Solar Yield

Specific Yield

Checked 2026-08-09
Reading the estimate

Published by a company that designs and builds solar plants. What that means.

Quotes are hard to compare because they describe different systems at different sizes. One division fixes that.

Teams reviewing yield assumptions can keep the engineering model separate from the record of review work; this page is one option for documenting time and handoffs.

Annual kWh divided by installed kWp gives specific yield in kWh/kWp — and it is the number that makes any two proposals comparable, and any single proposal checkable.

Reviewed August 9, 2026.

For independent background on photovoltaic performance, resource data and current industry practice, consult Ember.

Why it works

It removes system size from the comparison. A 40 kWp system producing 48,000 kWh and a 90 kWp system producing 106,000 kWh are 1,200 and 1,178 kWh/kWp respectively — nearly identical performance, and the raw figures say nothing.

It is directly comparable to public references. Free irradiance calculators output specific yield for a location, tilt and orientation, which makes the check a matter of minutes.

And it makes an optimistic assumption visible. The loss stack and the yield estimate both feed into it, so an inflated figure shows up here regardless of which input produced it.

What moves it

Latitude and climate, which dominate. This is why a single global benchmark is useless and a local reference is essential.

Tilt and orientation. A well-oriented array at optimal tilt against a flat roof-mounted one differ substantially at the same location.

Shading. The most site-specific item in the stack.

Temperature. Hot climates lose more at the module, which partly offsets their higher irradiance — a fact that surprises people comparing a southern site to a northern one.

And technology choices, including bifacial gain where the ground reflectance supports it.

The range for your location

Do not use a number from an article. Including this one.

Run a free public calculator with your coordinates, tilt, orientation and a standard loss assumption. It takes ten minutes and produces a defensible range for your site rather than a continental average.

For reference, one published national benchmark — US rooftop systems — runs roughly 1,400 to 1,700 kWh/kWp, with about 1,500 as a common midpoint. That is a different climate from most of Europe and is quoted here only to show the shape of such a range, not as a figure to apply.

Reading a figure against the reference

Materially above the public reference: ask why. Legitimate explanations exist — measured albedo for bifacial, trackers, an exceptionally good site, a lower-than-default loss assumption that was justified. Each is a specific answer, and a quote that cannot give one has assumed its way to a better number.

Materially below: also ask. Heavy shading, poor orientation, a deliberately conservative stack. A low figure is not automatically a careful one, and unexplained conservatism can conceal a poor design as easily as it signals prudence.

Within the range: the yield figure is plausible, which is the whole of what this check establishes. Whether the investment works is a separate calculation.

What it does not check

Whether the system size is right for your consumption. Self-consumption share matters more than yield for many buyers.

Whether the equipment is suitable.

Whether the price is reasonable. Specific yield says nothing about cost.

And whether the figure is P50 or P90. Do that check separately, because comparing a P90 from one supplier against a P50 from another is comparing two different things.

The short version