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Our new set of SunPower solar system panels
Our second set of SunPower solar panels was installed at the end of Sept 2022. Photo by Vijay Govindan.

Clean Power

SunPower Turns Our Roof Into A 30 MWh/Year Powerhouse

SunPower came by at the end of September and added 21 panels to my south-facing roof. This is only possible since SunPower understands the previous installation and knows what steps to take to upgrade the system. You can upgrade your solar in steps, as you see how your bill changes. I estimate the roof can generate 30 MWh a year. This is not a small sum. I have too much power generated from the sun for the moment. When you add in a future electric vehicle, electric room heaters, a heat pump water heater, and a heat pump air furnace, that sum gets whittled down quickly. Note the pun in the title: powerhouse. 🙂

Why add more solar?

This summer was brutal in Texas, involving high daytime temps, high nighttime temps, and the AC working hard. During the day, we set both thermostats to 78°F degrees (25.6°C). At night, it’s miserable to sleep at 78°F, so at 11:00pm, the AC would kick in and reduce the temperatures to 73°F. Our initial solar setup was good enough to cover 50% of our summer energy needs. The remainder was due to charging our Tesla and nighttime cooling. I have neighbors and friends that paid upwards of $500 to $700 a month on their summer energy bills.

The recent Inflation Reduction Act, heavily covered on these pages, gives 30% as a potential tax credit based on the solar installed cost. If you expect longer heatwaves, higher summer nighttime temperatures, higher summer daytime temperatures, and colder winters, having more solar makes a lot of sense. There is consensus that natural gas prices and electricity prices will be higher in the Northern Hemisphere in winter. Often not mentioned as one of the factors is Russia’s invasion of Ukraine, forcing Europe to scramble for natural gas supplies. Slava Ukraini!

The US EIA writes: “Many households across the United States are likely to spend more on energy in the winter of 2022–23 compared with recent winters. Higher forecast energy expenditures are the result of higher fuel prices, combined with higher heating demand because of a forecast of slightly colder weather than last winter.”

The NYTimes, in “Winter Forecast: Gas and Electric Bills Will Soar,” writes: “Utility companies warn that customers can expect increases of as high as 32 percent during the cold weather.”

The only people who will avoid that increase is those who have solar in the winter.

SunPower enhancements

The SunPower app has major enhancements, allowing real-time monitoring of home consumption, solar production, and net grid usage (import or export). It’s far better than checking the old SunPower app and our local utility app, which lagged behind by 2 to 3 days. I hoped to keep my solar production data from March to August, it got wiped out when they replaced the monitoring box.

August was an odd month, as it was cloudy, rainy, humid, and very hot. This decreased our solar production. September picked up as expected. As we produced more, our solar kWh cost went down, and our grid cost went down too. Our September grid energy charge was $101.80, and we had net consumption of 720 kWh. That gave us a rate of $0.14 per kWh. If I multiplied that by 1979.3 (our total grid consumption + solar production), our bill would be close to $280. That’s a savings of $42.27 for the month.

Estimates are that the price of electricity in Texas will go up to 18.5 cents a kWh, a surge of 70% year over year. See this Dallas Morning News piece and this additional analysis of that reporting (key parts below). The mythically cheaper deregulated Texas electric grid got sucker punched in the face by reality. Texas has the additional cost of the February 2021 winter freeze bankruptcies and the $1 billion extra for weatherization on its hands. Consumers will pay for it all.

“This month, the average residential rate listed on the site was 18.48 cents per kilowatt hour. That’s up from 10.5 cents in June 2021, according to data provided by the Association of Electric Companies of Texas.

“It also appears to be the highest average rate since Texas deregulated electricity over two decades ago.

“‘Wind and solar are saving our wallets,’ Silverstein said, and more renewable projects, including storage batteries, are in the pipeline.”

I expect to pay a fixed grid electricity fee of $20 in October, and about $265 for both sets of solar panels. This will be true until the summer months. Yes, I am paying more, and yes, I am fine with the extra power flowing to the grid. It means our utility doesn’t have to buy that electricity from wholesalers, which means lower marginal costs for everyone. Or an enterprising battery can store the energy cheaply for use at night. The good news is that our energy price is fixed for decades as the world adjusts to worsening climate impact and higher energy prices. Australia has proved what happens when renewables dominate — residential energy costs go down. We were lucky to lock in low solar costs. As interest rates increase, the financing cost for the panels increases too. This puts a dent in solar affordability. We need cheaper panel cost, higher efficiency per meter squared, and cheaper financing cost to reach the most vulnerable regarding energy security.

