I have a 20 kilo Detroit Diesel just for my house!!!
It is "Old and Noisy",but then so am I!!!I have a 3.6 kilo inverter with 8 batteries,but they won't "Pull" all my 220 needs,like air-conditioners,water pumps,and water Well!It is in it's own "house" with sound proofing and a muffler.It is still loud,but only to the neighbors!!!! I have my windows shut,with the "Air" blasting,so I am not bothered!!!When the power is off,I can run the "Planta" for the house,and charge the batteries for the inverter at the same time!
A 25 kilo will NOT be big enough for the apt. bldg.That is only 2.5 kw per unit.No way that will do more than a fan or 2,TV,small refridgerator,and light bulbs!
You are under size,and under budget!!!
Someone talked about "propane" generators here before,(Check the archives!) they were not given good marks!
The Diesel is like the "Energizer Bunny" it just keeps going,and going,and going!!! I have run mine for many days non-stop!!
Cris Colon