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rosglo
Newbie

Joined: 04/02/2011
Location: Australia
Posts: 1

Posted: 06:23am 04 Feb 2011

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Hello Folks,

I negotiated a "free" 36v 190w pv panel when I bought my grid-connected system.

Eventually it will be used to power an evaporative air conditioner but in the meantime I would like to use it for camping.

I am looking for a way of connecting this 36v panel to a single 12v battery.

The only device I have found so far is the Outback FM60 which is quite expensive and has more capability than I need.

Is a dc voltage down-converter and a conventional regulator a viable alternative?

All suggestions welcome.

Thanks,

Ross.

davef
Guru

Joined: 14/05/2006
Location: New Zealand
Posts: 499

Posted: 07:39am 04 Feb 2011

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Search for <buck converter> or <buck regulator> from the likes of National Semiconductors and Linear Technologies.

To get good efficiency you would need something that can accept, say 15 - 60 Volts and put out a current limited 13.5Volts. It also has to be able to handle possibly up to 250W as a new panel will put out more than the rated value in bright sunlight.

Your 36Volt panel will put out more like 50-60Volts at light loadings. Also, you will want to control the voltage to the battery to fit your charging regime, ie, bulk, float and equalise voltages.

Have you checked out Morningstar solar controllers?

Joblow
Regular Member

Joined: 05/01/2010
Location: Australia
Posts: 54

Posted: 01:05pm 10 Feb 2011

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Hi Rosglo,

There may be a possibility of using an automotive 12v regulater for an older model car, as some of these had seperate regulators and could handle the power output of your PV. try talking to an auto electrician

The man who never made a mistake never made anything

KarlJ

Guru

Joined: 19/05/2008
Location: Australia
Posts: 1178

Posted: 08:50am 12 Feb 2011

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Geez this is the crappiest advice if seen in a while no offense fellas.

NO is the basic answer
however if you are prepared to sacrifice a significant chunk of output
you can still connect this panel to a 12v battery via almost any controller
drawback will be about 1/3 the nominal output.

I suggest
get an MPPT regulator that will handle that voltage
typically no problem will set you back anywhere from $90
alibaba to $400 from someone like energymatters for a top of the line MPPT regulator (which comes with support).

eg http://www.apolloenergy.com.au/Renewable-Energy-Components/M aximum-Power-Point-Trackers/SS-MPPT-15L

cheers Karl

Luck favours the well prepared

rockabye

Newbie

Joined: 12/02/2011
Location: Australia
Posts: 4

Posted: 09:02am 12 Feb 2011

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Quite right Karl.

Temporarily you can connect the module directly to a 12V battery if it is in need of charging however you would have to monitor the battery voltage manually and disconnect it once the voltage rises to 14 -14.8V. Risky if you are not careful though.

Best to get an MPPT regulator and be done with. As you got the module for free the reg should be a worthy buy.

Cheers

Brian

Edit: I just noticed in the Electronics thread that Silicon Chip magazine have a kit MPPT regulator in the current issue.
Edited by rockabye 2011-02-13

Everyday is a chooseday

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