SunPower & Tesla Solar — Rooftop Solar Comparison

As part of my family’s journey to learn more about residential renewable energy, I decided to look into solar panels for our house. We are in the middle of Texas, and who can forget power going out for one week across the entire state in February. We were fortunate, but many of our neighbors had to be without power for a week. The state has done minimal winter weatherization for the coming winter. I fear this winter will be bad, and if not this winter, an upcoming one in short order. Natural gas prices are spiking across the world. According to the Dallas Fed, natural gas and coal make up the majority of power production in Texas. The good news is that wind and solar have made great strides in Texas, but there is much more to go.

A friend of mine mentioned that their average electric bill has increased to $170 a month this year from $140 a month last year. That’s a 20% increase. Retail consumers may have been isolated if they had a fixed rate plan during the freeze. Utilities had to keep buying at ridiculous wholesale prices. I’m sure they will lobby the government for rate increases to make up for all their losses. We can assume electricity prices will go up over the coming years. If the world continues warming, and summers get longer and hotter, that’s another reason our electric bills will go up.

Tesla Solar

Enter rooftop solar and batteries. The first step is having 12 months of electric bills handy. You want to calculate your total kilowatt-hours used in one year. That starts with finding your current electric rate. Ours is 10.9 cents per kWh. Our energy consumption was 14,400 kWh in a year. Our average electric bill was about $131 a month.

Second step: contact many solar providers to get a quote. Tesla makes it easy on its website. Enter your address and Tesla will tell you how much solar and how many Powerwalls you need. Our address was not found, so Tesla asked us to enter some house information.

Below is what Tesla recommends for a Solar Roof. Tesla is quoting $69,500 after the US federal tax credit, 100% estimated energy offset of our annual monthly bill, and 3 days of backup power using a Powerwall. Considering my roof was $35,000 to fix three years ago, and labor and construction costs have increased since then, this seems competitive.

Below is Tesla’s quote for solar panels. This is a great price. Tesla would provide a 8.5 kW solar panel system along with 1 Powerwall battery. The cash price is $20,412 after the federal tax credit. The estimated energy offset is 73%, which means 73% of $140 would be offset. Be wary of solar companies providing you a 100% solar offset of your energy bill. Your roof’s potential has to take into account trees, roof shading, weather, pitch of your roof, and which direction the solar panels would be facing. The solar panel preference in the northern hemisphere is south facing or an azimuth of 180 degrees. Azimuth is the angle of your roof position from true north, with roofs facing true north having an azimuth of 0 degrees, and those facing south having 180 degrees. The opposite will be true for those in the southern hemisphere. A pitch of 30 degrees is ideal for solar production. Tesla offers financing of 10 years, with 10% down and 2.99% APR. For the below system, that comes to a price of $240 a month. Readers will note that is almost double our $140 a month in current electric costs.

Savvy readers may ask, how long is the system guaranteed for? How much will it produce after 25 years? Tesla informs us on its Service and Warranty | Tesla Support page:

Your solar panels are guaranteed by their manufacturer to at least 80% of nameplate power capacity for at least 25 years.

Your entire Tesla solar system is covered by a 10-year comprehensive warranty.

This includes the following aspects of your solar system. For details and exclusions, you can check your specific purchase agreement.

    • Powerwall
    • Solar inverter
    • Roof mounting and leaks

I’m not thrilled the worst case capacity of the system might decrease by 20% over 25 years. That would leave us with a system size equivalent of 6.8 kW after 25 years. The average production size over 25 years is 7.65 kW (8.5 + 6.8, divided by 2). According to my utility, each 1 kW of system capacity facing south will generate 1,533 kWh per year. Taking the average system, we calculated that multiplying by 25 years and multiplying by 1,533 kWh gives us a total of 293,186 kWh produced. Our total cost is $240 * 12 months * 10 years, for a total cost of $28,800. That’s a cost of 9.8 cents per kWh after the credit. This cost would be locked in for as long as we own the panels. As a reminder, that includes one Powerwall battery, which makes this a great deal, especially if the power is to go out. There is a new option that allows you to remove a Powerwall if you don’t want one.

If you are interested in Tesla Solar, feel free to use my referral link.

Use my referral link to purchase Solar Roof or Solar Panels and get up to $500 award upon system activation: https://ts.la/vijay59877


We recently mentioned SunPower’s move to help historically marginalized communities here. I’m supportive of the move. SunPower is listed on the Nasdaq as a public company. This week, the company decided to focus purely on residential systems and sell off its commercial and industrial solar division. CNBC has more info.

I contacted the company on its website and set up an appointment. I met with Salvador V. twice over the course of a week. Below is some key information from the proposal we reviewed.

