Savings and payback
See how the same partial shading costs dramatically different amounts depending on inverter type, since string inverters suffer disproportionate losses.
How it works
Step 1
Use figures from the solar savings calculator for a clean, unshaded baseline.
Step 2
The tool applies a disproportionate loss factor for string inverters versus a contained per-panel loss for microinverters or optimizers, since the two setups respond to shade very differently, unlike the smooth annual decline in the panel degradation tool.
With a string inverter, panels are wired in series and one tracker manages the whole string, so a shaded cell limits current for every panel connected to it. Research shows a 10% shaded area can cause a 30% to 40% loss under this design, not a proportional 10%, since the weakest cell drags down the entire string's output. The US Energy Information Administration's solar explainer covers how solar generation works and where it fits in the wider grid.
For a system saving $1,800 a year with 10% shading, a string inverter loses roughly $630 a year, while microinverters or DC optimizers limit the loss to around $31.50 a year, since shade on one panel doesn't drag down the others. That's roughly a 20x difference for the exact same shading condition, driven entirely by equipment choice, worth factoring into the payback period calculator if your roof has any known shade sources. Output varies by roof and weather, and the output loss from partial shading tool shows what your site should produce in a typical year.
Both perform power conversion or maximum power point tracking at the individual panel level rather than across an entire string, so shade on one panel affects only that panel's output, typically 15% to 20% loss per shaded panel, without dragging down unshaded panels nearby. This is the core mechanism behind the dramatically smaller dollar impact. If you have not sized the system yet, start with the partial roof shading sizing adjustment and bring its kilowatt figure back here.
Often yes, if the shading is persistent rather than occasional, for example from a nearby tree or building rather than a passing cloud. The dollar gap shown here can be substantial enough over a system's lifetime, as tracked in the year by year savings breakdown tool, to justify the added upfront cost of microinverters or optimizers on a partially shaded roof, similar to how the real vs estimated savings gap calculator highlights other underappreciated cost factors. Utility rates drive the whole savings calculation, and the US Energy Information Administration's electricity data track them state by state.
Questions
With a string inverter, panels are wired in series and one tracker manages the whole string, so a shaded cell limits current for every panel connected to it. Research shows a 10% shaded area can cause a 30% to 40% loss under this design, not a proportional 10%.
Dramatically. For a system saving $1,800 a year with 10% shading, a string inverter loses roughly $630 a year, while microinverters or DC optimizers limit the loss to around $31.50 a year, since shade on one panel doesn't drag down the others.
Both perform power conversion or maximum power point tracking at the individual panel level rather than across an entire string, so shade on one panel affects only that panel's output, typically 15% to 20% loss per shaded panel, without dragging down unshaded panels nearby.
Often yes, if the shading is persistent rather than occasional. The dollar gap shown here can be substantial enough over a system's lifetime to justify the added upfront cost of microinverters or optimizers on a partially shaded roof.
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