A conventional 75 passenger ferry that has to be build with similar ergonomics and safety standards under classification society approval would cost about 150 lakhs. With a two 50 HP main engine and consumption of 15 litres diesel per hour on average, and total of 150 litres per day (engines are running all the time). At current price of diesel that amounts to ₹7500 per day and ₹26 lakhs per year (350 days running).
Lubricating oil can be taken as 10% of fuel cost, which is ₹2.6 lakhs per year. Maintenance cost for engines is another 5%, ₹1.3 lakhs per year.
Total operating cost per year is ₹30 lakhs (excluding labour and other expenses that are same in both). These are expected to grow each year at 10%.
For solar ferry an operating cost that comes is in sixth year is replacement of battery bank. This is ₹30 lakhs for 50kWh system. A daily grid charging cost of ₹400 (@ ₹10/ unit) and total of ₹ 1.4 lakhs per year expected to grow at 10% per year.
The total cost of ownership of a conventional ferry and that of a solar ferry is listed in the two graphs.
If we were to compare the total cost of ownership between the two boats, see graph on the left.
The graph shows that although solar boats have higher upfront costs, the total cost of ownerships is lower. This boat has a break-even period of six years.
The total cost of a conventional ferry and that of a solar ferry is listed in the two graphs on top. It clearly shows that from after second year, solar ferry boat saves money for the client. If we were to compare the total cost of ownership between the two boats, see graph below. If one were to factor the cost of pollution and uncomfortable journey by conventional ferry then the savings would be even greater.