How To Build A Simple 5 V USB Solar Charger (No Battery)?

 How to build Simple 5 V USB Solar Charger (No Battery)? Charge phones/power 5 V gadgets directly in sunlight.

Chosen specs

• Panel: 15 W “12 V” nominal mono panel, Vmp ≈ 18 V, Voc ≈ 22 V, Isc ≈ 0.9 A (common size ~300×350 mm)

• Output: 5.0 V regulated, up to ~2 A peak (realistic ~1–1.5 A in good sun)

Topology

Panel → blocking diode → buck converter (to 5.00 V) → USB-A

Panel + ── Fuse(2A) ──|<|── +IN  Buck (LM2596 or MP1584)  +OUT ── +5V → USB-A pin 1

            D1: SS34   |                         

Panel − ─────────────────────── GND ───────────────── GND → USB-A pin 4

                             TVS(SMBJ24A) across +IN↔GND (optional)

BoM (example parts)

• Solar Panel: 15 W, 12 V nominal, Vmp ~18 V, Isc ~0.9 A

• D1 Blocking Diode: SS34 (3 A, 40 V Schottky) — low drop, low reverse leakage

• Buck Module: LM2596 (3 A rated) or MP1584EN-based mini buck (3 A rated)

• USB-A Female Jack: panel-mount or PCB type

• Fuse (Panel+): 2 A blade or mini inline

• TVS Diode (optional): SMBJ24A across buck input

• Cable: 20–22 AWG for short USB, 18 AWG from panel to buck if >0.5 m

• Enclosure: Small IP65 junction box, cable glands

Build notes

• Set buck to 5.00 V with a multimeter before connecting a device.

• Many LM2596-USB boards include data-pin resistors for phone charging. If using a plain USB jack, add 49.9 kΩ pull-downs or a “dumb charger” divider (D+/D− short or 2.0 V/2.7 V depending on device). Most modern phones accept D+/D− short.

• Mount SS34 in series with panel + (stripe towards buck).

Testing

1. Measure panel Voc in sun: ~20–22 V.

2. With panel connected and no load, verify buck input 16–20 V, output 5.00 V.

3. Plug a 5 V dummy load/phone—expect 0.5–1.5 A; output should hold 4.9–5.1 V.

Sourced By: Streampowers