A Rooftop Solar Panel

Last year 2021, I have installed a Rooftop Solar Panel with Battery Backup. It was a very long process and full of many logistical challenges, that had nothing to do with technology mostly, but permitting and other regulational issue. I like to discuss a little bit of that here. Also this is my first post in STEMGeeks community, where I think this post could be appropriate.

First, how they look. Fairly standard, I should say. I have installed 21 panels. In theory that is meant to offset about 75% of my total electrical consumption over the year on average. The above were the installation of 13 panels on my west facing roof of my single-family home in Houston, TX.

This is the array of 8 panels on my south facing roof. This was at the nice of installation. This was finished last September. I will get into the time-line and the equipment etc.

Background

I have been buying expensive wind energy generated in West Texas for about 12 years now. Don't ask me why, as that will be different post :) Trouble is wind energy is expensive. I used to pay about 19.5 cents/kwh and my energy consumption was about 1500 kwh/month over an yearly average. The cheapest electricity in Houston that one can buy is about 10 cents/kwh. So, I was paying about 2X more (again, don't ask me why).

A neighbor in my community that I talk to quite frequently recently (in 2020) put in a roof solar system in his home. It is about 3 doors down from mine. So what happened in Jan 2021, Texas had a major snow storm, which is very usual, as it never snows (almost) in Houston, TX. It was a major event and got a lot of national (even international) coverage at the time.

Source

Basically, the problem were two folds. First, Texas electrical grid is not winterized (as it generally never snows in southern Texas). Second, Texas electrical grid is NOT a part of US national grid (Yeah! We like it here, its a different country didn't you know?). If you like any detailed discussion on these two points above, I can talk straight for 2 days without consulting any internet resources. But again let us not go there :)

https://en.wikipedia.org/wiki/2021_Texas_power_crisis

Point is during this event we lost power for 3 straight days (84 hours total). Our family have a natural gas fireplace and cooktop which also runs on natural gas, so we were relatively okay. However, I remember the first night being brutally cold (in Texas standard). It was 38 F inside kids bedroom. They did not like it. Their mom did not like it even more.

My neighbor Ann and Pat's home stayed bright during this time. Becuase it is really sunny from the second day of the power outage and they had enough backup battery power. So basically, this was the triggering event for our family. That late February 2021, 2 weeks past the backout, we ordered to install the rooftop solar panel system with backup batteries. Also mind you, Houston is no stranger to power outages. We have hurricanes. But this one we didn't see coming!

My System

I have a 7.67 kw system. I have 21 LG 355W NeON2 Solar panels. 13 on the west facing roof and 8 on the south facing roof. The panels have 25 years warranty. Houston gets about 204 sunny days on average in the year, which is not great, but its quite good.

Source

Now, for those who don't know, south facing panels are best for Solar Output. There are some good scientific debate on the subject. It is on the fact that based on pure output, south facing panels are the best, however, west facing panels capture a lot of electricity during later part of the day, especially in summer, when city grid demand is high.

Source

This is my roof from the top, trouble is I have more space towards the West facing roof than South

Trouble is in Texas, there are not enough Solar plans available for buyback. Those that are available are also fixed rate and doesn't offer cash out for the sold electricity. They only offer credits towards your electricity bill at this point. This means you can't take advantage of variable rate pricing of the elctricity, although your provider may charge you for it when you buy.

So currently, the best solution is not to generate too much power, because you don't have anything to do with it. Rule of thumb is to have a system that produces about 75% of your yearly consumption. Because, if you have some simple energy saving systems, like smart bulbs, or LED lamps, or energy efficient windows, you will likely be near 100%. In other words, you will have no net electricity bill.

Cost

This is what most people ask. Is rooftop solar panels worth it. It depends on where you are. In places like California (with both federal and state incentives, and high energy cost) it is no brainer. While in Texas, I will show you that it will probably take me about 12 years to breakeven, or recover the cost of installation. So in Houston Texas, probably it is not worth it. However, that was not my driver to do the installation personally. I simply wanted a backup power system that is clean and available when in need, and also I can afford it.

Here is close to my actual purchase overview. The final numbers are probably a few dollar different here and there, but this is as close as it gets. You can see all the rebates and discounts. For me the selling point was the Federal Tax Credit. I always have a lot of capital gain taxes, this purchase helps me offset nearly $11,000 of it (there is a discussion of elevating that to 29% instead of 26%, which would be even better). You can see the math here assuming 18 cents/kwh (my actualy is slightly higher) that my yearly cost of electicity that I pay is about $2642. To recover my total out-of-pocket cost of $31,182, I will need about 11.8 years. This assumes that I will generate about 8500 kwh per year. I am hoping I can generate a bit more than that, and also hoping to put on some energy efficient windows. If I am lucky, I can perhaps get it down to 10 or 11 years to breakeven. I am personally okay with that.

Current Power Production data

As I mentioned that I started ordering process in Late February 2021. The first problem I faced is the global supply chain issue. I was told that the Tesla PowerWall is on a 10 month backlog! I tried to find alternative (EnPhase), but that battery didn't fit my garage wall properly. So I had revert back to Tesla. There were permitting nightmare and logistical problems both at City of Houston and Centerpoint Energy (the utility provider). To make long story short, my system was finally installed in late September. However, that doesn't grant the permission to sell the electricity back to the grid. That permitting took more than 2 months, and finally on December 6, 2021 I could sell electricity back to the grid. My system is now fully operation, and I have about 1 month worth of actual data for the electricity production.

My solar arrays; you can see how the south facing panels are generating more cumumative power

Month of December was mostly cloudy, as expected. On the brightest of days, the system can generate about 30 kwh of power. Above is the actual data from the month of December, where the system generated 430 kwh from 6th of Dec to 31st of Dec (26 days), about 16.5 kwh/day on average. My monthly consumption was about 640 kwh, so it is not quite grid independent yet, but I am hoping in the spring and summer months, I will generate more than I consume, and receive some credits to be used in the next winter.