Solar Panel Comparison: Tesla Solar vs. SunPower
Tesla is synonymous with “sleek, luxurious electric car”, but when owner Elon Musk purchased SolarCity in 2016, diversification began. Tesla Solar, headquartered in California, does not actually manufacture solar panels. It currently uses the Q CELLS Q.PEAK DUO BLK-G6+ model, applies the Tesla quality control measures and resells it under the renowned Tesla brand.
SunPower manufactures its own solar panels and solar systems. It does only that and is consistently one of the most highly rated companies on sites like energysage.com. The panel comparable to Tesla’s model is its A Series 420–400 W Residential AC model, specifically the A420.
Before we look at these two companies' solar panels in more detail, let’s clarify something. Tesla solar panels are not Tesla solar roof tiles. Tesla roof tiles are roof tiles with solar cells incorporated into the actual tiles. They are a roof replacement, not just panels that go on top of an existing roof. They are quite new, barely more than a prototype and have some unique cost and design issues. Therefore, we will not discuss Tesla solar roof tiles here. But we will discuss the efficiency, degradation rates, warranties and aesthetics of Tesla and SunPower solar panels.
The amount of power a panel can produce under ideal conditions is called rated power, which is measured in watts. The amount of usable electricity a panel can produce from the sun is called efficiency and is measured as a percentage. The chart below compares rated power and efficiency values for Tesla’s Q CELLS Q.PEAK DUO BLK-G6+ 330–345 (Tesla G6+) and SunPower’s A420 solar panel models.
The SunPower model produces more power than the Tesla model, and it is also available in models that produce even more power up to 420 watts. The SunPower model also converts at least 1.4% more sunlight into usable energy for your home. That might not seem like much, but when you consider that you’ll own your solar panel for 25 years, it’s at least three months’ worth of free energy, not to mention the reduced environmental impact.
Power Degradation Rate Comparison
All solar panels lose efficiency over time. This is called the power degradation rate. Two things contribute to solar panel degradation: initial sunlight exposure and ongoing wear and tear from weather phenomena. The degradation suffered initially by a solar panel is called Light Induced Degradation (LID) and is usually on the order of 2–3%. SunPower solar panels do not experience LID because they are made of a different material than other panels, including Tesla’s, which loses 2% of its power within the first few weeks of operation.
Both Tesla and SunPower solar panels suffer ongoing degradation; you can’t stop Mother Nature. Solar panel companies guarantee a minimum rated power after 25 years and a maximum annual degradation rate (decline). Take a look at these values for Tesla and SunPower’s comparable models:
|Minimum rated power guaranteed after 25 years
|Maximum annual decline
Notice that the SunPower panel retains its power-producing capabilities better than the Tesla panel—9% better. The rated power guarantee (based on the maximum annual decline percentage) is important since you (or the next homeowner) will own your solar system for at least 25 years, and you don’t want a system that loses performance at a high rate. That means increasing bills and reliance on energy from the power company, which is exactly what you are trying to avoid.
Add the 9% increase in rated power to the 1.4% more power that the SunPower A420 produces over the Tesla G6+, and you’ll get 10.4% more power from SunPower’s solar panel. Assuming you own your system for 25 years (and it will likely last longer than that!), you’ll get almost 3 years’ worth of additional solar energy if you go with the SunPower A420 instead of the Tesla G6+.
You want your whole home to look incredible, including your solar panels. Aesthetics are an important point. The cell, the panel backsheet, the frame, the racking system and the size of your panels contribute to just how pleasing a panel set looks. Here are photos of the Tesla G6+ and the SunPower A420:
The Tesla G6+ panel on the left has a wired look. This is usually not something people want, however, they have done a good job at making the panel very uniform by making the individual cells nearly invisible. In low light situations, the panel looks almost completely black. The SunPower A420 panel shown on the right does not show wiring at all, but the individual cells are completely visible. Which one you think looks better is really a matter of personal opinion.
There are two types of warranties available when it comes to solar panels: the performance warranty and the product warranty. The performance warranty guarantees a certain power degradation rate and minimum rated power after a certain number of years (in this case 25 years). The product warranty is more like a traditional warranty that covers faulty workmanship or defects that cause the solar panel to stop working completely or correctly. A solid product warranty can save you thousands if a panel ever breaks. Let’s compare the coverage durations for the Tesla and Sunpower product warranties.
It’s obvious that the SunPower warranty is over twice as long for every important component. They stand behind their entire product for a longer time period and even warranty the monitoring system.
It’s time to choose. If you want the most efficient panel with the best warranty that retains its power-producing capabilities, choose SunPower’s A420 panels (or a higher wattage panel from the A Series if desired). If you want the sleekest-looking solar panel and don’t plan to stay in your home until it breaks, then choose Tesla’s G6+ panels.
In Summary, here is our comparison of SunPower solar panels vs. buying a solar system from Tesla: