Case Studies

Your local SUNZ Solar Energy Specialist can custom design an integrated solar energy solution, incorporating a wide range of domestic or commercial energy and heating products.

SUNZ can utilise heat from solar energy, electric element, heat pump, wetback fire, gas boiler, diesel or pellet boiler, or continuous gas hot water systems to provide heat for domestic hot water, swimming pool and spa pool heating, underfloor heating, or radiator heating.
Let your local SUNZ Solar Energy Specialist identify the most efficient and cost-effective solar power system for your specific conditions and New Zealand’s unique environment.

Domestic Solar Water Heating

Drain Back Solar with Mains Pressure and Wetback SUNZ 1st picture

This SUNZ domestic solar hot water heating system comprises of 2 x 2.5m2 solar collectors fitted to a 300 litre thermal store hot water cylinder. When the solar water heating system stops at night or when the cylinder is hot enough, the water drains down out of the solar collectors back to the cylinder. With no water in the collectors there is no requirement for frost protection.

The cylinder is also connected to the wetback fire for additional free hot water during the colder months. The controller is mounted in a hall way so the temperature of the cylinder can be monitored. The homeowners only turn the power on manually when absolutely necessary.

Equipment used:

2 x Solimpeks Marvels Solar Collectors
1x 300l Hunsen Thermal Store Hot water Cylinder

Project Cost Indication:



Retrofit to an existing cylinderSUNZ retrofit to an existing cylinder

This Sunz Systems comprises of one 2.5m2 solar collector retrofitted to an existing 180 litre low pressure cylinder. The cylinder also has a wetback fire fitted to it. A specialist 4 way fitting is used for the solar flow and return. Solar can be retrofitted to most existing cylinders, but the efficiency of the system will be dependent on the size of the existing cylinder and the number of people in the home. The solar controller turns the backup element on and off only when the solar or wetback have not got the cylinder hot enough.

Equipment used:

1 x Solimpeks Marvel Solar Collector
Advanced Differential Solar Controller with Element Control 

Project Cost Indication:



New Build Mains Pressure SystemSUNZ new build mains presssure system

This Sunz System was installed on a new build. The two solar collectors are installed on an elevated frames on the flat roof. Elevating the collectors to a steeper angle gives better performance in the winter months when the sun is lower in the sky. The collectors were located in the middle of the two story roof so they could not be seen from the ground. The collectors are connected to a 300 litre mains pressure solar cylinder with a mid element.

Equipment used:

2x Solimpeks Marvel Solar Collectors
Engineered Elevation Frame
1x 300l Stainless Steel Mains Hot Water Cylinder

Project Cost Indication:




Large Capacity Drain Back Solar with Mains PressureSUNZ 4 Large capacity drain back soalr with mains pressure

This Sunz System consist of three solar collectors connected to a Rotex Sanicube 500 litre storage cylinder. The Rotex Sanicube design allows the solar to be installed as a Drain back, so all fluid drains from the solar collectors back to the storage tank when the solar stops. This provides the ultimate frost and over temperature protection, something that needs to be considered in New Zealand's environment. The 500 litre storage volume and three solar collectors provide hot water for a large extended family.

Equipment used:

3x Solimpeks Marvel Solar Collectors
Rotex Sanicube 538/0/0
Advanced Differential Solar Controller

Project Cost Indication:



Swimming Pool Solar Water Heating

Matakana SchoolSUNZ 12 Matakana school

This systems was installed on 2 Roofs. It consists of 26 Techno-Solis Unglazed Collectors. The pool is 124m2 and the solar area is 81m2, which represents 66% of the pool surface area. A Thermal Blanket Pool cover is used.
“On behalf of the Matakana School Board of Trustees and the whole school community we wish to formally thank SUNZ for a job well done on the solar heating of our school pool. The solar heating was efficiently installed with minimal fuss or disruption to the school, and has worked very well and performed pretty well exactly as you indicated to us that it would. We would have no hesitation in recommending you to any other potential customer.” Graeme S.

