If you’re setting up a solar-powered greenhouse, selecting the right MPPT charge controller is essential for maximizing efficiency and protecting your batteries. The best MPPT controllers for greenhouse solar systems balance power output, durability, and ease of use, but tradeoffs exist. For example, higher-capacity models offer more headroom but come with increased cost and complexity. Conversely, smaller models are budget-friendly but might limit future expansion. The top choices include the 120A MPPT Solar Charge Controller for large setups and the Victron SmartSolar MPPT with Bluetooth for smart monitoring. Continue reading for a comprehensive breakdown of each option and how to pick the best for your needs.
Key Takeaways
- Capacity range varies widely; larger systems benefit from high-amp controllers like the 120A models.
- Bluetooth and smart features are common in premium controllers, aiding monitoring and setup.
- Durability and waterproofing are crucial for greenhouse environments exposed to humidity and weather.
- Price often correlates with features; basic controllers are affordable but lack advanced options.
- Compatibility with different battery chemistries (lead-acid, lithium) influences choice based on system design.
More Details on Our Top Picks
120A MPPT Solar Charge Controller, 12V-96V Battery System, LCD Display, Max Input PV 230V
This model stands out for its impressive efficiency and wide compatibility, supporting battery systems from 12V up to 96V, making it ideal for larger or more complex greenhouse setups. Compared with the Upgraded 100A MPPT Solar Charge Controller, it offers a broader voltage range and higher peak power, though it involves more complex installation and a higher price point. Its 99% MPPT tracking efficiency and comprehensive protections ensure maximum energy harvest and system safety, which are critical for maintaining reliable greenhouse power. The LCD display simplifies monitoring, but its setup may challenge those unfamiliar with advanced solar controllers. This pick makes the most sense for growers seeking flexibility and high capacity without sacrificing safety or efficiency.
Pros:- Supports a wide range of battery voltages up to 96V, accommodating large systems
- High MPPT efficiency of 99% maximizes solar energy capture
- Multiple protections safeguard system components from damage
- Easy-to-read LCD display facilitates real-time monitoring
Cons:- Complex installation may require technical expertise
- Higher cost compared to smaller or less feature-rich controllers
- Limited information on weather resistance and durability in outdoor conditions
Best for: Large-scale greenhouse operators with varied battery and panel configurations who need high capacity and detailed system management
Not ideal for: Small hobbyists or off-grid gardeners with limited space and simpler needs, as this controller’s complexity and cost outweigh benefits for tiny setups
- Max Input PV:230V
- Battery System Voltage:12V-96V
- Charging Power:up to 11520W
- Protection Features:Overcurrent, overvoltage, overload, temp
- Display:LCD
- Peak Efficiency:98%
Bottom line: This controller is best suited for experienced users managing large, diverse greenhouse solar setups who need maximum efficiency and robust safety features.
SOLPERK MPPT Solar Charge Controller 10A 12V Waterproof IP67
This controller excels in outdoor environments due to its waterproof IP67 rating and simple plug-and-play design. Compared to the Renogy 10A PWM Controller, it offers 30% higher efficiency thanks to MPPT technology, making it suitable for outdoor greenhouse installations where space and weather resistance are priorities. Its compatibility with various 12V batteries, including lithium, enhances flexibility for small to medium setups. Its LED indicators provide straightforward monitoring, but the limited 10A capacity restricts its use to smaller systems. Installation is straightforward, even for those with limited technical skills, but the small current capacity means it cannot support large solar arrays. This makes it perfect for small-scale, weather-exposed greenhouse projects.
Pros:- Waterproof IP67 design withstands harsh outdoor conditions
- Higher efficiency than PWM controllers improves battery charging speed
- Compatible with diverse 12V batteries, including lithium types
- Easy installation with plug-and-play SAE port
Cons:- Limited to 10A current, unsuitable for larger panels or batteries
- Lacks advanced features found in higher-end controllers
- LED indicators may be hard to see in bright sunlight
Best for: Gardeners seeking a reliable, waterproof MPPT controller for small outdoor greenhouses with limited solar capacity
Not ideal for: Growers with larger or high-demand systems, as the 10A limit restricts power output and scalability
- Model:SOLPERK MPPT 10A
- Voltage:12V
- Current:10A
- Protection:IP67 waterproof, over-voltage, overload
- Compatibility:AGM, Gel, Flooded, Lithium
- Indicators:Blue, Red, Green LEDs
Bottom line: This controller is ideal for small, outdoor greenhouse setups where weather resistance and simple operation are essential.
