I am trying to come up with a scale-able solar light design.


For my initial project I am going to use some 12v LED strip lights(3 sections, 9 LEDs total). I should preface this with I have very little idea what I am doing. Provided my test was correct these pull .05 amps. Does that sound right? I think that I am looking at about 3.6 Watt/hours. I want this light to come on at night automatically. I am not sure how I want it to shut off but I am leaning towards it shutting off at a set battery voltage to avoid damage to the battery. Does that sound reasonable? I want a minimum run-time of 4-6 hours. I have a 18ah SLA for initial testing but I would like to use something that is more appropriate. I have also have several 18650s that need a project. I would really like to incorporate these.

37°11′42″N 93°17′10″W The solar panel will have a clear view of the south and east sky. There are a lot a cloudy days in the winter. If there is a long cloudy stretch the light can remain off. I am looking at using 3-5 of these 18650s.


I have a few bits that may come in useful for this project. I would like to use these where possible.


Solar Panel 2.5W 5V/500mAh (x2)

Solar Panel 12V 3W

XL6009 DC-DC Booster Power Supply

Max DC-DC XL4005 Step 5A Down Adjustable Power Supply

Boost Buck DC-DC Adjustable Step Up Down Converter XL6009

Smart Electronics 5V Micro USB 1A 18650 Lithium Battery Charging Board With Protection Charger

Various Diods

Various Resistors

Various Capacitors

Photo Resitors

N-Channel MOSFET 60V 30A

P-Channel MOSFET 60V 27A

Voltage Regulator - 12V COM-12766 ROH basic L7812

Arduino Uno


I am still looking a for a nicely done diagram to base this project on, but so far I have been unsuccessful. If someone has something that would get me going in the right direction I would greatly appreciate it.

 

No time today, but seems that you have enough parts to get started. Two SP's in series, 12 V battery, & LED strips. Control comes later.

 

I don't think putting the 500mA and 250mA solar panels in series is a good idea.

 

It sounds like a pretty straightforward project, however, there may be a few things you need to consider before you start building it.

Firstly, battery protection. I'm gathering that you want a solar panel to charge an SLA battery, which will be the current source for your lights. You'll need to work on something that will prevent overcharge, an overcharged SLA battery isn't pretty.

Secondly, design brief. What will make the lights come on and go off? Will it be manual (a toggle switch) or automatic (a light sensor)? Do the lights need to work at full brightness or would it be acceptable to modulate their output in order to prolong battery life?

Also, are you hoping for a modular solution or do you want to use discrete components?

 

It sounds like a pretty straightforward project, however, there may be a few things you need to consider before you start building it.

Firstly, battery protection. I'm gathering that you want a solar panel to charge an SLA battery, which will be the current source for your lights. You'll need to work on something that will prevent overcharge, an overcharged SLA battery isn't pretty.

Secondly, design brief. What will make the lights come on and go off? Will it be manual (a toggle switch) or automatic (a light sensor)? Do the lights need to work at full brightness or would it be acceptable to modulate their output in order to prolong battery life?

Also, are you hoping for a modular solution or do you want to use discrete components?

My battery preference is some 18650s with the tp4056 (new version) charging boards.

I want the lights to come on with a light sensor.

I want the lights to go off when the batteries reach a set voltage. I am open to other ideas here.

I am not real concerned with the form factor. I will most likely have the solar panel(s) a few feet away from the light.