It’s almost human nature to assume anything above 95% is excellent – and, it is. However over the lifetime of your solar inverter, the difference from 98% to 97% can reveal itself on your power bills.
Efficiency is a critical specification, that is directly correlated to the production of your system, before you can utilize those solar rays in the form of AC power, an inverter must convert it, and although the core principals remain the same despite using alternative solutions such as a micro-inverter, the power must be converted. So, the higher the efficiency is, the more kilowatt-hours can be created. Simply put this may seem to be the perfect number, the closer to 100% the better, however it isn’t always.
Solar Inverter Efficiency isn’t as simple as it looks
Typically there will be two figures when it comes to efficiency, these will be maximum efficiency and European efficiency. European efficiency is the more reliable figure as it outlines average performance, as opposed to the highest level of efficiency possible. Unavailable to us are efficiency figures for Australia, as Europe is very different in terms of conditions, but that is not possible. This leaves us in Australia will slightly less accuracy, however, they are the best indicator available.
What do the numbers look like?
For the purpose of this article we won’t delve too much into the other possible types of inverters, such as Hybrids or Off Grid, we will focus on the String inverters which are the most common solution. Micro inverters won’t be as efficient as string converters, so they haven’t been included below.
Popular brands for Australian solar panel systems are,
A few of the relevant scores are below, all for a 5kW Inverter,
Assuming these are used for a 6.6kW system, which is a popular option for larger households, the difference between a SMA and Delta inverter represents a meager 1%. If we translate that to production numbers on the Gold Coast, the difference between using a 96.5% inverter, vs a 97.5% inverter is 96kW in a year – over 10 years let’s say, that makes up a 960kW difference, or in dollars $199.3 over a 10 year span.
Now these numbers are very far from perfect, they don’t account for a number of factors, and assume all other aspects of your solar panel system maintain in perfect working order for the next 10 years. However, it does show that it does make a difference, not only in production but in the money you spend.
What else is important in an inverter?
While $200 Is nothing to scoff at, it’s hardly a game changer. There are many other factors that play into installers and consumers’ minds, namely how durable an inverter is. This is a tradeoff, as to increase efficiency, some short cuts may be made in durability, such as effective cooling within the inverters. Removing this, therefore removes the required energy to cool the inverter, resulting in marginally higher efficiency.
Manufacturers will have warranties associated with their inverters which can provide some insight into the tradeoff. 10 years is considered a minimum for a lifespan, with warranties ranging to around 12 years on the high end. The higher the warranty, the more confident consumers can be in the longevity of their choice.
When working with a solar installer, it is important to discuss most important factors to yourself. Get them to explain why they have made particular choices for equipment, as there is never a correct answer, only a choice that applies better to some circumstances.