Frequently asked questions
Who can have solar PV?
In short, anyone can have solar!, We offer a range of products and solutions to suit residential properties as well as commercial solutions.
How much does it generate?
A 2kW (8 panels) solar PV installation produces about 2750 kWhrs a year in good conditions in the Auckland area. Good conditions are typically a North-facing roof, and a tilt of about 30 degrees. These conditions can be adjusted by tilt mount systems on roofs with lesser pitches or oreintations.
Metalcraft Roofing can perform modelling analysis to calculate your estimated produced energy, based on your location, current usage, and available installation space. Panels also work on cloudy days. Obviously, your geographical location and available levels of sunlight affect how much electricity your panels generate.
How many panels do I need?
The number of panels depends on your usage. For an average New Zealand household which uses about 9000 kWhrs, we suggest an installation of a 3 or 4kW System with 12 or 16 x 250Watt panels.
How much does it cost?
Please contact us for a quote.
Where will the panels be installed?
The usual place is the roof, but panels can also be mounted on the ground with special mounting kits. Some customers have even constructed their own self-build frames.
How does it work?
Solar PV (photovoltaic) panels directly convert light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. A mono-crystalline or poly-crystalline silicon material is used in the construction of PV panels. When these free electrons are captured, a DC electric current results in the PV panel that can be used as electricity. As most household appliances use AC current, an inverter is required to convert the DC current to AC. The electricity can then be used by your appliances. Any electricity you don’t use will be exported to the electricity network via an import/export meter, where a selected retailer can purchase the electricity.
How much money can I save?
Of course this is a relative question. It depends on different factors like the amount of sunshine, how you use energy, and the appliances you have in your home. The most important factor is how much of the energy generated by the solar PV installation is used within your property? If most of the energy generated is exported to the grid, this is likely to result in a reduced Return on Investment, as the buy-back rates for your electricity are likely to be less than your purchase rates. The best Return on Investment is to use as much of the solar PV generated electricity yourself.
Will solar work in my location?
If the sun shines in your location, then solar will work. The further North you are in New Zealand, the greater the benefit you’ll receive from the sun’s energy, and you’ll receive greater energy from the sun in summer months than in Winter.
I’ve heard the term “irradiance” used when referring to available solar energy. What does this mean?
Irradiance is a measure of the sun's power available at the surface of the earth and it peaks at a maximum intensity of just over 1000 watts per square meter in the North Island. With typical crystalline solar cell efficiencies around 14-17%, that means we can expect to generate about 140-170W per square meter of solar cells placed in full sun.
Which system is right for me? Grid tie, Off-grid or Solar Hotwater?
Grid-tie is suitable for all homes connected to the grid. You use the grid as a battery and earn money, when you put more power into the grid than you use. For example, if you are out at work during the day or on holiday, your PV (photovoltaic) system can generate money dependant on which energy retailer supplies you.
- Off grid is suitable for properties that are isolated from the grid and for homes for which it is prohibitively expensive to connect to the grid.
- Solar Hotwater is the direct heating of water from the heat of the sun and is much more efficient for direct water heating applications than PV. However, for low hot water usage situations, it may be more effective to use solar PV in a grid-tie scenario to heat the hot water.
Currently, Metalcraft Solar focuses primarily on Grid-Tie solutions. We are unable to offer Off-Grid or solar Hot Water solutions.
What happens if I sell my house?
Presently, there isn’t enough data to suggest that a solar installation will definitely improve the value of your property. Housing markets vary on a local/regional basis, i.e. buyers in certain locations may favour properties with PV or solar thermal installations, whereas this may not be the case in other locations. However, let’s look at the benefits here: would you prefer to purchase a house that has energy producing equipment already installed, providing lower energy bills, lowering dependency on conventional fuel sources, and requires very little maintenance?
It is also possible to disassemble the array pack it up and take it with you to your next home!
Besides generating my own power, what else should I be thinking about?
You should use energy efficient products instead of e.g. an old freezer, fridge, bulbs. The energy-hungry appliances should be used on sunny days and not at night. Most modern appliances have timer functions to allow you to run them during the day when you are producing plenty of power. Your house should be well insulated, especially if you’re thinking about using Renewable Energy for space heating.
How do I maximise my usage of the electricity I generate?
A general tip is to use your electrical appliances when the sun shines. More specifically:
Fit a timer to your hot water cylinder to heat during daylight hours. You may need to ask your electrician about moving the hot water cylinder from the controlled circuit to your regular circuit.
Similarly, fit timers to mechanically controlled appliances such as washing machines, dishwashers, tumble dryers.
Most digitally controlled appliances have delay functions so you can set them to operate during daylight hours.
Think about what other electrical appliances you could use during the day.
How long will the Installation take?
A: Usually, for domestic Grid-Tie installations this can be done in a day or two. However connection to the grid to allow you to export your excess energy can take up a month; this is in the hands of the energy retailer, but we administer this process on your behalf.
What do I need?
For domestic installations a suitable, structurally sound, North facing roof, with around 20m2 for a starter 2kW system. You just need enough installation area, sound wiring, and a functioning distribution board. We will advise you if it is impractical to install in your situation.
What equipment will I be supplied with?
Grid-Tie systems usually consist of panels, inverters, a mounting system and wiring. This installation will connect to your existing electrical infrastructure.
What happens when the sun doesn’t shine?
Panels also produce energy on cloudy days, although this obviously won’t be as much as on a sunny day. In these situations conventional power sources will have to contribute to your electricity needs.
Which factors affect the solar system?
The system is affected by shadows e.g. from structures above your house, trees, cables etc., and the amount of available sunlight. These factors are analysed by Metalcraft Roofing prior to installation. The panels should be cleaned occasionally, although the panels are generally installed at an angle that allows rainwater to provide a self-cleaning function.