Holosun SCS Review: Solar Glock Optic Tested

The Holosun SCS MOS mounts straight to a Glock MOS slide with no adapter plate, sits low enough to use the factory sights, and runs on a sealed battery that its solar cell recharges. On my 10mm Glock 20 it held zero, even after one mounting screw sheared (my fault, I likely overtightened it), and it survived half an hour underwater. Brightness is automatic only and runs a bit bright.

Specs, SCS vs SCS Carry and the verdict come first, then the full review.

Holosun SCS MOS Specs

	Holosun SCS MOS
Mounting	Direct to Glock MOS slide, no plate
Other versions	Walther PDP 2.0, Sig P320, H&K VP9, S&W M&P 2.0
Reticles	32 MOA circle with 2 MOA dot, 2 MOA dot, 32 MOA circle
Color	Green
Power	Solar cell charges a sealed internal battery; up to 20,000 hours (Holosun)
Brightness	Automatic, with a 30 minute max override
Construction	Grade 5 titanium
Water rating	IP68
Test pistol	Glock 20 MOS, 10mm
MSRP when tested	$412

SCS vs SCS Carry

The SCS covered here is built around full size slide footprints such as the Glock MOS. For the smaller carry version, see our Holosun SCS Carry review.

Verdict

• Good: no plate on Glock MOS, low enough for stock sights, no battery changes, titanium housing, simple controls.
• Know this: brightness is not user adjustable and runs about two levels bright, green reticle only, and torque the screws carefully.

See how it compares in our pistol red dot rankings.

Related: best Holosun red dots and the Solar Charging Sight debut.

🛒 Check Current Price for Holosun SCS on GunsAmerica

The Holosun SCS promises a pistol red dot with direct Glock MOS mounting, solar charging, no battery swaps, and enough toughness to ride on a 10mm Glock 20. I ran it like a defensive optic, worried about the solar power, broke a screw, dunked it in water, and still came away thinking this little green dot is one of the easiest pistol optics to live with.

Holosun is pushing boundaries with its new micro-optic, the SCS. It is not just another tiny red dot trying to crowd onto a pistol slide. The Holosun SCS is built around one big promise: make a pistol red dot easier to mount, easier to power, and easier to live with.

As a junior in college, I was short on funds but needed a solid red dot for my AR. After a bit of research and a friend’s recommendation, I bought a Holosun HS403R. Six years later, that sight continues to function, and I continue to look to Holosun whenever I’m in the market for a red dot.

That history matters because Holosun earned some trust the old-fashioned way: by selling me something when I did not have much money, then having that thing keep working long after I expected it to. So when the Holosun SCS MOS showed up with solar charging, a sealed internal battery, a Glock MOS footprint, and no adapter plate requirement, I was interested. Also skeptical, because “no battery changes” sounds great right up until the dot disappears when you need it.

Holosun SCS MOS Mounting: Direct Fit, Fewer Screws, Less Drama

The SCS sets itself apart from other micro-optics by having each model’s footprint tailored to a specific gun. In my case, the SCS MOS is made to mount directly to a Glock MOS slide without the need for an adapter plate. Models designed to fit the Walther PDP 2.0, Sig P320, H&K VP9, and S&W M&P 2.0 are also available.

The direct optic-to-slide connection requires half as many screws as mounts that use adapter plates. In my mind, that means half as many opportunities for the optic to come loose or lose zero. The SCS nests well into the optics cut of my Glock 20 MOS. The hefty slide of this 10mm is a bit wider than the body of the SCS but it makes no difference in its function. I checked the slide width of my Glock 19 and it matches the SCS closely.

The deletion of the adapter plate also lets the optic ride significantly lower on the slide. In fact, it is low enough for the stock sights to fully clear the optic. I have always replaced the plastic Glock sights with metal ones but at least I don’t have to buy suppressor height sights to be able to cowitness through the optic window.

Not having to deal with adapter plates, getting a slide milled, or aftermarket sights really lower the barrier to entry when someone wants to get their first pistol optic. I have had first-hand experience with people becoming uninterested once they learn it isn’t as easy as slapping a red dot on their flat-top AR upper. For those people, the SCS could be a simple plug-and-play solution.

That simplicity is the best argument for the Holosun SCS MOS. It does not ask a new pistol optic owner to understand plate systems, screw lengths, optic heights, or suppressor sight math before they even get to the range. Put it on the slide, zero it, and start learning the dot. That is exactly the kind of setup that can move someone from “I should try pistol optics someday” to actually showing up with one mounted.

Solar Powered SCS: No Battery Door, No Swap, No Excuses

The other feature that really sets this optic apart is in the name, SCS (Solar Charging Sight). Holosun has been using solar cells on their optics for years but up until now, it has only been as a backup if the removable battery fails. With the SCS the solar cell actually charges a battery that is permanently encased in the optic.

