By Ethan BrooksUpdated November 2026
Choosing a solar pool heater control is less about flashy features and more about whether the controller reads your panel and pool temperatures correctly, switches the pump at the right moments, and keeps your water from overheating or freezing. This list compares six products that share a common purpose: automating solar pool heating. Our selection method is research-based, looking at manufacturer specifications, brand reputation for solar differential controllers, and patterns in owner feedback about reliability, wiring, and setup. We did not test these units ourselves; the notes below reflect published listing details and commonly reported experiences.
Our top picks at a glance
- 1
TOP CHOICEBest overallHayward GL-235 AquaSolar Pool Solar Temperature ControllerView on Amazon - 2
TOP CHOICEBest for replacement jobsReplacement for Hayward Goldline GL-235 Solar Pool Differential Temperature ControllerView on Amazon - 3
TOP CHOICEBest budget pickAuto Solar Water Heat Control GL235 Control BoardView on Amazon - 4
Best for freeze-prone climatesSolar Hot Water Heater Output GL235 Temperature ControllerView on Amazon - 5
Best for whole-system heatingFlowMax80 Pool Heat PumpView on Amazon - 6
Best for nocturnal coolingGL-235 Pool Solar Temperature Controller 12/24VACView on Amazon
Our Top Picks
Quick Comparison
| Product | Best for | Key feature |
|---|---|---|
| Hayward GL-235 AquaSolar Pool Solar Temperature Controller | Standard solar pool setups | Differential sensing between panel and pool |
| Replacement for Hayward Goldline GL-235 Differential Temperature Controller | Replacing a failed GL-235 | Multiple 12/24VAC and 120/240VAC outputs |
| Auto Solar Water Heat Control GL235 Control Board | Budget-conscious owners | Board-level GL235 compatibility |
| Solar Hot Water Heater GL235 Temperature Controller | Freeze-prone climates | Freeze protection function |
| FlowMax80 Pool Heat Pump | Whole-system heating beyond solar | Smart Wi-Fi control and inverter operation |
| GL-235 Pool Solar Temperature Controller 12/24VAC | Cooling-aware solar systems | Nocturnal cooling and freeze protection |
Hayward GL-235 AquaSolar Pool Solar Temperature Controller
Hayward GL-235 AquaSolar Pool Solar Temperature Controller
Best for: Standard solar pool setups that need a reliable, well-documented differential controller.
This is the controller most pool owners and installers reference when they talk about solar pool automation. It suits anyone with a rooftop or ground-mount collector who wants the pump to run only when the panels are warmer than the pool.
Key specs:
- Differential temperature control between collector and pool sensors
- Designed for Hayward Goldline AquaSolar systems
- Supports standard low-voltage and line-voltage output configurations
Pros:
- Widely recognized design with broad installer familiarity
- Straightforward differential logic that is easy to troubleshoot
- Strong fit when matching an existing Hayward solar layout
Cons:
- Setup requires careful sensor placement and wiring
- Owners often mention the interface takes a few minutes to learn
Bottom line: The safest first choice for most owners running a standard Hayward-compatible solar loop.
Replacement for Hayward Goldline GL-235 Solar Pool Differential Temperature Controller
Replacement for Hayward Goldline GL-235 AquaSolar Pool Solar Differential Temperature Controller Solar Pool Control for Pool, Spa & Hot Tub 12/24VAC and 120/240VAC Output
Best for: Replacing a failed GL-235 without changing the rest of the system.
Owners whose original controller has stopped responding, or whose display has gone blank, often look for a direct-fit replacement. This listing targets that exact job.
Key specs:
- Differential temperature control for pool and spa solar systems
- Supports 12/24VAC and 120/240VAC outputs
- Designed as a GL-235 replacement
Pros:
- Matches the original GL-235 function for easy swaps
- Covers both low-voltage and line-voltage output options
- Lets you keep your existing sensors and plumbing
Cons:
- Compatibility should be confirmed against your existing wiring before ordering
- Third-party units can vary in build quality between sellers
Bottom line: A practical choice for a like-for-like repair; double-check your wiring diagram first.
Auto Solar Water Heat Control GL235 Control Board
Temperature Controller ,Auto Solar Water Heat Control ,Solar Hot Water Heater Output 12/24VAC and 120/240VAC GL235 Control Board for Hayward Goldline AquaSolar Pool SPA Solar
Best for: Budget-conscious owners who need GL235 logic in a board-style replacement.
This listing is aimed at people who already understand their controller wiring and want a lower-cost board to restore automatic solar operation.
