When using ssrs with a rapid switching frequency as employed by pid algorithms be mindful that they require a large heatsink to dissipate the heat that the rapid switching will generate. and if enclosed within a box vents and fans are a must. the 25a ssr used to switch the 3kw lwd elements in my brew kettle and hlt can hit 70c+ half way down the central vain of its heatsink during a 90 minute mash cycle maintaining 67C.
really over spec the ssr too I use 25a rated ssrs for my 3.5kw, 3kw and 2,4kw heating elements but i could have easily opted for 40a options
Also for connecting hi amp draw wires for an array of inductive heating elements and there is a real likelyhood of the wires getting hot its probably a good idea to consider using a ceramic terminal block to make the connections. the usual lego brick style of connector can easily heat up to the point that its insulation simply melts away when used with hi amp draw heating elements.
https://www.ebay.co.uk/itm/Ceramic-main ... ed08bd2f82
just an example quickly pulled from ebay NOT a recommendation of the seller..