While it MIGHT be possible to find what you are asking about, there is no possible way that I would get someone from that far away and with language and culture barriers to "design" anything for me. Also, getting a warranty covered or getting money back from a failed design, could be a nightmare. I doubt you would have much luck filing a lawsuit once the Alibaba party disappears. Alibaba does have safety measures in place, so the order has to be delivered before the seller gets paid but I have no idea how that would work with a "design" vs. the hard goods.
I have made 3 purchases off of Alibaba and have had 2 of 3 good experiences for batteries or cells BUT the first experience was pretty horrible because I was relying on THEIR expertise to help my ignorance and that was a mistake.
My suggestion to anyone buying on Alibaba at this point in time, is that you must know as much or MORE than the seller about what you want and that you use them ONLY as a SUPPLIER of the equipment that you are sourcing. It may be the culture, but they are not into hand holding and how they answer technical questions is not how most in the USA expect answers. It is just very very different and the language nuances is a huge barrier. You say black and they say that they understand black but it isn't what they really understand and you get grey or white. A photograph would be more helpful than words sometimes.
Next, when you contact an Alibaba seller of a product or "service", in my experience of contacting many sellers, you will always be assigned a SALES PERSON and ONLY THAT PERSON will be your contact and that person has pretty much zero to little technical knowledge and when you ask to speak to an engineer or designer or technical expert, you either cannot because that person does not speak English or they don't want you to talk to them or you get a 3rd person translation. In my bad and good experiences, no one has ever really answered any questions completely or helpfully. That is how I learned that I need to do my research ahead of time and to make sure that I know more about the product and what I want to purchase, than whomever I am talking to. Also, keep any questions SHORT and CLEAR. If you write long rambling questions with lots of what ifs, then you will be screwed, with either bad short replies, or whatever they think that you want to hear (which can be comical) or they will stop communication. My guess, is that they are more interested in piece meal sales than dialogue and a sales relationship, which require more time from them and more time means fewer sales by them to other customers.
Even Amy at Luyuan who has been super nice, helpful and tries hard, loses things in translation and understanding and so any more complex question than, is item A in stock and what is the price, is sometimes a waste of time. Adding photos to explain what you want is also very helpful and requires less translation. And she is from my understanding an owner and not just a sales person and she knows her product line but not much of other product lines or possibilities. Also I do not speak Chinese Mandarin or Cantonese and it is a big ask by me to expect them to perfectly understand me.
Also, most of the people on Alibaba and even North America, DO NOT and have NEVER LIVED off grid, so they may well sell the equipment but have never actually used any of it or have they lived with or built an entire off grid system. So their info is from reading data sheets or sales materials, so they might have a general idea of how things are supposed to work but they have no real world experience with their own products vs other products. They don't know of noise levels, idle current draw, over solar capacity, fusing, or electrical wiring. To prove it, ask any contact anywhere if they live off grid or have ever built a system. And good luck with that on Alibaba.
Personally, after my experiences I would not do what you are asking about. I would also be afraid of finding a very good English speaker that will again tell you what you want to hear and then under deliver. I had that from the sales people at GSL Energy, it was a horrid experience and the after sales service was horrible and frustrating. I would suggest that you learn all facets of your design needs, do not require any hand holding or suggestions and take your time. Hopefully I am either wrong and someone here suggests a great honest affordable "design company" or that you get lucky.
I know that when I was just learning what this was all about and I was living off grid at the time, I was easily convinced by sales people as everything was new to me and I was often overwhelmed and I trusted the sellers to give me good advice. Sadly that didn't work out that well because I did not understood enough to really know what I needed, vs what the sellers thought I needed or what they were selling. It is time consuming to teach and to learn. They don't make as many sales using time spent teaching and the danger is they could lose the sale with a wise customer.
After all, this is a DIY Forum, so the idea is that we are all interested in learning DIY solar builds and the help here can be amazing for you to learn all this. As well, buying "Kits" of any kind can be incredibly expensive. If you don't want to learn DIY, then find a good local Victron dealer that has or does live off grid but remember, most of these folks are sales people first and they get paid for sales vs design.