Victron Energy SmartSolar MPPT Solar Charge Controller (Bluetooth) – 100V, 20A, 48V
This controller offers intelligent system management through Bluetooth connectivity, making it a smart choice for greenhouse operators who want real-time monitoring without complex wiring. Compared with the Renogy 10A PWM Controller, it provides higher voltage and current capabilities, supporting 48V battery systems efficiently. Its features, like synchronized charging and load management, enhance overall system performance and longevity. The Bluetooth interface allows easy configuration and data logging via smartphone, a significant advantage over basic LCD-only models. However, it’s limited to 48V systems and may require a compatible app and devices for full functionality. Its moderate 20A capacity makes it suitable for medium-sized greenhouses but less so for very large arrays. It’s best for those prioritizing convenience and smart features over raw capacity.
Pros:- Bluetooth connectivity for real-time system monitoring and configuration
- Supports fast MPPT tracking to maximize energy harvest
- Synchronized charging and intelligent load management
- Supports 48V battery systems efficiently
Cons:- Limited to 48V and 20A, restricting larger system compatibility
- Requires compatible smartphone and app for full features
- Bluetooth range limitations may affect remote monitoring
Best for: Greenhouse owners who want intelligent, Bluetooth-enabled control for a 48V system with moderate power needs
Not ideal for: Large-scale operations with high current demands or those without Bluetooth-enabled devices, as the system relies on app connectivity
- Voltage:48V
- Current:20A
- Max Voltage:100V
- Connectivity:Bluetooth
- Features:Synchronized charging, load management
Bottom line: This controller is well-suited for greenhouse operators who value smart system control and moderate power capacity at 48V.
Renogy 10 Amp 12V/24V PWM Negative Ground Solar Charge Controller with LCD Display
The Renogy Wanderer provides a straightforward, reliable solution for small-scale greenhouses or off-grid projects. Compared with the MPPT options like the SOLPERK 10A MPPT Controller, it relies on PWM technology, which is less efficient but more affordable for low-demand systems. Its LCD display offers basic real-time data, making it suitable for users who prefer simple, no-frills operation. The negative ground design simplifies wiring in many setups, and its compatibility with various battery types adds versatility. However, its 10A limit constrains the size of solar arrays and battery capacity, which might be insufficient for larger greenhouses. The absence of MPPT means less energy is extracted from panels, especially in variable sunlight. This controller fits small, budget-conscious projects well but isn’t ideal for expanding systems.
Pros:- Affordable, straightforward PWM technology
- Negative ground design simplifies wiring in many setups
- Supports multiple battery types including lithium
- Easy-to-read LCD display for basic monitoring
Cons:- Lower efficiency than MPPT controllers, especially in cloudy conditions
- Limited to 10A current, restricting system size
- Lacks advanced protections or remote monitoring features
Best for: Entry-level growers or hobbyists managing small greenhouses with limited solar capacity and budget constraints
Not ideal for: Larger greenhouses or systems with high energy demands, as it cannot handle bigger arrays or higher current loads
- Max Voltage:12V/24V
- Current:10A
- Battery Types:AGM, Gel, Flooded, Lithium
- Display:LCD
- Grounding:Negative
Bottom line: This controller is best for beginners or small-scale greenhouse projects where simplicity and affordability are priorities.
Upgraded 100A MPPT Solar Charge Controller 12V 24V 36V 48V LCD Display Battery Intelligent Regulator Max 100V Input Dual USB for Lead-Acid/Lithium
This controller offers robust power management with its 100A capacity, suitable for large or expanding greenhouse systems. Compared with the 120A MPPT Controller, it provides similar high efficiency but emphasizes user-friendly features like multiple operating modes and dual USB outputs. Its wide voltage support from 12V to 48V ensures compatibility across different battery types and sizes. The large LCD display provides detailed system status and allows for precise adjustments. However, the complex setup may intimidate beginners, and its high capacity might be overkill for small greenhouses. The device’s extensive protections and multiple charging modes make it a reliable choice for demanding applications, though the initial configuration can be time-consuming.
