One of the more popular features of the current crop of red dots is the presence of solar panels. Holosun, a Chinese company, has made solar fail-safe backups a part of its core brand. I own and use a few Holosun optics and have had almost no real complaints. My oldest is an original 507C with the big buttons, pre-Trijicon lawsuit.
I’ve used solar panels on red dots quite a bit. I use the Holosun 510C as my rifle review optic, and it hasn’t had a battery in at least a year. I’ve run with just the solar panel during reviews, and living in the Sunshine State is one of the few reasons why this works so well for me.
Last year, I attended a class on red dots at War Hogg Tactical. The lead instructor, Rick Hogg, didn’t discuss the various brands of red dots much, but briefly discussed solar panels in a surface-level conversation about red dots.
He relayed a story about witnessing two optics with solar panels go down due to water intrusion. I can’t recall if he mentioned a specific brand or model, but he didn’t care for solar panels on his optics, saying they were a weak point and not suitable for duty optics.
Are Solar Panels A Weak Point?
As a guy with more than a few red dots with solar panels, this banged around in my head for quite some time. Were my Holosuns just waiting to die? I bookmarked the idea and kept a close eye on my optics. This was in the summer, and by January 2025, I noticed the solar panel of my Holosun SCRS was cracked.
I’m always looking for an opportunity to test and evaluate a piece of gear’s durability, so I took this as an opportunity rather than fretting about a broken part of an optic. How the solar panel cracked is unknown to me. I pulled the gun out of the safe, shot it, and then put it back.
Somewhere along the way, it broke, or maybe it broke in the safe, and I simply didn’t notice. Regardless, I had a broken solar panel and an opportunity to see if it would lead to water intrusion or cause the optic to stop working completely.
How do we test something like this? First, I wanted to see if there were any issues before testing with the panel. I adjusted the brightness up and down without a problem. I switched to automatic mode and tested the optic; no problems were noticed. Next, I switched to lockout mode, and it worked fine.
It was functioning completely fine. With that established, I started with water intrusion.
Solar Panels and Water
Water intrusion is the fancy, dare I say tactical, way to say I put the optic in the sink, turned on the faucet, and let water stream over the solar panel. I did 30 seconds. No problems. From there, I added 30 seconds and rechecked it, and there were no problems.
After a minute, I kept upping the time between checks. I went from 60 seconds to 90, to 120, and then to 180. Then my wife said to get out of the way because she needed the sink.
The last part is a joke, but the optic had direct water flow for 6.5 minutes and worked every time. Looking over the now-clean optic, I realized the panel wasn’t broken. What if it was more broken?
I gave it a handle-first tap with the screwdriver — nothing crazy, but the handle’s weight was enough to split the panel slightly more. I gave it a few more taps, and the lines in the glass increased.
I checked the function, and it still worked fine. I resubmitted it to the water test, and once more, it passed.
Outside/Inside
Water wasn’t a problem, so what about fog? Rapidly moving the optic from hot to cold would show me whether there were any internal fog problems or whether the cracks in the solar panels caused any internal changes.
I hit it with my wife’s hair dryer. Imagine her face — I was putting a red dot in the sink 10 minutes ago, and now I’m using her blow dryer to heat it up? I didn’t have to imagine it.
It was a bit of a curious annoyance. I assured her it was in the name of science. I didn’t heat the optic to an absurd temperature until it was cozy and warm to the touch.
Then I chucked it outside into the cold winter night and waited a few minutes. At this point, I kinda wanted something to happen, but alas, I was disappointed. We got some external fog but nothing internal.
Finally, with limited options, I filled a bowl with water, tossed the optic in, and went to bed. The following day, I pulled it out, dutifully washed the dish, and discovered that the optic had remained waterproof.
However, I could no longer switch to manual mode. The optic was permanently stuck on automatic mode. No combination of button presses would swap to manual mode. I even broke out the manual and ensured I was doing it right. It’s stuck on auto.
End Result
Did the solar panel breaking cause the automatic mode to lock in? Probably not. It might have just been a night’s worth of water, changing temperatures, and raps with a screwdriver. That doesn’t mean it’s not a possibility.
It does seem like breaking solar panels doesn’t break optics, at least with the Holosun SCRS. Solar panels could be a weak point, but it likely isn’t a major concern. Optics quality differs, and while Holosun is Chinese, they build sturdy optics.
While I don’t carry a firearm for a living I would feel confident with a solar panel on my home defense or concealed carry firearm. Duty guns, though, get exposed to a ton of exposure and abuse and I’d prefer a sealed optic in that case. I’d take Rick Hogg’s advice and stay away from solar panels for duty use.
