For Ontario dairy farms, the profitability criteria are acceptable for all but the smallest farm size (1e32 animals), with a payback period of, at most, 6 years and an ROI of at least 15.8% as shown in Table 5. A payback period of 5 years is realized for the three largest farm sizes analyzed (123e177 animals, 178e272 animals and 273e527 animals), with an ROI of at least 18.9%. The ROI for farms of the size of 178e272 animals is higher than that of the size of 273e527 animals. This is due to the fact that the larger farm size has a capacity of over 100 kW, and, therefore, is receiving a lower tariff of 0.185 CAN$/kWh.