Above: A picture of our roof. We upsized our system by adding four more panels from the original proposal (dark orange).

SunPower would install 22 panels, with a total solar system size of 7.194 kW. Lifetime production is estimated at 264,337 kWh. To repeat, we had calculated my monthly bill to be $131. Based on that, the system would offset 78% of my electricity consumption.

The total out of pocket cost was noted as $24,287 after the US federal tax credit. (Note: This does not include a Powerwall battery or any kind of energy storage battery.) The monthly cost of the system would be $109 a month over 25 years. That is how long SunPower will warranty the system, 25 years, which is phenomenal. Salvador noted a Powerwall from SunPower is an extra $16,000. Tesla Solar has a Powerwall listed for $10,500. The interest rate they offered me was 1.99%. Over 25 years, the total cost is $32,700 ($109 * 12 * 25). If we divide that by a total production of 264,337, that gives us a total cost of 12.4 cents a kWh.

SunPower’s warranty specifies the DC power will decline by no more than 2% a year for the first year, and the following years will not decline by more than 0.25% a year for the next 24 years. That means the system will be guaranteed to generate 92% of its capacity after 25 years. SunPower will repair, replace, or refund the original purchase price over 25 years for any valid claim. In their own words:

“… will be at least 92% of the Minimum Peak Power rating (the “Guaranteed Peak Power” rating) and the AC power of the system will be at least 90% of the Peak System Power for the full 25-year warranty period.”

That is an impressive warranty. When you install a solar system, the parts can be from different distributors and labor from another subcontractor. Who do you go to if you have a warranty claim? What happens if your part is no longer available? SunPower makes it easy. The company sells all of its equipment to one state distributor, and that distributor is captive to SunPower. In our case, Freedom Energy is SunPower’s captive distributor in Texas. If we had a warranty claim, I would contact my rep, Salvador. Freedom Energy would be responsible for the labor, fixing the system, and any parts needed under a claim. If needed, we can add a battery or more panels in the future. If you are in Texas and have interest in SunPower, you can contact my rep Salvador at salvador@freedomsolarpower.com. Mention my name, Vijay Govindan, to him and you’ll save money on the system, I’ll make money, and we’ll being doing good together.


Here’s where we stand:

After all was said and done, we went with SunPower for a few reasons. Reason 1: the lower monthly cost. Reason 2: no down payment. We can invest the down payment and $111 monthly savings compared to Tesla Solar in outside investments. Reason 3: the higher production capacity of the panels over 25 years. This advantage is offset by the larger Tesla Solar system size. Reason 4: time. SunPower estimates it can get the licensing, permitting, HOA approvals, and installation done within 2 months. I do not know how long it would take for Tesla Solar to do the same. I might not know until I finalize my order. Reason 5: the peace of mind of the long warranty period and ease of getting claims resolved. Reasons against the SunPower system are the expensive cost of the battery, higher system cost, smaller system size, and no battery being included in the proposal. If you can pay cash for your system, it’s a no-brainer — go with Tesla Solar and invest your savings. The SunPower app is not as good as Tesla’s, but with the changes at the top of the article, I am sure they will work to improve it soon.

The bottom line is, whoever you go with — Tesla Solar, SunPower, someone else, or doing it yourself — it’s a good idea to explore renewable energy production for your home. Give it back to the governor, legislature, and utilities on escalating energy costs, brownouts, blackouts, and poor maintenance of the grid.

I’ll leave you with the final slide in the SunPower proposal. Outside of the financial savings, the savings to the environment are significant. Below is the estimated impact form switching to the solar panels, every year. Stick it to the fossil fuel companies, their lobbyists, and favored donation recipients known as politicians. Take control of your energy production. At scale, this would dent natural gas and coal plants until they become unprofitable.

Final note on net metering

What happens in those months when we produce more than we consume, such as spring and fall? According to our utility, we would get no credit for those kWh, and they would go back to the grid for free. The utility will give us credit for what we produce at our retail rate, and charge us only for the net amount of electricity consumed. The catch is the full retail credit is only given if the solar panels did not produce more energy than our house consumed at the end of the billing cycle. That’s Texas for you.

The ultimate goal for our family is creating apartment complexes that are sustainable, fashionable, and low cost. Solar and renewable energy will play a big role in bringing that vision to life. It’s one reason why we want to learn more about solar panels.

Note: I own shares in Tesla, I own no shares in SunPower. You know by now this is not investment advice. Do your own diligence, read from a variety of sources on what you need to move to solar, and do what’s best for you.

Thanks for reading and warmest regards.


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