# SolarMark vs CairnOS

The clearest difference is update cadence: CairnOS at every 4 days against SolarMark's monthly. SolarMark's advantage is iOS requirement (15.1 vs 18.0). On price, rating, ratings volume and ads there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

On the App Store both sit at effectively the same score — 5.0 for SolarMark against 5.0 for CairnOS. Both are backed by a comparable volume of ratings — 1 and 2 respectively.

SolarMark ships an update monthly, CairnOS every 4 days. The most recent releases landed on November 5, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | SolarMark | CairnOS |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [5.0 (1 ratings)](https://appshunter.io/ios/app/solarmark/id6776068343/reviews) | [5.0 (2 ratings)](https://appshunter.io/ios/app/cairnos/id6819076554/reviews) |
| Number of ratings | 1 | **2** |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Monthly | **Every 4 days** |
| Monetization | Free | Free |
| Size | 55 MB | 54 MB |
| Requires iOS | **15.1** | 18.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [SolarMark Software LLC](https://appshunter.io/developer/6776062789) | [Christopher Van Hoose](https://appshunter.io/developer/1510007987) |

## What reviewers say

### SolarMark

[App page](https://appshunter.io/ios/app/solarmark/id6776068343)

Monitor your solar power generation and battery storage systems locally and privately. Visualize real-time energy flow, get intelligent predictions, and receive protection alerts without relying on cloud services.

**Highlights:** Direct Modbus TCP polling, Live power flow dashboard, Multi-device infrastructure management, Localized weather-based generation predictions, On-device analytics ledger, Open data export (CSV), Protection alerts (no-generation, performance, thermal)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### CairnOS

[App page](https://appshunter.io/ios/app/cairnos/id6819076554)

Communicate off-grid using a mesh network of radios. Send messages, monitor network status, and explore maps without cell service or internet. Features include direct messages, channels, and on-device translation.

**Highlights:** LoRa mesh network communication, Direct messages and channels, On-device message translation, Network status dashboard, Offline map downloads, Message signing and verification

**Features:** macOS Compatibility, Siri integration, Vision Pro support, iPhone Duo support

**In-app purchases:** none


## Frequently asked questions

### Is SolarMark free?

SolarMark is free to download, with no in-app purchases.

### Is CairnOS free?

CairnOS is free to download, with no in-app purchases.

### Which has better reviews, SolarMark or CairnOS?

SolarMark and CairnOS are both rated 5.0 out of 5 on the App Store, from 1 and 2 ratings respectively.

### Do SolarMark or CairnOS have ads?

Neither SolarMark nor CairnOS shows ads.

### Which is updated more often, SolarMark or CairnOS?

SolarMark ships an update monthly, and CairnOS every 4 days. Most recently, SolarMark was updated on November 5, 2026 and CairnOS on October 31, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*