The parallel ability ensures you the chance for coupling two units for doubling the power ability. Keep in mind that the units have to have to same size capacity. The identical ability will let you utilize two light and small units for making the work of a larger and heavier unit. Moreover, a new transfer switch connection won’t be even required. Don’t forget that 4000 watts of power is what’s capable of an average model. You will double the power if you plan on coupling two identical generators.