Which inverter brand has the Highest Convert Efficiency and Mppt Efficiency?
It is well known that the smallest difference in the efficiency of a solar inverter can result in considerable variation in their cost. This is true because a PV inverter is expected to work for decades and therefore the total energy yield which can be extracted by the inverter need to be considered in the initial investment calculation.
The PV inverter efficiency is a very complex concept, it is not simply the ratio of the output power to the input power as it comprises of two parts; conversion and MPPT efficiencies
The conversion efficiency is the ratio of the output AC energy to the input DC energy within a defined measuring period, while the MPPT efficiency is the ratio of the energy drawn by the device within a fixed period to the energy provided theoretically by the PV simulator in the MPP. Also, the conversion efficiency can be divided into two types, namely Peak efficiency and Weighted efficiency. The weighted efficiency can also be called as European efficiency. Same goes to the MPPT efficiency be of two types; static and dynamic.
- Peak Efficiency:
Peak Efficiency or Rated Output Efficiency are the terms most commonly used to describe PV, it can be found written on the data sheet or label. As stated in IEC 61683:1999. In formula ηR = (Po / Pi) x 100 where ηR is the rated output efficiency (%) Po is the rated output power from inverter and Pi is the input power to inverter at rated output power.
- Weighted EU
Throughout the day solar array constant; it is lower in the morning and evening and higher in the afternoon when the sun is shining. PV inverters do not always operate in optimal condition. Therefore, weighted or averaged efficiency come into being, it reflecting the true efficiency more correctly.
- Static MPPT Efficiency
The static MPPT efficiency describes the ability of the MPPT to find and hold the MPPT under constant environmental conditions.
- Dynamic MPPT Efficiency
The dynamic MPPT efficiency describes the ability of the MPPT in tracking the MPP in case of variable conditions.
Those four are the most critical factors when evaluating the true efficiency of an inverter. This information will make it simple to judge the performance of inverters.
The survey was conducted to measure inverter efficiency with popular brands such as Sungrow, Goodwe, Huawei, SMA, Solis, Fronius, Growatt and Each Energy, and the result is shown in the table. For single phase inverter, the max efficiency is among 97.0% to 98.8% and the EU efficiency is among 96.5% to 98.1%. The Brand of Each Energy is the best.
For three phase inverters, the max efficiency is among 97.0% to 98.8% and the EU efficiency is among 96.5% to 98.1%.
The Brand of Each Energy is the best of 98.8% and 98.1%. When choosing an inverter, the 0.1% of difference in efficiency really counts as it will work for decades and in the long run, that means considerable amount of yield. For economical point of view, the brands in the table can all be considered, especially Each Energy.