Expert elicitation of future energy technology costs can improve energy policy design by explicitly characterizing uncertainty in future costs. However, the recent surge in the use of the expert elicitation methodology raises questions about the reliability and comparability of their results. In this paper, we standardize disparate expert elicitation data from five EU and US studies, involving 66 experts, of the future costs of photovoltaic (PV). We show that in-person elicitations are associated with more optimistic 2030 PV cost estimates but have little impact on the uncertainty range. Expert selection (affiliation type and nationality) also affects results, although these effects are less significant. In contrast with previous research on expert elicitations in nuclear power, EU experts and private sector experts in our sample are more optimistic about future PV costs than their US and non-private sector counterparts. We suggest that this difference may be due to availability heuristics related to the greater deployment of solar in the EU and the direct exposure of private sector experts to declining costs. As expected, higher R&D investment is associated with lower future costs and greater uncertainty about those costs, although with a diminishing effect in both cases.