diy solar

diy solar

Hi from the frozen north

4

45North

Let it shine!
Joined
Jan 2, 2020
Messages
977
Location
Canada
Hi all, and Happy New Year!

Love Will's videos and book and currently making a small hobby system to play with, learn from and drive a few lights in the yard. Seems to me this type of tiny, inexpensive solar system has been largely overlooked and I hope to change that.

I've been lurking for a while and I'm impressed with the depth of knowledge and experience I find here. Looking forward to participating in the Forum
 
Welcome. I love the idea of the small system. I'm looking forward to seeing what you build.

My wife wants a couple lights in her garden so I decided that was a perfect excuse to build a solar solution that will cost WAY more than just buying all-in-one solar landscape lights.

My parts list so far:
I'm working on a couple of other projects over the winter, so I'll hopefully get to this landscape stuff in the spring.
 
Bob142 said:
Welcome. I love the idea of the small system. I'm looking forward to seeing what you build.

My wife wants a couple lights in her garden so I decided that was a perfect excuse to build a solar solution that will cost WAY more than just buying all-in-one solar landscape lights.

My parts list so far:
I'm working on a couple of other projects over the winter, so I'll hopefully get to this landscape stuff in the spring.
Click to expand...

Exactly Bob!

I needed an excuse to get started so, not having a man cave shed, I thought I'd start with the existing 110vac Christmas lights on the shrub in the backyard! And then I'll look at some of those 12v garden spotlights in the spring.
So far I have these parts:
  • 25W PV panel
  • panel to be mounted on my wife's portable metal clothes drying rack (OK for now but she may want it back in the spring!)
  • 10W PWM charge controller
  • 12V 7Ah SLA battery
  • 150 W inverter (awaiting delivery with "cigar lighter" adapter)
  • to be housed in an existing small plastic tool box (if it fits)
  • Kill-a-watt clone wattmeter to monitor watts used
  • sunset switch to control lights
So far, so good. I have it in the basement now - testing under the flourescent lights in my workshop. Looking forward to seeing how this particular set of devices play together.

All I need now is some sun!
 
Welcome!!! We are all crazy tinkerers and it sounds like you will fit right in.

You probably already know this but given the name on this thread and your screen name: Be sure to never try to charge the batteries if they are below 0C/32F.
 
Bob142 said:
Lights TBD but looking at something like these.
Click to expand...

I've found a lot of this type of stuff to be driving the LEDs really hard so the emission of the LED falls off and the phosphor dies too. Knocking them down to 11.5v usually gives good brightness but extends their life quite a bit. Only important if replacing them is going to be a PITA of course.
 
Thanks!!! Could you point me to info on the SLA's you are using? You are the 3rd person to mention them too me in the past few days. I have a cold-climate condition I am designing for and maybe I need to look at SLA.

Another option is LiFeYPO. They tend to have good cold-climate specs as well.
 
FilterGuy said:
Thanks!!! Could you point me to info on the SLA's you are using? You are the 3rd person to mention them too me in the past few days. I have a cold-climate condition I am designing for and maybe I need to look at SLA.

Another option is LiFeYPO. They tend to have good cold-climate specs as well.
Click to expand...

Look at gel battery specs.
 
45North said:
Hi all, and Happy New Year!

Love Will's videos and book and currently making a small hobby system to play with, learn from and drive a few lights in the yard. Seems to me this type of tiny, inexpensive solar system has been largely overlooked and I hope to change that.

I've been lurking for a while and I'm impressed with the depth of knowledge and experience I find here. Looking forward to participating in the Forum
Click to expand...

There is an ongoing thread about a 1.5 watt system. Can't get much smaller than that! Welcome to the forum.
 
FilterGuy said:
Thanks!!! Could you point me to info on the SLA's you are using? You are the 3rd person to mention them too me in the past few days. I have a cold-climate condition I am designing for and maybe I need to look at SLA.

Another option is LiFeYPO. They tend to have good cold-climate specs as well.
Click to expand...
A 7AH 12V SLA is typically a UPS battery. I always upgrade my 7AH to 8AH ($17) when I replace the batteries. Tons of options, too, such VRLA AGM.

1578174101918.png
 
Last edited:
FilterGuy said:
Could you point me to info on the SLA's you are using?
Click to expand...
The small one I chose for this project is:

www.power-sonic.com

PS-1290 12V 9Ah General Purpose VRLA Battery | Power Sonic

The Power Sonic PS-1290 is Part of our Class-Leading Battery Range. Find Out More Today.
www.power-sonic.com www.power-sonic.com

It's an Absorbent Glass Mat (AGM), which is a type of Valve-Regulated Lead Acid (VRLA). AFAIK, VRLA and Sealed Lead Acid (SLA) are synonymous. The gel batteries @Lost In The Desert referred to are also SLAs. This stuff has been around forever and you can find a lot of posts on this forum talking about the pros and cons of them vs. LiFePO4, so I won't get into it here.
 
BIG slap on the forhead!! SLA is Sealed Led Acid. Duhhh! I knew that but when I read it in the post I assumed it was some kind of alternative lithium chemistry.

The only advantage of being old is that I can blame brain farts on my age!
 
gnubie said:
I've found a lot of this type of stuff to be driving the LEDs really hard so the emission of the LED falls off and the phosphor dies too. Knocking them down to 11.5v usually gives good brightness but extends their life quite a bit. Only important if replacing them is going to be a PITA of course.
Click to expand...

Thanks for the tip but can we really change the output voltage on these inexpensive SCC's?
I don't know about Bob's Renogy, but on my Chinese special I don't see anywhere to change the voltage coming from the timed load output screws so I assume the default is 12V, take it, or leave it.
 
I use small buck regulator boards from ebay for each strip. The SCC doesn't actually regulate the voltage on its switched output terminals. If there is a battery connected, what ever voltage is on the battery will be the voltage on the switched output.

If those lights are what I suspect, simply a string of diodes that tally up to roughly 12v, you can vary the voltage and reduce the output. At 250mA a pop (12volt, 3 watts) you could run several of them via a 2 amp adjustable buck module off ebay ( example only ). Doing this only makes sense if changing the lamps is not easy/convenient, given the cost of the things.
 
gnubie said:
I use small buck regulator boards from ebay for each strip. The SCC doesn't actually regulate the voltage on its switched output terminals. If there is a battery connected, what ever voltage is on the battery will be the voltage on the switched output.

If those lights are what I suspect, simply a string of diodes that tally up to roughly 12v, you can vary the voltage and reduce the output. At 250mA a pop (12volt, 3 watts) you could run several of them via a 2 amp adjustable buck module off ebay ( example only ). Doing this only makes sense if changing the lamps is not easy/convenient, given the cost of the things.
Click to expand...
Wow! Those things are so cheap - $3 a pair! Who knew?
But, I notice they recommend maintaining a 1.5v difference. So if I'm aiming for 11.5v out, I should maintain the battery no lower than 13V.
Is this really necessary? Or even possible? I tried raising my low-level cutoff earlier to 12.2v (as per Will's book) but on my particular SCC couldn't get it above around 11.something (after starting at 10.7!) So, these things are somewhat adjustable, but there are limits.
But, as you say, the yard lights are pretty cheap so probably easier to do nothing and see what happens. When they die you buy more.
 
Nope, none of this is necessary at all, it's only useful if the lamps are a PITA to swap out. :)

Once you get down to the point where they are under their regulation voltage they more or less pass through as they can only drop the voltage not raise it (although you can get combo buck/boost regulators).
 
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