Dear T-Sole.
Thank you for your reply.
1- A1 or A2 in all system i find electricity saving even in swimming pools not just in DHW .
2-The additional heating heater for DHW or pool is electrical.
i am talking in general ,every report i find electricity saving more that solar contribution, it almost more than the solar contribution around 20%.
Based on your justification above due to the efficiency of the electrical heater ,i think electricity saving 20 % still is more than the losses and efficiency difference between solar contribution and electricity saving.