I live in SoCal so looking to connect with others who live in this area and I can possibly work with.

I have about 15k liquid cash and live in MA.

You will continue to live in Spain, but is there someone else that might live in California?  

In theory we could buy a house with him and rent it for ten years and break even, pay the debt down, build credit, and later maybe he lives there.

There are only three instances where it makes sense to buy solar panels for your house.1 - You are living off grid. 2 - You live in a state that has sky high electric costs AND great tax insensitive.3 - You have lots of money, don't care if you are paying more, and want to feel like you are saving the planet (even though you really are not). 

@Emily Wolters buy a 2-4 unit to live in and rent the rest, via FHA 203(k) mortgage, which has 3.5% investment and  allows financing of repairs.

Either the owner or the co-host will need to live locally in order to register.

If you live in one unit and do the house hacking thing, your mortgage gets subsidized. 

Here are a few potential types:* House hackers trying to figure out how to do accounting (I fall into this category, as I live in one unit of a 2-unit property)* Real estate agents who need accounting software, or transaction management software, or marketing software (I also fall into this category)* Landlords who self-manage and want something to help them with marketing, tenant management, accepting rents, etc., and also need bookkeeping/accounting software.

Also, the state of formation is likely where internal disputes would be brought among LLC members, so if you and a partner and/or spouse live in CA, you probably want to arbitrate in CA if the two of you had a disagreement.