Off grid LED solar lighting without batteries


Joined Oct 29, 2009

Here it is sorry..
But I thought Voltage needs to be limited too as it can bea above14v and i planned to use the LED at 13V / 3,5 A. But as i said the voltage of the panel can get as low as 12 V for the worst Case with 400 w/m2 irridiance and 75 Celsius Panel temp and in this Case i need to Booster the voltage a Bit altough it needs to lowered the Rest of the time.

Assuming these are actual LEDs: The forward voltage is 12V. Meaning your supply needs to be something above that. The current is 3750 ma. You woul need to limit the surrent to that. The simplest way to do that is using a resistor but with a 21 panel you would need a 2.4Ohn resistor @ 33W. That is impractical.

They make LED drivers for such a purpose that is a switched mode supply. Far more efficient than a resistor.

But you panel is only 21volts @150W. That means , under ideal conditions, the panel is only going to be able to supply 7 amps. You will likely only be able to light one of those LEDs in real life conditions and will probably not be for more than a few hours a day..


Joined Oct 29, 2009
Those LEDs might have internal current limitation. If so they are designed at to work at 12V so you would need to step down your voltage. It might be best to contact the seller to see if they have current limitation and the 12V rating is the required operating voltage and not a forward voltage.

Thread Starter


Joined Mar 11, 2019
I sent the question to the seller.
I now ordered a Automatic Buck-boost converter but a mppt Charge Controller (that i have to adjust?or is it enough to connect the battery first with the chargecontroller? ) and a small battery would be better for more continous LED lightning. I found this one ... In combination with a small 12V 20AH solarbattery.. just to average the Output of the panel? But first i will try it Out without battery so heres my First Plan: So do you think it works out when i Just wire the 150 W Solarpanel (21,8V opencirc. V) with the Buck-boost converter (How about the polarity of the voltage with buck-boost converters i think i did not fully understood this till now will/can it work too with a combinated step Up/down module instead of a normal Buck converter?) and then to the one cob led that is mounted to an Aluminium heatsink? I also ordered two Buck converters to experiment.

Here are the links to all the articles that i ordered to make it complete: BUCK BOOST CONVERTER 5-30V



12-14V 3,75A LED: