One of the most common components to deteriorate in a solar field are what are called IGBTs, or Integrated Bipolar Transistors. They are often referred to as “stacks,” and more specifically here at Solar Support, SEMIKUBE® IGBT Stacks.
The SEMIKUBE® IGBT Stacks consist of three individual phase assemblies called “kubes.” All three phase assemblies make up the SEMIKUBE. Since all three kubes work together, they tend to fail at equal rates. This is the reason Solar Support sells the stack of three together in our SEMIKUBE® IGBT Stacks.
Some solar companies opt to refurbish their kubes instead of replacing them. Generally, we don’t recommend this because the parts that are being refurbished are roughly 6+ years old, making the life expectancy of the stack shorter. While it seems like a cost effective solution in the short term, in the long term it always proves most beneficial to replace instead of refurbishing.
Still, some companies are in need of a short-term solution, and refurbishment can be a viable option.
New or refurbished?
So, how do you know if buying new or refurbished is the best option for your company? There are a few key cost drivers for refurbishment:
- What is the cleanliness character of the assembly? (Is it environmentally dirty, soot covered, or clean?)
- Is the source of the contamination from the assembly, or an adjacent unit’s issues?
- Can the general source location be identified (Capacitor Section/IGBT Section)?
- Is there heavy mechanical damage on drive, frame, busbars, heat sink?
- Is there metallic/plasma splatter from an electrical event visible in the Capacitor or IGBT Sections?
- How hot is the environment the stacks are in? The hotter the environment, the faster electronics will deteriorate.
In the picture below, you can see an example of an affordable refurbishment. The capacitor section has only minor cleanliness spots, the IGBT gate drive is very clean, and the driver is not mechanically damaged and is also clean.
A moderate refurbishment is often the hardest to identify via a visual inspection as the contamination source could be adjacent or could be one of the kubes itself. Additionally, it could be electrically damaged in a way that is not visually clear. This is particularly true when it comes to kubes that are adjacent to one that has a significant event.
The picture below shows just a few of the issues that are difficult to determine for a moderate refurbishment.
Expensive refurbishments are typically easy to identify as the IGBT Section and the Capacitor Sections are generally both compromised.
The picture below shows an easily-identifiable expensive refurbishment. Notice the visual damage.
Depending on the condition of the capacitors, mechanical damage (to the driver, the frame, or heatsink) and whether the contamination was internal (meaning another part of the kube caused the damage) or due to an external event will determine the cost of the refurbishment.
If the board is dirty overall or has just a small bit of damage, it could be easier to repair and thus, cheaper to refurbish. Some may have extensive damage and may call for a full new part.
Need some help figuring out what’s the best option for you? Send us a picture and we can get you started in the right direction!
The refurbishment process
We accept refurbishments in compatible sets of 3 kubes and each assessment fee is $325/per kube, $975 per set of 3, plus shipping. Once we receive your kubes, it takes us about 4-6 weeks to assess the condition and extent of the repair. We will report these details back to you, then it will take an additional 4-6 weeks to repair, for a total of 2-3 months from start to finish for your repair.
Once you’ve decided that a refurbishment is your best option and you’re ready to move forward, submit your request through this online form. Or if you have any additional questions, feel free to contact us and we would be happy to help answer any questions.