Tandem unvented cylinder configuration

[Glenn1863]

Any thoughts on this installation I have been asked to look at? 2 direct unvented HW cylinders, both have 2 immersion heaters, one has solar heated coil in addition. Cylinder with solar is fed by standard means of mains water through combination valve with expansion vessel. Outlet goes to the combination valve to feed the other cylinder. Secondary hot return comes back into this combination valve but into the balanced cold outlet. There is an anti-stratification pump but only on the 2nd cylinder without the solar. This is an unusual layout to me but would appreciate any second opinions. Please let me know if more detail is required. Thanks.