Armed with a good feasibility assessment, the first major step in hardware deployment is the engineering design. For modular renewable technologies (solar thermal hot water, solar photovoltaic, wind, and some biomass technologies), much of the engineering design will have already been accomplished by the equipment vendor. For non-modular renewables (geothermal, concentrating solar power, small hydro power, and other biomass technologies), considerable systems engineering may be required. For this second set of options, it is probably best to contract with an engineering firm or a systems integrator to get through the engineering design stage.
Either way, the objective of this step is to end up with a complete set of component or systems specifications, drawings, performance specifications, and construction management plans that can be used for hardware procurement and on-site construction. The engineering design should also include the development of a detailed construction timeline identifying long-lead-time items and construction sequencing. The larger the project, the more important these documents become.
Also, the engineering design will result in an increasingly good estimate of actual construction costs. For instance, there may be the need for some on-site testing, such as soil drilling and compaction, which can impact foundation design. Transmission interconnection requirements will impact substation design. Air and water quality requirements may mean additional equipment for air emissions control, or waste water cleanup. The detailed engineering design is the time to catch and design-in this equipment. Retrofits are nearly always more expensive than doing it right in the first place.