​Garmin Instinct Solar review: best battery under the sun

The sun makes this hiking watch a powerful upgrade
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Garmin Instinct Solar
By Garmin
The Garmin Instinct Solar is a tangibly improved version of the original, and plenty of people will find the benefits of the $100 premium easy to quantify. The battery life and advanced power modes are superb, the GPX navigation and hiking tracking excellent. If you’re more of a casual day hiker then the standard Garmin Instinct is still a great buy. But Garmin has made the best hiking watch even better.

  • Big battery improvements via solar
  • More control over battery
  • Clear screen
  • Chunky design not for everyone
  • Pricey given lack of dedicated data

The Garmin Instinct Solar is a beefy upgrade to the company’s dedicated hiking watch.

For the uninitiated, the Garmin Instinct brings much of the outdoor features of the Fenix, such as long battery life and elevation tracking, in a cheaper package.

The solar edition of the Fenix 6 adds just a few hours of battery life, but the Garmin Instinct Solar ups battery life dramatically. It improves what is already a superb all-rounder.

But the Instinct Solar brings more than just extra battery.

Pulse ox is great for those planning adventures at altitude, and it doubles up for better sleep tracking.

We already reviewed the standard Garmin Instinct, so we’re going to keep this review more focused on the new additions.

Read on to find out which you should go for.

Battery life and price

​Garmin Instinct Solar review: best battery under the sun

The standard Garmin Instinct is still available at . That means anyone considering paying more to get the Solar edition will have a serious eye on battery life.

And the good news is, unlike the Fenix 6 Solar, the Instinct Solar’s battery life improvements are much more drastic.

And the Instinct Solar adds more control over battery life, with the same power saving modes as found on the Fenix range.

Here’s a breakdown:

  • Smartwatch: Up to 24 days/54 days with solar
  • Battery Saver Watch Mode: Up to 56 days/Unlimited with solar
  • GPS: Up to 30 hours/38 hours with solar
  • Max Battery GPS Mode: Up to 70 hours/145 hours with solar
  • Expedition GPS Activity: Up to 28 days/68 days with solar

So let’s run through the caveats first. You need to 3 hours of 50,000 lux sunlight to get the charge to hit the maximum numbers above.

50,000 lux is strong sunlight, so if it’s cloudy you’ll need to be out for longer.

It’s a hugely subjective sliding scale of time and sun strength, and the upshot is these are theoretical numbers.

You’re going to want to use the Solar’s jacket mode and wear it over your clothing to make sure you’re maximising light.

And those walking in winter climates or under tree cover may not get the extra hours at all.

Smartwatch mode is essentially the watch in usual use, with notifications and all-day heart rate turned on.

Battery saver is a new mode, that allows granular control over every charge-zapping feature.

To get unlimited battery life, you’ll need to toggle off activity tracking, HR, phone connectivity, and have the screen in a low power mode that means it only updates the time every minute.

That gave us 66 days of battery life, but get that 3 hours a day of 50,000 lux (or equivalent) and your Instinct will never run out.

In terms of GPS tracked workouts if you do a workout and get the lux, you can extend battery life by 8 hours, from 30 to 38 hours, which isn’t too shabby.

But now the Instinct Solar gets GPS max battery, which is the new name for UltraTrac. That pings the satellite a lot less, which extends battery at the sacrifice of accuracy. That should be fine for walking pace, however.

But you’re also in control of what features you get. 70 hours is the base level with 145 hours if you get all the lux hours. But that means wrist HR is off (turning on will remove 10 hours of battery), and so on.

Finally, Expedition Mode just pings GPS once an hour, so it will only give a general idea of where you've been. That will last a couple of month, with all watch features turned off, and a couple of minimal data screens displayed. It's useful for thru-hikers, and possibly backpackers heading across continents.

It’s a very granular and personal experience. But that means the headline numbers about battery life almost become meaningless. However, in our testing we found these numbers stood up to scrutiny, on hikes, runs and use as a smartwatch.

The upshot is the Instinct Solar adds a lot of use, if you get the lux.

Design and features

​Garmin Instinct Solar review: best battery under the sun

In terms of design, almost nothing has changed from the original Garmin Instinct.

It’s still an over-sized, rugged watch with a 45mm case that’s designed to take a bashing. It’s compliant to military toughness levels and has 10ATM water resistance.

It’s unsubtly styled as a Casio G-SHOCK, and only chunky watch fans need apply.

However, a large case doesn’t mean it’s heavy. The Instinct Solar is so lightweight, weighing just 53g, making it roughly 30% lighter than a Fenix 6.

The screen is a monochrome affair, with a simple 128x128 transflective display.

It’s objectively basic but we love it. The whole interface is designed to be simple and clear, and it’s so easily readable, even in direct sunlight.

The reason for the increased battery advantages by solar is that there’s more room set around the LCD panel than on the Fenix. It’s not really noticeable, but in some light you can see the solar cells.

And then there’s the secondary display. The Instinct has an inset screen in a circle to the top right. It stands apart from the rest of the display and is used to add context to what you’re looking at.

