What is Distributed generation with renewable energy?
Distributed generation is the arrangement whereby small renewable energy systems can be connected into the local electricity networks that provide electricity to homes and businesses.
The generator type best suited to an urban environment is solar electric power, called Photovoltaics (PV). These types of solar systems are easily attached to the outside of buildings, particularly roofs.
The renewable energy produced by the system is used within the building to offset power coming in from the local network. However the building still draws from the local electricity network, so there is no chance of running short of electricity.
If the building produces an excess of electricity, for example on a bright sunny day when no one is home, the excess produced is fed into the network for someone else to use. This happens automatically without any form of management, as electricity flows around the system rather like the way water always runs downhill.
The electricity 'exported' to the network is measured, and should be sold to the electricity supplier. We assessed whether each company offers the possibility to connect a distributed generation system to the local network and included that information in ranking the companies for the first time in the Clean Energy Guide - 2nd edition.
The beauty of a solar system tied to the local electricity network is that you always have enough electricity to do what you need - you don't have any problems when the sun goes down, or a cloud darkens the sky.
There are some wind turbines of a suitable size for household generation and Vector, the owner of the electricity lines network in Auckland, is currently researching the effectiveness of these systems in Auckland. It is also possible to install mini turbines in your down pipes to generate electricity when it rains.
Installing a wind turbine may involve a building / planning consent in an urban environment, whereas installing PV system is not likely to need a consent unless it breaks the skyline of the building significantly. Most small wind turbines must be installed around 6 to 10 m above surrounding rooftops and trees in order to get a clear windflow, for if the wind is not a clean flow the efficiency of the turbine will likely be much reduced.
The Ministry of Economic Development has developed a set of Regulations covering distributed generation connections to local electricity networks. These should come into effect in the second half of 2007. These will provide clear guidance as to the way to make an application to your local electricity network operator to connect any distributed generation system. The rules are different for larger, commercial scale systems (over 10kW) that would be bigger than normally used on a typical house.
The new regulations require that two meters must be installed, as any electricity exported into the local network must be separately recorded (Schedule 2, 4.1 meters).
http://www.med.govt.nz
Why should I install my own renewable energy system?
Electricity is the easiest part of our energy use to produce from renewable sources. If you install a solar electric generator on your roof you are taking a big step to reduce greenhouse gas emissions. About one third of New Zealand's electricity is produced by burning fossil fuels. Every unit of electricity we can produce from renewable sources will help decrease our greenhouse gas emissions and reduce our contribution to climate change. New Zealand could generate all its electricity from renewable sources.
Also, an electricity system with more, smaller generation, distributed close to where the electricity is needed, is more stable and efficient. Energy loses from transporting the electricity from one part of the country to another (transmission) are avoided. About 15%.of the electricity generated can be lost through transmission. There are also benefits in avoiding upgrades to transmission or lines networks.
On a personal level, the greatest immediate benefit is that people who own their own generation systems become very aware of their electricity use, and this helps them make savings right across their electricity use. This means that they make real reductions in their emissions, and find efficiencies in their electricity use. Being more efficient with our energy use is the number one place to look for reductions in our greenhouse gas emissions.
How can I install my own renewable energy generation system?
Using the example of solar power, which is in many ways the simplest technology to install, requires the least maintenance, there are a series of simple steps that must be taken.
- The first step is to review the potential site. Do you have a sunny place (usually a roof area) that gets good, un-shaded sunlight for most of the da during both summer and winter? This is usually best checked in mid winter, as when the sun is low trees or other buildings can obscure the sun for a large part of the day.
- Is there a mains electricity connection, ideally the meter box, close by?
- How much money are you prepared to spend? Solar PV systems are modular, and so can be fairly easily sized to suit a budget, within certain limits.
- Contact a company or two that sells suitable equipment, and discuss your plans with them. Unfortunately there are not many companies in New Zealand that have experience in this area. They should be familiar with the up-to-date situation and the relevant regulations. Check to see if they have installed any other similar systems, and if possible, visit a working system. You can contact a local member of the Sustainable Electricity Association of New Zealand www.seanz.co.nz for possible assistance, or the New Zealand Photovoltaics Association www.photovoltaics.org.nz
The Energy Efficiency and Conservation Authority has a database that you can serarch
- Check the summary of electricity company's distributed generation offers to see which electricity company will give you suitable arrangement to purchase your exported energy. Contact that company to ensure that they offer such arrangements in your location.
- Make an application to the electricity company through the standard process prescribed by the regulations. Your electricity company should be able to provide you with the relevant forms but discuss this with your company. The company you purchase the equipment from should be able to help with this.
You will need to know exactly what and how much equipment you are buying. Under the new regulations, a company must connect you, and limits are set on the charges for applications and time taken to process the application.
The best thing is to join up with a company that actively seeks to have distributed generators connected to its network. Don't waste time with companies that are not enthusiastic.
Ideally you should be paid at least the same rate for electricity that you export as the price at which you buy. Different companies offer different rates - for example Contact will pay the full retail price for electricity generated onsite but you have to be a member of the New Zealand Photovoltaic Association to get the deal, whereas TrustPower offers to pay about 5c per kWh (about 1/3 the retail price). The application fee should not be more than $200.
- Purchase equipment. It should be possible to install the equipment on the outside of the building, including the wiring, avoiding the need to drill holes through walls, though this will depend on what inverter you choose and your installation location.
The equipment to generate the electricity and the inverter can be purchased from the supplier you've chosen above. Talk to your electricity company about buying an electricity meter - they will specify the meter you must buy.
Important: Any wiring over 50 volts must be installed under the supervision of a licensed electrician - this is a legal requirement. An Electrical Certificate of Compliance must be obtained from a registered electrician before connecting to the AC mains electrical system.
The Energy Efficiency and Conservation Authority also has a factsheet on installing your own electricity system.
- Prior to connection, the electricity supply company will likely wish to test the equipment at the time of connection whilst one of their staff members are present. The installer should also be present at this time. You will be charged for this by the electricity company, but they should not charge more than $60.
- Connect. Make your own carbon-free power!
Will I need a new meter and how much will it cost?
The new regulations will require that a separate meter is installed to measure how much electricity your system puts back into the network.
You will be charged for the meter, but you should be charged a fair price for the unit under the provisions of the regulations. Suitable electricity meters are not particularly expensive, perhaps $100-150 but you should check with your electricity company at the application stage.
It is important to recognise that there are two ways of connecting the system. One way exports ALL the electricity produced by the generator through a meter into the network.
The other way only measures the excess electricity exported (that is the amount of electricity you cannot use at the time it is generated as you have enough already).
How you wire up the system depends very much on the contract with the electricity company. If the company will pay you more than the normal price you buy electricity at (in order to sell your units at a premium as 'Green Power') then it makes sense to export all units produced by your system. However, if the price is the same, or lower, than the rate at which you buy electricity, then wire the two meters in a parallel arrangement so that only the excess is recorded as exported.
At the moment, companies only offer to pay equal or less than the retail price.
Old-style rotating disc electricity meters run in either direction, but most of these have been replaced by digital meters that only read electricity in one direction.
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