Solar nuts and bolts
Made up your mind to get solar panels on your roof? Here’s what you need to know.
Since we aren’t all solar gurus, we’ve taken it on ourselves to do the nitty gritty research for you and put the shine into solar so you have the basic need-to-knows if you’re thinking about installing solar at home, the office or your sun-drenched summer bach.
No longer just a nice-to-have luxury for the financially elite, solar technology and economic payback have improved dramatically in recent years and installing solar onto your home or business is becoming increasingly straightforward – if you know the basics.
The standard solar photovoltaic (PV) residential installation consists of not only panels, also often referred to as “modules”, but also an inverter – the power controller, or “brains” of the system, and the associated racking and mounting system. Most are grid-connected (wired into the National Grid), but some have battery storage, and some have both.
Solar panels Panels are essentially the solid-state, passive component of the solar power system. A wide range of solar panels are available internationally, and a plethora of brands are now on the New Zealand market. But not all solar panels are created equal and a key consideration to take on board when investing in solar is, first and foremost, the quality of the components used.
As a way to help you distinguish the wheat from the chaff the industry has developed a three-tier rating system (Tier 1, 2 or 3) that ranks the numerous panel manufacturers in terms of their quality, reliability and history.
Tier 1 represents only a small slice of the total number of manufacturers on the market (2%) but is by far the best option to choose. A number of attributes clearly sets them apart from their competitors. First, manufacturers are ‘vertically integrated’, meaning the company you’re investing in controls the entire production process and is accountable for everything – from the silicon cells to the modules, frames and ultimately panel assembly. Tier 1 manufacturers have also invested heavily in research and development (R&D), use highly automated manufacturing techniques and have at least five years’ history in manufacturing solar panels. In other words, if something goes wrong you know you’re safely covered and there’s a high likelihood that that company will still be afloat in 20 years’ time to honour its warranties.
Tier 2 manufacturers ranked are the middle ground, and comprise 8% of the market. They have less experience in producing panels (2 – 5 years) and invest relatively little in R&D compared to Tier 1. Comprising the bulk of the market (90%), Tier 3 manufacturers typically assemble panels using components manufactured by other companies. They also have the least experience, investment focus and credibility.
To ensure you don’t end up with a lemon of a solar system, it is important to make sure that the panels that you purchase are from reputable Tier 1 manufacturers. Fortunately most panels available in NZ are Tier 1 or, at worst, Tier 2 products. Internationally, there are cases of house fires being caused by faulty panels. Further, while Tier 1 options appear more costly than Tiers 2 and 3, the warranty on the product is only as good as the company behind it. Some products on the market boast long or extended warranty terms, but when you look closer the warranty is “underwritten” by a third party. These warranties are hence only good while the premium is being paid. In the event the company where panels are sourced cease business for any reason or stop paying the warranty you will likely have problems claiming in the case of product failure.
If panels are the hardware to your solar system, the ‘inverter” is the brains behind it. The most electronically complex part of the system, the inverter essentially coverts the direct current (DC) generated by the solar panels into alternating current (AC) – the power that can be used in your home. The inverter also has inbuilt protection circuits to control the import and export of generated power from the system.
Make sure you prioritise high quality over cost when buying an inverter. This is because more often than not solar system failures are due to inverter failure rather than panel failure. This is also important because the tier system doesn’t apply for inverters, so you have to do your homework on the quality of the product.
Micro Inverters are becoming more common. With a small inverter attached to each solar panel, they covert power from DC to AC at the panel – rather than at one single point in the system. The benefits are that if one panel is shaded then only the solar production of that panel is affected. With conventional, less costly, “string” inverters, if one panel is shaded then the whole array’s performance is limited to the level of the lowest producing panel.
Nonetheless, unless you envisage having significant shading issues the price premium of micro inverters is generally unnecessary. If your property is somewhere in the middle – where partial shading is likely, then ‘optimised panels’ can offer an alternative solution. These have inbuilt optimisers into each panel that individually optimise each panel’s output and performance like micro inverters, but without changing the current at panel level.
Solar storage (battery) technology has not kept pace with solar cell technology, and neither has the price drop. But as solar uptake and power prices continue to soar the development of cost-effective, longlife battery technologies is the energy market’s fastest growing sector. It is now only a matter of time before affordable ‘hybrid’ solar systems – ie those that have a level of battery storage while also being grid connected – becomes a reality.
With your Solar 101 lingo downpat, understanding the process of connecting you up to solar– both at your home, and with a power company – is the next important step. This process is reasonably complex and onerous if you do it yourself, so choose an installer who can provide an end-to-end solution.
You first need permission to connect to your local power network prior to installation (involving application documentation and submitting system design details and electrical specification). Then you need to have a registered electrician install it. After this it must be inspected and issued a certificate of compliance by a registered electrical inspector. An application must also be made to your power retailer to swap your existing meter out with one that will measure both imported (power from the power company) and exported (solar) power. This new meter can take up to two months to install and only after this is done are you able to enjoy the cash benefits of your new system.
It’s up to you to decide on your electricity provider. Currently Meridian and Mercury Energy are the best, offering decent rates for the excess power you produce.
Ongoing maintenance and monitoring
Generally speaking, regularly cleaning the panels and an annual supplier check of the system to ensure that the system is operating properly are sufficient. From a performance monitoring perspective, whether you’re interested in daily performance or in the monthly power savings, most inverters include simple readouts to wireless or Bluetooth monitoring via laptop or smartphone to indicate your system’s performance. The level of monitoring is up to you. Advanced systems on the market monitor both solar and mains power usage, are especially useful in commercial applications where the system can measure usage by various aspects of a property’s energy consumption such as lights, aircon or electronic equipment.
In terms of warranty cover there are two things you need to look out for. The first is the manufacturer’s product warranty of the panels. This covers against panel manufacturing faults and provides a 10 – 12 year product warrantee. The second concerns power production and generally warrants power production on a sliding scale over 25 years. Better panels generally warrant a production of 90% or better after 10 years and 80% or more after 25 years. It is also useful to look for established, reputable suppliers who offer ongoing maintenance programmes.
If you are thinking about adding battery storage to your solar system in the future, considerthe cost and convenience of doing so, and question whether micro inverters are in fact the best solution to choose. Why? Storing solar in battery requires energy to be re-inverted back to DC to feed batteries which adds unnecessary expense and multiple inversion decreases overall solar efficiency.
In addition to making sure you are purchasing a Tier 1 system, verify that the installation is being completed to regulation standard. Make sure you are dealing with registered master electricians. It is also important to make sure you are buying the right size system for your requirements–last month’s Element article on system sizing can help guide you on this (find it at elementmagazine. co.nz). Finally, be wary of newcomers to the industry who may be here today and gone tomorrow, leaving you with no ongoing support. This editorial series is made possible with funding from Solar King. To find out more about Solar King’s products visit solarking.co.nz