NOVELTY - Apparatus for storing sunlight-derived energy and providing electrical power comprises: (a) a container structure; (b) an aqueous catholyte; (c) photosynthetic organisms; (d) an anolyte; (e) a semi-permeable barrier; (f) a cathode electrode; (g) a first electrical conductor; (h) an anode electrode; and (i) a second electrical conductor.    USE - The apparatus is useful for storing sunlight-derived energy and providing electrical power (claimed).    ADVANTAGE - The apparatus provides a photosynthetically replenished microbial solar cell with the capability of electrical power generation during light and dark periods.    DETAILED DESCRIPTION - Apparatus for storing sunlight-derived energy and providing electrical power comprises: (a) a container structure comprising: (i) at least one wall defining an interior including a first interior portion, and a second interior portion, the wall including a transparent or translucent portion allowing external light to enter the first interior portion; and (ii) first and second electrical connectors mounted to the wall and electrically coupled to an external circuit; (b) an aqueous catholyte in the first interior portion; (c) photosynthetic organisms within the catholyte in the first interior portion; (d) an anolyte in the second interior portion; (e) a semi-permeable barrier separating the catholyte from the anolyte; (f) a cathode electrode within the catholyte in the first interior portion; (g) a first electrical conductor coupled between the cathode electrode and the first electrical connector; (h) an anode electrode within the anolyte in the second interior portion; and (i) a second electrical conductor coupled between the anode electrode and the second electrical connector. INDEPENDENT CLAIMS are included for:    (1) a method of storing sunlight-derived energy and providing electrical power comprising: (a) reducing an oxidant of a catholyte to remove electrons from a cathode electrode and to generate a cathode by-product; (b) oxidizing a reductant of an anolyte to transfer electrons to an anode electrode and to generate an anode by-product; (c) conducting electrons as electrical current from the anode electrode through an external circuit to the cathode electrode; (d) transferring ions between the anode electrode and the cathode electrode via a semi-permeable barrier to maintain charge balance; and (e) exposing photosynthetic organisms in the catholyte to light to regenerate the reductant and the oxidant using the anode by-product and the cathode by-product; and    (2) a microbial solar cell comprising: (a) a sealed container; (b) a microbial fuel cell with a cathode electrode within a catholyte in a first interior portion of the container, an anode electrode within an anolyte in a second interior portion of the container, and electrical conductors electrically coupling the electrodes to an external load outside the container; and (c) photosynthetic organisms within the first interior portion of the container generating reactants of the microbial fuel cell and the products of the microbial fuel cell from sunlight.    DESCRIPTION OF DRAWING(S) - The drawing shows a side elevation view of the apparatus.    Container (110)    Aqueous catholyte (120)    Photosynthetic organisms (130)    Anolyte (140)    Semi-permeable barrier (150)    Cathode electrode (160)    First electrical conductor (162)    Anode electrode (170)    Second electrical conductor (172)