The power bank that charges on solar energy is amazing in itself, but the problem you are talking about is that it is not charging on solar and it barely charges your phone from zero percent to 70 percent. So you need to show it to a good electrician so that he can fix whatever problem is causing it. I also want to buy a power bank like this that charges without electricity, that is, charges with sunlight and has a good backup. During the night, when there is no light, I can charge my mobile through this power bank. Tell me about its price and how much it cost you.