# DC Voltage Control from Solar Panel for direct usage

May 9, 2016
77
Hi Guys!

I bought a solar panel which is producing 22v (Open circuit) and 6Amps (Short Circuit). These are the results at 11:15am.
Basically I want to use following to appliances directly with the solar panel (without charge controller and battery):
1. 12v 4Amp DC Motor
2. 12v 1Amp Water Pump

Please suggest me how can I reduce voltage from solar panel with minimum possible loss of amps.
I also thought of connecting one 6v bulb in series and both 12v appliances in parallel. Is it a good idea?

I would be grateful if someone can share simplest circuit for doing so. (I want 5~6Amps with 12v(on load).

Last edited:

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,194
Please suggest me how can I reduce voltage from solar panel with minimum possible loss of amps.
Use a step-down converter (Google). To get the most from your solar panel use a converter with build-in MPP tracking.

I also thought of connecting one 6 V bulb in series and both 12 V appliances in parallel. Is it a good idea?
Typically a bad idea. The resistance of the 6 V bulb will limit the current available to the 12 V appliance. Use a separate 6 V regulator for the bulb (regulate either from the already stepped-down 12 V or regulate directly from the solar panel's 22 V.

Always connect different loads in parallel. Only identical loads (same current) should be connected in series as long as the total of the voltages across the single components matches the available source voltage.

#### AnalogKid

Jun 10, 2015
2,742
A solar panel is an imperfect voltage source. That is, its output voltage sags as the load current increases, but more than it would with a "true" voltage source such as a regulated power supply. If possible, increase the load on the panel in stages and see what the output voltage is with 1 A, 4 A, and 5 A loads. You might not need a step-down (buck) regulator at all, and in fact might need a step-up (boost).

ak

#### dave9

Mar 5, 2017
1,181
It is unlikely that your panel can directly power the motor, 6A short circuit probably isn't 4A at 12V.

Thus, your best bet is charge a 12V battery with it. There are many solar battery chargers out there. If you needed to power the motor continuously then you simply need more solar panel(s) to get the job done, then a buck SMPS regulator, but you still need a battery or ridiculously big and expensive supercap array.

Stating "without charge controller and battery" is a waste of our time because then you are deliberately refusing to use the appropriate measures. You can just keep adding more solar panels if that's what you want to do, but for intermittent duty a charge controller and battery is the right solution. For continuous duty it still is because the sun is unpredictable and moving around, hiding at night, etc, lol.

Last edited:

May 9, 2016
77
Thanks all! Will definitely go for charge controller and battery then!

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