Introduction
Installing an underwater lighting system can beautifully illuminate your garden pond or pool at night. However, running electrical cords across your yard to power the lights can be an eyesore. A better solution is to build your own solar generator to cleanly provide electricity right at the water's edge. In this comprehensive DIY guide, I will walk you through every step needed to build a custom solar generator for your garden's underwater lighting, from choosing components to final installation.
Choosing a Solar Panel
The solar panel is the heart of your DIY solar generator. This panel will capture sunlight during the day and convert it into electricity to recharge the battery that will power your pond or pool lights at night.
When selecting a solar panel, there are 3 key factors to consider:
Wattage
The wattage of a solar panel indicates how much electricity it can produce at peak sunlight. For most pond/pool lighting needs, a 100W to 200W solar panel will be sufficient. Panels at this size range are compact enough for inconspicuous placement while generating enough power.
Voltage
Ensure the solar panel's voltage matches the charging input voltage of the battery you plan to use (more on batteries next). Most 12V batteries can be charged by 12V or 24V solar panels.
Type
Polycrystalline silicon solar panels offer the best value for home DIY projects. More efficient monocrystalline panels are great too but cost more. Avoid thin-film panels - they degrade faster than silicon.
I recommend a 100W polycrystalline solar panel with a 12V output. This strikes the ideal balance of size, efficiency and cost for powering pond/pool lighting.
Choosing a Battery
The battery stores the energy from the solar panel during the day to power your underwater lights at night when the sun goes down. There are two main types of batteries to choose from:
Lead-Acid Batteries
The most affordable option. Can withstand long discharge cycles. However, they are large/heavy and must be replaced every 2-3 years.
Lithium-ion Batteries
More expensive but last 5+ years. Lighter and smaller than lead-acid too. Lifepo4 lithium batteries are the best for solar storage.
For pond/pool lighting, I recommend a 100Ah 12V Lifepo4 lithium battery. This provides ample nighttime capacity while still being reasonably portable.
Sizing the Solar Charge Controller
The charge controller manages the power flow between the solar panel and battery. It prevents overcharging/discharging and extends the battery's life.
When selecting a charge controller, it should have:
- Same voltage as your solar panel and battery
- Current capacity at least 20% higher than your solar panel's wattage
So for a 100W 12V solar panel, get a 12V charge controller rated for at least 120W (10A).
Look for a model with MPPT (maximum power point tracking) to maximize solar charging efficiency.
Selecting the Remaining Components
To complete your solar generator, you will also need:
- Fuse - Protects against short circuits. Get a 15A DC fuse.
- Wires - 10AWG copper wire to handle up to 15A.
- On/Off Switch - For disconnecting the battery when not in use. A locking rocker switch works great.
- Enclosure - Houses all the components. A weatherproof plastic case will do the job.
I also recommend adding battery terminals and USB ports to cleanly connect your lights and devices.
Assembling the Solar Generator
Now it's time to wire up all the components:
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Mount the solar charge controller and on/off switch to the enclosure.
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Connect the solar panel to the controller's "solar" terminals using 10AWG wire. Add the 15A fuse in line on the positive wire for safety.
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Connect the battery's positive and negative terminals to the controller's "battery" terminals, also using 10AWG wire.
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Install battery terminals and USB ports on the outside of the enclosure. Wire them to the battery/controller appropriately.
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Attach lids and test all connections before closing up the enclosure.
Be sure to follow the charge controller's specific wiring instructions as well.
Installing the Solar Generator
When installing your DIY solar generator for your pond/pool lighting system:
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Place the solar panel in full sun, angled towards the south.
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Position the enclosure near the lights, on a dry surface protected from the elements.
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Run wires underground from the lights to the enclosure's battery terminals. Use watertight conduit for protection.
With everything wired up properly, your solar generator can provide renewable energy to illuminate your garden pond or pool for years! Turn it on at dusk and enjoy the sights.
Troubleshooting Issues
If your underwater lights are dim or not turning on, check that:
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Solar panel is clean, unshaded and facing the right direction
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Battery is fully charged - give it some sunny days
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Wiring connections are tight and corrosion-free
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Charge controller and lights are functioning
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Fuse is not blown
With a bit of maintenance and care, your DIY solar generator will provide off-grid power to your garden lighting for a long time. Have fun showing off your creation!