Selective coating for solar panels

• US 4,055,707 A
• Filed: 12/22/1975
• Issued: 10/25/1977
• Est. Priority Date: 12/22/1975
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: McDonald, Glen E.
• Primary Examiner(s): Hoffman, James R.
• Application Number:
  US05/643,041
• Time in Patent Office: 673 Days
• Field of Search: 126/270, 126/271, 350/1, 427/162, 427/160, 428/652, 428/667, 428/679
• US Class Current: 428/652
• CPC Class Codes: F24S 70/225 for spectrally selective absorption
• CPC Class Codes: F24S 70/25 Coatings made of metallic material
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y10S 126/908 Particular chemical
• CPC Class Codes: Y10S 205/923 Solar collector or absorber
• CPC Class Codes: Y10T 428/1275 Next to Group VIII or IB metal-base component
• CPC Class Codes: Y10T 428/12854 Next to Co-, Fe-, or Ni-base component
• CPC Class Codes: Y10T 428/12937 Co- or Ni-base component next to Fe-base component

Abstract

The energy absorbing properties of solar heating panels are improved by depositing a black chrome coating of controlled thickness on a specially prepared surface of a metal substrate. The surface is prepared by depositing a dull nickel on the substrate, and the black chrome is plated on this low emittance surface to a thickness between 0.5 micron and 2.5 microns.

Claims

1. In apparatus for collecting solar energy of the type having a composite heating panel for absorbing said solar energy and converting the same to heat, the improvement comprising

a metallic substrate forming a high conductivity base for said panel, said substrate having at least one surface exposed to said solar energy,

a layer of dull nickel on said one surface to lower the emissivity of said surface, and

a coating of black chrome on said layer of dull nickel, said coating having a thickness between about 0.5 micron and about 2.5 microns and being highly absorbtive in the visible range.

2. Apparatus as claimed in claim 1 wherein the substrate is steel.

3. Apparatus as claimed in claim 1 wherein the substrate is aluminum.

4. Apparatus as claimed in claim 1 wherein the layer of dull nickel has a thickness of about 0.0005 inch.

5. A method of making a composite heating panel for a solar collector comprising the steps of

depositing a layer of dull nickel to a thickness of about 0.0005 inch on a surface of a high thermal conductivity substrate to lower the emissivity thereof, and

coating said layer of dull nickel with black chrome to a thickness between about 0.5 micron and about 2.5 microns to raise the absorbtivity of said surface in the visible range.

6. A method of making a composite heating panel as claimed in claim 5 wherein the surface of the substrate is roughened.

7. A method of making a composite heating panel as claimed in claim 6 wherein the substrate surface is roughened by physical abrasion.

8. A method of making a composite heating panel as claimed in claim 7 wherein the substrate surface is grit blasted to a roughness of between about 0.75 μ

m and about 25μ

m.