The initial design incorporated one more panel and was rated at 5.17kW. With a new lower rebate structure currently in effect, we were faced with reducing the number of panels to stay within our original budget.
We explored the option to purchase 2-additional panels for a system that would produce 5.39kW. With Francisco Reina’s help, we determined the smaller 4.9kW system would cost us an additional $40 – 50/year in electricity, while the larger 5.39kW system would save us about the same amount. Both calculations were based on a higher rate of .14/kilowatt hour (kW h) versus our current Xcel rate of about .115/kW h. With rebates and tax credits, the cost for 2-additional panels would take over 25-years to pay back at .14/kW h.
Even if energy rates were to climb above .14/kW h, the return on investment would not achieve our Project Goals for a 7-year or less payback on all systems. We’d already compromised our goal with our base system, which will provide a 10-year payback.
Francisco advised us to focus more on decreasing the overall amount of energy we will use in our new home by increasing the building envelope efficiencies. Our advanced framing techniques and additional rigid foam insulation at the foundation walls will make our smaller solar PV system more effective and will provide a quicker payback than adding 2-panels.
We will install an underground conduit from our garage to our electrical entry service at the house for the future possibility of additional solar panels on the garage roof. With continual advancements in solar technology, panels will become more efficient and should provide a quicker return on investment.