# LSI Calculator vs Erebus Solar

The clearest difference is review sentiment: LSI Calculator at 100% against Erebus Solar's 0%. LSI Calculator also leads on rating (4.4 vs 3.7) and device support (3 vs 1). Erebus Solar's advantage is update cadence (every 2 weeks vs every 2 months). On price, ratings volume, ads and in-app purchases there is nothing between them.

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

LSI Calculator holds the better App Store score, 4.4 against 3.7. Both are backed by a comparable volume of ratings — 5 and 3 respectively. Written reviews point the same way: 100% of LSI Calculator's written reviews are positive against 0% of Erebus Solar's.

LSI Calculator ships an update every 2 months, Erebus Solar every 2 weeks. The most recent releases landed on October 5, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | LSI Calculator | Erebus Solar |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.4 (5 ratings)](https://appshunter.io/ios/app/lsi-calculator/id1233049990/reviews)** | [3.7 (3 ratings)](https://appshunter.io/ios/app/erebus-solar/id6790828521/reviews) |
| Number of ratings | **5** | 3 |
| Positive reviews | **100.0% of reviews** | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 2 weeks** |
| Monetization | Free | Free |
| Size | 52 MB | 19 MB |
| Requires iOS | **11.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 12+ | 4+ |
| Developer | [Pure Planet Science & Technology, Inc.](https://appshunter.io/developer/1234693265) | [Todd Evans](https://appshunter.io/developer/6790828523) |

## What reviewers say

### LSI Calculator

[App page](https://appshunter.io/ios/app/lsi-calculator/id1233049990)

This app provides tools and educational resources to help users manage water systems, focusing on eco-friendly treatments for pools and spas. It aims to make water maintenance accessible to everyone, regardless of their experience level.

**Highlights:** Water science education, Pool and spa water management, Eco-friendly treatment guidance, NSF/ANSI Certified product information, Tools for water system management

**Features:** macOS Compatibility

**In-app purchases:** none


### Erebus Solar

[App page](https://appshunter.io/ios/app/erebus-solar/id6790828521)

This app helps solar professionals measure on-site shade using their phone's sensors. It generates horizon files compatible with leading PV design software, aiding in accurate solar production estimates.

**Highlights:** AR sun path visualization, Automatic sky capture, Sky Editor for obstruction tracing, Annual solar access analysis, PDF shade report export, Horizon file generation for design tools, Project organization by site

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

**In-app purchases:** none


## Frequently asked questions

### Is LSI Calculator free?

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

### Is Erebus Solar free?

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

### Which has better reviews, LSI Calculator or Erebus Solar?

LSI Calculator is rated higher. LSI Calculator averages 4.4 out of 5 from 5 ratings, while Erebus Solar averages 3.7 from 3 ratings.

### Do LSI Calculator or Erebus Solar have ads?

Neither LSI Calculator nor Erebus Solar shows ads.

### Which is updated more often, LSI Calculator or Erebus Solar?

LSI Calculator ships an update every 2 months, and Erebus Solar every 2 weeks. Most recently, LSI Calculator was updated on October 5, 2026 and Erebus Solar on October 14, 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.*