A homeowner has panels installed across a south facing roof. The quotation showed an annual generation figure and the array looks impressive.
A chimney casts a shadow across part of the array from the middle of the afternoon. With a conventional string arrangement, that shadow costs considerably more than the panels it touches.
The installer never mentioned it. The generation figure in the quotation was calculated as though the chimney did not exist, and the system will underperform quietly for twenty years.
The first failure: shading is not assessed at all
Many quotations are produced from a roof orientation and an area. Nothing about the actual obstructions on that specific roof enters the calculation.
The second failure: the effect is underestimated
Shading part of one panel in a conventional string can reduce the output of the whole string. Homeowners reasonably assume the loss is proportional to the shadow.
The third failure: the survey happens after the sale
Where an assessment does occur, it is frequently after the contract, which means the design is adjusted rather than the decision being informed.
The fourth failure: shading moves through the day
A roof clear at midday may be shaded from three. A single visit at one time of day tells you almost nothing about the pattern.
The fifth failure: shading changes through the year
The sun's path is lower in winter, so obstructions that are irrelevant in June are significant in December, which is when generation is already lowest.
The sixth failure: trees grow
A young tree that shades nothing today will shade the array in twelve years. Nobody plans for this and the system is a twenty five year asset.
The seventh failure: neighbouring buildings are ignored
An extension next door, a new building or a growing hedge are outside the homeowner's control, and the risk should at least be identified.
The eighth failure: small obstructions are dismissed
Aerials, satellite dishes, vent pipes and flues cast narrow shadows that move across panels, and their effect is disproportionate to their size.
The ninth failure: the mitigation is not offered
Panel level electronics, a different string layout or simply positioning the array elsewhere. These have costs and they are frequently worth it.
The tenth failure: the generation estimate is not adjusted
The figure in the quotation is the one the payback calculation rests on, which is the arithmetic in solar enquiries from homeowners still doing the maths.
The eleventh failure: the customer is not shown the assessment
A shading analysis is straightforward to produce and persuasive to look at, and an installer who shows one distinguishes themselves immediately.
The twelfth failure: the monitoring will not reveal it either
A system underperforming from day one looks normal to an owner with nothing to compare against, which is why it persists for years.
The fix: assess the shading before the design is fixed
An assistant that asks about chimneys, dormers, aerials, nearby trees and neighbouring buildings, and flags where a proper shading assessment is needed, means the conversation happens before a contract rather than after an installation. The cleaning and output questions sit in solar panel cleaning enquiries from homeowners, the longevity in panel lifespan and degradation questions, and the care needed with a large financial decision in how to handle sensitive questions in your chatbot. Start at try, see features, and the sector view sits under solar installers.