Building geometries strongly constrain the on-site solar energy use. In this work, solar energy use is measured by solar energy penetration and capital costs for the photovoltaic panel installations. This work provides a novel typological method for investigating interactions between solar energy use and urban design. Compared to other studies using typological methods, this work uses a typological method that highlights both computational efficiency and relevance to the vernacular contexts. Typical vernacular block typologies are formulated using a case study of built urban form featuring various combinations of block dimensions, building patterns, floor area ratios, and site coverage. We develop the Urban Block Generator, a tool to parametrically model such block typologies in Rhino/Grasshopper. We assess the solar energy penetration and the capital costs for these block typologies using the Urban Block Generator and the City Energy Analyst, an urban energy modeling and simulation program. We demonstrate this workflow on a case study in Singapore formulating 18 vernacular block typologies. The results are discussed and interpreted into urban design options and suggestions on various urban design parameters for different main driving forces, either maximizing the solar energy use or achieving a certain floor area ratio. (C) 2020 The Author(s). Published by Elsevier Ltd.