My experience has been that they usually outlast a standard electric water heater. Essentially ALL tanks are 6 year units. You just pay for an insurance policy when you buy 8, 9, 10, or 12 years heaters. With one company you install the 6 year heater then pay about $200.00, depending on the size, for a sticker to make it a 10 year unit. You pay more for the solar tank, even though it only has a single heating element, because of the added openings and the smaller production run for those units.