# Watt: Solar for Van & RV — Battery, panels, wire & fuse

> Solar system sizing assistant for DIY van, RV, cabin, and tiny home conversions. (iPhone/iPad app by Roman Kopaliani.)

- Source: https://appshunter.io/ios/app/watt-solar-for-van-and-rv/id6777471058 (this page in markdown: same URL + `.md`)
- Developer: [Roman Kopaliani](https://appshunter.io/developer/1635315269)
- Category: Utilities, Lifestyle
- Price: Free with in-app purchases
- Rating: 5.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 17.0 · 3 MB
- Languages: American English
- Released: 2026-06-11
- Data updated: 2026-08-21
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/watt-solar-for-van-and-rv/id6777471058/reviews.md

## What is Watt?

Pay once. No subscription, no ads, no account. Works offline.

Watt is the iOS solar sizing assistant for DIY van conversions, RVs, off-grid cabins, and tiny homes. Enter the appliances on board, pick your gear, and Watt computes the exact battery bank, panel array, MPPT controller, inverter, wire AWG, and fuse rating you need — with cited sources at every step.

Try every feature free for 2 days. Then unlock for good with a one-time purchase.

Features
• Daily energy audit — Σ(W × h) across appliances, AC loads divided by inverter efficiency
• Battery bank sizing — required usable Ah for your autonomy goal, chemistry-aware safe depth-of-discharge (LFP, AGM, flooded, gel)
• Solar array sizing — required panel wattage from US state-level NREL PVWatts peak sun hours
• MPPT controller sizing — output current with NEC 690.8 ×1.25 safety multiplier
• Cold-Voc check — warns when worst-case Voc lands within 10% of your controller's max input (the failure mode that kills MPPT controllers)
• Inverter sizing — continuous wattage with 1.1× safety on simultaneous AC load
• Wire AWG selection — NEC 2023 Table 310.16 ampacity sized to keep round-trip voltage drop ≤ 3% per NEC 210.19 Note 4
• Recommended fuse — 1.25× continuous current rounded to standard sizes per NEC 210.20
• Brand-cited gear picks — Renogy, Battle Born, Victron, Ampere Time, Redodo, Eco-Worthy, Bluetti, EcoFlow, Goal Zero, Rich Solar, BougeRV, Sunpower, Newpowa, HQST, Outback, EPEVER
• 92 cited appliance templates — from MaxxFan and 12V fridges to Starlink, e-bike chargers, and induction cooktops
• Universal app for iPhone and iPad

For van life — sprinter and promaster DIY conversions are the lead audience — plus RV upgraders, off-grid cabin builders, and tiny home setups.

$6.99 one-time after the 2-day trial. No subscription, no ads, no account, no cloud.

Educational guidance: Watt presents brand-cited sizing for educational purposes. Consult a licensed electrician for code-compliant installation, especially wire and fuse sizes.

Privacy: Watt collects nothing. No analytics, no accounts, no network requests. Your rig setup lives on your device.

## Key features

- Solar system sizing calculations
- Battery bank and panel array estimation
- MPPT controller and inverter sizing
- Wire AWG and fuse rating recommendations
- Appliance and gear selection
- Cited sources and brand recommendations
- Offline functionality

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Watt Pro (lifetime) | $6.99 | one-time |


## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/watt-solar-for-van-and-rv/id6777471058/reviews.md

### 5/5 — Nice

*2026-06-15*

Surprisingly useful for the price

## Frequently asked questions about Watt

### What is Watt used for?

Watt is an iOS solar sizing assistant designed for DIY van conversions, RVs, off-grid cabins, and tiny homes. It helps users calculate the necessary components for their solar power systems, including battery banks, solar arrays, controllers, and inverters.

### Does Watt have a subscription?

No, Watt operates on a pay-once model. After a 2-day free trial, you can unlock all features permanently with a one-time purchase. There are no ongoing subscriptions, ads, or accounts required.

### Can I use Watt offline?

Yes, Watt is designed to work offline. This means you can access all its features and perform calculations without needing an internet connection, making it ideal for remote locations or during van conversions.

### What kind of appliances can I input into Watt?

Watt includes 92 cited appliance templates, covering a wide range of devices commonly used in off-grid setups. This includes items like MaxxFans, 12V refrigerators, Starlink systems, e-bike chargers, and induction cooktops.

### Does Watt provide specific brand recommendations?

Yes, Watt offers brand-cited gear picks for various components. It lists popular brands such as Renogy, Battle Born, Victron, and EcoFlow, among others, to help users select compatible equipment.

### What is the pricing for Watt?

Watt is free to download and use for a 2-day trial period. After the trial, a one-time purchase of $6.99 is required to unlock all features permanently. There are no subscriptions or ads.

### Is Watt suitable for beginners?

Watt provides educational guidance and cited sources for its calculations, making it a valuable tool for beginners. However, for code-compliant installation, especially for wiring and fuse sizes, consulting a licensed electrician is recommended.

### What devices does Watt support?

Watt is a universal app that supports both iPhone and iPad devices. This allows users to access the solar sizing assistant on their preferred Apple mobile device.

## Version history (last 3 releases)

### 1.2 — 2026-08-15

Maintenance update. No feature changes.

### 1.1 — 2026-07-16

The number keyboard now has a Done button, so you can dismiss it when you're finished. Thanks to everyone who wrote in about this.

### 1.0 — 2026-06-11

No release notes.

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## More apps by Roman Kopaliani

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All apps by Roman Kopaliani: https://appshunter.io/developer/1635315269

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-21.*