How to Mount Solar Lights to 4×4 Aluminum Deck Posts (Without Glue)

We just had our deck rebuilt, and I knew right away I wanted to add some solar lights to the posts. It wasn’t just about function, sure, a little light is nice but more about that clean, finished look.

The solar lights I picked are LED and can switch between different colors, which is perfect for setting the mood be it a summer barbecue or a quiet night with a drink in hand.

But there was a catch.

These lights were designed for wood posts, and my deck has 4×4 aluminum posts. Most solar post caps are made to be compression-mounted on wood, meaning they just slide on and stay in place. That wasn’t going to work here. I didn’t want to glue them down either. I wanted something clean, secure, and removable.

Here’s exactly how I made it work, and how you can too.

Why It Matters: Installing Solar Lights on Aluminum Deck Posts

If you’ve got aluminum posts, your options are limited unless you’re willing to do a little work. But don’t worry, it’s not complicated. You just need the right tools, a little patience, and a clear plan.

This guide walks you through everything: what tools to use, why they matter, and how to get the best-looking result.

What You Need to Install Solar Lights

• LED solar lights (for 4×4 wood posts)
• 1/8 in. x 2-3/4 in. Cobalt metal drill bit
• Cordless driver drill
• WD-40 (or any cutting oil)
• #8 1/2-inch black hex head screws
• Safety goggles
• Tape measure and pencil
• Level (optional but helpful)

Best Tools for Aluminum Post Installation

Cobalt Drill Bit

Cobalt bits are designed for drilling into metal. They stay cooler longer and resist dulling better than standard steel bits. Aluminum is a soft metal, but you still want something that won’t wear out halfway through the job.

Pilot Holes

Drilling pilot holes is critical when working with metal. They help prevent the material from cracking or distorting, and they make it much easier to drive screws straight. Plus, your screws will hold tighter and last longer.

WD-40

Spraying WD-40 (or any lubricant) onto the bit helps reduce heat and friction, which preserves both your drill bit and your post. It also gives you cleaner holes and less chance of damaging your light base.

Hex Head Screws

I used black #8 1/2-inch hex head screws. Why hex head? They look sharper than standard Phillips screws and are easier to drive straight. And I went with black because it blends better with the post and light base. It’s a small detail, but it makes a big difference.

Related: How To Clean Wood Flooring: A Landlord Answers

Step-by-Step Guide: How to Mount Solar Lights on Aluminum Posts

Step 1: Check the Post and Test the Fit

Before doing anything, take a good look at your 4×4 aluminum post. Wipe down the surface to remove any dust, grime, or oxidation. Make sure the post top is flat and free of dents or irregular edges.

This gives you a clean base for your light to sit flush and helps prevent any wobble or long-term shifting.

Tip: Use a level if you want to make sure the light is square on all sides, especially if your post isn’t perfectly symmetrical.

Step 2: Position the Light and Drill Pilot Holes

Now grab your solar light and set it on top of the post. Most models come with a base that has small screw holes in the corners. Line it up just how you want it to sit, check that it’s centered and square.

Then, while holding the light in place, use a pencil or fine-tip marker to mark the screw holes. Once marked, drill pilot holes straight through the base and into the aluminum post using a cobalt bit.

Also, don’t forget to throw on some safety goggles, metal shavings will fly once you start drilling. Use WD-40 to keep your bit cool and reduce friction as you go. Go slow, let the drill do the work.

Tip: If you notice the bit heating up or the aluminum discoloring, stop and let it cool before continuing.

Step 3: Use the Right Tools and Prep the Screws

Before attaching the light for good, get your tools lined up: a cordless drill, a hex-head bit adapter, and some black #8 ½-inch hex screws. These are easier to drive into metal and look cleaner against dark posts.

Step 4: Drive in the Screws and Finish It Off

With the pilot holes drilled and your light still lined up, it’s time to secure it for good. Grab your black #8 ½-inch hex screws and start driving them in.

A hex-head bit adapter on your drill will make this easy and keep things straight. Go one screw at a time and keep the pressure firm but controlled. Don’t overtighten, aluminum can strip if you push too hard.

Once all screws are in and the light feels solid, you’re done.

Related: How to Fix a Door That Won’t Close Properly: Easy Hinge Repair Guide

Bonus Tip: No-Drill Way to Mount Solar Lights

If drilling feels intimidating or you’re worried about damaging your posts, consider using industrial-strength Velcro strips or VHB (very high bond) tape as a last resort. They won’t last as long or be as sturdy, but it’s a non-permanent solution that works if you’re renting or not ready to commit.

How to Mount Solar Lights to 4×4 Aluminum Deck Posts (Without Glue)

Find out how to mount solar lights to aluminum deck posts easily, ensuring a clean and secure installation.

Print Recipe Pin Recipe

Prep Time 20 minutes mins

Equipment

• LED solar lights (for 4×4 wood posts)
• 1/8 in. x 2-3/4 in. Cobalt metal drill bit
• Cordless driver drill
• WD-40 (or any cutting oil)
• #8 1/2-inch black hex head screws
• Safety Goggles
• Tape measure and pencil
• Level (optional but helpful)

Instructions

 

• Before doing anything, take a good look at your 4×4 aluminum post. Wipe down the surface to remove any dust, grime, or oxidation. Make sure the post top is flat and free of dents or irregular edges. This gives you a clean base for your light to sit flush and helps prevent any wobble or long-term shifting.
  
• Now grab your solar light and set it on top of the post. Most models come with a base that has small screw holes in the corners. Line it up just how you want it to sit, check that it’s centered and square. Then, while holding the light in place, use a pencil or fine-tip marker to mark the screw holes. Once marked, drill pilot holes straight through the base and into the aluminum post using a cobalt bit. Also, don’t forget to throw on some safety goggles, metal shavings will fly once you start drilling. Use WD-40 to keep your bit cool and reduce friction as you go. Go slow, let the drill do the work.
  
• Before attaching the light for good, get your tools lined up: a cordless drill, a hex-head bit adapter, and some black #8 ½-inch hex screws. These are easier to drive into metal and look cleaner against dark posts.
  
• With the pilot holes drilled and your light still lined up, it’s time to secure it for good. Grab your black #8 ½-inch hex screws and start driving them in. A hex-head bit adapter on your drill will make this easy and keep things straight. Go one screw at a time and keep the pressure firm but controlled. Don’t overtighten, aluminum can strip if you push too hard. Once all screws are in and the light feels solid, you’re done.
  

Making the Most of Your Solar Light Setup

Mounting solar lights to aluminum posts takes a little effort, but the result is worth it. The glow at night looks great, the lights are secure, and it adds a big finishing touch to any deck or patio.

If you just had a deck rebuilt like I did, take the time to do it right, you’ll be looking at those posts every day. Might as well make them shine.

🙋‍♀️If you like what you just read, then subscribe to my newsletter and follow us on YouTube.👈

• How to Fix Gaps in Luxury Plank Flooring
• How to Replace or Clean a Bathroom Faucet Aerator: Save Water, Boost Pressure, and Cut Costs
• How to Easily and Safely Get Rid of Bacon Grease