Support
Sun Sizer Pro & Sun Sizer
Need a hand?
Found a bug, have a feature idea or a question about a calculation? Send an email. It helps to include your device model and iOS version.
Email supporttachena@me.com · Replies usually within 2 business days
Frequently asked questions
How does the free trial work?
Every tool is unlocked free for 14 days. Nothing is charged, nothing renews, and it's not a subscription. When the trial ends, String Sizing and Sun Path & Tilt stay free and your projects stay viewable and exportable. The other tools wait for the one-time Premium unlock. The trial is tied to your Apple Account, so every device shows the same days left, and reinstalling doesn't reset it.
What does Premium cost, and is it a subscription?
Premium is a single one-time purchase (US $19.99, or the equivalent in your region), not a subscription. It unlocks every tool for good on all devices signed in to your Apple Account.
How do I restore my Premium purchase?
Open Settings (the gear icon), or tap any locked tool, and tap Restore purchase. Make sure you're signed in to the App Store with the Apple Account you bought it with.
How do I sync projects between my iPhone and iPad?
Sign in to the same Apple Account with iCloud turned on, on both devices. Sync is on by default (Settings → iCloud sync). Changes usually arrive within seconds to a minute, and bringing the app to the front nudges it. It works offline too and catches up when you're back online. If a change doesn't appear, check that you have free iCloud storage and that both devices are running the latest version of the app.
Some settings don't match between my devices.
That's by design. The active project, units, display settings and quick-calculation fields are kept per device. Projects, saved calculations and the equipment library sync.
Does the app need an internet connection?
No. Every calculator, the equipment library, the NASA climate data and PDF export work fully offline, so it works on a roof or a remote site with no signal. An internet connection is only used by iCloud to sync, and that happens in the background.
I deleted a project by mistake.
Tap Undo straight away to bring it back. With sync on, deleting a project deletes it on all your devices, and Undo restores it everywhere.
Why does it ask for my location?
Only to fill in your site's coordinates and altitude, and to find true north when measuring a panel. You can say no and type coordinates in by hand. Location is never sent to us.
The tilt reading won't settle.
Lay the device flat on the panel frame with the top edge pointing up the slope, and hold still. Keep it away from metal racking and magnetic cases, which throw off the compass. The app hides the compass reading when iOS reports poor accuracy. Moving the device in a figure-8 recalibrates it. You can always enter the tilt by hand.
How accurate are the results?
Solar position is accurate to about ±1°. Production figures are estimates, typically within ±10%. Code checks follow the US National Electrical Code using reference tables built into the app. Always check against the equipment datasheets, the NEC edition your area has adopted, and your local authority having jurisdiction (AHJ) before installing. Sun Sizer Pro is a design aid, not a substitute for review by a licensed professional.