solar industries

Solar energy is the single most abundant form of renewable energy in the world. It is the energy that comes from the sun in the form of sunlight. This energy can reach the earth's surface with a maximum intensity of more than 1000W/m².

Solar heating is the process of taking the solar energy and converting it into usable energy for heating water.

There are two types of solar water heating systems available in New Zealand:

• Thermosyphon systems use the theory that hot water will rise through cold water and thus rely on convection to circulate the water through the system. Therefore the solar panels need to be located below the water storage cylinder to ensure that this convective circulation can occur.
  
• Pump circulated systems allow more freedom with regards to the positioning of the solar panels and the cylinder due to there being a small electric pump in the system. This pump is used to generate water flow within the system.

There are two ways of getting the heat from a collector panel to the storage container:

• In an open loop system the cold water from the storage container is circulated through the collector and back to the storage container. This can also be called a direct heat system.
  
• In a closed loop system a glycol type heat transfer fluid is circulated from the collector to the contaner and back to the collector in a closed loop. The heat is transferred from the loop to the water in the container via a heat exchanger in or associated with the container.

There are two types of collector both of which have a number of variations in specific design.

• Flat plate.
  
• Glass tube.

A Solar water heating system can be supplied as a packaged system or custom built.

Where a solar water heating system is supplied as a packaged system it will be supplied with all components (tank, collector, pump, controllers) which have been designed for complementary and optimal energy performance. Systems supplied and installed as complementary packaged systems can be tested for energy performance as packaged systems with nominated sized and type of containers, and any claimed performance relate to the system as a whole.

A customised system may be constructed for a special application or be where solar components from a packaged system are connected to an existing hot water cylinder. Such systems should only be put together by Approved Installers from components of packaged systems and connected to other existing components such as a hot water storage cyclinder. Where systems are custom built using components, suppliers must be able to provide evidence that the individual components meet the approapriate standard tests, and that the customised system as a whole meets any claimed performance levels by demonstrated similarity of performance to a representative product that meets the requirements of the standard.

For more information on solar water heating click here.

As a member of the Association manufacturers and importers of overseas manufactured equipment are required to periodically demonstrate that the equipment meets the manufacturing and operating standards set by the Association from time to time and that the equipment supplied will be consistently manufactured and supplied to meet the required equipment standards. For more information on the manufacturing standards and where to get system testing click here.

The Association has developed a "Solar Water Heating and Manufacturing and Installation Code of Practice for New Zealand". The currently approved code is available here. Associated with the Code is a "Manual for Structural Assessment for Installation of Solar Water Heating in Domestic Dwellings" available here.

SIA administers the Code on behalf of the industry. Any comments or suggestions for improving the Code are welcomed and should be forwarded to the SIA Executive Officer.

Installation of solar water heating systems is regulated by the need for Building Consents from local Councils. To obtain a Building Consent the system installer needs to demonstrate to the Council Building Inspectors that the system installation will meet the NZ Building Code. The Code establishes the standards for installation. In particular for safe loading on roofs and safe supply of potable water.

The SIA Code of Practice sets out for Councils, the solar industry, and the public the compliance standards and good installation practices that all installations should achieve. These are set out in Clause G12 of the Code. Compliance can be achieved by installations being done to meet the Acceptable Solution G12/ASI. A specific Acceptable Solution for SWH (G12/A52) is in preparation and a draft is available here.

The government is currently undertaking a review of the Building Code. In that review the SIA position is that;

The Solar Industries Association (SIA) will assist with the review to ensure that solar water heating;

• is included as an acceptable solution to meeting the sustainability requirement;
• there is a form of Home Energy Rating developed as a means of measuring compliance with the Building Act 2004.
• SIA will work with other industry bodies such as those interested in other energy efficiency products (insulation, double glazing, space heating etc) to ensure that the results of the review are obtained quickly and efficiently. SIA believes that by cooperative action with other industry bodies and government agencies that the energy efficiency parts of the Code will be concluded quicker. Building Code Review document available here.

New Zealand currently provides more than 40GWh of equivalent electricity consumption per year through the use of solar water heating. It is widely thought that by 2010 this figure could be upwards of 600GWh per year. The total amount of solar energy that the New Zealand land mass collects is approximately 400 million GWh per year which gives an indication of the potential for solar energy use.

Currently the two major regions at the forefront of solar technology are Australia and Western Europe. The abundance of sunlight in New Zealand places us on an even par with the levels found in Melbourne and above that of the levels found in Europe. This shows that the future of solar heating in this country is very attractive and with greater knowledge of the technology, we can only assume steady growth.

For more information on the potential of solar heating click here.

The various advantages of solar heating include:

• It produces zero net emissions of greenhouse gases, enabling both industry and government to work towards meeting New Zealand's Kyoto commitments.
• solar energy is renewable, abundant and a natural energy source;
• the rooftop of the average New Zealand house collects about 50 times as much energy from solar as is required for water heating;
• solar water heating supplies 50 to 75% of the annual water heating energy requirement when installed correctly;
  
• the lifetime of solar heating technologies is usually greater than 20 years;
• solar heating can be easily integrated into the existing water heating systems of buildings;

Purchase and installation costs of a commercial solar hot water system in a domestic residence are in the range of $4000 to $7000 depending on:

• the size of the collector panels;
• the capacity of the cylinder;
• whether you are installing a new system or retrofitting an existing system;
• whether you connect into the existing hot water cylinder or not; and
• the degree of installation complexity, which depends on the building design.

