Is this inverter the right size?

A ratio outside the usual band is a trade-off you can make on purpose. A datasheet maximum is not. This page keeps those two apart.

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Is this inverter the right size?

The DC to AC ratio is a trade-off. A datasheet maximum is not. This keeps the two apart.

Advanced tool — planning check only. This compares figures you enter against figures you enter. It does not size conductors, overcurrent protection, disconnects, grounding or rapid-shutdown equipment, and it makes no claim of compliance with any electrical code. A licensed professional and the authority having jurisdiction decide those, and their requirements override anything here. Where a manufacturer's documentation disagrees with this page, the documentation is right.

The array

The inverter, from its datasheet

A hard limit. Leave blank if you genuinely do not have it.

The band you consider normal

Editable, because it is a convention rather than a rule, and it moves with panel prices and tariffs. Your manufacturer's own guidance beats it.

Trade-offs and hard limits, kept apart

Inverters that would suit this array

← Check the string voltages
Your data stays in this browser. Everything on this page is calculated on your own device. Your electricity use, roof dimensions, prices and equipment details are never uploaded, stored on a server, or included in analytics.
Planning estimate — not an engineering or installation plan. Results depend on the information and assumptions you enter. Output, savings and equipment behaviour vary with weather, shading, tariffs, temperature, ageing and installation. Verify equipment limits against current manufacturer documentation. Permits, structural capacity, electrical protection, conductor sizing, grounding, rapid shutdown, fire access, utility interconnection and code compliance must be reviewed by qualified professionals and the applicable authorities.
How this is calculated

DC to AC ratio = array kW (DC) ÷ inverter rated output kW (AC)

Two different kinds of result, never blurred together:

A trade-off is a design judgement. A ratio above the band means more of the array's peak will be clipped on the brightest days — which is frequently the right choice, because those peaks are brief and inverters cost money. A ratio below the band means you have bought more inverter than the array can use. Neither is a fault.

A hard limit is what the manufacturer permits. Exceeding the maximum DC input is not a preference; it is outside the equipment's rating and may void the warranty.

No annual clipping percentage is given. Estimating that honestly needs hour-by-hour irradiance for your site, your orientation and your shading. A figure worked out from the ratio alone would be invented, and it would be quoted back as though it were measured.

Clipping is not waste

An array larger than its inverter will, on the brightest few hours of the clearest days, produce more than the inverter can pass through. The excess is lost. This sounds like a fault and is usually a bargain: those peaks are rare, the shoulders of the day are where most energy actually comes from, and a larger array fills those shoulders better. Paying for an inverter sized to a peak that occurs twenty hours a year is generally worse value than accepting the clip.

What matters is knowing which one you are choosing. This tool tells you where you sit relative to the usual band and leaves the judgement with you — it will not pretend to know how much energy you would lose, because that genuinely requires a year of hourly weather for your specific roof.

The limit that is not negotiable

Maximum DC input is different in kind. It is a number the manufacturer publishes because beyond it the equipment is outside its design envelope. Some inverters tolerate a substantial overshoot and simply clip; others do not, and the warranty language is usually unambiguous. If you are above it, the answer is a different inverter or a smaller array — not a judgement call about clipping.

Backup power is watts, not watt-hours

For hybrid and off-grid inverters these get confused constantly. The inverter determines how much you can run at any instant — its continuous rating for steady loads, its surge rating for the second or two when a motor starts. The battery determines how long. An inverter with a huge surge rating and a small battery starts your pump and then runs flat; the reverse combination has plenty of energy it cannot deliver fast enough. Both have to be right, and they are separate purchases.