Solar photovoltaic projects have very high additionality risks. The technology is mature, and many countries support solar power with feed-in tariffs, renewable energy auctions, tax credits, or other policy instruments. Quantification methodologies containing equations and permissible data sources for calculating and monitoring emission reductions for an solar photovoltaic project have shortcomings. We estimate that quantification methodologies likely overestimate emission reductions by about 10 to 30 percent. The project type is a backbone for the global energy transition and indispensable for reaching net zero emissions. It also likely reinforces many Sustainable Development Goals.