My main concern with a solar-powered optic is that one day I may draw my gun from a bag or other dark place and have a dead battery. After doing some research and tests of my own, I found these worries to be unwarranted. When fully charged, the internal battery can power the sight for up to 20,000 hours, depending on brightness and reticle selection. That’s over two years of life, and don’t forget, every time the solar cell sees a glimpse of light, natural or artificial, the battery will recharge.

That does not mean I suddenly stopped being suspicious of anything battery-powered on a handgun. I still like simple things, and I still like things I can verify. But the Holosun SCS gives you a pretty comforting margin. If the optic has enough charge to run for up to 20,000 hours, and it is constantly topping itself off whenever it sees light, the usual “did I change that battery?” anxiety starts to fade into the background.

Holosun SCS Reticles: Three Green Options Without the Button Circus

The SCS has three reticle options. First, A 32 MOA circle with a 2 MOA dot in the center. Next, just the 2 MOA dot. This is the most power-efficient and generally my favorite. Finally, the 32 MOA circle without the dot. The three reticles are changed by holding down the button on the side of the optic. After you cycle through all the reticles, the next press will turn the optic off.

Currently, the reticle just comes in green. The only reason I see to go with green vs. red is that our eye picks up the green color more easily so the dot doesn’t need to be as bright. With a tiny internal battery, I am sure they want to save power wherever possible.

The brightness is not user-adjustable. The unit takes in ambient light levels and automatically adjusts the brightness accordingly. I am not usually impressed with auto brightness but this one generally does a good job. My only gripe is that it’s a little too bright for most lighting conditions. If it were a sight with manual brightness controls I would say it is about two levels too high. But, considering its role as a defensive optic, I would rather have my two MOA dots bloom out than have it too dim and not be able to see it in a bright environment.

That is the kind of tradeoff I can live with. For target work, a dot that is two levels too bright might annoy me. For a defensive pistol optic, I am far more forgiving. A little bloom is not ideal, but a disappearing dot is much worse. The Holosun SCS MOS leans toward visibility, and while I would still like manual control, I understand the decision.

In the unlikely scenario where the dot is too dim, you can tap the button to activate the brightness override. Doing this will max out the brightness for half an hour. Pressing the button again will put the brightness control back in auto.

10mm Recoil, Water, and One Broken Screw: How Tough Is the Holosun SCS?

A Grade 5 titanium construction makes the SCS both durable and lightweight. To test the optic’s ability to retain zero, I mounted it to my 10mm Glock 20. I figured the heavy recoil would accelerate any problems that may take longer to appear on a lighter recoiling gun. I only had one issue throughout my test.

Before I had finished my first mag, one of the mounting screws sheared off. The optic retained zero with the one screw it had left so I finished off the box of ammo before heading home. I was able to extract the broken screw and replace it with a new one. In retrospect, I probably overtightened them the first time. I have had no issues since.

That little screw drama is worth mentioning because it is exactly the kind of thing that can happen when mounting pistol optics. It also says something useful about the SCS. Even after losing a screw, the optic stayed in place well enough to retain zero through the rest of the box. I would not recommend running it that way, obviously, but it was a better accidental test than I planned.

The unit has an IP68 immersion rating. This means that it can withstand submersion in at least one meter of water for at least half an hour. Unless you plan to go scuba diving with your carry gun, this optic should have no problem withstanding the wettest environments.

I submerged the sight for half an hour without issue, which is about as much water testing as most normal pistol optics will ever need. Rain, sweat, mud, wet range bags, and the kind of miserable weather that makes you question your hobbies should not be a major concern here. The SCS is not just a clever solar experiment. It is built like an optic meant to stay mounted.

Holosun SCS Pros and Cons: Simple, Smart, and Slightly Bright

Holosun SCS Review Verdict: This Is the Easy Button for Pistol Optics

I think this is a good option for anyone who values simplicity. Easy mounting and no battery changes make it very easy to own and operate. The price is pretty reasonable too. The MSRP is currently $412 which is higher than most Holosun micro-dots but the others don’t offer the same benefits.

What makes it work is not one single feature. It is the stack of convenience. No plate. No battery door. No suppressor-height sight requirement on my setup. No constant brightness fiddling. No complicated reticle menu. For someone who already likes pistol optics, those are nice benefits. For someone buying their first pistol optic, they may be the difference between actually using the thing and tossing it into the parts drawer with the other “great ideas” that became projects.

The Holosun SCS MOS has flaws. I still want more brightness control, and my broken screw was a reminder that mounting details matter. But as a solar-powered pistol optic designed to make the Glock MOS system easier, cleaner, and less intimidating, the SCS does what it set out to do.

FAQ

Does the Holosun SCS need an adapter plate for Glock MOS?

No. The SCS MOS mounts directly to a Glock MOS slide.

How long does the Holosun SCS battery last?

Holosun rates it up to 20,000 hours depending on brightness and reticle, and the solar cell recharges it in light.

Can you co-witness the Holosun SCS with stock Glock sights?

On my Glock 20 MOS, the optic sat low enough for the factory sights to clear it.