Oversizing solar heating plants in industry: A cost-effective solution to increase solar fractions

Solar heat for industrial processes (SHIP) is one of the solutions to decarbonise industrial heat demand and reduce CO₂-emissions. One of the barriers to the promotion of solar heat, often cited in addition to economic aspects, is the low share that solar heat is able to provide. The VDI 3988 guideline is a standardised methodology for pre-designing the collector field and estimating the specific yield. It focuses on the summer heat demand which results in comparably low solar fractions especially when the heat demand profile is seasonal. Based on TRNSYS simulations, this study analyses the reduction of the specific solar yield and the impact on the solar fraction and LCOH when the collector area is oversized. It is found that the specific yield decreases, as expected, with increasing collector area due to solar excess heat, with this effect being more significant for non-seasonal process heat load profiles. Furthermore, the LCOH is stable or can even be increased by a moderate oversizing of 25..50 % compared to the design of the VDI 3988 design due to economies of scale.