Pros:- High 100A current capacity supports large solar arrays
- Supports multiple charging modes and battery types
- Multiple protections enhance system safety and longevity
- Large LCD for detailed real-time monitoring
Cons:- Complex setup may require technical knowledge
- Potential underutilization in small systems
- Cost may be prohibitive for hobbyists or small greenhouses
Best for: Large or high-demand greenhouses requiring maximum power and flexible configuration options
Not ideal for: Small or simple setups where such high capacity and complexity are unnecessary, as it might be cost-prohibitive and overly complicated
- Maximum Current:100A
- Input Voltage:Max 100V
- Supported Systems:12V-48V
- Display:Backlit LCD
- Protection Features:Over-voltage, over-current, overcharge
Bottom line: This controller is ideal for large-scale greenhouses with high energy demands needing maximum capacity and flexible settings.
Victron Energy SmartSolar MPPT Solar Charge Controller (Bluetooth) – 50A, 12/24V, 100V
This model stands out for its fast MPPT tracking and ability to synchronize with multiple units, making it ideal for larger greenhouse setups where maximizing solar harvest is critical. Compared to the Renogy Rover Lite 60A, it offers more advanced Bluetooth monitoring and load management, but at a higher price. The Bluetooth app provides real-time data, simplifying tuning and troubleshooting. Its intelligent load output helps protect batteries, ensuring longevity. However, reliance on Bluetooth for full functionality may be limiting in low-signal areas, and the cost might be a barrier for smaller operations. Overall, this controller suits serious growers seeking maximum efficiency and system integration.
Pros:- Fast MPPT tracking maximizes energy harvest
- Supports synchronized charging with multiple units
- Bluetooth connectivity enables easy real-time monitoring
- Includes intelligent load output for battery protection
Cons:- Requires Bluetooth app for full feature access
- Higher price compared to simpler controllers
- Installation complexity may challenge beginners
Best for: Large greenhouse operators who need precise monitoring and robust performance.
Not ideal for: Small-scale hobbyists or those on a tight budget, as it may be more than they require and comes at a higher price.
- Max Voltage:100V
- Current:50A
- Voltage Compatibility:12/24V
- Connectivity:Bluetooth
- Features:MPPT, synchronized charging, load management
Bottom line: This controller is best suited for users who prioritize system performance and monitoring in a larger greenhouse setting.
Renogy 60A MPPT Solar Charge Controller Rover Lite 12V/24V/36V/48V, 150V Max Solar Input, Compatible with Lithium, AGM, Gel Batteries
The Renogy Rover Lite 60A supports a high solar input voltage of 150V, enabling connection of multiple panels for sizable greenhouse systems. It excels in extreme temperature environments, from -31°F to 113°F, ensuring reliable operation year-round. Its LCD interface offers straightforward setup, and Bluetooth monitoring is available as an add-on, making it flexible for users who want to upgrade later. Compared with the Victron SmartSolar 50A, it provides broader battery compatibility and a more rugged build for harsh conditions. The installation process might be complex for beginners, and the need for a separate Bluetooth module could add to the initial cost. This makes it a strong choice for growers with larger, more demanding setups who value durability and adaptability.
Pros:- Supports high solar input voltage for larger arrays
- Works reliably in extreme temperatures
- Compatible with multiple battery types including lithium
- Includes an LCD display for straightforward monitoring
Cons:- Bluetooth monitoring requires additional purchase
- Installation may be complex for beginners
- Higher upfront cost than smaller controllers
Best for: Growers managing extensive or variable solar arrays needing robust temperature tolerance.
Not ideal for: New entrants or small-scale setups where simplicity and lower cost matter more than high capacity.
- Maximum Solar Input:150V
- Battery Voltage Range:12V/24V/36V/48V
- Maximum Current:60A
- Temperature Range:-31℉ to 113℉
- Supported Batteries:Lithium, AGM, Gel
Bottom line: This controller is ideal for growers with large or complex setups requiring durability and high voltage support.
Victron Energy SmartSolar MPPT Solar Charge Controller (Bluetooth) – 75V, 15A, 12/24V
This Victron 75V, 15A model offers reliable MPPT technology in a compact form, making it suitable for small greenhouses or supplementary solar systems. While it provides excellent power optimization for systems up to 75V, the limited current of 15A restricts its capacity for larger arrays. Bluetooth monitoring simplifies setup and allows for convenient system adjustments. Compared with the 100V, 30A Victron model, it’s more suited to smaller, less demanding applications. The main tradeoff is its lower current capacity, which could limit future expansion. Overall, this unit works well for growers with modest energy needs who prefer a streamlined, easy-to-manage system.
