A little over one year ago I turned on my solar panels at my house. Now that a full year of use has passed, I can assess their effectiveness. My goal was to generate from solar 100% of the electricity I use. I didn’t quite make it – I generated 96% of the electricity my house consumed. But that included charging my electric car for the year, which means I was driving on sunshine.
If you are anything like me, you want to geek out on all the numbers. So here they are.
The Panels
- I have 30 panels, 320 W each, for a total capacity of 9.6 kW (LG320 NeON2 MonoX Plus panels)
- Installed cost: $28,000
- Austin Energy Rebate: $7,500
- Federal tax credit: $6,100 (30 percent of the cost of the system)
- Net cost: $14,400
Energy Usage and Generation for Year One
- Consumed: 13.59 MW-h
- Generated: 12.75 MW-h
- Net Consumption: 540 kW-h
Monthly generation and consumption at the Mack house in 2017
Electric Car Energy Consumption
- Nissan Leaf Miles Driven: ~8,000/year
- Mileage: 3.3 miles/kW-h
- Approximate energy consumption: ~2,400 kW-h/year (about 18% of my total house consumption)
I’ve geeked out about our array (SunPower 327W panels with Solar Edge inverter). It’s been in for 3 years, does not supply electricity needs for the full house though, too much shading from our live oaks on the roof to allow for that many panels and I was not about to sacrifice the live oaks for this project 🙂
One of my favorite graphs is plotting kWhrs used against median temperature for the month, going back 5 years. It shows efficiency gains from shading of the roof (and new HVAC system). Not sure if the efficiency of the panels has decreased in these three years or if it’s just variability in cloud cover. Need more data.