UK's Specflue has developed a common thermal storage unit that can accept inputs from solar, fire(wood stove or pellet), boiler, backup heat source and then act as a single point source for distribution.
http://specflue.com/catalogue/product/thermal-store#
![[Hearth.com] Thermal storage unit [Hearth.com] Thermal storage unit](https://www.hearth.com/talk/data/attachments/178/178659-6412bafc580eea70b63d391de3a93e6f.jpg?hash=q31T1kkvEi)
http://specflue.com/catalogue/product/thermal-store#
![[Hearth.com] Thermal storage unit [Hearth.com] Thermal storage unit](https://www.hearth.com/talk/data/attachments/178/178659-6412bafc580eea70b63d391de3a93e6f.jpg?hash=q31T1kkvEi)