It's more of a cost than an efficiency equation. The efficiency only matters in the sense that it drives up the cost because you'd need more equipment to produc

It's more of a cost than an efficiency equation. The efficiency only matters in the sense that it drives up the cost because you'd need more equipment to produce hydrogen. The equipment is fixed cost investment. So, the longer it runs, the more fuel it will produce. Using stored energy to produce light to produce energy does not make a whole lot of sense. It's a very lossy process. If you have stored energy, maybe just use it directly?