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I have a solar panel that is rated below (old stored away unused panel)

Maximum Power (Pmax) 200Wp
Maximum Power Voltage (Vmp) 19.3V
Maximum Power Current (Imp) 10.0A
Open Circuit Voltage (Voc) 23.0V
Short Circuit Current (Isc) 11.2A

I want to hook it up to LED light(s) rated at 12v to brighten up multiple dark corridors during the day and will continue to light up until sundown. e.g. LED will be bright (12v) on good day, dimmed on rainy/evening (below 12v). No battery storage, just good ole skylight style.

How do I limit the output voltage to 12v but accept anything below 12v?

  • I search around and can do this with 12v DC to DC Converters but they have low input cutoff.
  • does this means if solar panel input is below 12v, they will be no output?

So basically, what I need is limit panel output to 12v but still continue output anything below 12v (output will be variable at 12v max with no minimum/cutoff).

Thanks heaps.

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  • \$\begingroup\$ Did you achieve what you wanted? If not I can provide enough detail to help you achieve the best possikle with what you have BUT do not want to spend time on this if it is not of practical use. || A 19V Vmppanel will make > 12V until close to sundown - they act ~= as a current source prioportional to brighrtness. I LEDS ar N Watts then a panel pointed somewhat towards the West will produce >= NWatts until light level is about N/Wmp / Kfactor. Kfactor 0...1 depends on losses, pointing goodness etc. Say about 0.7 to start. eg k=0.7 LEDS = 35W. Light = 35/200/.7 = 35/200/0.7 = 35% of noon max. \$\endgroup\$
    – Russell McMahon ♦
    Commented Oct 30, 2023 at 9:57

1 Answer 1

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There are DC-DC converters called "buck-boost", which can produce a fixed output voltage from an input both less than and greater than the output.

Some examples I found at Mouser are:

You might have some luck with Ebay cheapies (use at your own risk):

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  • \$\begingroup\$ I don't need a fixed 12v output. variable 12v(max)-0v. Is this achievable with a DC-DC Buck converter? \$\endgroup\$
    – CKey
    Commented Aug 22, 2023 at 1:48
  • \$\begingroup\$ @CKey How do you intend to determine and "set" the output voltage? \$\endgroup\$
    – Simon Fitch
    Commented Aug 22, 2023 at 1:52
  • \$\begingroup\$ does not need to. it will be for powering led lights to mimic the sky. if it's sunnier, LED will be brighter (12v max). if it's cloudy, LED will be dimmer (<12v) \$\endgroup\$
    – CKey
    Commented Aug 22, 2023 at 3:05
  • \$\begingroup\$ or what are the better options to accomplish this? \$\endgroup\$
    – CKey
    Commented Aug 22, 2023 at 8:03
  • \$\begingroup\$ is this the same as Buck converter? victronenergy.com/upload/documents/… \$\endgroup\$
    – CKey
    Commented Aug 22, 2023 at 8:09

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