Batteries for Our Solar Power System
We have had a major renovation of the roof, with an installation of a 40-panel Solar Power system. There are still some corrections to be done by the installation company later this fall. We expect to convert some 13 MWh of solar energy to electricity per year. Some of my friends have asked me if I plan to save the energy for later usage. The short answer is "no - too expensive and too little storage capacity". Generally, it is cheaper to sell electricity to the power grid and buy when needed. Let's explore what it would mean to save energy and sell when it is more expensive: Normally, the productive hours are between 10:00 and 16:00. On a particular day (2021-09-16), the price fell to 1.35 SEK/kWh at 2 PM. If I stored 10 kWh (13.5 SEK) at that time, I would have 9 kWh in the battery, assuming 10% heat loss for the battery. Later that evening, the price increased to 1.95 SEK per kWh. When selling that energy to the grid, I would get 17.55 SEK. That would make me 4 SEK.