Key specs:
- GL235-compatible control board for Hayward Goldline AquaSolar systems
- 12/24VAC and 120/240VAC output options
- Solar differential control logic
Pros:
- Lower-cost route to restoring automatic solar control
- Board format suits owners comfortable with panel-level wiring
- Covers common output voltage options
Cons:
- Less documentation than name-brand controllers, according to owner feedback patterns
- Requires confirming the output voltage matches your pump relay
Bottom line: Good value for experienced DIYers who can verify voltage and wiring before power-up.
Solar Hot Water Heater Output GL235 Temperature Controller
Auto Solar Water Heat Control ,Solar Hot Water Heater Output 12/24VAC and 120/240VAC GL235 for Hayward Goldline AquaSolar Pool SPA Solar Temperature Controller
Best for: Freeze-prone climates where the controller must protect plumbing as well as heat the pool.
Pool owners in cooler regions often need the controller to switch the pump on for freeze protection, not only for heating. This listing emphasizes GL235 compatibility with that type of setup.
Key specs:
- GL235 control function for Hayward Goldline AquaSolar systems
- 12/24VAC and 120/240VAC output options
- Solar temperature control with differential logic
Pros:
- Suited to systems that need winter freeze protection
- Output options match a range of pump relays
- Compact layout for panel-side installation
Cons:
- Freeze-protection settings need correct sensor placement to work as intended
- Owners report that documentation quality varies by seller
Bottom line: A sensible pick for cold-climate owners who want automatic freeze protection through the solar loop.
FlowMax80 Pool Heat Pump
80,000 BTU Pool Heat Pump for In-Ground Pool, 208–240V Inverter Pool Heater with Cooling for Up to 22,000 Gallon Inground Pools, 16.2 COP Smart Wifi Control, FCC & CEC Certified – FlowMax80
Best for: Owners who want a smart, whole-system heater rather than a solar-only controller.
This is a heat pump, not a solar differential controller. It fits pool owners who want to supplement or replace solar heating with an electric system that has its own smart controls.
Key specs:
- 80,000 BTU heating capacity as listed
- 208–240V inverter operation
- Smart Wi-Fi control and cooling capability
Pros:
- Smart app-based control for scheduling and monitoring
- Inverter operation can reduce cycling compared with fixed-speed units
- Provides heating in periods when solar gain is weak
Cons:
- Requires a dedicated 208–240V electrical circuit
- Operates on electricity, so running costs depend on your utility rates and usage
Bottom line: Best for owners wanting an all-season, app-controlled heater; consult an electrician before installing.
GL-235 Pool Solar Temperature Controller 12/24VAC
For Pool/Spa/Hot Tub, 120/240VAC Input, 12/24VAC Output, Differential Temp Control, Freeze Protection, Nocturnal Cooling GL-235 Pool Solar Temperature Controller for Goldline Aqua Solar 12/24VAC
Best for: Solar systems where nocturnal cooling and freeze protection matter as much as daytime heating.
Some owners want their solar loop to pull heat out of the pool at night on hot days, or to protect the system in cold snaps. This controller is described with those functions.
Key specs:
- 120/240VAC input, 12/24VAC output
- Differential temperature control
- Freeze protection and nocturnal cooling functions
Pros:
- Covers more operating modes than a basic differential controller
- Low-voltage output suits common relay setups
- Useful for pools in hot, dry climates with night cooling needs
Cons:
- Extra modes need to be configured correctly to avoid unwanted pump run time
- Owners often recommend reviewing the manual before first use
Bottom line: A strong choice for owners who want cooling and freeze control in one solar controller.
Buying Guide
Differential Temperature Sensing
A solar pool heater control should compare collector temperature with pool temperature and run the pump only when the collector is meaningfully warmer. Look for a controller that lets you set the on and off differential, usually a few degrees Fahrenheit, so the pump does not short-cycle.
Good picks for this: Hayward GL-235 AquaSolar Pool Solar Temperature Controller, Replacement for Hayward Goldline GL-235
Voltage and Output Compatibility
Check the controller output voltage against your pump relay or contactor. Many solar controllers offer 12/24VAC outputs for relays and 120/240VAC for direct switching. Mismatched voltage is one of the most common causes of a controller that appears to work but never starts the pump.
Good picks for this: Auto Solar Water Heat Control GL235 Control Board, GL-235 Pool Solar Temperature Controller 12/24VAC
Freeze Protection
If your pool sees freezing nights, the controller should be able to run the pump when the collector approaches freezing, even if the pool does not need heat. Confirm the freeze threshold is adjustable and that sensors are placed where they read collector temperature accurately.
