Comparison

Solar Potential vs Postfach

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

Head to head
About

Solar Potential

Estimate your solar energy generation and potential savings by simulating solar panels using your phone. Simply place your device in the planned panel position to get an instant estimate of yield in kWh and Euros, considering location, orientation, tilt, and weather trends.

Highlights
  • Simulate solar panel placement with phone
  • Estimate energy yield in kWh
  • Calculate potential savings in Euros
  • Consider orientation and tilt
  • Factor in long-term weather trends
  • Supports balcony power plants
Features
Read full description

Discover your solar potential with Solarize! Find the best spot on your balcony or property with our app by using your phone to simulate the solar panel. 1. 1. place your cell phone on the planned position of the panel 2. start the check 3. in just a few seconds you will get a precise estimate of the possible yield in kWh and Euro Repeat the check as often as you like. We take into account - the exact position of your phone - the orientation of your phone - the tilt of your phone - and the long-term weather trend and expected sun hours at your location Find out how much energy you can generate and how much money you can save with a balcony power plant simply by positioning your phone. Put the sun to work for you and make an informed decision for a greener, more sustainable future. Download Solar Potential now and start making your solar project a reality!

About

Postfach

Features
Read full description

We run no servers, so there is nothing of yours on one. A call from our hosting provider started it. They asked whether one of our important addresses had anything to do with a big cloud company โ€” it didn't. It turned out the mail app we were using was routing through that company to deliver push notifications. We had tried nearly every mail app by then and were never quite happy, so we built our own. Here is why that call mattered. To push a notification for an ordinary IMAP account, an app has to keep your password โ€” or a token that opens the same door โ€” on its own server, and watch your mailbox from there. Postfach never does this. Your password stays in your Keychain, and new mail is announced by your own device once it has fetched it: on the Mac within seconds while the app is running, on the iPhone whenever iOS grants a check in the background. Instant push is the one thing we gave up, and that is why. WHAT IT DOES - Any IMAP account: Zimbra, Gmail, and the rest. Zimbra servers are found from the address alone. - Write, reply, forward, and send, with attachments. - All Inboxes: one list over every account, newest first, with each message acting on its own account. - Conversations, with replies from every folder gathered under the message you are looking at. - Every message kept on your device in full, so reading works offline and search finds words anywhere in years of mail in a fraction of a second. - Templates with placeholders for the replies you write again and again. - Folders: create, rename, move, and delete them, on the server. - Swipe to delete, flag, mark as junk, or archive. - New-mail notifications from your own device, once it has fetched, per account, and the unread count on the icon. - HTML mail rendered with scripts off and remote images blocked until you ask for them. - Light and dark appearance. English, German, French, Italian, Spanish, and Japanese. WHAT IT DOES NOT DO No analytics, no crash reporting, no advertising identifier, nothing measured and sent anywhere. No AI: no summaries, no smart replies, no sorted inbox, and no model of ours or anyone else's sees a word of your mail. No account with us, because there is nothing to have an account for. That is why the privacy label reads "Data Not Collected", and why there is no setting to turn any of it off: none of it is there. PRICING Every feature is free for 60 days. After that, sending and receiving mail need a single purchase, Postfach Pro โ€” one price for your Mac, iPhone, and iPad, no subscription. Mail already on your device stays readable and searchable whether you buy or not.

Screenshots

Solar Potential4 screens
Postfach4 screens

Verdict

The call

The clearest difference is price: Postfach at Free against Solar Potential's $1.99. Postfach also leads on update cadence (daily vs every 8 days). Solar Potential's advantage is in-app purchases (none vs 1) and iOS requirement (13.0 vs 18.0). On ads and device support there is nothing between them.

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

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Postfach is free to download; Solar Potential costs $1.99 up front. Postfach sells 1 one-off in-app purchase. Solar Potential asks for nothing beyond the download.

UpkeepUpdate frequency

Solar Potential ships an update every 8 days, Postfach daily. The most recent releases landed on October 8, 2026 and October 13, 2026 respectively.

Scorecard4 real differences ยท 4 level
Solar Potential versus Postfach: the parameters behind the verdict, then further details
ParameterSolar PotentialPostfach
Price$1.99Free โ€” better
Positive reviews60.0% of reviewsโ€”
Update frequencyEvery 8 daysDaily โ€” better
AdsNoNo
In-app purchasesNo โ€” betterYes
MonetizationPaidโ€”
DevicesiPhone, iPodiPhone, iPad, Mac โ€” better
Requires iOS13.0 โ€” better18.0
Further details โ€” not scored
Size1 MB19 MB
Age rating4+4+
Developersoft-evolution GmbH & Co. KGesense GmbH

In-app purchases

None

Solar Potential

No in-app purchases

1 purchases

Postfach

One-time1
  • Postfach Pro$22.99

Questions

Is Solar Potential free?
Solar Potential costs $1.99, with no in-app purchases.
Is Postfach free?
Postfach is free to download, with in-app purchases available.
Do Solar Potential or Postfach have ads?
Neither Solar Potential nor Postfach shows ads.
Which is updated more often, Solar Potential or Postfach?
Solar Potential ships an update every 8 days, and Postfach daily. Most recently, Solar Potential was updated on October 8, 2026 and Postfach on October 13, 2026.

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