To make it simple, a solar heat plant heats up water (or another fluid) by the radiance of sunlight. This energy can be stored either in a tank or it can be passed on directly to a process by a heat exchanger.

Ideally, a solar heat plant heats up water to approx. 95°C. Processes that require warm water can be supplied directly by a heat exchanger. In Processes that require steam, e.g. for softening bentwood, this water can be fed into a steam generator. It is then not needed anymore to heat up the water from supply temperature up to steam temperature.

Example:

Feeder water has to be heated up from supply temperature 10°C to steam temperature of 110°C. When heating up this water directly in a steam boiler, the required energy is to heat up this amount of water for 100K (consumption of electricity or fuels). When using a solar process heat plant, that feeder water is first heated up from 10°C to 95°C in the solar heat plant for 85K and then fed into the steam boiler, where it has just to be heated up from 95°C to 110°C for another 15K. In this way, 85% of the energy can be saved easily by a solar process heat plant.