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Process

Work Progress Report — Solar Wearable Prototype

1. Initial Testing of Solar Panels

After receiving the solar panels, I began by measuring the voltage (Voc) of each panel individually using a digital multimeter.

All panels were tested under two different weather conditions:

  • Cloudy / overcast daylight
  • Direct sunny weather

The results were recorded for documentation and comparison.

Panel Groups Under Test

The project uses three panel sets:

  • 1.5 V / 0.3 W panels — 10 pieces total (two strings of five planned)
  • 2.0 V / 0.5 W panels — 4 pieces planned for one string

Measurement Method

For each panel:

  1. Multimeter set to DC voltage.
  2. Probes connected directly to panel terminals.
  3. Panel oriented toward brightest available daylight.
  4. Voltage allowed to stabilize for ~2–3 seconds.
  5. Maximum observed stable value recorded.
  6. Measurement repeated once if reading fluctuated.

Under cloudy conditions: - The 1.5V panels mostly showed values between 1.4V and 1.8V, with one lower result close to 1.0V. - The 2.0V panels mostly ranged between 1.4V and 1.7V, with one panel dropping to around 0.75V.

Under sunny conditions, the voltage values were noticeably higher and more stable, confirming that all panels were functional and responsive to light changes.

  • The 1.5V panels mostly showed values between 2.03V and 2.20V.
  • The 2.0V panels mostly ranged between 2.04V and 2. 22V.

This step helped me: - Confirm that the panels were working - Identify weaker units - Plan grouping for balanced branches

For additional verification of the panels’ functionality, we connected two panels in series and attached them to an LED bulb. When the circuit was closed, the LED lit up, confirming that the panels were generating power correctly.

2. Panel Assembly into Branches

After testing, I connected the panels into three separate branches:

  • Branch 1 – 1.5V panels connected in parallel
  • Branch 2 – 1.5V panels connected in parallel
  • Branch 3 – 2.0V panels connected in parallel

Then:

  • Branch 1 and Branch 2 were connected in parallel with each other
  • The combined result was connected in series with Branch 3

This configuration was chosen intentionally.

The goal was to ensure that the total voltage does not exceed 6.5V, which is the maximum input voltage supported by the solar charge controller.

After assembling the full panel system, I tested the output voltage.

Measured system voltage: 4.2V

This result confirmed that: - The configuration works as expected - The system remains safely within controller limits - The voltage is suitable for charging a 3.7V lithium battery

3. Connection to Solar Controller (CN3065)

The assembled panel system was connected to a CN3065 solar charge controller.

When connected, the LED indicator on the board turned on.
This was an encouraging sign and confirmed that the controller was receiving power and operating correctly.

Since I did not have the proper connector plug available, I soldered a small component manually to enable the panel connection.

Although this solution is temporary, it allowed me to proceed with testing without delays.

4. Power Bank Integration

I purchased a compact 5000 mAh power bank.
The original plan was to connect it directly to the solar controller.

However, attempts to modify ready-made charging cables did not produce stable results.

After discussing the issue with my instructor, Mkhitar, I decided on a different approach:

Instead of modifying the power bank internally, I would create a removable battery holder.

The idea is to: - Insert and remove the battery easily - Treat it similarly to a standard replaceable battery - Keep the system modular and serviceable

This solution simplifies maintenance and improves flexibility.

5. 3D Modeling and Printing the Battery Holder

I found a ready-made 3D model of a battery holder and modified it in Blender by adding four sewing holes so it could be attached to textile.

The model was sliced and printed using Orca Slicer.

Unfortunately, I did not double-check the real dimensions of the battery before printing.
As a result, the first holder was too small.

I adjusted the dimensions and printed a second version.

Although the second version fits better, I am still not fully satisfied with how securely the battery sits inside the holder. I am considering designing and printing a third improved version to achieve:

  • Better fit
  • Improved stability
  • Easier insertion and removal
  • Cleaner integration into the garment

Current Status

  • All panels tested and documented
  • Electrical configuration assembled and verified
  • Solar controller successfully powered
  • Power solution concept redesigned
  • Battery holder prototyped (iteration 2 complete)

The system is functioning at a prototype level, and the next steps will focus on refining mechanical integration and improving battery mounting stability.