Solar Power Supply

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Ton_vN
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Re: Solar Power Supply

#51 Post by Ton_vN » 28 Aug 2019, 14:23

@Wiki

You confirm my view on the matter.
In this post the configuration comprises 5 such 'naked' cells (because the PCBs in the lamps went rusty, and the batteries not surviving either).
Fans each require max. 100mA and 5V ~12V, ESP8266s far less.
My sun-operated fans now being served, and a few more solar lamps approaching end-of-life, makes one think about recycling of those upcoming cells for sun powered supply for a small configuration ........
Current does not seem a problem, but voltage also has to fit the ESP8266, and therefore, either a stepup converter seems required, or some waiting until you have sufficient cells to apply a controller like TP4056.

Cost for the experiment is neglectable; just a pity that reliability/quality is a critical issue, not favourable for the operation of ESP8266s+sensors.
;-) Only for uncritical missions .......

Out-of-the-box thinking (getting headaches related to that TP-board)
KISS as a credo, ;-) perhaps (for my ESP8266s+Light sensors) I should replace the TP4056+battery for an LM7805 (with a thick condensator in front as a buffer):
- sufficient sun during daytime = operation
- insufficient sun & night = 'silence', but who cares ......

Wiki
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Re: Solar Power Supply

#52 Post by Wiki » 29 Aug 2019, 13:01

Ton_vN wrote:
28 Aug 2019, 14:23
[...]
(getting headaches related to that TP-board)
[...]
There is no need to get headaches related to an TP4056 board.

My solar-powered Temp/Humidity/Pressure Station (Stephenson screen 3D-printed):
Wetterstation.jpg
Wetterstation.jpg (92.94 KiB) Viewed 337 times
using a modified Wemos D1 china clone as described here (as you can see, no big capacitor, no diodes, no resistors, inside the battery housing a TP4056 pcb) delivers beside the sensor data its battery voltage to my Domoticz:

Unbenannt.JPG
Unbenannt.JPG (45.46 KiB) Viewed 337 times
Currently it is configuered to wake up every 5 minutes, staying awake for 20 seconds. This configuration I have chosen to make sure that the battery doesn't stay all the time in fully charged state. During wintertime I think I have to reduce the deep sleep cycle to 5 mins. sleep, 5 secs. awake.

But for your purpose of just running a light sensor I am pretty sure that the combination LM7805/1-4F capacitor will fullfill your needs. And it could be done with recycled solar panels, yes. I personally would prefer instead of the recycling somewhat like this.

Ton_vN
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Re: Solar Power Supply

#53 Post by Ton_vN » 29 Aug 2019, 23:01

@Wiki

Sure!

Variant with that type of solar panel in a transparant box almost ready to go for the ESP8266 controlling the light-measurements.
Variant with such solar panel plus TP4056-board will shift to an ESP8266-application with operation 24/7:
need to check on charging & discharging rythm ..............

Wiki
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Re: Solar Power Supply

#54 Post by Wiki » 30 Aug 2019, 08:47

Discharge behaviour of a modified (as linked above) Wemos D1 china clone with a pretty power consuming ultrasonic distance sensor (cisterne) driven only by 3000 mAh liion battery, no solar panel, deep sleep 30 mins, awake 5 secs, power supply of the sensor switched by a transistor.:
Unbenannt.JPG
Unbenannt.JPG (46.87 KiB) Viewed 315 times

Wiki
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Re: Solar Power Supply

#55 Post by Wiki » 30 Aug 2019, 10:00

Ehm, I forgot: I would not place solar panel inside your transparent box together with the battery. On full sunlight temperatures inside the box may raise up to 50-60 °C caused by the heating of the panel.

Ton_vN
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Re: Solar Power Supply

#56 Post by Ton_vN » 06 Sep 2019, 01:30

@Wiki

;-) Same lesson meanwhile learned:
solar panel inside the transparant box becomes so hot that the cover at the panel's backside glued over the panel wiring drops from the panel.
Must split the panel (to fit on a plate allowing ambient cooling) and the electronics (in a box for weather protection).

TD-er
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Re: Solar Power Supply

#57 Post by TD-er » 06 Sep 2019, 10:32

Ton_vN wrote:
06 Sep 2019, 01:30
@Wiki

;-) Same lesson meanwhile learned:
solar panel inside the transparant box becomes so hot that the cover at the panel's backside glued over the panel wiring drops from the panel.
Must split the panel (to fit on a plate allowing ambient cooling) and the electronics (in a box for weather protection).
What came actually loose?
The glue?

