Micro CoGen.

I used the wrong word technically, should have said load the panels voltage down to  battery voltage + (drop through fets in the controller) .3 from memory in a the c60. I stand  corrected

"Only a pv charge controller that is chosen for a higher voltage input and 12 v battery output will do this- lead acid batteries don't ''clamp'' anything, they would just go over voltage and start generating hydrogen and oxygen gas like crazy before self destructing"

Both those units have specs that greatly exceed the voltage from any 24 volt panel I have ever seen, those are the only two I mentioned as while I am sure there are many others, those are models in existing systems charging 12 volt banks with 24 volt panels,that I know work. I never recommended doing this without a controller so "generating hydrogen and oxygen like crazy before self destructing" is not a issue. Duel fuel mentioned the C60 so I thought maybe he has one already, and with free panels thought he could be up and charging without further cost. Without further cost is always good

I may not be understanding what you are saying but I had the same situation where my system is 12 volts as built years ago then when the price of panels fell a couple years back I just bought another xantrex c60 (non mppt) and hooked up 8 24volt panels (225 watt panels). Its been working perfect for the last couple years. Am I getting the most out of my panels?...no, but I keep the most (money) in my pocket because a mppt that would handle 1800watts of panels would have cost me more than all the panels did. Works for me. The batts will clamp your 24 volt panels to 12 volt you don't need anything else (other than a c60 or a tristar works too)