Pros:- Efficient MPPT technology maximizes power output
- Bluetooth connectivity for simple monitoring
- Supports system voltages up to 75V
- Compact size fits tight spaces
Cons:- Limited to 15A current capacity
- Less suitable for larger or expanding systems
- Requires Bluetooth device for full monitoring
Best for: Small greenhouse setups or supplemental solar installations needing reliable MPPT without high capacity.
Not ideal for: Large-scale operations or systems requiring more than 15A of current, as it won’t meet higher energy demands.
- Voltage:75V
- Current:15A
- Voltages Supported:12/24V
- Features:MPPT, Bluetooth
Bottom line: This controller is a good fit for small greenhouses or as a supplementary system for limited space and moderate energy output.
Victron Energy SmartSolar MPPT Solar Charge Controller (Bluetooth) – 100V, 30A, 12/24V
The Victron 100V, 30A model combines high current capacity with Bluetooth monitoring, making it a versatile choice for mid-sized greenhouses. Its fast MPPT tracking maximizes energy harvest, similar to the 50A version but suitable for slightly smaller or less complex systems. Compared to the Renogy Rover Lite 60A, it offers easier integration for typical greenhouse sizes and straightforward Bluetooth setup. The load output feature protects batteries from over-discharge, improving longevity. The main limitation is its maximum voltage of 100V, which might restrict very large arrays. For growers seeking a balance between capacity and ease of use, this model provides a strong, reliable option.
Pros:- High current capacity with efficient MPPT
- Bluetooth monitoring for easy system management
- Supports system voltages up to 100V
- Includes load output to safeguard batteries
Cons:- Limited to 100V maximum input voltage
- Bluetooth range might be limited in larger setups
- Still requires compatible Bluetooth device for full features
Best for: Mid-sized greenhouse systems or growers wanting a balance of capacity and manageability.
Not ideal for: Very large or high-capacity systems that surpass 30A or need support for voltages above 100V.
- Voltage:100V
- Current:30A
- Maximum Voltage:100V
- Connectivity:Bluetooth
- Features:MPPT, load output, synchronized charging
Bottom line: This controller balances capacity and ease of use for mid-sized greenhouse setups needing reliable, monitored power.
Renogy Rover 20A MPPT Solar Charge Controller for 12V/24V Batteries
The Renogy Rover 20A offers essential MPPT features in a compact, affordable package, making it suitable for small greenhouses or off-grid applications. Its multi-stage charging and protections provide reliable operation, and the LCD display simplifies setup and monitoring. Compared with the Victron 50A models, it has a lower capacity but remains efficient for modest systems. The main drawback is its 20A maximum current, limiting expansion or high-energy systems. Additionally, Bluetooth monitoring requires a separate module, adding to the overall cost. This makes it a practical choice for hobbyists or growers with small, straightforward solar needs who prioritize affordability over capacity.
Pros:- High MPPT efficiency with multi-peak tracking
- Supports multiple battery types including lithium
- Built-in protections against common faults
- LCD display for real-time monitoring
Cons:- Limited to 20A current, not suitable for large systems
- Bluetooth monitoring requires additional purchase
- Setup can be complex for beginners
Best for: Small-scale greenhouses or off-grid setups where budget and simplicity matter most.
Not ideal for: Larger or expanding systems that demand higher current and capacity.
- Model:Rover 20A
- Input Voltage:12V/24V auto-detect
- Max Current:20A
- Battery Types:Gel, Sealed, Flooded, Lithium
- Display:LCD
- Protection Features:Reverse polarity, overload, lightning surge
Bottom line: This controller is ideal for small-scale, budget-conscious growers needing dependable MPPT performance.
