First off, the current system of forcing utilities to buy excess electricity generated by distributed photovoltaic cells at a premium is the one thing that likely will impact power company PROFITS. For those not familiar with this, in the US (at least, not sure of other markets) power companies buy your unused power you put on to the grid at a price that is above the retail price your neighbors will pay for their electricity from the utility. THAT policy, coupled with extremely generous incentives from the government is what makes photovoltaic cells an 'affordable' power source.
Second, utility company profit is typically regulated to be a percentage of revenues, and reduced sales (because of conservation, self-generation, or whatever) will reduce power company revenue, but profits will remain at the regulated percentage of revenue. (Back when AT&T was *the* phone company, they enjoyed a federally guaranteed profit of around 6% of revenue. They couldn't make more than 6% profit on phone service, but they could keep raising rates until they hit 6% profit. Six percent isn't an unreasonable profit, but when it is guaranteed, it is great. This helps explain why the phone company did so much research and paid such high salaries - these increased costs required increases in revenue, which increased profits.)
The thing that hurts the power company are the regulations, not the lost sales:
Install solar panels on your roof, gov't covers half of the cost (50% discount)
Generate electricity with those solar panels, sell the excess to power company at premium (retail plus) price.
Forcing the power company to buy electricity it doesn't want when it doesn't need it and can't predict or rely on it is what will kill their profits, not you buying less electricity on sunny days with your federally discounted solar panel array on the roof.