Solar panel with circuit inside a PC box -Not working

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Discussion Overview

The discussion revolves around a solar panel setup integrated within a PC box, focusing on issues related to charging a battery when the assembly is enclosed. The scope includes technical challenges related to thermal management, material selection, and electrical performance in a sealed environment.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes a solar panel generating 300mAh outside but failing to charge the battery when placed inside a PC box, raising concerns about thermal effects.
  • Another participant suggests posting pictures and considering a metal enclosure with thermally conductive epoxy to dissipate heat.
  • A participant responds that a metal enclosure is not feasible due to the need for transparency for LED lighting, emphasizing the use of polycarbonate for its light transmission properties.
  • Concerns are raised about the driver board potentially malfunctioning due to high temperatures (around 60°C) inside the sealed box, which may affect charging behavior.
  • It is noted that the battery may have a thermistor that prevents charging if temperatures exceed safe limits, suggesting that the controller may also shut down under high temperatures.
  • One participant proposes adding copper plates beneath the potting to help manage heat, though this would require additional engineering considerations.

Areas of Agreement / Disagreement

Participants express varying opinions on the feasibility of different enclosure materials and methods for managing heat. There is no consensus on a definitive solution to the charging issue, and multiple competing views on how to address thermal management remain.

Contextual Notes

Limitations include the challenge of achieving IP68 waterproofing while managing heat dissipation, as well as the potential impact of the driver board's thermal response on charging behavior.

Madhumkm12
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TL;DR
Solar panel and circuit not working as intended inside a Polycarbonate box.
Hi,
I am trying to build a product where i am placing a solar panel along with a driver board inside a Polycarbonate housing and closing it with a ABS cover at the back.
The driver board is soldered at the back of the solar panel and placed inside the PC box. Then a RTV(silicone sealant for leds ) layer is applied to hold still the setup inside the PC box. Then a 2 potting component is mixed and poured to make it waterproof IP68.

Here comes the problem. The panel is generating around 300mah when the panel board and the battery is outside in open air and the battery goes from 2.9v to 4v. But when the same setup is placed inside the PC box and kept for testing the battery is not getting charged. Still the solar panel generates the same 300mah current inside the box as well.

The doubt is whether the driver board is acting weird inside the PC case as the temperature inside the box is around 60'C and since the back is also covered there is a hot air inside thats not circulating. So some thermal reaction is happening.
How to over come this situation. There is no way i can make an air vent or Heat sink because in order to achieve IP68 i need to seal with potting.

Please help me out with a solution on this or the way it has to be approached
 
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Welcome to PF.

Can you post some pictures? (Use the "Attach files" link below the Edit window.)

Also, can you consider a metal enclosure and thermally conductive epoxy to help get the heat out of the enclosure?
 
There is no possibility to go for a metal enclosure as we are putting LED to light up at night. so need a transparent material so only chose PC. which allows 88% of light inside. Tested on that.
we use Potting which is thermally conductive only so that it doesn't allow external heat inside and absorb from the panel or driver board as well.

Before doing this we try to test in once before pouring potting. But now there is an anomaly caused because of this charging issue
 

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Madhumkm12 said:
The doubt is whether the driver board is acting weird inside the PC case as the temperature inside the box is around 60'C and since the back is also covered there is a hot air inside thats not circulating. So some thermal reaction is happening.
The battery has three wires so it's likely with a thermistor, which is monitored by the controller board. It'll stop charging if the temperature is too high.
The controller will likely monitor its own temperature too and shut down if it is too high.
Though it should still charge periodically. Just not full time. You should be able to check that.

Since it's just the normal operation I guess the only thing you can do is to remove the heat and maintain stable temperature (for both the battery and the controller).
Maybe you can add some copper plates below the potting. But this will require some engineering...