Photoelectrochemistry of the dye-sensitization of oxide semiconductors, based on technology of silver halide photographic materials, has started late 1960's and evolved to realise utility-type photovoltaic (PV) modules that compete with thin-layer silicon PVs. Organic PVs, now being aggressively studied, are coming to combine dye-sensitised mesoporous layer to develop hybrid PVs. Flexible plastic dye-sensitized solar cell (P-DSC) proved itself to be a cost effective device for industries of consumer electronics with environmental recyclability. In order for an energy device to capture consumer's market, it should have high credibility in minimising process cost. We are focused on developing extremely low-cost power source and storage device of fairly high durability by eliminating high-temperature & vacuum preparation processes. This challenge leads to partial replacement of heavily consumed batteries of high environmental load with solar energy. We recently showed several routes to realizing easy-to-make P-DSCs, which reached a highest power efficiency of 7%. Large lightweight P-DSC modules proved to be sensitive to weak diffused light, indicating advantage for indoor and ubiquitous application. Electrochemistry and use of ionic electrolytes show various possibilities toward solidification of the cell and endowing charge (storage)-discharge ability for solar cell (design of photo-capacitor). Current experiments in our laboratory are to be introduced.