Equipment used:

28 x 2.4m Long Techno-Solis Unglazed pool heating collectors
Solar pool Circulator pump
Differential controller

Project Cost Indication:



Residential Pool with No CoverSUNZ resi pool no cover

This system consists of 11 Techno-Solis swimming pool collectors mounted on the house roof. The owners did not want a pool cover as the pool has beautiful surroundings and is all lit up at night. The implication is we need to put a much larger solar heating system in to compensate for the extra heat the pool will loose at night when not covered. The pool is 46m2 and the solar area is 49m2, which represents 105% of the pool surface area. The owners are delighted with its performance and are often swimming in 30 degree water in September. Our normal expectation is 28 degrees towards the end of October as a swimming start date.

Equipment used:

11 x 3.66m Techno-Solis Unglazed pool heating collectors
Solar pool Circulator pump
Differential controller

Project Cost Indication:


Devonport Primary SchoolSUNZ Devonport primary school

This unglazed pool heating system was installed to reduce the gas consumption on the existing heating system. It performs so well it has almost eliminated the gas use entirely. It was a challenging installation as the nearest roof was quite a distance away and 22 meters above the pool .The pool is 135m2 and the solar area is 73m2, which represents 54% of the pool surface area. A thermal Blanket pool cover is used.
“We are delighted with the results of our SUNZ solar pool heating system at Devonport Primary School … not only will it enable us to hugely cut our gas bills, it will enable our students to enjoy a longer swimming season.” Mrs H.

Equipment used:

16 x 3.0m Long Techno-Solis Unglazed pool heating collectors
4 x 3.66m Long Techno-Solis Unglazed pool heating collectors
Solar pool Circulator pump
Differential controller

Project Cost Indication:



Rest Home Solar Water Heating

Aparangi Residential Care
SUNZ Aparangi 2

Aparangi Village is a unique lifestyle retirement village in the rural township of Te Kauwhata, North Waikato.  Redevelopment of the Residential Care Unit 2010, and Stage 2 was completed in October 2011. These two stages encompass 11 premium rooms which offer ensuite toilet and washbasin, and seven studio rooms which offer full ensuite bathroom and kitchenette.

Stage 1:
6 x Marvel Solar Collectors connected in drainback configuration to a 500 litre mains pressure solar pre heat cylinder. The Solar pre heat cylinder feeds 4 domestic hot water cylinders which service the rooms.

Stage 2:
10 x Marvel Solar Collectors connected in drainback configuration to a 1,000 litre mains pressure solar pre heat cylinder. The Solar pre heat cylinder feeds 7 domestic hot water cylinders.

SUNZ Aparangi 1

Equipment used: 

Stage 1:
6 x Solimpeks Marvel Solar Collectors
1 x 500l Stainless steel mains pressure cylinder
1 x 90l drain back tank
1 x Differential Solar Controller
Stage 2:
10 x Solimpeks Marvel Solar Collectors
1 x 1000l Stainless steel mains pressure cylinder
1 x 200l drain back tank
1 x Differential Solar Controller


Project Cost Indication:

Stage 1: $30,000
Stage 2: $42,000


Dairy Farm Solar Water Heating

Northland InstallSUNZ 6 northland install

This SUNZ installation comprises of 3 x 2.5m2 solar collectors fitted to a 500l dairy cylinder with solar ports. The farm is a 90 hectare block milking 300 cows through a 32 aside herring bone. The farm is a winter milker so the solar collectors are evevated for better winter performance. The power that is used to “top up” and maintain the temperature has been converted to a night rate which is half the price on normal day rate.

Equipment used:

3x Solimpeks Marvel Solar Collectors
Advanced Differntial Solar Controller

Project Cost Indication:



Waikato InstallSUNZ Waikato install

This installation comprises of three solar collectors fitted to two domestic dairy cylinders. The configuration of the cylinders in the ceiling cavity of the shed was unique so a divert system was installed. The solar heats one cylinder at a time and automatically switches depending on which cylinder is calling for heat. The electric element backup is on a timer so power to the elements can be kept off giving the solar a change to heat the water first, before power is used to top up and maintain the temperature.

