S&G Wooldridge Ltd


Rookery Farm,




01206 230 488

01206 231 542 




Rookery Farm,
Essex ,


Contact Us Here



Solar PV Heating Switch

Solar PV  export power sense proportional controller.

Prices reduced further now.

Most accurate Solar PV export sense and controller available Class 1 (1%)

Well proven professional design to military design standards and tolerances

Electric_Vehicle_charging_from_excess_PV_power  now or add easily in future

Compatible loads when driving external load controllers:-

  • DHW immersion heater
  • Storage heater, Towel rail heater
  • Underfloor electric heating
  • Electric Vehicle charging ( does not require a slave unit just a compatible EV charger)
  • Motors eg fans, pumps etc.


The Sola Controla sense and control unit provides a 0-10 volt analogue control signal and can  drive the following external  load controllers:-

  • Voltage controlled switched mode inverters.
  • Single or three phase switched mode motor inverters.(to drive fans etc.)
  • Electric Vehicle chargers eg Mainpine EVSE
  • Voltage controlled battery chargers.
  • Phase angle and zero crossing heating controllers

Several of the above load controllers can be used to drive extra or mixed loads or by  parrallelling.

The Sola Controla Sense and control unit consumes less than 3 watts.

Solar PV heating controller Sola Controla trumps Immersun PV heating

Can be used with existing immersion heater and a suitable load user fitted load controller.

No need to change the immersion heater.

Uses every last  fractional KWatt to dump excess generated Solar PV power into the load.

Unlike other simple switcher systems this will constantly monitor for any excess power generated over consumed power.

You will not spend a single penny unnecesarily on water heating again with this system! ( assumes of course your solar array is adequately sized)

Other simple switching systems merely monitor when PV power is generated wait for an excess of say 1kW then switch on the heater.

Such systems A/ waste that first KW or so to export and B/ don't utilise the export power above 1.5 kwatts

It can easily be shown that such systems extract less than half to a third the available potential power compared to our unit.

Our Solar PhotoVoltaic immersion load  controller  constantly monitors export power accurately, and can drive an optional proprietry load controller to proportionally diverts all available surplus PV power to the load or loads.

Can drive multiple loads so even when water is up to temperature  and the thermostat switches off, the excess power can be used as background heating. * May need auxiliary modules depending on function required.

This Solar PV controller therefore can use every last unit of excess power generated.

Is it legal? Yes

Is it ethical? Yes, solar power thus used merely displaces alternative higher cost energy  for water and heating.

Is it environmentally sound? Yes Using generated power at source saves energy distribution losses which would otherwise heat the environment . (Applies to both the exported energy and imported alternative heating energy eg oil, gas etc)

 Full production over 4years. UK design and manufacture.

Solar PV Controller type SPVHC/1  will drive external load controllers from 4 kwatts    now reduced to £245 plus 20% VAT

recorded delivery £10

Should easily pay for itself within two years especially if used for background heating and hot water.

The remainder of the 25 year+ life of your Solar PV , the controller will give you free heat and power.

There are very few if any legal schemes to give a 50% ROI

Payment accepted by BACS or Paypal ( please add 4% for Paypal charges)


  •  Accuracy better than 1% of fullscale. (Biased 50watts towards export.)
  • Phase and Power factor correctly taken into account unlike most energy monitors.
  • Accurate power monitor  mimics consumer meter circuitry, hence imports no unnecesary power.
  • Tested in the field 4 years continuously.
  • MTBF 40 years.
  • All solid state.
  • 5 year guarantee repair or replacement. 

Comparisons with other products.

Beats all simple Solar switch units hands down (eg Parsons etc)

More accurate and stable than the Immersun and similar Solar controller ( no flicker)

Better IP rating than the Immersun, and double insulated for safety.

Will drive any voltage controlled  external load controller.

Ev charger ready ( just add compatible EV charger)

Three phase systems easily catered for.

Sola Controla control unit  can be located seperately from an external load controller  for  remote load locations.

Electric Vehicle Charging ready.

Now can control EV charging under closed loop control of a standard Sola Controla via SmartEVSE charger

see video of Tesla Model S under closed loop control responding to PV surplus power available.


Two compatible EV chargers available. Smart EVSE and Mainpine.

 Below the SmartEVSE ( with modified firmware) used in the control loop:

 SmartEVSE driven by Sola Controla. EV charging using PV controller

Compatible Mainpine EV charger below

Mainpine EV charger

See our ebay shop at stores.ebay.co.uk/rookeryblue  or contact us direct



Electronics Design > Solar PV Switch