Investing in a solar photovoltaic (PV) system is a great way to lower energy bills and reduce your reliance on the grid. Solar installations typically last 25+ years, so it’s important to evaluate ways that maximize the performance of the system, which will maximize the returns on your investment.
One way to maximize the performance of your solar PV system is to install module level power electronics (MLPE). MLPE connect to the back of each solar panel (also known as module in the solar industry) and offer many different features such as rapid shutdown for safety, module-level monitoring, and optimization. The focus of this blog is the optimization feature, and specifically what they do and how beneficial they are.
The term ‘optimizers’ is often used interchangeably with MLPE, but they are a sub-set of MLPE that have a very specific function: they reduce the impact shade or mismatch have on your solar installation.
According to the US National Renewable Energy Laboratory (NREL), “Partial shading can lead to annual performance losses of 10%–20% or more in residential installations.” Also, according to NREL, “Module level power electronics such as microinverters or DC power optimizers have been shown to reduce mismatch in systems, recovering 30%–40% of the power lost due to partial shading.” So basically, optimizers help you reclaim the energy that would have otherwise been lost due to shading.
According to Aurora Solar, a leading solar design software provider, “Whenever a cell or panel does not receive sunlight due to a shaded obstruction, it lowers the amount of electricity generated by that solar section... Such obstructions can come from a variety of sources:
Most residential rooftops and many commercial buildings have some sort of shade present. And even without any shade, mismatch can occur from soiling and varied degradation rates of solar modules. To learn more about the other causes of mismatch and how it happens, we put together this whitepaper.
According to Aurora, “when a solar cell is shaded, the current through the entire string is reduced. This is significant because every cell in the cell string has to operate at the current set by the shaded cell. This prevents the unshaded cells from operating at maximum power.... So yes, only a small amount of shading can have a dramatic effect on the power output of a solar panel.”
Solar panels are typically installed in series (connected directly with one another in a chain) and the entire string operates with the same electrical current. When one panel has shade or mismatch, it can bring down the current – and therefore the electrical output – of the entire string of panels.
Optimizers mitigate mismatch by monitoring and adjusting currents and voltage when needed. By constantly monitoring the voltage and current that are passed between each panel, optimizers can learn the average rate and quantity at which the solar panel produces energy. If it senses a change in voltage or current that is caused by mismatch, it automatically adjusts to make sure each panel operates at the string’s maximum power potential.
Let’s take a look at a case study to see optimizers working in action. Here at Tigo, we offer optimizers that also have module-level monitoring and rapid shutdown capabilities as a packaged deal. Therefore, system owners can get a glance of their system performance to ensure everything is working properly and have peace of mind with built-in safety features.
A homeowner in San Jose, California had a PV system without any module-level monitoring, rapid shutdown compliance, or optimization and wanted to get an upgrade to increase power output from shading on the system from nearby trees (see Figure 2). After adding Tigo optimizers, specifically the TS4-A-O, onto each of the solar panels the homeowner was able to generate more electricity than they did previously and have more visibility into their system. To quote the homeowner,
“My PV system was originally installed in 2009 and adding Tigo optimizers to my system in 2017 was a big improvement. I’m getting more than 5% more output on average per year. I am also able to see when the solar modules need cleaning, and immediately see the results of each cleaning. I get interesting monthly reports showing which solar modules are producing the most and the least energy.”
If you look at the bar chart in the demo or in Figure 3, the green tips are Reclaimed Energy that is enabled by Tigo optimizers. Tigo is the only major MLPE provider that shows customers the additional electricity that is enabled by its optimization technology.
Tigo analyzed tens of thousands of sites with optimizers installed and the optimizers improved solar production by an average of 6.6%. If you have a 10-kilowatt (kW) system, this would produce 1,156 kWh more electricity and save you more than $6,000 over the 25-year life of the project (assuming electricity rates are $0.18/kWh and growing at 3% per year). For more information on Reclaimed Energy, check out this case study.
Optimizers are a very popular component of rooftop solar systems to help increase your energy production and help reduce the cost of your electricity bill. For any home, investing in optimizers is an easy way to meet safety codes, enable module-level monitoring, and maximize system energy production.
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About the timeline of solar: https://www1.eere.energy.gov/solar/pdfs/solar_timeline.pdf
U.S. solar capacity data: https://www.energy.gov/eere/solar/solar-energy-united-states
Environmental benefits of solar: https://www.seia.org/initiatives/climate-change#:~:text=Through%20Q2%202020%2C%20the%20U.S.,tons%20of%20carbon%20dioxide%20emissions
Global solar capacity data: https://www.nsenergybusiness.com/features/solar-power-countries-installed-capacity/
TED-Ed: How do solar panels work? https://ed.ted.com/lessons/how-do-solar-panels-work-richard-komp#watch
How to read your electricity bill https://www.aurorasolar.com/blog/reading-your-electricity-bill-a-beginners-guide/