No two PV systems are the same and even systems that are identical in components have unique characteristics and nuances that set them apart. That means the system you design has to be tailored to your needs and the equipment you buy must fill your system requirements not the requirements of a cookie-cutter product. Keep this in mind and consider the following general advice as you look at grid-tie inverters (including the Fronius grid tie inverter) to ensure that what you buy serves your system in the most efficient manner possible.
Before you go any further, you have to compare the inverter you want to purchase with your module specifications and manufacturer recommendations. Even products that look the same may have different specifications, characteristics or features. Taking the time to compare the specifications of Fronius grid-tie inverters with its competition, for example, might make it clear the Fronius is a good fit, great fit or no fit at all as it pertains to what you want your PV system to be capable of doing.
Some inverters have specialized needs as it pertains to heat displacement, weather exposure, shading, module coordination, etc. Make sure you factor in the unique aspects of your roof or solar array set up and match that with the needs of your inverter before you make any purchases. Make sure you select your inverter based on your actual situation and not what you see in a manual or would like to have as a PV system.
Grid-tie inverters are usually rated by their AC output power capability, which is an indicator of how many watts the inverter can put out continuously. This rating dictates the PV arrays maximum power output threshold. That means you have to design a PV system that does not exceed that rating. If you exceed that rating, the inverter will waste excess power as heat. Unnecessary heat can adversely affect the inverter’s lifespan.
Most manufacturers will include in their specifications a “sizing ratio.” This range includes the optimum output by the PV system to the inverter and the maximum. In most cases, the maximum should not exceed 125% of the rating. Since the cost of an inverter is comparatively small when taking into consideration the entire PV system, most PV designs recommend a conservative sizing ratio of 10 to 15% above the inverter’s output range.
Getting an inverter that can work off your solar array in the most efficient manner possible is critical to getting the most out of your PV system. Whether you are looking at a Fronius grid tie inverter alone or designing an entire system, making sure you keep the three guidelines above in mind will ensure you do that.