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OT-- Solar panel overvoltage

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vozzen

Joined: 25 Aug 2006
Posts: 12

Posted: Tue Jan 15, 2008 8:16 pm Post subject: OT-- Solar panel overvoltage

Sorry to drift off topic, but chalk it up to Remote Hangar Power-Supply Project.



I've got a couple solar (PV) panels, each rated 48 watt, 3 amp (at) 16 volts, 18-19 volts open circuit.  Problem is that I bought an inverter that has a 15.5 high-voltage cutoff, so no worky for 110a/c.

My question(s): 

If I got a "Solar Charge Controller", designed to limit charge into batteries, could I use it to supply the inverter ??



  And how about a 12-v. resistive load, or pump/fan motors, (no inverter) that would pull down the voltage at max draw ??   ... assuming the charge controller could handle the current.



Any other ideas for regulating 16 v down to a usable 13-14 (for 6 A.)



Thanks in advance for any advice.

--Richard V., 601xl in a cold shop in KC

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rjquillin

Joined: 13 May 2007
Posts: 123
Location: KSEE

Posted: Tue Jan 15, 2008 9:12 pm Post subject: OT-- Solar panel overvoltage

At 20:16 1/15/2008, you wrote:

 	  Quote: 	
		  



Sorry to drift off topic, but chalk it up to Remote Hangar 

Power-Supply Project.



I've got a couple solar (PV) panels, each rated 48 watt, 3 amp (at) 16 

volts, 18-19 volts open circuit.  Problem is that I bought an 

inverter that has a 15.5 high-voltage cutoff, so no worky for 110a/c.

My question(s):

If I got a "Solar Charge Controller", designed to limit charge into 

batteries, could I use it to supply the inverter ??



   And how about a 12-v. resistive load, or pump/fan motors, (no 

 inverter) that would pull down the voltage at max draw ??   ... 

 assuming the charge controller could handle the current.



Any other ideas for regulating 16 v down to a usable 13-14 (for 6 A.)



Thanks in advance for any advice.

--Richard V., 601xl in a cold shop in KC


	


Why not just dump them into a battery and the inverter in parallel?



Ron Q.

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echristley(at)nc.rr.com
Guest

Posted: Wed Jan 16, 2008 5:51 am Post subject: OT-- Solar panel overvoltage

Ron Quillin wrote:

 	  Quote: 	
		   

 <rjquillin(at)gmail.com>



 At 20:16 1/15/2008, you wrote:

> 

>

> Sorry to drift off topic, but chalk it up to Remote Hangar 

> Power-Supply Project.

>

> I've got a couple solar (PV) panels, each rated 48 watt, 3 amp (at) 16 

> volts, 18-19 volts open circuit.  Problem is that I bought an 

> inverter that has a 15.5 high-voltage cutoff, so no worky for 110a/c.

> My question(s):

> If I got a "Solar Charge Controller", designed to limit charge into 

> batteries, could I use it to supply the inverter ??

>

>   And how about a 12-v. resistive load, or pump/fan motors, (no 

> inverter) that would pull down the voltage at max draw ??   ... 

> assuming the charge controller could handle the current.

>

> Any other ideas for regulating 16 v down to a usable 13-14 (for 6 A.)

>

> Thanks in advance for any advice.

> --Richard V., 601xl in a cold shop in KC



 Why not just dump them into a battery and the inverter in parallel?



 Ron Q.

My thought exactly.  This will have the added advantage of allowing you 
	


to draw more than 6amps on the rare occasion that you need it.

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vozzen

Joined: 25 Aug 2006
Posts: 12

Posted: Wed Jan 16, 2008 5:54 am Post subject: Re: OT-- Solar panel overvoltage

>Why not just dump them into a battery and the inverter in parallel? 



I really wanted to see what was possible without a battery...

--RJV

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echristley(at)nc.rr.com
Guest

Posted: Wed Jan 16, 2008 6:53 am Post subject: OT-- Solar panel overvoltage

vozzen wrote:

 	  Quote: 	

> Why not just dump them into a battery and the inverter in parallel? 

