Sun power

Solar-powered phone charger

A small panel, a USB booster module and a battery charge a phone, handy where power cuts are common.

₹300 to 50060 minutesMedium

Jump to the steps
USBPanelBooster moduleBatteryPhone charges

The big idea

Where power cuts are common, a solar charger keeps a phone alive. It is a real, useful project that shows how the parts of a solar system fit together.

You will need

Tick things off as you gather them.

Step by step

  1. Understand the parts

    The panel makes electricity when the Sun shines. The battery stores it for later. The booster module steps the voltage up to the 5 volts a USB port gives out.

  2. Check the module

    Read the markings on the module. Find the input pins (from the panel and battery) and the USB output. Check which pin is plus and which is minus.

  3. Connect the battery

    With a teacher, connect the battery pack to the module input, plus to plus and minus to minus. Never wire a bare lithium battery yourself.

  4. Connect the panel

    Connect the solar panel to the charging input of the module, plus to plus and minus to minus.

  5. Check the output

    Put the panel in the sun. Use a multimeter on the USB socket pins. It should read about 5 volts.

  6. Charge a phone

    Plug in a phone and place the panel in full sun. Watch for the charging icon. It will charge slowly with a small panel. Be patient.

  7. Record the charge

    Note the phone's battery percentage every 15 minutes in sun and in shade. How much charge did you add in an hour?

What to look for

  • The phone charges only when there is enough light.
  • The battery lets you charge after the Sun has gone.
  • A bigger panel charges the phone faster.

Why it works

A solar panel gives a voltage that changes with the light. A phone needs a steady 5 volts. The booster module takes the panel voltage and turns it into a steady supply. The battery acts as a store, so the Sun can charge it during the day and the phone can use it at night. Big solar plants do exactly this with large batteries.

Try this next

  • Compare charging speed with one and two panels.
  • Add an indicator LED that shows when the battery is full.
  • Calculate how long it would take to fully charge a phone with your panel.

Stay safe

Lithium batteries can overheat if wired wrongly. Use a ready-made module with protection and ask an adult to check every connection before you switch on.

Link to the grid

Solar plus a battery is the same design the grid uses, only larger. Batteries hold daytime solar power for the evening peak.

Learn how the grid works

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