This is from 2010 so I'd imagine the figures have likely changed significantly since then, along with all the economics of photovoltaics. Today's inverters are almost certainly more reliable than pre-2010 models.
Cleaning is certainly a cost in dry areas where dust can coat the panels. But generally not in temperate climates where you can rely on self-cleaning via regular rainfall.
This site https://www.scottmadden.com/insight/solar-photovoltaic-plant... estimates $60 per kW-year for maintenance. Half cleaning; most of the rest in inverter replacement. How does that compare with turbine I wonder.