>     

 I really wanted to see what was possible without a battery...

 --RJV

You can operate without a battery.  Anything is possible, if you throw 

enough money at it.  But the utility you will get from a couple of 

batteries will be by far the biggest bang for the buck.  Not only will 

they let you have an occasional large power draw that the panels 

wouldn't support, but they will let you have limited power at night or 

when it's cloudy.  If you're rotating cheap batteries as Bob suggests, 

then you should be able to rotate the 2yr old battery into a "solar 

panel support" position.  A spare lawn tractor battery would suffice 

until it's time to rotate one in from the airplane.  The batteries 

should last a LONG time, being constantly charged and only occasionally 

drained, so you can keep adding capacity by hooking more up in series as 

they rotate out of the plane.

Again, it's possible to solve the problem with some creative 

electronics.  You could chop the panel's DC to create AC, then run that 

through a regulator, then rectify it back to DC.  Or you could put a 

large capacitor and enough Zener diodes to handle 6amps across the 

panel's output.  What you'll end up  with is some electronics to 

maintain, without the added benefits of the stored capacity.  You'll 

spend a lot more than the $30 battery will cost, even if you kit and 

build it yourself.

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nuckolls.bob(at)cox.net
Guest

Posted: Wed Jan 16, 2008 7:18 pm Post subject: OT-- Solar panel overvoltage

Sorry to drift off topic, but chalk it up to Remote Hangar Power-Supply 

Project.



I've got a couple solar (PV) panels, each rated 48 watt, 3 amp (at) 16 volts, 

18-19 volts open circuit.  Problem is that I bought an inverter that has a 

15.5 high-voltage cutoff, so no worky for 110a/c.



My question(s):



If I got a "Solar Charge Controller", designed to limit charge into 

batteries, could I use it to supply the inverter ??



    Kinda, sorta . . . Solar panels have a significant source

    impedance. Hence the drop from 19 volts no load to 16 volts

    at a 3A load.  DeltaV of 3 volts divided by DeltaI of 3A

    yields a source impedance on the order of 1 ohm. Two panels

    in parallel would drop this to 1/2 ohm for the array.



    16 volts would smoke most 12/14v accessories and some

    accessories would draw less than 6A which boosts the

    voltage still more.



    The most "stable" application of solar power is to combine

    the array with a battery maintainer designed to integrate

    the array with a rechargeable battery. This allows you to

    store energy even if you're not using it for the moment

    (until battery is charged). It also allows you to tax the

    system with loads much larger than 6A albeit intermittently.



And how about a 12-v. resistive load, or pump/fan motors, (no inverter) 

that would pull down the voltage at max draw ??   ... assuming the charge 

controller could handle the current.



Any other ideas for regulating 16 v down to a usable 13-14 (for 6 A.)



    A Google search for "solar battery charger" yielded

    a bucket full of hits . . . a few are cited below.



http://tinyurl.com/ybh9wz



http://tinyurl.com/246w34



http://tinyurl.com/2c3orf



    Suggest you team the solar panels with a regulating

    charger, the largest battery you're willing to

    acquire and maintain. NOW you have an energy source

    that will run a pretty hefty inverter and permit

    you to run a variety of loads rain or shine.

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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vozzen

Joined: 25 Aug 2006
Posts: 12

Posted: Thu Jan 17, 2008 9:02 am Post subject: Re: OT-- Solar panel overvoltage

> Suggest you team the solar panels with a regulating

charger, the largest battery 



Yep, those are the charge controllers I'd looked at, and I understand the role of the battery.   

I had tested a direct-driven 12v. boat bilge pump (1.5A) in a water-garden-fish-pond, but found the 16-18v roasted the pump (it did work for a whole summer).   Other thought was for an attic exhaust fan-- but without controller, will have same problem.



Will head down to local H.F. Chinese outlet store, get a controller, and go from there.

Thanks, Bob, and others, for suggestions.

--RJV

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