Equipment used: 

3x Solimpeks Marvel Solar Collectors
Elevated Frame
Powered divert valve
Advanced differential controller

Project Cost Indication:



Dairy Shed Pre Heat

SUNZ 8 Dairy shed pre heat

This system comprises of 2x 300 litre tank on roof systems used to pre heat the existing dairy cylinder. The requirement for hot water varies in this dairy so directly heating the existing cylinder was not an option. Space in the Shed was also limited so on roof storage tanks were used. The roof structure had very wide spacings so a custom frame had to be designed.

Equipment used:

2x Solimpeks TSM300 Tank on roof Systems
Custom frame
Copper auto fill system for the existing Cylinder

Project Cost Indication:





Calf Rearing ShedSUNZ 9 Calf Rearing shed

This tank on roof system is used to proved warm ater for a calf rearing shed.

Equipment used:

Solimpeks YSM300 Tank on Roof System

Project Cost Indication:








Accommodation Solar Water System

Ibis WellingtonSUNZ Ibis Wellington

Ibis Wellington is in the heart of Wellington near the bustle of Lambton Quay and walking distance to Parliament, TSB Arena, Westpac Stadium and Te Papa. A qualmark rated 3.5 star hotel with 200 contemporary guest rooms. Ibis Wellington's quality has been recognised with international ISO 9001 and its environmental commitment with ISO 14001.

Old System:
The old hot water system consisted of 2 x Raypak boilers (505kw each) and 4 x 500l
storage tanks. Energy is supplied to 4 x air handlers via a plate heat exchanger.

New System:
8 x Rotex Callorifiers and 8 x Rinnai HD200. Air handlers now heated from new Heat Pump.

End Result:
No more complaints about lack of hot water. Gas Consumption has dramatically reduced.
Very Low maintenance costs.

Equipment used:

8 x Rotex Sanicube 544/0/0 Storage tanks
8 x Rinnai HD200 Gas Boilers
2 x Hot Water Circulators
1 Digital Thermostat

Project Cost Indication:



Silverstream RetreatSUNZ HOtelMotels silverstream

Silverstream Retreat operates from the refurbished world war 2 Hospital. The Retreat caters celebrations, community events and school is only a 25 minutes drive from Wellington city Forest Wing ablution block. Forest Wing accommodation block sleeps 77 people. The refurbishment included construction of a new ablution block, with 12 showers and basins.

System Design:
Eight solar collectors heat the Two Rotex Solar pre heat tanks, and a single gas boiler heats the two Rotex Final heat tanks when the block is occupied. When the block is unoccupied, the gas boiler is turned off and the solar heats all four tanks. The underfloor heating for the ablution block runs of the 2 final heat tanks, so is 100 %.

End Result:
Solar heats the floor when the accommodation block is empty, keeping the ablution block warm and dry heats all four Rotex Calorifiers. Gas is only used when solar energy is exhausted. Very low running cost system.SUNZ HOtels 2 silverstream

Equipment used:

2x Rotex Sanicubes 544/16/0 Final Heat Tanks with Underfloor Coils
2x Rotex Sanicube 544/0/0 Solar Pre Heat Tanks
1x Bosch 32c Condensing Boiler
1x Advance Differintial Controller with Transfer
1x Floor Controller

Project Cost Indication:



Industrial Solar Water Heating

ANZCO Foods Meat Works - ManawatuSUNZ 17 Factories

Staff Amenities gas hot water services.The existing Rheeme gas Storage cylinders had reached the end of their life after 10 years service. One had failed completely and the second was only just working. Our Dealer Ross Clark-The Plumber Completed the installation consisting of 2 x Rotex Sanicube and two Rannai HD200 Boilers. 

Engineering staff at ANZCO were a bit sceptical about the Rotex system at first, but when comparing cost of the Rotex system against another Rheem system they discovered there was little difference yet the Rotex system offered them better hygiene, better serviceability and better life span. The Rotex system also provides better reliability as if one boiler needs to be serviced or replaced in years to come, it can be isolated and replaced while the rest of the system continues to function. Reliability in providing hot water for the staff is paramount in a food processing environment.

Equipment used:

2 x Rotex Sanicube 544/0/0 Storage heat exchangers
2 x Rannai HD20 Gas Boilers
1 x Lowawa Hot Water circulator


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