Solution: DC optimizers and DC-Coupled Batteries

DC architecture systems eliminate many of the inefficiencies of AC Architecture, or microinverter-based designs. There are 3 primary components of DC architecture:

• DC:DC optimizers to maximize output
• DC-coupled ‘hybrid’ inverter that connects to solar and the battery
• DC-coupled battery to minimize conversion losses

By leveraging optimizers and DC-coupled storage, this DC architecture avoids clipping losses at the module-level, eliminates multiple battery conversion losses, and minimizes the equipment required for optimal performance.

Let’s break down how a DC optimized system works—and why it’s the preferred solution for homeowners who want to maximize energy production, efficiency, and savings.

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1. DC Optimizers: Maximize Production

DC optimizers, like Tigo TS4 Flex MLPE, manage power at the module level but leave the DC-to-AC conversion to a central string inverter. DC optimizers will:

• Mitigate Mismatch: Optimizers adjust the output of each module independently, reducing the impact of shading, soiling, or module degradation
• Enable module level monitoring for visibility, troubleshooting, and performance validation.
• Meet safety requirements by performing module-level rapid shutdown
• Handle High-Wattage Modules: Tigo optimizers are rated for 700W+ modules eliminating the clipping issues
• No AC/DC Conversion: DC optimizers don’t convert the module production to AC. So, there’s less equipment required, and the DC energy can flow to the battery without conversion losses

“Power optimizers combine the advantages of both central inverters and microinverters, providing efficient performance with a centralized conversion system.” - Aurora Solar

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2. DC-Coupled Hybrid Inverter: Connects to solar and battery

One product, multiple functions: The hybrid inverter can convert DC solar to AC, route energy to a DC-coupled battery, and convert DC battery energy to AC, all in one unit

Easy to access: The inverter is doing work at ground level, making it easier to access and manage

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3. DC-Coupled Storage: Maximize Battery Efficiency

Direct Energy Flow: DC-coupled batteries charge directly from the solar without unnecessary conversions.

Higher Efficiency: By avoiding conversion losses, DC-coupled storage systems achieve efficiencies of 95%+, compared to 87-90% for AC-coupled setups.

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The Tigo EI Residential Solution: Real-World DC Optimization

The Tigo EI Residential Solution combines everything you need for an efficient, future-proof solar system:

• TS4 Flex MLPE: Optimizers ensure every module operates at peak performance, even with shading or module mismatch.
• EI Inverter: A single inverter manages both solar and battery energy, eliminating the need for extra hardware.
• EI Battery: A modular, DC-coupled battery that charges efficiently and delivers maximum usable energy.

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Conclusion

Increasing module wattage, growing battery adoption, and rising utility rates are three major trends that are shifting the optimal technology stack for residential solar installations. Together, these trends give rise to the Microinverter Tax, a combination of taxes on performance and hardware required that makes solar installations using AC architecture less viable.

Throughout we’ve used the example of a 15kW residential solar + storage site. Here’s how the Microinverter tax adds up:

• Clipping Tax: $10,274 in clipping losses (assuming 3% average annual clipping losses)
• Conversion Tax: $2,654 in conversion losses (assuming 10kWh daily battery discharge)
• Equipment Tax: 88% more inverter capacity required (11.4kW microinverters + 10kW battery inverter)
• Total: $13,378 total losses with 88% more inverter capacity required

A DC-optimized system solves these issues with:

• DC:DC optimizers to capture every watt-hour of module energy
• A hybrid inverter that simplifies the system by efficiently performing multiple functions
• DC-Coupled batteries for efficient energy charging and discharging

If you’re looking to maximize your energy savings, simplify your system, and prepare for the future of solar + storage, a DC-optimized solution is the answer.

That's it for main chapters of the Microinverter Tax series. If you would like to dive deeper into clipping, check out the bonus chapter - Clipping showdown: MLPE vs. Optimizers

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Want more?

Webinar: On April 15 (Tax day in the US), we're hosting a webinar that will dive into the details of the Microinverter Tax series. Sign up for the webinar here.

Below is a full list of chapters included in this series (links will be added as chapters are published):

Below is a full list of chapters included in this series (links will be added as chapters are published):

1. Summary: The Growing Microinverter Tax
2. Trendlines: Major Changes in the Solar Industry
3. Clipping Tax: Leaving energy on the table
4. Conversion Tax: The hidden cost of AC-coupled batteries
5. Equipment Tax: More gear, more problems
6. The solution is DC: DC optimizers, DC coupled batteries
7. Bonus: Clipping showdown: MLPE vs. Optimizers
8. Glossary of terms

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