LiTime 60A MPPT Solar Charge Controller – 12V/24V/36V/48V Auto, Max PV Input 200VDC, LCD Display, No Built-in Bluetooth
The LiTime 60A MPPT Solar Charge Controller stands out for its high efficiency—over 99%—and its support for multiple system voltages and battery types, making it ideal for varied greenhouse setups. Unlike the POWLAND 120A, which offers higher capacity, this model emphasizes precise MPPT tracking and ease of use with its clear LCD display. Its dual cooling system ensures reliable operation even under intense sunlight, but the absence of Bluetooth connectivity means manual adjustments are necessary, which could be less convenient for some users. This controller is especially well-suited for those who prioritize efficiency and durability over remote monitoring features, though it might feel limited for users wanting wireless data access.
Pros:- Over 99% MPPT efficiency ensures maximum energy harvest
- Supports multiple voltages and battery chemistries for versatile use
- Easy-to-read LCD display simplifies monitoring and setup
- Robust dual cooling system enhances reliability
Cons:- No built-in Bluetooth or wireless connectivity for remote management
- Requires manual configuration for different battery types
- Limited to 60A capacity, which may restrict larger setups
Best for: Greenhouse owners who need a dependable, high-efficiency controller with straightforward manual monitoring and support for multiple battery types.
Not ideal for: Users seeking remote access or wireless monitoring, as this model lacks Bluetooth or Wi-Fi features, making it less suitable for those who prefer remote adjustments.
- Max PV Input:200VDC
- Current:60A
- Supported Voltages:12V, 24V, 36V, 48V, Auto
- Battery Types:LiFePO4, Lead-acid
- Cooling System:Dual forced cooling with heat sink and fan
- Protections:Overpower, over-voltage, short-circuit, over-temperature
Bottom line: This controller offers excellent efficiency and flexibility, making it ideal for greenhouse operators who prioritize performance and durability without the need for wireless features.
POWLAND 120A MPPT Solar Charge Controller for 12V-96V Systems
The POWLAND 120A MPPT Solar Charge Controller provides a significant upgrade in capacity and compatibility, supporting voltages up to 96V and currents up to 120A, making it a strong choice for larger greenhouse or off-grid systems. Compared to the LiTime 60A, it offers almost double the current capacity, which is essential for high-demand setups. Its 98% efficiency and comprehensive protections extend battery life and safeguard against common issues. However, its complex setup and lack of detailed documentation could challenge beginners, and its higher capacity may be unnecessary for smaller or simpler systems. This pick is best suited for experienced users needing a robust, high-capacity controller capable of managing extensive solar arrays.
Pros:- Supports voltages up to 96V for large systems
- High efficiency of up to 98% ensures maximum energy transfer
- Comprehensive protection features extend component life
- Real-time monitoring via high-resolution LCD
Cons:- Complex installation process may intimidate novices
- Limited detailed technical specifications in the description
- Requires careful wiring and safety measures due to high capacity
Best for: Experienced greenhouse growers or off-grid enthusiasts with large, high-voltage solar arrays requiring maximum capacity and flexibility.
Not ideal for: Beginners or small-scale setups where simplicity and ease of installation are priorities, as this model demands careful wiring and safety precautions.
- Max Input Voltage:230V
- Voltage Compatibility:12V, 24V, 36V, 48V, 60V, 72V, 84V, 96V
- Charging Capacity:120A
- Protection Features:Reverse polarity, overload, open-circuit
- Battery Types:LiFePO4, AGM, GEL, flooded lead-acid
- Display:High-resolution LCD
Bottom line: This high-capacity controller is ideal for advanced users managing large or complex greenhouse solar systems that demand maximum power and safety features.
How We Picked
The products in this roundup were selected based on performance, build quality, ease of installation, and versatility. We prioritized controllers with sufficient current capacity for typical greenhouse setups, focusing on models that support a wide voltage range and multiple battery types. User interface features like LCD displays and Bluetooth connectivity were also key, as they improve usability. Price-to-value ratios and reliability over time were considered, with a preference for brands known for solid support and durability. The ranking reflects a balance between advanced features and practical usability for various greenhouse sizes and budgets.Factors to Consider When Choosing Best MPPT Charge Controller For Greenhouse Solar
Choosing the right MPPT charge controller for your greenhouse involves understanding several critical factors. Beyond raw capacity, considerations like compatibility, environmental resilience, and feature set can significantly impact your system’s performance and longevity. Making informed decisions can prevent costly mistakes and ensure your solar setup runs smoothly for years to come.Capacity and Current Ratings
Matching your charge controller’s capacity to your solar array and battery bank is vital. Overloading a controller can reduce lifespan and efficiency, while undersized units limit your system’s growth. For greenhouse setups, consider future expansion needs and choose a controller with at least 20-30% headroom. Larger models like 120A controllers are better suited for extensive setups, but smaller controllers can suffice for modest systems, offering savings and simplicity.
