Google intelligible did not answer, here, too, found nothing, so turn to Habra-community:
On the Internet in large quantities sold solar batteries for the laptop, for the price of 3 for 10 + kilorubley.
I have a friend who wants to go camping (for 3 days or more) and wants to sit with a laptop.
Actually a question: how these batteries can charge the laptop and what it is worth/not worth taking. Personal experience in the matter is welcome.
PS: If you need any details please ask, I will specify)).