It was a bit awkward at first, coming from Fenix and Forerunner devices, but we ended up loving this extra information.

It can be used to icons to help you navigate menus, estimate battery life, and when following GPX breadcrumbs, it shows the next turning direction.

It’s a clever piece of design and makes the Instinct somewhat unique.

In terms of features there’s naturally a heart rate monitor, with pulse ox capabilities and GPS with GLONASS support.

Sports tracking and data

​Garmin Instinct Solar review: best battery under the sun

The Instinct Solar is an outdoors watch, and that means it’s focussed on hiking, trekking (by that we mean hiking really far) and ultra-running.

Of course, trail runners, general runners and swimmers will find the Instinct useful ¬– but will be better served by other, possibly cheaper, devices such as the Forerunner 245.

The Instinct has modes for swimming, MTB, cardio, yoga, and all sorts – but these are general tracking modes that aren’t worth examining in depth.


​Garmin Instinct Solar review: best battery under the sun

As a hiking watch the Instinct Solar really excels.

First, as we’ve already outlined, is the UltraTrac mode with its huge solar assistant battery potential.

If you’re doing multi-day treks, this offers you the chance to track the whole thing with perfectly decent level of accuracy.

Runners will want to stick with GPS has the low frequency of pings to the satellite does affect accuracy, but for hiking it’s just perfect.

In terms of data it tracks speed, time, distance and elevation ¬– and of course heart rate and calories (if battery saving modes haven’t nixed these features).

​Garmin Instinct Solar review: best battery under the sun

There’s no TOPO mapping which you’ll find on Fenix 6, but you can track breadcrumbs of your walk and you can return to start if lost and the compass will guide you back.

The built in compass uses the inset screen and has its own widget, which can help you keep a heading.

We found it slightly slow to respond to changes in heading, but generally spot on.

Hiking tracking really comes into its own when you load a GPX route.

You can follow the course on the Instinct’s screen using the compass, and the inset screen will show you the upcoming turn direction, like a trekking satnav.

The watch will count down to turns too, giving you notice of a change in direction.

You can zoom and pan, which is a little fiddly, which we actually needed to do quite a lot on our test hike. However, we loved the elevation screen that shows your progress through the elevation profile.


​Garmin Instinct Solar review: best battery under the sun

The run tracking is no-where near as detailed as the Fenix 6 or top end Forerunners, and is certainly better suited to trails with a focus on elevation.

Auto Climb kicks in when ascending and descending, giving you a focus on your speed and elevation climbed.

On standard runs you get the usual basic metrics, with elevation and heart rate zones.

However, there’s no focus on VO2 Max, recovery, or training effect that you get on any of the mid-range Forerunner devices.

That makes the Instinct a little lacking in our books, and just proves this is a niche device for the trekking and hiking crew.

Heart rate tracking

​Garmin Instinct Solar review: best battery under the sun

The Instinct Solar will track heart rate 24/7 and during activities.

We found identical performance as Fenix and other top-end Garmins.

For most people, the optical Elevate HR sensor will be fine.

In steady sessions, hikes, runs, trail runs we found solid performance against a chest strap.

Every optical sensor falls down when pushed to the max, and if you do want to take the Instinct Solar for a HIIT session, you will find lags and bad data.

You can always pair an ANT+ chest strap, which will offer more reliable data when pushing and recovering quickly.

There is one difference though with the Instinct Solar.

If features an SpO2 sensor, which is not present on the first Instinct.

This can be used in two ways.

There’s a new Acclimation widget, from which a blood oxygen check can be performed by pressing the main button.

That will show your current blood oxygen level, and is predominately useful for those at altitude, checking how their body is adjusting.

It’s useful for those plotting mountain treks, or perhaps spending time in countries like Argentina or Bolivia where altitude acclimatisation is important.

Fitness tracking

The second use is to turn SpO2 on for tracking during sleep. This can then pick up possible sleep issues.

It’s a useful data point, although turned off by default. If you feel you’re sleeping badly, or spending time sleeping at altitude, it’s there to be turned on.

There is a downside, however. Turning on pulse ox for sleep will half your battery life, just for taking some oxygen readings at night. For most people, that will be a deal breaker.

The rest of the fitness tracking is a pretty standard affair, with HR over the last four hours and weekly resting HR tracked on the watch and in Garmin Connect, as well as steps, calories and more.

The Instinct Solar does tap into Body Battery and Stress Monitoring algorithms.

They heart rate variability to see how much pressure your body is under, and can be a great tool for those who are training, doing long adventures, or taking an interest in wellness.

TAGGED Garmin Sport

How we test

James Stables


James is the co-founder of Wareable, and he has been a technology journalist for 15 years.

He started his career at Future Publishing, James became the features editor of T3 Magazine and T3.com and was a regular contributor to TechRadar – before leaving Future Publishing to found Wareable in 2014.

James has been at the helm of Wareable since 2014 and has become one of the leading experts in wearable technologies globally. He has reviewed, tested, and covered pretty much every wearable on the market, and is passionate about the evolving industry, and wearables helping people achieve healthier and happier lives.

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