Compatibility with Battery Types
Not all controllers support every battery chemistry—lead-acid, lithium, AGM, or gel. Verify that your chosen controller explicitly states compatibility with your batteries. This affects charging profiles and longevity. Ignoring this can lead to improper charging, reduced lifespan, or safety hazards. For greenhouse systems using lithium batteries, prioritize controllers with specific lithium support and balancing features.
Environmental Resilience
Greenhouses are humid, and controllers exposed to weather need to withstand moisture, dust, and temperature swings. Waterproof and weatherproof ratings like IP65 or IP67 are important. A controller with robust casing reduces maintenance and prevents failures caused by environmental stressors. If your setup is in a challenging climate, investing in a more durable model pays off in reliability.
User Interface and Monitoring Features
Ease of setup and ongoing management matter, especially if you’re new to solar. LCD displays provide real-time data, while Bluetooth or Wi-Fi connectivity enables remote monitoring. These features help diagnose issues early and optimize performance. However, they often come at a higher cost, so weigh their importance against your technical comfort level and budget.
Price and Value
While high-capacity, feature-rich controllers tend to cost more, they also offer better long-term value if your system demands it. Smaller, basic models are more affordable but may lack expandability or advanced diagnostics. Consider your current needs and future plans—sometimes investing in a slightly more capable controller now saves money and hassle later. Balance features against your budget, ensuring you don’t overpay for unnecessary extras or underbuy for your system’s size.
Frequently Asked Questions
Can I upgrade my MPPT controller later if my greenhouse expands?
Yes, many MPPT controllers support a wide voltage and current range, making upgrades feasible within the same system. However, it’s important to check compatibility with your existing batteries and solar array. Planning for future expansion by choosing a controller with surplus capacity can save you from replacing the unit prematurely. Keep in mind that wiring and mounting considerations might also influence your upgrade options.
Is Bluetooth connectivity necessary for a greenhouse solar system?
Bluetooth connectivity enhances ease of monitoring and troubleshooting, especially if you prefer remote access. It allows you to view real-time data on your phone or tablet, simplifying system management. However, it isn’t essential for basic operation, and some users find manual monitoring sufficient. Consider your comfort with technology and whether added convenience justifies the extra cost for Bluetooth-enabled controllers.
How important is environmental sealing for a greenhouse controller?
Environmental sealing is critical if your controller is exposed to high humidity, watering, or temperature fluctuations common in greenhouses. A controller with an IP65 or higher rating provides resistance to dust and water, reducing maintenance and risk of failure. In less harsh environments, a standard model might suffice, but investing in a sealed unit generally extends lifespan and reliability.
Should I prioritize features like LCD display or Bluetooth over capacity?
Balancing features depends on your system size and your technical skills. For small setups, an LCD display and Bluetooth can simplify management without needing additional tools. For larger, more complex systems, capacity and durability might take precedence, with monitoring features as a bonus. Ultimately, the best approach is a controller that matches your current needs while allowing room for growth.
What is the most cost-effective way to power a greenhouse with solar?
Starting with a controller that offers enough capacity for your current setup and some headroom is wise. Avoid overbuying to reduce initial costs but also steer clear of undersized units that limit expansion. Investing in a reliable, well-reviewed controller with robust environmental ratings and support for your battery chemistry often provides better long-term value. Proper system design and quality components can make solar power both affordable and dependable.
Conclusion
For most greenhouse owners, the 120A MPPT Solar Charge Controller stands out as the best overall choice, offering ample capacity for expansion and robust features. If you prioritize value, the Renogy 10 Amp or 20 Amp controllers deliver solid performance at lower prices, ideal for smaller or budget-conscious setups. Those seeking a premium experience with smart monitoring should consider the Victron SmartSolar with Bluetooth, perfect for tech-savvy users. Beginners or hobbyists will benefit from simpler, more straightforward models, while larger operations should invest in higher-capacity controllers like the 120A options. Match your choice to your system size, future plans, and technical comfort to ensure reliable, efficient greenhouse solar power.
