ThermokSolar Menu▼

ThermokSolar Menu


The ThermokSolar-4A is a solar heating differential temperature controller for PV and DC powered applications. It is configured with four temperature sensor channels, an LCD display for real-time view and easy programming, and two solid state DC relay outputs. Designed to run directly from a PV panel, the ThermokSolar-4A is unique in the industry in that it requires no outside power.

ThermokSolar ThermokSolar

Pictured above: Front and back of ThermokSolar-4A, with RS-232 and counter options


The ThermokSolar can be used in both Solar Hot Water and Solar Hot Air configurations. Click here for diagrams illustrating these applications.

ThermokLogger Diagrams

Live Internet Data


APRS World offers our World Data service free for our customers. Using an optional internet gateway module, our products can send live data to our hosted data service. Using your web browser you can view live and historical performance data and graphs. This allows your customer to see how their system is performing and allows you to troubleshoot the system without going on site.


Measurement Inputs
Four 10K Thermistor
    Typically measure -40°C to 150°C (-40°F to 302°F)
    Screw terminals and RJ-45 wired in parallel
Optional Pulse Counter
    Screw terminals
User Interface
16x2 Character LCD, backlit
Three push buttons
Temperatures update once per second
Relay / Alarm status visible
Lithium polymer battery (included)
Charging input, 7 to 38 volts DC
Can run directly from 12 volt PV panel for
     batteryless and gridless systems
Relay / Alarm Outputs
2 x DC relay, solid state, 6 amps @ 39 volts DC max
Independently programmable for:
    Differential Control
    On above temperature set point
    Off above temperature set point
    Always On
    Always Off
RS-232 Communications (optional)
ASCII or binary data, selectable
Screw terminal, 4 position
Data compatible with our World Data internet service
9600 to 57600 baud
Can enable / disable Morningstar Tri-Star based
    on temperature
Mounts in double gang electrical box or panel
3.7cm (1.45”) deep

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Pricing and Purchasing

Now you can purchase these products directly through our sister website: Off Grid Options

ThermokSolar-4A starter package

$240.00 USD

Part: APRS5501
Weight: 4.00 lbs

Package includes:

  • 1 x APRS5500 ThermokSolar-4A module
  • 4 x APRS1692 10k ring terminal thermistors
  • 1 x APRS5510 LiPo+ battery
  • 20 m (65 ft) of green UV resistant sensor cable
  • Heat shrink labels for identifying sensor cables
  • 4 x #6-32 machine screws and KL nuts

ThermokSolar Cut Sheet

ThermokSolar-4A, module only

$220.00 USD

Part: APRS5500
Weight: 1.00 lbs

ThermokSolar-4A module only. Provided with four #6-32 machine screws and KL nuts. Packaged in pink anti-static bubble bag. No accessories provided.

ThermokSolar Cut Sheet

ThermokSolar-4A, module only, with RS-232 and counter options

$250.00 USD

Part: APRS5503
Weight: 1.00 lbs

ThermokSolar-4A module only. Includes RS-232 port and counter input port. Provided with four #6-32 machine screws and KL nuts. Packaged in pink anti-static bubble bag. No accessories provided.

ThermokSolar Cut Sheet

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ThermokSolar Accessories and Replacement Parts

LiPo+ battery for ThermokSolar

$20.00 USD

Part: APRS5510
Weight: 0.13 lbs

Required for operation of ThermokSolar directly from PV panel. These are very slim, extremely light weight batteries based on the new Polymer Lithium Ion chemistry. This is the highest energy density currently in production. Each cell outputs a nominal 3.7V at 860mAh. Comes terminated with a standard 2-pin JST connector - 2 mm spacing between pins.

Thermistor, NTC, 10k, #6 ring terminal, 152 mm (6 in) long

$4.00 USD

Part: APRS1692
Weight: 0.10 lbs

10k ring terminal thermistor. Manufactured by Ametherm as part number PANR 103395-408. A data sheet is available.

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