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PV Standard Test Conditions

Standard Test Conditions, or STC; what does that mean in terms of a solar panel? To define STC, we must look at current competitors in the solar industry to better understand what you (the buyer) needs. These STCs are the set of criteria that a solar panel is tested at. Since voltage and current change based on temperature and intensity of light, among other criteria, all solar panels are tested to the same standard test conditions. This includes the cells’ temperature of 25° (77°F), light intensity of 1000 Watts per square meter, which is basically the sun at noon, and the atmospheric density of 1.5, or the sun’s angle directly perpendicular to the solar panel at 500 feet above sea level. Let’s dive into what this entails for a San Antonio homeowner.  

STC in Texas

Now that we have an understanding of the way solar panels are tested, what does that mean for ACTUAL numbers in the Lone Star state? For starters, with up to 3,700 sunny hours or 233 sunny days a year, it is truly a great place to install solar panels. Solar panels in Texas can significantly offset your electric bill, take care of the environment and your wallet, and increase your property’s value. STC has been the same since production began and there’s no real difference per state; which means that energy absorption and productivity depends every day, every month, all around the world.  

solar for home in Texas

Normal Operating Cell Temperature 

 For most buyers, the solar panel installation will be mounted on the roof. Looking back at the PV Standard Testing Conditions’ cell temperatures; we can easily comprehend that in Texas, the minimum Normal Operating Cell Temperature, or NOCT is much higher than 77°. Our rooftops get the most sun exposure, so that generally produces as a buffet of sunlight for solar panels. With San Antonio being an above-average benefactor for STC, what option besides “yes” is available? The average high in San Antonio has not surpassed 98°F since the 90s, which is another branch of data we can branch into and discuss. 

Does Texas Get Close to STC Numbers?

For the residents of Texas, we know full well that a constant, day-to-day average of 77° isn’t achievable until the middle of Fall (i.e. October – December) if we’re lucky. In regards to the relevance of STC, the main focus should lean more towards the durability of the panels when harsh weather conditions roll by.  For those who are still concerned about STC, the ideal temperature for power producing panels should be anywhere between 77° and 98°F. While that average is achievable in Texas, it sure goes well above 98°. Note: just because the average sets at around 98°, the heat does increase the longer the rays of the sun hit the rooftop and panels directly. 

Can my Panels Overheat?

Is STC an important factor when going solar? In short, tests and practice are detrimental for production, but real daily numbers over time are what us (the consumer) look towards. One question for a Texas homeowner looking to buy solar panels would be do they overheat? No they do not. Generally, STC isn’t a huge factor when considering solar because these test conditions have not changed for a great deal of time. Let me give you an example: Solar Edge Pros has installed over 5,000 solar systems since their journey began in 2005 and since then there hasn’t been a single concern regarding the panels overheating. What else is a huge takeaway from this data? Knowing that during the hot Texas summers, the panels are still performing their best, which in the long-run can show even more promise for solar panels in above-average-temperature areas. 

Solar Panel Production in Texas

With a grid that is independent to the rest of the states, Texas is especially vulnerable to large-scale demand and supply fluctuations. However, having the ability to produce significant amounts of energy on their own soil and having that energy come from a variety of electricity sources increases the resilience that Texas has and leads to high energy independence. While many large-scale solar projects have been undertaken and have proven to yield high amounts of electricity, the households in this state should also install their own solar panels. It is only this type of network that can be truly resilient, as the majority of consumers would turn out to be prosumers or producers and consumers at the same time. The current Texas solar capacity of 9,311 MW is expected to grow by another 4,600 MW in 2021 and an additional 5,400 MW in 2022. This would increase the total solar production capacity of this state to almost 14,900 MW and bring it much closer to California, which is currently the largest solar producer in the USA. 

Will There Be Future Changes to STC?

So what does the future hold for solar panel development? Will the STC ever change? Climate conditions have definitely fluctuated time and time again, but that’s a whole different discussion. The STC numbers have not changed in a long time so there’s a high chance that it will possibly never change. However, technology is at a constant rise and whenever new numbers and evidence populate, we share it to the ones who care to learn. The Solar Edge Pros newsletter is a very useful resource to stay up to date with any breakthroughs or new intel regarding solar. Customer or not, we are here to help because like you, we’re constantly learning new information on the development of solar power and energy. 

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Solar Edge Pros is a trusted leader in the solar energy industry. Since 2005, we have provided solar energy solutions to over 5,000 Texas residents making the switch to cleaner, greener, cheaper, solar power. We believe in the positive effects of working hard, treating people with respect, and doing the right thing. Our values transfer to both the customer experience as well as the culture within the Solar Edge Pros Family. 

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Meet The Author

John Garcia

John Garcia

John's been employed at Solar Edge Pros for 7 months and since then moved up from a Front Desk Receptionist to now a Content Creator for the company. His passion for creating is not something he discovered while in the solar industry, of course. Since High School, John's passion for poetry, music, socializing and video editing remains his constant motivators for making an impact on his career and happiness. If John isn't coming up with out-of-the-box ideas for solar industry content, he's at home making music and gaming.

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