The SunPower app shows solar system production, home usage, and energy changes to the grid

The new app is similar to Tesla’s app. We can see how much we are producing from solar, how much the home is consuming, and exports to or imports from the grid.

SunPower solar system panel production for 10/14/2022

SunPower’s updated app shows Solar Production, Home Consumption, and Net Grid Usage (Export or Import) in real time. I prefer the Power view over Energy to smooth out the graph.

Our previous production was about 45 kWh a day during the summer. The new panels benefit from facing south, generating almost 10% extra for the same system size. Always prioritize south facing panels! That was my mistake, first installing west. It worked out to our advantage, though, since the new south-facing panels have a larger capacity than the west facing ones.

Starting with August data, our solar energy mix is 87% of our total usage. I expect that to increase for the remainder of 2022

SunPower app shows 2022 Savings for solar system

The app now adds estimated cost savings. I’m not sure how that is calculated. It continues to include CO2 emissions avoided, trees planted and fully grown, miles not driven, and gallons of gasoline not used.

Individual solar system panel production in real time from the SunPower app

This is a beta feature in the app. I love it. It’s unique. You can see which panels are producing electricity at the current moment. I’m betting it is possible because each panel has a microinverter.

The above beta image is new. You can see in real time how much each of the panels is producing. There is a cool video view with the sun and moon, showing how the panels light up as the sun moves throughout the day. I hope this detailed panel data will allow architects to better design houses for solar and will allow solar engineering teams to minimize costs while maximizing production.

The worst part

My daughter and I estimate only 6 houses in our community out of 300 have solar on their roofs. That’s a solar penetration rate of 2%, which is awful for a place that is ranked highly for getting sun. There is a lot of interest, not a lot of movement. People like throwing away their money to keep the fossil fuel companies alive and the banks that finance them in business.

The best part

The recent Inflation Reduction Act, heavily covered on these pages, gives 30% of the installed cost of solar as a potential tax credit. This credit is good until 2032.

On a personal note, I am happy that we will save about 24 tons of carbon dioxide from being generated every year. The current savings of 251 gallons of gasoline is about 6 barrels of oil not consumed. This will increase in October with more solar production. More people are asking us about solar, which is good all around.

If you are skittish about making the large investment like we did in solar, take heart — you can build out solar incrementally with the right company. As you become more comfortable, you can increase the size of the system. The benefit of waiting is you may get better panels for lower cost. The downside is financing may become more expensive. If you want a solar quote from SunPower, try here: If you like Tesla, I got you covered there as well:

Some tips

  • The ideal roof angle in the Northern Hemisphere is 30 degrees, facing fully south. The opposite is true in the Southern Hemisphere — 30 degrees with the roof facing fully north. I have never seen a Texas roof built with solar in mind.
  • Most companies allow you to have the traditional style panels with dots, or panels without dots for the same cost. Go without the dots. It’s a sleeker look.
  • Submit the solar plan to your HOA yourself. Follow up relentlessly.
  • In Texas, if you can show that moving your solar panels elsewhere on your roof results in 10% lower production, the HOA can’t force you to move from the better location. This might help those of you where the house front faces south.
  • Check multiple providers. Negotiate. This is a big purchase.
  • In my next article, I’ll go over solar irradiance, the factors that go into it, and where you should start first to maximize solar production for the lowest cost.

Note: We own shares of SunPower and Tesla. Featured image shows our 21 new panels, bringing the system size to 16.119 kW.

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Written By

Vijay Govindan is a Cleantechnica writer part-time. Through his writing Vijay seeks to elevate the realized potential of humankind. Against human trafficking. Tesla Model 3 LR owner. His claim to fame is Tesla and Elon have commented, liked or re-tweeted an article he wrote with the Tesla community. Just once. ;) #WeChooseTesla, #RenewableEnergy and #YangGang supporter. Long Tesla shares. Has a healthy skepticism of the Q branch of the Tesla investment community. Made it to one $tslaq block list. If you read this far, wow, 👏🏽 and 🙏🏽.


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