Solar power solutions for hospitals
Adopting to Solar energy to power operations can be a lucrative option for hospitals in India. The primary reason to consider solar as a viable option is that hospitals have a constant load throughout the entire year, without any holidays. Hospitals usually adapt to ongrid systems as a industry standard practice to make sure their night time energy requirements are also covered. Even though battery backup systems might sound like an alternative idea it is not advised to go with battery backup for night time usage. High capital cost for the battery, overheads like maintenance cost, space for the battery, risk of explosion if it is Li-ion battery makes battery a non viable option for hospitals.
Another fatAs a safety precaution, every hospitals have diesel generators to meet the power outage in case of natural calamities.
Based on the unique needs and constraints faced by hospitals, When combined with a battery bank, a solar plant can be used to reliably support some critical loads; which critical loads can be decided in consultation with the hospital’s infrastructure team. In the event of a power failure these loads will be supported by solar power and the battery bank will compensate for any deficiency in solar power at that time Battery backup – The battery bank will be charged by solar power, and will support critical loads of the hospital for short durations during the daytime when solar output may be reduced. Night time support is also possible, depending on the size of the battery bank Battery sizing decides the duration of battery backup available. Batteries add significantly to the cost of the project, need to be replaced every few years, require maintenance, and impose weight and space requirements. Therefore we recommend limiting the battery bank to about an hour of backup Hybrid inverter – A rooftop solar PV system that utilises a hybrid inverter will allow the solar plant to integrate with a diesel generator. Here the rooftop solar plant serves to reduce diesel bills by supporting part of the load Integrating a rooftop solar plant with a diesel generator involves several challenges (discussed here) that need to be overcome with careful design and sizing of the rooftop solar plant Alternative 2 – Without clear separation of loads If it is not possible to isolate critical loads through a dedicated feeder, the solar power will have to be fed along with the diesel generator/EB power to the entire facility. Such a plant will contribute to savings in diesel, but support to specific loads in the event of a power failure will not be provided. This configuration also require a hybrid inverter, but batteries will not be required. It should be noted that in the event of a power failure, if the DG is shut down the solar plant will also shut down. For either alternative, we recommend net metering to ensure that excess solar generation, if any, is monetised. Cost of a Rooftop Solar Plant The cost of a rooftop solar plant is discussed in detail here (including incentives and subsidies) and returns from substituting diesel with solar are discussed here. As a rule of thumb, a 1 kW solar plant that generates 4 kWh of solar power per day (on average) will cost Rs. 1 lakh (without considering subsidies, including installation charges but excluding batteries).