Solar PV Forecast Apps: Why I Ditched the Complicated One and Never Looked Back

Let me set the scene

You've just had solar panels installed. You're excited. You want to know what they're doing, when they peak, whether today is going to be a good one. So you go looking for a solar PV forecast app.

You download one that looks professional. It has charts. It has alerts. It says it supports PV systems. You open it and... you're immediately asked for your inverter model, your panel tilt angle in degrees, your azimuth, your nominal system capacity in kWp, your shading coefficient, and to create an account.

You don't know your azimuth. You thought an azimuth was something on a compass.

Half an hour later, you've either given up or just entered approximate numbers that probably aren't right. The app gives you a forecast that may or may not be accurate, surrounded by adverts — some of which pop up mid-screen when you're trying to read a number.

Sound familiar?

The solar app problem nobody talks about

There are solar PV forecast apps that are genuinely impressive engineering achievements. They're built for people who work in the renewables industry. If you know the difference between STC and NOCT ratings and you manage a small solar farm, those apps are probably great for you.

But most of us? We just want to know: is today going to be a good solar day, and when should I run the washing machine?

That's not a complicated question. It shouldn't require a 45-minute onboarding process and a solar engineering qualification.

There's also the ad situation. Look — ads are how apps stay free. Nobody begrudges that. But there's a difference between a tasteful banner at the bottom of the screen and a full-page interstitial that ambushes you every time you tap to check your forecast. When an ad is more prominent than the actual forecast, something has gone wrong.

What "simple" actually looks like in practice

When we built Sun Hours, we started from a different question: what is the absolute minimum information needed to give someone an accurate solar PV forecast?

The answer turned out to be just two things:

1. Your location — so we can pull live, hyperlocal weather and irradiance data for your exact postcode.
2. Your best solar day — the best single-day kWh output your system has ever produced. This one number tells us everything we need to know about your real-world system performance, without needing your panel brand, your tilt angle, or anything technical.

That's it. Two inputs. Setup takes about 8 seconds.

From those two things, Sun Hours builds you a personalised solar generation forecast that accounts for your actual panels, your real-world location conditions, and the actual weather coming your way. No approximations from specs you had to look up. Your real system, your real forecast.

What you actually get

Once you're set up — again, 8 seconds — here's what's waiting for you:

A personal welcome from Sol. Sol is our friendly sun mascot, and every day he gives you a personalised message about what your solar day looks like. It's a small thing, but it makes checking the app feel like something you genuinely want to do.

Today's hour-by-hour breakdown. See exactly when your panels will peak, which windows are your best for high-draw appliances, and how cloud cover is tracking through the day.

A 7-day solar PV forecast. Plan ahead. Know whether to save the big laundry load for tomorrow's clearer day or crack on this afternoon.

A 30-day view based on historical weather. Solar is about understanding your site's seasonal rhythm, not just the week ahead. The 30-day view pulls historical weather patterns for your exact location to give you that longer picture.

Sun Hours alerts. Every morning you get a notification telling you your best two-hour window for solar generation that day. So when your phone says "best window today: 11am–1pm," you know exactly when to charge the car, fire up the hot tub, or run your heaviest appliances on your own free electricity rather than grid power. You opt in on your own terms, and you can turn them off whenever you like.

On the subject of ads

Yes, Sun Hours has ads. We're a small indie app and ads help keep the lights on.

But here's our commitment: we're not going to ambush you. Our ads are infrequent and non-intrusive — not full-screen takeovers, not auto-playing video, not an advert between every single tap.

And if ads genuinely bother you? We have a no-ads-for-life in-app purchase. But even better than that: email us at support@sunhours.app and mention "solar forecast" in your message, and we'll send you a promo code for it. Solar panel owners who just want to see their forecast without distraction shouldn't have to jump through hoops.

Accurate without the faff

Here's the thing about complicated solar PV forecast apps: complexity doesn't automatically mean accuracy.

When we tested Sun Hours side by side during development, our dead-simple two-input approach produced comparable forecast accuracy to apps requiring far more detailed system configuration. Because your local weather conditions and your system's real-world best-day output are the two variables that actually drive the numbers — not how many fields you filled in during setup.

More inputs doesn't mean a better forecast. It usually just means more friction and more chances to enter something wrong.

One frustrated solar panel owner to another

We didn't build Sun Hours to compete with industrial solar monitoring software. We built it because we were frustrated — genuinely, personally frustrated — trying to find a simple, honest solar PV forecast app that didn't make us feel like we needed an electrical engineering degree just to get started.

If you've ever closed a solar app in annoyance because it was asking you things you didn't know, or because an advert covered the chart you were trying to read — Sun Hours was built for you.

Try it. Set it up in 8 seconds. Say hello to Sol. See your forecast. And if the ad-free experience matters to you, drop us an email and mention "solar forecast." We'll sort you out. ☀️