How To Make Solar Charger with Day Night Switch

What I have done is to link up a 15w, 1.2 A solar pannel to 2 by 7.2 AH batteries. This I run trough a controller that charges the batteries during the day and then runs the lights at night. During the day I use the system to power my hydroponic motor.


  • 40v to 13.3 v, 1.5A voltage regulator, mounted on pc heat sink.
  • 10v low battery cut off.
  • 12v regulator that is switches the power from day night sensor.
  • 3 diodes to modify the output of the regulator to 14.4 to charge my 12v battery.
  • Gate controller circuit to switch off the pump after 15 min.
  • Day night sensor with sensitivity switch to control the power to the relay.

Step 1: Setup charger
Step one was to set up the panel and the charger unit. I took a PB137 voltage regulator, max 40 volt in @ 1.5A and attached it to a heat sink as my panel will supply up to max of 26v at 1.2A 15w. I think took 3 1N5408 diodes connected in series to the earth pin of the regulator to modify the output to 14.4 to charge my 12v batt

Step 2:
I now take the +/- 14.4v (depending on weather conditions and cloud coverage) and pas sit though the relay up to the to the low battery cut out sensor. this is set to 10v to prevent damage to your batteries from excessive discharge. I need this as I often used to forget to turn off the hydroponic pump.

Solar charger with day night switch

Step 3:

The batteries are off the pic are 3 x 7.2Ah 12 volt batteries the same used in computer UPS linked in parallel
I set up a day night sensor that I got from a electronics website here this is a 2N3904 NPN Transistor, linked to photo transistor and then using a 100k pot to regulate the sensitivity level. This controls the step 2 relay. At night I am running about 100 ultra bright LED's in and around the house to provide off the grid light and security lights. during the day the relay allows me to run my hydroponic pump

Step 4 :
I set purchased a timer relay that they use in electric gates to control the run time of the pump. If  you are anything like me you will forget to switch it off so I had to set up some sort of forget me not system. These units are easy to find and cheap about R100.00 (15usd) this unit has a trigger point and a reset so I inserted to switches on to set it off and then to kill it is I need to. You can set them to run for anything from 30sec to 3 hours.
I like to give my plants 15min water every 3 hours ... this will be the next step is to build in a 24h timer.

So far day 1 on the system so let us see how she handles the changes and I will get back to you with more info.

Comments and suggestions welcome on how to make the system better and fool (me) proof .....

Fb Comments
Comments :

1 comment:

  1. You have shared nice content, thanks for posting....

    Get the best Fastest solar charger with Evolution wear.

    EvolutionWear’s RapidSol claims to be up to 90 per cent faster than rivals

    Rapid Sol and Winter Solstice Solar Jacket is the coolest way to charge your smart phone
    There is cooler way to charge your mobile devices these days and that is by harnessing the power of the sun. Yes now it is possible and all this has been possible due to the effort of Evolution Wear, a state of the art cloths design company that has merged fashion with science.
    Often people find themselves in a situation where they do not have any electrical socket to power their devices but these days one also carries portable batteries but they also need charging which makes it vulnerable.However with Evolution Wear Rapid Sol and Winter Solstice Solar Jacket you never have to worry about charging your phone batteries because you now posses the unlimited and free power of the sun.

    Source: Shop From IndieGoGo
    Evolution Wear: Worlds Fastest Solar Chager