A solar photovoltaic cell (10,110) comprising: a substrate (12, 112) having a first (12a, 112a) and a second (12b, 112b) substantially planar face; a series of grooves (14, 114) in the first substantially planar face (12a, 112a); wherein each groove of the series of grooves (14, 114) has a first and a second face, the first face of each groove is coated with a semiconductor material so that the semiconductor material coats from 20 to 80% of the first face, and the second face of each groove is coated with a conductor material so that the conductor material coats from 20 to 80% of the second face; wherein the semiconductor material and the conductor material are in contact with another semiconductor material at least partially filling each groove such that within each groove a junction is formed between the semiconductor and the another semiconductor materials; characterized in that the solar photovoltaic cell (10, 110) further comprises a first (16a,116a) and a second (16b, 116b) electrical conductor on the second substantially planar face (12b, 112b); wherein a first face of the first electrical conductor (16a, 116a) and a first face of the second electrical conductor (16b, 116b) reflect light that has passed into the surrounding substrate back through the junction between the semiconductor and the another semiconductor materials, so as to generate electrical energy; and wherein the solar photovoltaic cell (10,110) further comprises a first outer electrical conductor (19a, 119a) spaced from the first and second electrical conductors (16a, 116a, 16b, 116b) by a layer of capacitor material (18, 118) or a layer of supercapacitor material. a substrate (12, 112) having a first (12a, 112a) and a second (12b, 112b) substantially planar face; a series of grooves (14, 114) in the first substantially planar face (12a, 112a); wherein each groove of the series of grooves (14, 114) has a first and a second face, the first face of each groove is coated with a semiconductor material so that the semiconductor material coats from 20 to 80% of the first face, and the second face of each groove is coated with a conductor material so that the conductor material coats from 20 to 80% of the second face; wherein the semiconductor material and the conductor material are in contact with another semiconductor material at least partially filling each groove such that within each groove a junction is formed between the semiconductor and the another semiconductor materials; characterized in that the solar photovoltaic cell (10, 110) further comprises a first (16a,116a) and a second (16b, 116b) electrical conductor on the second substantially planar face (12b, 112b); wherein a first face of the first electrical conductor (16a, 116a) and a first face of the second electrical conductor (16b, 116b) reflect light that has passed into the surrounding substrate back through the junction between the semiconductor and the another semiconductor materials, so as to generate electrical energy; and wherein the solar photovoltaic cell (10,110) further comprises a first outer electrical conductor (19a, 119a) spaced from the first and second electrical conductors (16a, 116a, 16b, 116b) by a layer of capacitor material (18, 118) or a layer of supercapacitor material.