Comparison

Penned vs Erebus Solar

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Penned

A minimalist handwriting app designed for privacy, keeping all your notes securely on your device. It features natural writing with Apple Pencil, on-device AI text recognition, and smart tagging for easy searching. Export your notes as PDFs in a clean, distraction-free interface.

Highlights
  • Natural Apple Pencil writing
  • On-device AI text recognition
  • 100% private, no cloud
  • Export beautiful PDFs
  • Smart tagging and search
  • Distraction-free interface
Features
Read full description

Your thoughts deserve privacy. Penned Notes is a minimalist handwriting app that keeps everything on your device. - Natural Apple Pencil writing - AI text recognition (on-device) - 100% private - zero cloud required - Export beautiful PDFs - Smart tagging & search - Clean, distraction-free interface Unlike other note apps, Penned Notes uses Apple's Neural Engine to recognize your handwriting locally and nothing leaves your device. No accounts, no tracking, no subscriptions to complex features you don't need. Perfect for: - Daily journaling - Class notes & studying - Meeting notes - Sketches & brainstorming - Sensitive work documents Privacy-first architecture means your notes stay truly yours. Download Penned Notes.  Where your thoughts are penned, not surveilled.

About

Erebus Solar

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
Read full description

Measure shade on site with the hardware already in your pocket. Erebus Solar was designed by an electrical engineer and an architect with years of experience designing solar systems around the world. We were fed up with the horizon-finding hardware the industry still relies on: dedicated devices that haven't been meaningfully updated in decades, are slow to use and slow to find a GPS fix, and analog tools that need paper, a pencil and a latitude template that may not exist for your site. Erebus Solar is our answer. Your iPhone already has the camera, compass and sensors the job needs. WHY HORIZON FILES MATTER Far-field shading from trees, terrain and neighbouring buildings is one of the largest sources of error in a PV production estimate. A measured horizon profile, captured on site, lets your design software model that shading instead of guessing. Erebus Solar produces horizon files that leading PV design tools such as HelioScope and PVsyst read directly, and PV*SOL accepts the same convention. CAPTURE • AR sun path: today's arc, the solstice and equinox arcs and the live sun drawn over the real sky • Tap the real sun to calibrate the compass to true north • Automatic sky capture: sweep the envelope band and frames capture themselves, no buttons • Sky Editor: review the stitched sky and trace obstructions by hand, so the report reflects what you saw ANALYSE • Annual solar access and TSRF for each array area • Month-by-month charts and the sun-path chart with your obstructions • Aerial view with each area's boundary and the solar envelope over satellite imagery EXPORT • PDF shade report with your company name and logo • Horizon files for HelioScope, PVsyst and PV*SOL, generated from the same capture • Share straight from the phone ORGANISE • One project per site, located by address or GPS, with status from Created to Completed • Areas for each roof face or ground section • Everything stored on your iPhone: no account, no upload Erebus Solar's outputs are a design aid for qualified professionals. Results depend on the phone's sensors, compass calibration and sky conditions; check them against your own observations and your design tool's simulation before relying on them. Privacy Policy: https://erebussolar.app/privacy Terms of Use: https://erebussolar.app/terms

Screenshots

Penned4 screens
Erebus Solar4 screens

Verdict

The call

The clearest difference is review sentiment: Penned at 50% against Erebus Solar's 0%. Penned also leads on rating (4.6 vs 3.7) and ratings volume (87 vs 3). Erebus Solar's advantage is price (Free vs $4.99) and update cadence (every 2 weeks vs every 2 months). On ads, in-app purchases, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Erebus Solar is free to download; Penned costs $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Penned holds the better App Store score, 4.6 against 3.7. That said, the two scores are not equally well evidenced: Penned has 87 ratings behind it against 3, so its average is the more settled of the two. Written reviews point the same way: 50% of Penned's written reviews are positive against 0% of Erebus Solar's.

UpkeepUpdate frequency

Penned ships an update every 2 months, Erebus Solar every 2 weeks. The most recent releases landed on October 10, 2026 and October 14, 2026 respectively.

Scorecard6 real differences · 4 level
Penned versus Erebus Solar: the parameters behind the verdict, then further details
ParameterPennedErebus Solar
Price$4.99Free — better
Rating4.6 (87 ratings) — better3.7 (3 ratings)
Positive reviews50.0% of reviews — better0.0% of reviews
Number of ratings87 — better3
Update frequencyEvery 2 monthsEvery 2 weeks — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
DevicesiPhone, iPad — betteriPhone
Requires iOS16.6 — better17.0
Further details — not scored
Size1 MB19 MB
Age rating4+4+
DeveloperEdwing H Santos MenaTodd Evans

Customer experience

Penned

All ratings87 ratings
Positive92.0%
Neutral3.4%
Negative4.6%
Written reviews14 reviews
Positive50.0%
Neutral21.4%
Negative28.6%

Erebus Solar

All ratings3 ratings
Positive66.7%
Neutral0.0%
Negative33.3%
Written reviews1 reviews
Positive0.0%
Neutral0.0%
Negative100.0%

In-app purchases

None

Penned

No in-app purchases

None

Erebus Solar

No in-app purchases

Questions

Is Penned free?
Penned costs $4.99, with no in-app purchases.
Is Erebus Solar free?
Erebus Solar is free to download, with no in-app purchases.
Which has better reviews, Penned or Erebus Solar?
Penned is rated higher. Penned averages 4.6 out of 5 from 87 ratings, while Erebus Solar averages 3.7 from 3 ratings.
Do Penned or Erebus Solar have ads?
Neither Penned nor Erebus Solar shows ads.
Which is updated more often, Penned or Erebus Solar?
Penned ships an update every 2 months, and Erebus Solar every 2 weeks. Most recently, Penned was updated on October 10, 2026 and Erebus Solar on October 14, 2026.

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