.... stayed for 7 days. You get 7kw electric free but they still managed to charge us an extra €15 for extra electric. ..
Are you sure they offered 7 kw free? I suspect they offered 7 kwh for free?
7kw is a rate of power supply not an amount.
7kw draws about 30 amps and to use 30 amps is very excessive!
The most I've ever seen offered on a site is 16 amps. The ring main in your house is limited to 13 amps.
7kwh is 7kw for 1 hour or 1kw for 7 hrs or 1/2 kw for 14 hrs or any other combination where usage rate x hours = 7.
As a guide these are the kw of things you may have in your caravan:-
Battery Charger = 0.25 kw / 1000w heater = 1 kw / 2000w heater = 2 kw /
Caravan low wattage Kettle = 0.75 kw / Household Kettle = 3 kw / Fridge = 0.15 kw / Air Con Unit 1 kw / Microwave = 1.2 kw / T V = 0.06 kw
To work out our many kwh you used multiply the kw by how many hours you used it.
e.g. having the TV on has background noise from 0800 to midnight everyday = 0.06kw * 20 hours * 7 days = 8.4 kw
Boiling a household kettle 3 times a day at 5 minutes each time = 3kw * 1/4 hr * 7 = 5.25 kw
A moho fridge typically uses 3 kwh (0.15kw * 24 hrs =3kwh) every day. So your fridge alone used over 20 kwh during the week !
Unless you are under a heavy canvas (common on Spanish sites to provide shade) don't bother paying for mains just to charge the batteries.
We've just got back from 7 weeks over there with typically 5 -10 days at each site. We never used EHU, our 100w
solar kept the batteries charged.
We ran the fridge / hot water / cooking on gas and the TV (but not 20 hours a day) on 12v.