Hi Richtea, The smallest size generator you should consider buying is 3.5kw
allmost certainly needs to be a diesel or an lpg unit, It would also be worth the extra cost of an auto start unit.That is one that starts up when you switch a light on etc, To keep it running all the time would cost you a fortune,
I had one at my place in scotland and the cost was crippling..I dont know what you would have to pay for such a unit in portugal.Dont know if what ive said helps..May i wish you luck and all the best in your venture..Jack and Marie.