Sandwich structure unit for solar collector mirrors

Solar panel mirror unit being shaped and having a sandwich structure, said sandwich structure comprising the following material layers:

• an outermost front reflecting layer, intended as the sun reflecting layer and therefore having a reflective coating, said outermost front reflecting layer consisting of a first material having a first thermal expansion coefficient;
• an intermediate layer having a honeycomb structure and being the core of the sandwich structure, wherein the thickness of the honeycomb structure does not exceed 50 mm;
• and
• an innermost rear layer consisting of a second material having a second thermal expansion coefficient;
• wherein the solar panel mirror exhibits a symmetrical cross section in relation to layer materials on both sides of the intermediate layer,
• wherein said first and second thermal expansion coefficients are equal or substantially equal, and wherein the average solar reflectivity is at least 90%.