How to Connect Solar Panels to Your Garden's Lighting System

Installing solar panels to power your garden's lighting system can reduce your energy bills and carbon footprint. With some planning and basic electrical skills, you can successfully connect solar panels to your garden lights.

Determine the Power Requirements

The first step is calculating the power requirements for your garden lighting system.

• Make a list of all lighting fixtures in your garden, such as path lights, spotlights, string lights etc. Note the wattage of each light.

• Calculate the total wattage by adding up the wattages of all lights. This is the minimum power your solar panel system needs to produce.

• For example:

  • 5 x 10W path lights = 50W
  • 3 x 20W spotlights = 60W
  • Total wattage = 50W + 60W = 110W

• It's best to add 20-30% more capacity to account for aging solar panels, cloudy days etc.

• So in our example, the solar panel system should be around 140W to 150W.

Choose the Solar Panel Size

• Solar panels are rated by their power output in Watts.

• Select a panel or panels that can produce at least 20-30% more power than your lighting system requires.

• For the 110W lighting system above, a 150W or 200W solar panel would be ideal.

• Larger panels produce more power but also cost more. Find the right balance for your needs and budget.

• You can wire multiple smaller panels together to achieve the desired wattage.

Select a Charge Controller

• A charge controller regulates power from the solar panels to the batteries. It prevents overcharging.

• The charge controller's amperage rating should exceed your total solar panel amperage.

• Most controllers have a display to show battery charge status and power production. Select one with lighting protection and temperature compensation.

• MPPT charge controllers are more efficient than PWM controllers.

Choose a Battery

• Batteries store power produced by solar panels for use at night.

• For grid-tied systems, batteries are optional but they provide backup power.

• The battery's amp-hour (Ah) capacity determines how long it can power your lights.

• For grid-tied systems, a 100Ah battery should work. Off-grid systems need at least 200Ah.

• Get deep cycle lead-acid or lithium-ion batteries designed for solar storage. Avoid car batteries.

• Calculate batteries needed:

  Ah = Lighting load in Watts / Battery voltage

  Example: 110W load / 12V battery = 110/12 = 9.16Ah

  For 2 days backup: 9.16Ah x 2 days = 18.3Ah
  So get a 20Ah battery.

Size the Inverter (If Going Off-Grid)

• Grid-tied systems don't need inverters. For off-grid systems:

• Inverters convert DC battery power to standard AC electricity to run lights.

• Choose an inverter with at least 25% more capacity than your lighting load.

• For a 110W load, get a 150W inverter or higher.

• Pure sine wave inverters are best as they provide clean AC power.

Mount the Solar Panel

• Solar panels produce the most power when pointed directly at the sun.

• Use a south facing roof or wall if possible.

• The panel should be tilted at your latitude angle for optimal exposure.

• Alternatively, use a pole mount in an open spot to allow adjustment.

• Ensure the mounting location gets full sun for at least 6 hours daily.

• Place the panel away from shade and obstructions. Keep it clear of leaves, snow etc.

Connect the Components

• Start by determining the placement of all components - solar panel, batteries, charge controller, inverter etc.

• Mount the charge controller and inverter (if using) close to the battery bank.

• Run wires from the solar panel to the charge controller. Use 10 gauge wire for runs up to 50 feet.

• Connect the battery to charge controller observing polarity. Tag positive and negative wires.

• Connect the charge controller output to the lights and/or inverter input.

• Use wire nuts, crimp connectors or screw terminals for secure connections.

• Size all wiring for 15% more than your maximum power requirement.

Activate and Test the System

• Check all connections against wiring diagrams before powering up.

• Activate the charge controller and program any settings like battery type.

• Power on the solar panel and verify the controller shows charging status.

• Check the battery voltage. Fully charged lead-acid batteries should show ~12.7V.

• Turn on your garden lights and test their functionality for an hour.

• Adjust any underperforming light fixtures and their alignment.

Once everything is working, your solar powered garden lighting system is ready for energy-efficient operation! Check the charge controller periodically and clean the solar panel regularly for optimal power generation.