Because literally one size doesn’t fit all, it’s critical to do your homework before you install solar panels on your roof. In this article we’ll provide you with some food for thought as you consider a solar panel solution on your home.
Will you use your solar energy immediately or store it for later?
Whether you’re building a new home or looking to add a solar panel system to your existing dwelling, you’ll need to understand how your household uses power. Will you need it immediately, or will you store it for use at other times of day? The variables of a solar power system will help you suss the type of equipment you need and the resulting cost. But remember, not all panels are created equal.
Size of PV panels
It’s almost counter-intuitive but the size requirements of your photovoltaic (PV) panels is a calculation based more on your daily kWh output and less on how big your roof is. Since an average household chews through 20 kWh per day, a 5kWh solar system will be sufficient. How many panels you’ll need will be determined by the output of the panel.
Most panels are around 1.6m - 2 square metres with varying specifications in output, length and width. With output of your system being the main factor rather than the size or number of panels, quality not quantity provides the best bang for your buck. You should invest in the most energy efficient panels your budget allows.
The options are to either install cheaper less efficient panels and have more of them (if your roof size allows it), or have fewer panels on the roof but with a higher power rating. And remember, fewer panels at the time of installation will likely cut down on your labour costs, when factoring in your overall budget.
Get your roof assessed before buying anything
It may be over your head most of the time, but do you know what it looks like up there? Is your roof concrete tiles, corrugated iron, shingles? Solar panels can be affixed to all of these but will need different approaches are needed. First and foremost, your roof will need to be assessed as structurally sound to manage the addition of a solar system.
Although PV panels are surprisingly lightweight, don’t assume that their impact to your roof will be minimal. Calling on an industry expert to assess the suitability of your roof is key to the whole process and will establish the direction you take for your chosen solar panel system.
Avoid overpaying: find the right system for your usage needs
You don’t need to buy a hefty off-road vehicle to drive to the supermarket and back, and the same principle applies to getting solar panels. By picking the system that’s right for you, you minimise the risks of paying too much for a system you’ll never fully use.
On the flip side, you’ll want to factor in any expansion to your system that could kick in later. For instance, if you’re considering an EV purchase in the next couple of years, an extension to your home, or an increase in family members, you’ll need to consider this when choosing the system’s capacity.
Polycrystalline, monocrystalline and thin-film – understanding the difference
Let’s get a bit science-y for a moment. The differences between the three different types of panel are worth getting your head around before you press ahead. These are: polycrystalline, monocrystalline and thin-film. It’s kind of like choosing a kitchen bench – whether you’re budgeting for solid marble, composite stone or a laminate you need to know how they perform and fit with your needs and habits.
- Monocrystalline silicon PV cells are made from one long continuous piece of silicon. Considered the most energy efficient, they have the highest performance, are longer lasting and better at higher temperatures. They’re the most expensive due to the high manufacturing cost. But, because they’re more efficient you may need fewer of these panels.
- Polycrystalline silicon PV cells are made from melting down silicon crystals. These are then poured into a mould and cut up into the wafers for each panel. Manufacturing them is more straightforward, with no wastage, keeping costs down. But efficiency is slightly compromised. As technology improves, these cheaper panels are giving monocrystalline a run for the money.
- Thin film is a relatively new technology, involving the layering of semiconductive materials including silicon, copper, indium, gallium, and other elements to create the solar cell. Lighter and more flexible, it’s cheaper to manufacture, but a greater number are needed. Thin film is currently more popular for commercial or large building use.
Polycrystalline silicon PV cells are still the most preferred solar panel material on New Zealand residential homes today, thanks to their winning combination of performance and price.
Choosing a system that’s covered by long term warranty
If you’re about to invest $10,000+ of your hard-earned money on a solar power system, then the long term warranty on your panels is critical. In shopping around for quotes, ask to see the fine print of their wording on their warranties and undertakings and what this means for you. A 10 year warranty on the product against defects should go hand-in-hand with a 25 year performance warranty – eg, a commitment that the power output won’t drop below 80% of that stated at time of installation is a good benchmark. To be protected as a consumer you’ll prevent the risk of a dispute over solar system faults and failures if you select a provider and installer who stands behind their clear warranty terms and conditions.
A product that’s supported locally
To ensure you’re covered as a consumer it makes economic sense to support local products in setting up your home solar power system. You may see cheap second-hand panels advertised online as a bargain, but it’s a false economy if there’s no agent in New Zealand to help you if they malfunction. A local retailer and reputable installer will understand not only your local environmental conditions for recommending the appropriate system but will be on hand when you need back up. Although two thirds of the world’s solar panels are manufactured in China there’re other countries making panels who have distributors here. Ask your installer to recommend a panel product that can be backed up with excellent service and ongoing support.
Learn more about solar power
Check out our comprehensive Solar Power guide to learn more about using solar power in New Zealand, and whether it might be right for you.