DIY solar panel for a boat: José's project

Customer projects · marine

A DIY solar panel for the boat: José's project

José, a sailor from Santander, wanted to charge his onboard battery without paying chandlery prices. With an MR WATT cell kit he built a panel of more than 70 W.

Kit used

36 cells 3"x6"

Power

70+ Wp, 18 V

Application

Sailing boat, 12 V

To build this project today

The 70 W kit José used has been replaced by a version with more powerful monocrystalline cells. On a boat we also recommend a controller that charges two batteries.

DIY solar panel kit 80W – 36 cells 3x6

The same layout as José's, 36 cells of 3"x6", with grade-A monocrystalline cells.

See the 80W kit

DuoRacer 10A dual-battery MPPT controller

Charges the house and engine batteries together: ideal on board.

See the controller

Why build it yourself

On a boat everything costs more. For the power he needed, 60 to 70 W, José was finding panels at around 280 euros or more at the time. So he decided to build his own, starting with the solar panel and leaving the idea of a small wind turbine for later.

He knows northern Spain is not the sunniest place in Europe, but the goal was simple: keep the onboard battery charged at a fair cost.

José and the panel he built for his boatJosé and the panel he built for his boat

José and the panel he built for his boat

The materials

  • 1 kit of 36 solar cells 3"x6", grade A, with ribbon and flux
  • 1 charge controller, 10 A 12/24 V
  • 2 polycarbonate sheets, 1.2 × 0.5 m
  • aluminium profiles and clear silicone
The cell kit and the charge controllerThe cell kit and the charge controller

The cell kit and the charge controller

Polycarbonate, aluminium and silicone: the rest of the materials

Polycarbonate, aluminium and silicone: the rest of the materials

Assembly, step by step

José sized the panel to hold 3 rows of 12 cells. The steps:

  1. apply flux to the cells and carefully solder the tabbing ribbon;
  2. connect the cells in series, row by row;
  3. glue the three rows onto a backing board with silicone;
  4. cover all the cells with clear polycarbonate and close it with the aluminium frame.
Soldering the ribbon onto the cellsSoldering the ribbon onto the cells

Soldering the ribbon onto the cells

The rows of cells connected in seriesThe rows of cells connected in seriesThe rows of cells connected in series

The rows of cells connected in series

The panel in numbers. Each cell produces about 0.5 V and 3.6 A, i.e. more than 1.8 Wp. The 36 cells in series give over 70 Wp at 18–19 V: the right voltage to charge a 12 V battery through the controller.
The three rows assembled under the polycarbonateThe three rows assembled under the polycarbonate

The three rows assembled under the polycarbonate

The result

The finished panel, tested first under artificial light and then in the sun, delivered the expected voltage.

Left, the test under artificial light; right, in the sunLeft, the test under artificial light; right, in the sun

Left, the test under artificial light; right, in the sun

The last step was installing it on board.

The panel installed on the boatThe panel installed on the boatThe panel installed on the boat

The panel installed on the boat

“I started with the solar panel to give it a try, and luckily I didn't waste time, work or a lot of money. And it was quite fun, too.”

— José, Santander (Spain)

Want solar power on board too?

Build your own panel with a cell kit, or choose a ready-made marine kit with panel and controller.

DIY kitsCamper and boating kits

Related guides

How to solder solar cells · Camper solar panel: kits and sizing

Project and photos by José, originally published in Spanish on his blog. We thank him for letting us share them.