Good picks for this: Solar Hot Water Heater Output GL235 Temperature Controller, GL-235 Pool Solar Temperature Controller 12/24VAC
Nocturnal Cooling
Nocturnal cooling lets the solar loop remove heat from the pool overnight when the air is cooler than the water. This matters in hot climates where pools overheat during the day. Not every controller offers this mode, so check the listing before buying.
Good picks for this: GL-235 Pool Solar Temperature Controller 12/24VAC, Hayward GL-235 AquaSolar Pool Solar Temperature Controller
Sensor Quality and Placement
Controllers are only as accurate as their sensors. Use sensors rated for outdoor and wet conditions, mount the collector sensor on the panel outlet line, and keep the pool sensor in the return flow away from direct sun. Poor placement is a frequent source of owner complaints about erratic pump behavior.
Good picks for this: Hayward GL-235 AquaSolar Pool Solar Temperature Controller, Replacement for Hayward Goldline GL-235
Whole-System vs. Solar-Only Control
A solar controller manages only the solar loop. A heat pump or electric heater has its own control logic and a different electrical requirement. Decide whether you need a controller for solar alone or a complete heating system, since they solve different problems.
Good picks for this: FlowMax80 Pool Heat Pump, Hayward GL-235 AquaSolar Pool Solar Temperature Controller
Installation Skill and Safety
Low-voltage control wiring is manageable for many DIYers, but line-voltage connections and any work at a pool panel or electrical box should follow local code. If you are not confident with wiring diagrams, hire a licensed electrician or a pool professional.
Good picks for this: Replacement for Hayward Goldline GL-235, Auto Solar Water Heat Control GL235 Control Board
FAQ
What does a solar pool heater control actually do?
It compares the temperature at the solar collector with the pool water temperature and switches the circulation pump on when the collector is warmer by a set amount. When the difference falls below the off threshold, it shuts the pump down. This prevents the system from pulling cold water through the panels or running when no heat is gained.
Can I replace a Hayward GL-235 with a compatible controller?
Yes, many owners do this, but you should confirm voltage outputs, sensor types, and terminal layout against your existing wiring. A like-for-like replacement is usually the simplest path. If the wiring is unfamiliar, consult a licensed electrician or pool professional.
What is the difference between a solar controller and a heat pump?
A solar controller manages only the solar loop and decides when the pump runs based on temperature differences. A heat pump is a separate electric heating appliance with its own compressor and controls. Some owners use both, with the solar controller handling daytime gain and the heat pump supplementing when needed.
Why does my solar pump keep cycling on and off?
Short cycling often comes from a differential setting that is too narrow, sensors placed where they read unrealistic temperatures, or cloud cover that causes rapid changes in collector temperature. Widening the on/off differential and checking sensor placement usually helps.
Do I need freeze protection if I live in a mild climate?
It depends on how often temperatures drop near freezing where you live. Owners in mild regions often skip it, while those in colder areas use it to protect panels and plumbing. Review your local winter lows before deciding.
How do I know if my controller is working correctly?
Check that the display shows reasonable collector and pool temperatures, then watch the pump switch on in direct sun and off after clouds or evening. Verify that the output relay or contactor responds. If readings seem wrong, test or replace the sensors first.
Conclusion
For most standard solar pool systems, the Hayward GL-235 AquaSolar controller is the most straightforward first choice, and the replacement GL-235 listing suits owners fixing an existing unit. Budget-minded DIYers with GL235 experience may prefer the control board option, while cold-climate owners should look at the freeze-protection-focused controller. Those who want cooling and freeze functions together should consider the GL-235 12/24VAC model. If you need a full heating system rather than solar-only control, the FlowMax80 heat pump is the one non-solar option here. Match the controller to your voltage, sensor setup, and climate, and confirm wiring before you power on.
Sources
- Background on solar thermal systems and how collector-based heating works (energy.gov)
- Electrical and pool equipment safety guidance for consumers (cpsc.gov)
- Electrical code principles relevant to pool and low-voltage control wiring (nfpa.org)
Related reading
- Xtremepowerus Solar Pool Heater: Setup, Sizing and Common Mistakes
- What Is a Solar Pool Heater Vacuum Breaker and Why Does It Matter?
- Top 7 Swimming Pool Solar Water Heater Options Compareds (2026)
- Top 7 Solar Pool Heaters for Inground Pool Options Compared (2026)
- Top 5 Solar Water Pool Heater Options Compareds for 2026
- Top 5 Above Ground Solar Pool Heaters for Every Setup
About Ethan Brooks
Ethan Brooks is part of our editorial team and reviews and edits our solar water systems guides, checking product details against manufacturer specifications and owner feedback.
