What caused this burn out?

[Refugee]

The solar panels do not have a laminated transformer. They have a 10Khz one that whines like a 405 line TV set with a 100hz ripple on it.
They just modulate the chopper unit to reconstruct the 50hz sine wave. I presume it is filtered to some extent.

[boater sam]

The power distribution guys take some inspired guesses sometimes in the name of expediancy,
A case in point many years past now.
We were involved in building a sauna into a very swish new property at a desirable Cheshire location.
Total connected single phase load 15 or 12.5 kW depending on sauna element arrangement.
We ran 25mm SWA from the garage incomer 30m through the garden, buried.
New sub board and switch at the meter position.
Board arrived and connected to meter, all proper, no cowboy own connections. 100 amp meter.
On switching the sauna on the mains practically disappeared!
The feed to the head was a bit of concentric.
Board man pronounced feed inadequate but was not surprised. He remembered that the site had been occupied by one old house, probably an 80 amp max feed. They had spliced the 4 new 100 amp feeds for 4 upmarket properties  onto this existing old spiral wrapped cable.
I bet these houses have a good few kw of solar power going down that same old cable now.

[Refugee]

Does that mean that saunas blow there feeders in winter them?
Did it go with a nice big bang like the solar panels did?

[boater sam]

No, but all the fluorescent lights went out and restruck!
We had to reduce the loading on the heater, it doubled the heat up time unfortunately.

As far as I know, the cables have not been changed...........

We also had a client with a 3 phase pool heater, 39 kW total load.
If we had run the supply cables through the water we could have recovered some of the wasted power. The electricity board paid towards us converting it to gas fired as they got sick of coming out to replace the company fuses. The underground cables eventually failed an insulation test, I believe in winter the patio used to steam where the cables were buried.

[Murphyv310]

Ah just get two big metal plates and submerge them in the water and connect to the mains...... Don't forget to switch off before jumping in

[Refugee]

Ah just get two big metal plates and submerge them in the water and connect to the mains...... Don't forget to switch off before jumping in      

Is that not the way they make "fake dirt" in those foot spas that are for ever advertised in newspapers.
The electrolytic corrosion makes the water "dirty" and the redundancy is that the electrodes run out of metal so that the thing stops "working"?