Professor Rizzo was keen that I check out the $12,000 solar picnic table at University of Rochester
Most kids use this to hook up their laptops. Here are a few assumptions
- 3 hours of use per day (heroic, I am pretty sure it is less than this)
- 65 watt draw from one laptop
- 160 days with sun (Rochester is apparently in the top 10 US cities for number of heavy cloud days)
- 10 cents per kw-hour
This means the table would produce 31,200 W-hr per year or 31.2 KW-hr per year. This yields an annual electricity savings of $3.12, giving the table a payback time on its investment of 3,846 years. If one assumes a cost of capital anywhere north of 0.026% per year, then the sun will go dark before this table pays itself off.