Thank you, both of you. The calculations are difficult but I have a lot of parts in the basement, parts I actually have no other use for so this will not be a fair calculation. To get confirmed that a SSR is good, for this is a positive feedback for the possibility to use a smaller cabinet. My main concern is to not increase the risk of failure. This setup will result in longer periods of full load, and if we have a weak point, that may be a risk of fire.
Our codes has been changed due to observations of hot connections, the old 16Amp (schuko) are not allowed for continuous loads as 2 kW water heaters in new buildings. In my house, this has worked for 30 years with no problems, putting in this modification, it will probably be vise to change that to a CEE 17 system, this is also used in USA. http://internationalconfig.com/prod_shot/888-2126-NS.jpg
I remember those from the building of the Oakland bay bridge project. The only US job I ever has been involved in.