Editor’s Note: This is the first in a two part series on my (so far) discouraging effort to equip my north Texas home with solar powered electricity. This first part sets up the technical aspects and the second part addresses the financial considerations.
I am and have been interested in solar power for decades when the technology involved cumbersome panels that heated water and created inefficient electric power. Since my Congressman lived two houses away on the same street, one Saturday morning in 1979 I knocked on his door to ask his assistance. His wife instructed me to contact his local office. When I did, his martinet minions were zero help. That was then.
Those days of solar power and ancient technology have been replaced by grid tied inverter systems. Any electricity produced would have been very inefficient and expensive. Now a Certified Green Purchasing Professional (CGPP), a lifelong environmentalist (in the apolitical sense), and an engineer by education, I am ready to revisit the roof top solar panel question.
My interest rekindled after reading a story about the soaring market for residential roof top solar energy so I decided to pursue it. At first blush, the $4.20/watt price tag seems enormous. The unit price changes very little as the size of the installation grows. Despite the drastic price reduction of solar panels over the past few years, the cost of solar power remains dauntingly expensive.
I own an average size home in north Texas, where summers are blistering hot and electricity bills, predominantly due to air conditioning, usually exceed $500 per summer month. So I chased down local solar contractors to determine if conversion of my house to solar energy would be economically feasible.
The technical basics
According to the National Association of Home Builders, my home is average size is average. Electricity consumption ranges between 3,800 kilo-Watt-hour (kWh) in summer to about 1,000 kWh in the winter. Our south facing roof lines are on the front of the house, which is a barrier, albeit surmountable with the Home Owners’ Association (HOA). One contractor recommended the black panels and framing as these are not as objectionable as the blue ones.
Given the un-shaded roof areas available, our choices were a 5kW or a 10 kW system. For those who are unfamiliar with the engineering and physics involved, kW or kilo-Watt is a unit of power, and kWh, or power through time, is a unit of energy. The 5kW system requires 20 panels and measures 11 feet by 33 feet. The 10 kW system needs double the panels and roof area. Skipping the boring techno-mumbo-jumbo, depending upon the season a 5kW system energy output averages 750 kWh/month and the 10kW system averages 1,500 kWh/month. Contractors allow for up to 20% deviation from these averages and assume 5.2 hours annual sun panel hours per day.
Those are imprecise figures upon which to base a big financial decision.