# Fire Alarm System vs PV Calculator.

The clearest difference is in-app purchases: Fire Alarm System at none against PV Calculator.'s 1. Fire Alarm System also leads on update cadence (every 5 days vs every 7 months). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. PV Calculator. sells 1 one-off in-app purchase. Fire Alarm System asks for nothing beyond the download.

Fire Alarm System ships an update every 5 days, PV Calculator. every 7 months. The most recent releases landed on September 19, 2026 and August 20, 2026 respectively.

## The numbers

| Metric | Fire Alarm System | PV Calculator. |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (2 ratings)](https://appshunter.io/ios/app/pv-calculator/id6758427564/reviews)** |
| Number of ratings | — | **2** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Every 5 days** | Every 7 months |
| Monetization | — | Free with in-app purchases |
| Size | 33 MB | 52 MB |
| Requires iOS | **12.4** | 13.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Hoan Ho](https://appshunter.io/developer/1631498878) | [Nanjibhai Gorasiya](https://appshunter.io/developer/1834066312) |

## What reviewers say

### Fire Alarm System

[App page](https://appshunter.io/ios/app/fire-alarm-system/id6479693179)

**Features:** macOS Compatibility

**In-app purchases:** none


### PV Calculator.

[App page](https://appshunter.io/ios/app/pv-calculator/id6758427564)

This tool simplifies solar photovoltaic system design and analysis for professionals and students. It offers a comprehensive Energy Hub with multiple calculators, providing instant results, visual charts, and clear insights for efficient PV system planning and optimization.

**Highlights:** Energy Hub with multiple solar calculators, Calculate solar panel power output, Analyze energy generation (daily, monthly, yearly), Design solar array size, Calculate system voltage and configuration, Instant calculation results, Visual charts and performance summaries

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Lifetime premium | $9.99 | one-time |


## Frequently asked questions

### Is Fire Alarm System free?

Fire Alarm System is free to download, with no in-app purchases.

### Is PV Calculator. free?

PV Calculator. is free to download, with in-app purchases available.

### Do Fire Alarm System or PV Calculator. have ads?

Neither Fire Alarm System nor PV Calculator. shows ads.

### Which is updated more often, Fire Alarm System or PV Calculator.?

Fire Alarm System ships an update every 5 days, and PV Calculator. every 7 months. Most recently, Fire Alarm System was updated on September 19, 2026 and PV Calculator. on August 20, 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.*