful energy into the battery is 5.88A x13.6v =80 W

The missing 20watts goes into panel heating

Same set up but MPPT reg

The reg searchs for the max power point [which will vary with solar radiation]

The current from the panel remains @ 5.88A but due to impedance matching the whole 17v is available to the MPPT reg

Neglecting losses the output from the reg is now  it's input @17v x 5.88A v Theoretically 100watts

The actual extra depend on the panel max powerpoint @ particular time

They work to their best advantage under poor light conditions

Re panels 12v or 24v

I donot like the idea of 2x12  =24 v,if one s shaded the output of the other can be seriously restricted

-- Edited by oldtrack123 on Saturday 22nd of October 2011 09:56:21 AM

As a "non-solar" person (but may soon become a "solar" person, hence my interest) may I be so bold as to summarise this thread for the benefit of Bill (and Ma and others, including myself).....

1. Don't waste your money on 24v panels to charge 12v batteries, just make sure the cable sizes are adequate.

2. Regulators...

.....Basic regulators/controllers.... least cost, ok but not as good as the following:

.....PWM...smarter and will do a better job of charging the battery but still doesn't make best use of the panel's output

.....MPPT...smartest, advantages of a PWM and makes best use of the panel's output.

3. The Ctek D250S Dual offers the best of both worlds as it combines a 12v - 12v smart charger (for charging from the vehicle's engine) and a MPPT solar regulator.

4. Locate the regulator as close as is practical to the battery.