Because of the tax incentives available for investments in renewable energy, the payback for commercial photovoltaic systems is rapid. On Oahu, the combination of electricity cost savings and tax incentives ensure that the full system cost is recouped in a little more than 3 years. On the outer islands, payback takes a little less than 3 years because electricity rates are higher. The figure below shows the payout over time for a $1,000,000 investment on five islands.