My 40 solar panels lifetime production after 21 months
May 6th 2014 was the first day my 40 solar panels started generating electricity to HydroOttawa’s grid. Over a year ago, I wrote the article 40 solar panels + 1 Volt where I described the installation. As a reminder, with Ontario’s MicroFit program, I signed a 20 year contract. I sell the electricty generated by the panels at 0,396$/kWh.
All panels are 250W with micro-inverters. There are 33 panels are on the house’s rooftop and 7 on the garage’s rooftop. Since the garage’s rooftop is lower, the house’s rooftop creates shadow in the afternoon. Another important information : my neighbour’s 30 year old huge pine tree does create shadow on my house early in the morning and most of the day in winter.
21 months later, the 40 solar panels have generated 18.9 MWh of electricity. which represent a carbon offset of 13.1 tons.
In 2015, the panels generated 10 840 kWh, but the grid calculated 10 179,73 kWh. There are different places where there is a loss. I will let you speculate or explain this.
I have included different screen shots of statistics from the Enphase’s Enlighten Manager. Feel free to comment !
40 solar panels configuration (33 on house rooftop and 7 on garage’s rooftop)
Electricity production in 2014 (from May 6)
Electricity production in 2015
Electricity production in 2016 (until February 6)
Lifetime electricity production since May 6 2104
Best production day in 2015 – June 19 – 74,312 kWh
Best production day in 2014 – June 19 – 74,867 kWh
When it comes to AC power, there are subtle differences between Volt-Amps, and Watts. The difference is phase-related – what parts of the AC cycle have the volts, and what parts have the amps. The ratio between the two is called Power Factor. A purely resistive load (heaters, most non-CFL lights) will have a 1:1 Power Factor, so VA and W are actually the same. Inductive or capacitative loads (CFLs, motors, transformers, TVs, computers, wall-warts, etc, almost everything EXCEPT heaters/lights) will usually be drawing the most current on a part of the cycle that does NOT have the most voltage, and they end up with a lower power factor, EG they might be using 0.7 kW but 1 KVA for a PF of 0.7. To add to the confusion, various bits of equipment will often measure VA whilst claiming to measure W, or vice-versa, or using the wrong units and thus implying they are measuring the other.
You can ALMOST guarantee your power company is measuring kW, not VA, which actually works to your advantage if you’re a crappy-PF consumer, but not if you’re a producer, where you really need the PF to be as close to 1:1 as possible.
I don’t know if your panels are ACTUALLY measuring VA or W, nor if they are doing so before or after the inverters, but a 0.94 PF, and/or a 94% efficiency in the inverters would both be pretty good. Energy Star ratings typically require >0.7PF, some better ratings require >0.9, pretty much the best I’ve seen on any equipment is 0.97.
I guess the all-important question… The panels have earned you (back-of-envelope) $4000/yr? What did they cost to install, and when do you hit the break-even point? Also, instead of buying+installing the panels, if you had put the money in high-interest savings, you’d have MORE money now. At what point do you break even against THAT and start earning more money than the equivalent savings would have done?