Reviewing Your First Full Year of Solar Generation

A first full year of real generation data is the first point you can actually check a system against its quote, not a simulation against another simulation. Before that, every number was a projection. After it, one of them is real.

• Compare a full twelve months of generation against your original quote, never a single month or season on its own.
• A result 5 to 15% below the quoted figure is normal simulation-to-reality variance, not a problem.
• Meaningfully beyond that range is worth raising with your installer, ideally before any defects liability period expires.
• Self-consumption and export split, and the actual bill reduction, matter as much as the raw generation total.

What's actually worth checking after a first full year?

Three numbers, all pulled from the same twelve months of monitoring app data: total generation against your original quote, the self-consumption versus export split, and how much your actual electricity bill dropped.

Each tells you something different. Total generation checks the system's raw performance, and the consumption split checks whether your household's actual usage pattern matched what the quote assumed.

The bill reduction is the one that matters most in practice, since it checks whether the first two numbers actually translated into money saved, not just generation that looked good on a dashboard.

What if year one actually comes in above the quoted estimate?

Coming in above the quoted estimate is good news, and worth understanding rather than just enjoying. A properly conservative quote sometimes uses a cautious estimate deliberately, closer to a P90 figure than an optimistic P50 one, precisely so a real first year has room to land at or above it rather than consistently falling short.

Coming in above estimate isn't a sign the original quote undersold the system on purpose, it's what a genuinely conservative estimate is supposed to do when Singapore's weather that particular year runs slightly better than typical.

How do I fairly compare actual generation against what I was quoted?

Add up a genuine twelve months from your monitoring app, not a strong month cherry-picked to look good or a weak one cherry-picked to complain about. See Sunnify's guide to reading your monitoring app data for exactly which figures to pull and where they sit on the dashboard.

Compare that annual total against the annual estimate your original quote gave, the number a simulation produced before installation, not against a single standout day the app might have highlighted.

What counts as genuinely underperforming, versus normal variance?

A gap of roughly 5 to 15% below the quoted figure, and Sunnify's own guide to what actually happens versus what the quote simulated covers exactly why that range exists, real-world soiling, shading, temperature effects, and inverter clipping, not a sign anything went wrong.

Meaningfully beyond that, well past 15% below quote, is different. That's worth raising directly rather than assuming it will correct itself the following year, since the same underlying cause, whether shading, an equipment issue, or a sizing miscalculation at quote stage, tends to persist rather than resolve on its own.

Does the self-consumption split from year one predict future years?

Year one's self-consumption split predicts future years reasonably well, provided your household's actual electricity use stays roughly the same. A new aircon unit, an EV charger added later, or simply more people home during the day all shift how much of your generation gets used directly versus exported.

If your usage genuinely changes, it's worth re-running the numbers rather than assuming year one's split holds indefinitely, since self-consumption is what most of a landed home's solar savings actually come from.

What if my first year came in meaningfully below what I was quoted?

Raise a meaningful shortfall with your installer while it's still fresh, and ideally while any defects liability period covering workmanship is still active. Sunnify's guide to that period covers what it actually protects and how long it typically runs.

If the shortfall traces to the equipment itself rather than the installation, a manufacturer's warranty claim is the separate, correct path, covered in Sunnify's warranty claim guide. Knowing which one applies before contacting anyone saves a genuinely frustrating back-and-forth about whose responsibility it actually is.

Is there anything else worth doing at the one-year mark?

A proper health check, if you haven't already had one, timed well against the annual cadence covered in Sunnify's health check guide. A first full year is also a reasonable point to confirm your actual bill reduction against Singapore's current tariff, since the rate itself can move independently of anything your system is doing.

Is it worth checking the export credit line on my SP Group bill too?

The export credit line on your SP Group bill is worth checking too, and it's an easy one to overlook since it sits quietly on a bill most people scan rather than read closely. Confirm the credit actually appears month to month and roughly tracks your monitoring app's export figures, rather than assuming it's being applied correctly just because the system is generating.

What's the actual next step?

Pull twelve months from the monitoring app this week if you haven't already, and run the comparison honestly rather than skipping it because the number might disappoint. If it holds up, that's real confirmation, not just a sales projection. If it doesn't, you now know early enough for a defects liability claim to still be live.