The solar inverter is an electronic equipment, like any other electronics, its price varies from one manufacturer to another, one brand to another, and even one country to another, etc based on its quality and performance, because high quality inverter will be translated to longer life time expectancy. Actually in general the high quality solar inverter will be more expensive than lower quality one. 
So, when we intend to purchase our new solar inverter we have to decide whether we need the high performance and robustness or the cheaper one.
The specialized solar engineer will assist us in choosing the high quality solar inverter, however there are some general indices of high quality, like inverter manufacturer commitment, transparency and experience, the quality of solar inverter internal components and its ability to withstand harsh weather, the inverter enclosure protection to insect’s entry, does the inverter has sufficient cooling fans to maintain its internal operating temperature within the safe level, so we can assure longer life time, and are these quality features real or spam?
In general, the solar inverter quality will be assured via features like high operating efficiency, and ability to provide maximum power under various conditions. Although the solar inverter prices decrease dramatically recently, we actually get what we pay for, so its strong relation between the quality and price.
Where we should install the solar inverter?
We should carefully consider where to mount/install the solar inverter to avoid noise, and vibration. As although the solar inverter is an electronic device, it produces a little noisy sound from time to time due to its internal cooling fans, especially for transformer based inverter, its noisier and more resonant, but it’s cheaper. So, for locations and areas in where disturbances like vibration and noise is not allowed, we have to search for another installation location, especially for light weight walls which easily vibrate than the solid brick wall.
Also, we have to install the solar inverter on the best ventilated and coolest location, as actually with the lower operating temperature, the higher efficiency and good performance we can get from the solar inverter.