On a side note about gluing plastics.
I also have had issues finding proper glue that will stick to the smooth surface of ABS used in most enclosures.
For example to stick 3D printed parts to an enclosure.
What finally worked for me, was hot glue. At our local DIY store, they had the normal glue sticks and the "extra strong" ones.
Not sure if the "extra strong" part is the key feature here, or the fact that the glue gets over 200 degree C while applying, but this is the only way I could make parts really stick.
So maybe it is just melting stuff together, causing a blend of ABS & PLA in my projects, or the "extra strong" element is really helping :)

Just an idea to help holding stuff together.
Still the heat must be taken into consideration.
I also have a box outside, which is directed right into the sun's path and this summer I recorded 70 degree inside.
It doesn't have a solar panel inside.

Wiki
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Re: Solar Power Supply

#58 Post by Wiki » 06 Sep 2019, 13:21

Well, the heating of the solar panel is one thing. The worse thing is, that liion batteries don't like it being heated. They are aging pretty fast and in worst case they may exhaule tiny blue smoke - pretty fast, pretty loud and pretty hot.

To get cables into and out of the boxes I am using this kind of plugs:https://www.aliexpress.com/item/3275735 ... 4c4d9Ibgqo

Ton_vN
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Re: Solar Power Supply

#59 Post by Ton_vN » 08 Sep 2019, 21:21

See the 2 pictures.
The solar panel is 14cm*9cm.
The black box at the back is the junction box for the wiring, filled with a black compound, also acting as glue for the cover of the box:
the sun's heat melted the compound, causing drop of the cover.
SolarPanel_5W5V_Front.jpg
SolarPanel_Front
SolarPanel_5W5V_Front.jpg (287.45 KiB) Viewed 221 times
SolarPanel_InterfaceBox.jpg
SolarPanel_Back
SolarPanel_InterfaceBox.jpg (98.13 KiB) Viewed 221 times
Reading the stories and my own experiences trigger some rethinking:
- solar panels to be well-cooled in open air,
- batteries to be located in shaded, cool place,
- power supply should mimick real USB-supply, not simple 5VDC-generators

'Lessons learned', but requiring time to develop alternatives .....

Jack_T
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Re: Solar Power Supply

#60 Post by Jack_T » 21 Sep 2019, 10:54

You can refer to operation principle of solar street light. Most solar lights turn on and turn off automatically by sensing outdoor light using solar panel voltage. Solar streetlights are designed to work throughout the night. Modern designs use wireless technology for battery management. https://en.wikipedia.org/wiki/Solar_street_light
Looking at below power station diagram you can build, a real example of this is portable power station design like Suaoki https://www.bestpowerstation.com/suaoki ... and_Weight
Image
For an solar power generator system, you need basic components
1. Solar Panel (PV Panel)
2. Charge Controller
3. Battery
4. ESP8266s
5. blacking diode
6. DC usb plug (If you need)
7. Photoelectric Switches
8. Other (Duct tape, glue, screw terminals etc.)
9. Inverter (depend on battery watts)
Image
Photoelectric Switches: Functions as a light sensitive switch that will turn off devices in the presence of light and turn them back on in the absence thereof. Ideal for requirements. UL LISTED & CERTIFIED SAFE Controller features 7 Inch Long Wire leads and easy wiring.

Drum
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Re: Solar Power Supply

#61 Post by Drum » 20 Oct 2019, 04:03

Have a look at this
https://www.adafruit.com/product/390
This will maximize charging with a bit more circuitry and a big capacitor. They use the cap to "stabilize" the power from the solar cell. From what I can tell when the output from solar is below optimal, it charges and drains the cap to charge the battery. It is very effective and well documented in the linked pages.
For a 1 off or proof of concept this with a solar cell, battery and feather board
https://www.adafruit.com/product/2821
With an extra connector or two works great. None of the frustration I had with the really cheap boards I bought when I first started with the esp8266! They tend to do a really good job with design and documentation.

Having said that, I found using a tp4056 board and18650 battery I can run a esp8266 on 10 minute deep sleep cycle year round with no problem with the solar cell in a window. But I am also using a custom designed pcb because the USB powered boards are not designed to be power efficient. They are designed to be as cheap as possible and still work, mostly. Better quality parts (voltage regulator and diodes especially) are not expensive. But when you are selling on aliexpress pennies count.

My biggest problem now is condensation on the sensors boards causing oxidation. The sensor boards are not made for outdoor use and do not last long here.

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