Here is some advice!
Don't let the "Contractor" get ahead of you with your money!Pay 10% at a time,as construction is completed."Holdback" 15% to be paid only after the house is complete to YOUR satisfaction!I don't see how you are NOT going to get taken Do you know the "average" cost per M2 of construction where you are? The cost of "Block",4",6",8",a bag of cement,sand,gravel,PVC,wire,windows,doors,daily wage per worker,a "Tinaco",do you speak "Dominican"?Do you know the different types of wood used for doors and cabinetts?and their cost per foot?Do you know what wood is eaten by termites,and what wood is "Safe"?Septic system?Water system,Cisterna,or not?
Just some things to consider.How long will construction take? Have you had a "Title Search" done.Do you plan to stay for the entire time that it takes to build? That could be 6 months!(Always double what they tell you!)
I tell you these things so you can be ready,not to discourage you.
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Your "Inverter" question is impossible to answer,until you tell us what you want to run on the system.1 lightbulb,2,50,tv,5 tvs,a water pump,are you going to want 110 volts and 220 volts,computers.air conditioners!How long do you want to have power from the batteries?You may have done "ALL" your homework,but your questions should be very specific.