SWH system performance depends on a number of aspects in which collector performance is just one characteristic. More importantly is where and how the system is installed, how the hot water is being used on a daily basis, and how the supplementary heating controller is configured.

Most systems gives similar performance in NZ - the aspects above are more important than any differences between the systems.

Potential purchasers of systems should check if the information provided by SWH suppliers relates to total system performance or is just relating to the efficiency of the collector. Much information provided to the public by some suppliers is misleading as it only relates to the collector. Collector performance has little relevance as it is the performance of the whole system that affects the efficient use of solar energy to heat water. System performance can be significantly affected by pump flow rate, location of inlet and outlet ports on tanks, location of supplementary heating in a tank, and supplementary heating controller settings.

A standard AS/NZS 4234 is available so that systems can be tested under standard reference conditions. This will provide a good guide on system performance in individual situations. It should be noted however that system performance calculations are based on packaged systems. Packaged systems are fully designed systems where all the components have been tested to ensure that they each meet the standard. The design of a packaged system is based on optimal integration of the components. Some suppliers are importing components and making what are called "custom built" systems. A retrofit installation where the existing hot water cylinder is used is a custom built system. The energy performance of a custom built system can not be calculated until after it is built and it is likely that energy performance will be lower than for a similar packaged system which has been designed as an integrated whole for optimal energy performance.

The standard AS/NZS 4234 sets out a methodology for calculating the energy performance of an SWH system under reference conditions in specific climate zones . In Australia there are four zones and in New Zealand two zones for which the energy performance is calculated.

If thermal performance of a system is to be claimed the method of calculation should be AS/NZS 4234. While the calculation is under specific reference conditions these have been chosen so as to closely resemble actual performance. However because every solar water heating application is different it is necessary to standardise variables such as hot water demand, irradiation, inclination and orientation.

The methodology is based on measurement of the performance of each system component eg collector, tank, supplementary heating controller and pump. The performance characteristics of each element are then combined in a computer simulation to calculate the likely energy performance of that particular arrangement of the system components and under the reference conditions.

Only packaged systems where identifiable system components are combined in specified arrangements and with specified pump flow rate, supplementary heating control settings, and differential temperature settings can have their energy performance calculated. The advantage of using computer simulation to calculate energy performance is that different arrangements or settings can be easily specified and the recalculation done.

When reference is made to a system performance it is important that all characteristics of the system including flow rate and controller settings are specified otherwise the performance data provided is meaningless as it is not identifiable to a specific nominated packaged system.

If a supplier can not provide you with certified energy performance results defined from AS/NZS 4234 then a comparison of systems may be obtained from the Australian Office of the Renewable Energy Regulator website. This site only refers to systems they have listed for the four Australian zones, but Zone 4 is similar to the New Zealand Zone 5 which covers the North Island and warmer parts of the South Island..

The list of systems is in Schedule 7 of the regulations Renewable Energy (Electricity) Regulations 2001 (incorporating Amendment Regulations 2005 (No. 2) ).

Calculating the likely energy performance of commercial scale solar water heating systems requires computer simulation modelling of the system. A solar simulation tool SolSimNZ is available here. The tool is aimed at helping solar suppliers, designers and architects better understand how their proposed solar water heating system will work and will help system designers size components and choose the appropriate collectors. SolSimNZ allows the most common solar water heating systems to be modelled for 16 areas in New Zealand. The instructions for operating the simulation tool are available here. (You should note that it is a 10mB file so loading via dial-up will be slow. As the file to be downloaded is a .msi file you will be asked if you want to run it. If you click yes then it will automatically load the files to the desktop of your PC).

There are a wide number of typical situations where solar water heating is being installed. Examples are shown on the attached reference sheets.

Solar Water Heating Reference Installations 1.

All members of the Association are expected to meet the Association's Code of Conduct. For a copy of the Code of Conduct click here (pdf 26kb).

• Harnessing the Power of the Sun: Future of Solar Energy, by Brian Cox, SIA Executive Officer, December 2009
• Get more from your Hot Water - Action Sheet, EECA, Oct 09
• Greenlane Clinical Centre - Leaders in SWH, EnergyWise Newsletter article, Feb 07
• Solar Heating Worldwide - Markets & Contribution to Energy Supply - 2005, IEA Solar Heating & Cooling Programme, April 2007, Edition 2007
• SWH - Quality Assurance Newsletter, September 2006
• Introduction to SWH, article in NZ Plumbers Journal Aug/Sept 06
• Timers on Water Heaters, article in Solar Action Bulletin, Issue 76, May 2006
• Cools Homes, Solar Progress Article, Vol 26, No 4, December 2005
• Solar Heating Worldwide - Markets & Contribution to Energy Supply, IEA Solar Heating & Cooling Programme, May 2005, Edition 2005
• The Job Creation Potential of Solar Energy in Canada, Rob McMonagle, January 2005
• Solar Heating Worldwide - Markets & Contribution to Energy Supply - 2001, IEA Solar Heating & Cooling Programme, February 2004
• Review of Overseas Inititatives, report by East Harbour Management Services (EHMS) and Energy Library & Informtion Services, February 2002
• Solar Water Heating in NZ, article in Energy Wise News, May 2001
• Victoria Solar Hot Water Rebate Program - Review of outcomes 2000-2004, review by KI Guthrie, R Hines, S Stockwell and A Doddathimmaiah, Australia
• Take Yourself into the Future with Free Hot Water, NZ Solar Industies Association pamphlet
• Solar Heat for Industrial Applications, Earthscan UK