It does work ofc while overall effectivity might be considerably lower than form solar panels installed on roofs or ground installation.What about attaching the panels to the wall instead of roof?
Any decent installer should to mod ...g. calculation process and this does take time from real specialists in field and they are using guys really interested in this stuff....even if these are apprentices, they aren't dumb.
In Northetn Euro in some cases wall installations are preferred choice while this usually is after discussions etc in place and in person...after modelling will be done.
If about financial risk, for short term this usually is lower than for installation on the roof .... for medium term it is going closer cos IF shit will happen, problems in $ you usually will get more than if you had ground based installation. Especially cos to repair etc stuff associated with wall will not be cheap and fast process at all.