Over the past three years we have conducted field trials on our Dairy Shed Solar Water Heating Installations.  The results have been computer logged and demonstrate that with solar energy alone we can heat water to achive an annual average water temperature of 72 °C (top up is with electricity) and therefore provide energy savings of up to 85%.  Some customers report a 50% reduction of the dairy shed energy bill.

  • Our Dairy Solar equipment has a minimum service life of 20 years
  • Your energy savings over 20 years will be 4 to 12 times the capital investment.
  • Returns calculated on 10% annual energy increase and initial $0.16 per kWh
  • Our Dairy Solar Water Heater pays for itself in between 2 and 4 years
  • 15% TAX FREE Return on investment

Solar Corp NZ is the pioneer for Dairy Shed Solar Water Heating, and has been able to provide dairy farmers with 85% odf Performance data from our dairy shed solar water heating installations, collected from sites throughout NZ over the past three years, makes it possible for us to accurately computer model the expected energy savings for your dairy farm.

Your dairy farm hot water consumption will be computer modelled and the solar water heating system custom designed to suit your hot water consumption requirements and location within New Zealand.

We stand by our products and will advise the energy savings and expected return on investment so you know what you are getting back for your dollar.

Our Solar Dairy installations typically generate a TAX FREE return on investment of between 12% and 22%.  Your returns are guaranteed and will continue to increase in direct proportion to your increase in energy costs.  With a minimum 20 year service life, your investment will pay for itself many times over, and will typically return 8 to 10 times the initial investment.

To request a no obligation free quotation please click on the link below:


This system utilizes our solar water tanks and does not require an electricity supply.  It is the most reliable and guarantees hot water even during a power cut.

  • Series HP70T - All year ultimate performance water heating
  • Series 358T - All year high performance water heating

This system utilizes our vacuum tube solar collectors and will require a reliable electricity supply or photo voltaic collectors to run the circulating pump.  The collectors can be integrated with existing dairy sheds but is most suitable for new builds or if your existing hot water cylinders need replacing.

  • HP100M - All year ultimate performance water heating
  • HP70M - All year high performance water heating

We provide different levels of automation.  Automation optimizes energy savings and removes the human error element, and prevents constant overheating of the solar tanks.

Automation also ensures the solar tanks are drained automatically into the dairy hot water cylinders when at the required temperature, and the dairy hot water cylinders receive any top up heating but only when required.

If you are looking for the best in all weather performance, tank and vacuum tube durability, you need look no further than our HP70T thermo siphon solar tanks. We have combined our high performance 70mm solar fin vacuum tubes with a heavy duty enamel over 3mm steel water storage tank.  The tank is encapsulated in 50mm of polyurethane foam and encased with zincalume for superior heat retention.  Also included is an annodised aluminium frame.

The solar fin vacuum tubes are completely separated from the water supply. The solar fin vacuum tube condenser fits inside a pocket within the tank. Heat is transferred from the condenser to the pocket, which in turn heats the water.  The vacuum tubes can therefor be removed at any time without loss of water.

Water heated by the condenser socket will thermosiphon within the tank.  Water heating does not require electricity or circulating pumps.

For the fully automated drain / fill / top up heat system we have provided motorized valves with a very simply to use 'push and turn' manual override. You will be able to fill or drain the solar water heaters just like during the automated process.

The key difference between the HP70T and 358T solar water heaters is in the vacuum tubes and how they are integrated with the solar tank.  The 358T solar tank provides a direct connection.  Water from the tank flows into the double glass vacuum tube where heating takes place.  Heated water rises from the tubes and enters the tank, heavier cooler water flows into the tubes.  This is a simple but efficient thermosiphon process.

We only fit the most efficient double glass, triple coated vacuum tubes.  These tubes are first sputter coated with Copper - Stainless Steel - Aluminium Nitride.  This provides the most durable coating, generates higher temperatures and provides the most efficient heat transfer process.

Like all our solar systems, our dairy system is also fully automated. After the morning milking simply drain the required amount of hot water from your dairy HWC into your vat for the cup wash. Do not refill the dairy HWC. At some stage during the day, the solar tanks will automatically drain into the dairy HWC. The Solar tanks are automatically refilled with cold water. The electric backup heating element will be switched at the required times to provide any heat top up as required. It really is that simple.

The 358T solar tank system works on a simple thermosiphon principle.  Water heating does not require electricity or circulating pumps.

For the fully automated drain / fill / top up heat system we have provided motorized valves with a very simply to use 'push and turn' manual override. You will be able to fill or drain the solar water heaters just like during the automated process.

Your modern dairy HWC are either manufactured from Duplex Stainless Steel (grade 2304) or Copper. Duplex stainless steel (grade 2304) exceeds marine grade stainless steel (grade 316), so why would you even consider a grade 304 SS tank?

There is a misconception that 304 stainless steel is a suitable durable material for hot water storage tanks.  If that was the case, all domestic and dairy hot water cylinders would be manufactured from this cheap grade of stainless steel and we would all save a fortune.  (See durability problems below.)

For long term durability and reliability the industry standard for domestic hot water cylinders is either Enamel over Steel, Copper or Duplex Stainless Steel (grade 2304).  You can expect a warranty of between 5 and 10 years, and it will probably last twice that long.

To ensure high performance, durability and cost effectiveness, our thermosiphon HP70T and 358T solar tank water heaters are manufactured from Enamel over Steel tanks, insulated in 50mm of Polyurethane foam for superior heat retention and encased in high quality Zincalume.

After extensive research and trials, we have concluded that incorporating enamel coated tanks in our non pressure and mains pressure solar water heaters is the most cost effective and long term durable solution for our thermosiphon water heaters.

After the tank is fully welded the enamel coating is applied at 900 degrees C.  The enamel provides an impenetrable barrier to the oxygen molecule and any minerals in the water supply, thereby eliminating corrosion.

For added protection a sacrificial magnesium anode is fitted.  The anode can be replaced quickly and when maintained will ensure many years of reliable service.

During the manufacturing process the ends of the tank are welded, and the molecular structure of the stainless steel immediately adjacent to the weld is altered.  When this weld is exposed to moisture and minerals the oxygen molecules in the water react with the impurities in the metal, a chemical reaction takes place and this results in pin hole corrosion.

The corrosion accelerates under high temperatures and when there are impurities in the water.

We think of solar water heating as a long term investment.  At Solar Corp we believe in doing the job right first time.