Archives February 2021

Going Solar, Part Six: Results!

West-facing panels, note anti-pigeon fencing

We have ignition!

NV Energy replaced my meter and gave me thumbs up on January 6, so I pulled the handle to connect my panels to the grid (and my home). That afternoon, the panels generated 4.441 kWh of AC energy. The first full day was 18.292 and we were just getting warmed up as the days after that registered 24 kWh or more per day. Overall trend was increasing production as days grew longer.

January 2021

I started getting data from NV Energy on 1/16/21 so for the last 16 days of the month I know I received 370 kWh from the grid and delivered 200kWh of solar power to the grid. My total consumption of electricity for those 16 days was 529 kWh, so by my calculation the panels saved about $20. Add in the 10 days without data and I may have cut my expected $65 bill to $35. I’ll let you know exact numbers after I receive my first bill.

These numbers are in line with the estimate from my solar contractor that my panels would generate approximately 628kWh every January. From 1/6-1/31 (25.5 days) they actually generated 593, average 23 per day. 23 x 31 = 713 for a conservative estimate of what total January production might have been. PVWatts was a little optimistic predicting I might generate 902 kWh, but they apparently assume mostly-sunny days, whereas about 1/3 of the days this January were cloudy or partly cloudy. Daily production ranged from 8 kWh to 36 kWh depending on amount of sunshine.

Is it worth it?

Considering that I made the first of 144 loan payments of $182.71,saving $30 on my first monthly bill might not be cause for much celebration. Fortunately, the savings should be much greater in warmer months, and the up-front $5400 tax credit reduces the cash flow pain significantly.

A lot depends on how much I get for delivering excess solar power to the grid during summer peaks. In July I should be able to generate 1500 kWh and deliver much of that back to NV Energy for about 32 cents per. That’s a big chunk of change if I use the AC sparingly during peaks and don’t crank it up too much in the off-peak hours.

The future

Assuming my installation proves reliable and free from major maintenance costs, most other factors seem likely to increase cost-effectiveness of my investment:

  • Summer days grow hotter
  • Electricity rates increase
  • Public perception of the value of solar panels increases

Meanwhile, I can take some satisfaction that I am reducing my carbon footprint (particularly important in US with its inefficient carbon-based generating plants) and have somewhat limited the risk of climate-related impact on energy costs for my home. After one month of production, my monitoring program cheerfully informs me I’ve saved the planet from 1,222 pounds of carbon, the equivalent of planting 9 trees.

First Bill (January)

Today I received my first post-solar bill from NV Energy. It covers the day of installation (1/6/21) to 1/28/21, 22 winter days. The combination of TOU Rates and Solar Power are saving a lot of money.

The grid delivered 423 kWh and the panels sent 323 kWh out of about 500 kWh generated from solar panels to the grid, for a net 100kWh billed at full rate, total $6.25. Various fees on the full 423 kWh were $1.36. Electricity costs total $7.61 or $0.35 a day. The base service was $9.53 making the total bill $17.24, an average of $0.78 per day.

Last year my daily average was $2.24, $1.46 more per day. This year we are using a lot more electricity due to the pandemic. Last year we used about 15 kWh per day but this January we used almost double, 27kWh per day.

27 kWh at full rate would have been about $1.69 per day (base service additional.) TOU saves about $1 of that. My original projected solar savings, pre-TOU were $0.12 per day, so it looks like my projections were very conservative.

These numbers will be very different in summer, when costs and savings will be higher, and conservation during peak hours more essential.

February, 2021

For the period 2/1/2021-2/28/2021, my solar panels generated 971kWh. That exceeds the estimates from PVWATTS (924) and my contractor (790). I used 449kWh from the grid and sent back 703kWh for a net of 254kWh to my credit. My total consumption was 717kWh (971-703+449) which would have cost $47.11 from the grid. Instead my bill will be an effective credit of $14.22 for a savings of $61.54.