Solar Panels in Sunny New Orleans (Part 2)

In January I posted that we had a 3.36 KW solar panel system installed. Though I've still not heard from the Feds or State of Louisiana about our 2009 tax rebates (we should get back about $20,ooo of our $26,225 investment), we have received two Entergy bills. I should point out early that this post is full of technical data and boring numbers so you should probably stop reading here unless you're thinking about installing panels. Here's the data:

Entergy Bill from February 17 to March 18, 2010

We used 785 kWh from Entergy (cf. 1063 kWh 2009 bill), and we sold back 219 kWh from electricity produced by the panels. Thus Entergy charged us for a net of 566 kWh which cost $16.78. Each kWh cost 2.96 cents.

Enphase, which I use to monitor my system, records that my panels produced 463.89 kWh of energy during this same period. So why is there such a discrepancy between the 463 that my system claims and Entergy's claim of only 219? Anthony Reis from Solar Works clarified that the difference comes from when we're at home in daylight hours and consuming electricity at the same time the panels are producing it. Thus the Entergy meter registers a much lower number.

Bottom line: Total Entergy bill (gas and electric) was $125.79, compared to $194.27 for same period in 2009. Savings = $68.48.

From March 18 to April 15, 2010

We used 770 kWh from Entergy (cf. 798 kWh 2009 bill), and we sold 259 kWh back, for a net of 511 kWh which cost $16.31. Each kWh cost 3.2 cents (notice the increase from last month, and thanks Entergy).

Enphase records that my panels produced 523.17 kWh.

Bottom line: Total Entergy bill was $90.69, compared to $124.23 for same period in 2009. Savings = $33.54

Analysis

It's way too early to accurately predict overall performance with just two months of data. But thus far we've saved an average of $51 per month. That means it would take 10 years for the system to pay for itself, a bit longer than the six years we predicted. However, we're entering the summer months when the panels will produce more electricity, and as electricity charges go up, so does the value of my system. Plus, it's not so precise to calculate the benefit of the solar panels by just comparing the Entergy bills, as they also include charges for gas, base rate charges, and charges being added on to Entergy New Orleans customers for "Emergency Storm Reserve Fund." So at this point, I'm happy about the panels. This is mostly because I'm paying Entergy less money than I would be without the panels. But also, with a giant oil spill in the Gulf of Mexico with 11 dead, and a mining explosion in W. Virginia with 29 dead, I'm reminded that there needs to be an increased focus on renewable energy.