In Down and Out in Paris and London, Orwell doesn't present a specific solution to the Depression. He sees the poverty of the 1930s not as if it were an aberration (as it was generally seen in the US), but simply a continuation or intensified form of what has always taken place throughout history: the exploitation of the working class by the rich. That said, Orwell was not a Communist and apparently never endorsed a violent revolution as a means of solving this problem.
Orwell deliberately placed himself in situations where, though he was of upper-middle-class background himself, he could act as a poor person and experience as closely as possible the situations in which the working poor found themselves. In all his books, he implies that "democratic socialism" is the ideal scheme that will supersede capitalism, but he never says how this will come about. Despite being anti-capitalist, Orwell is in some sense like his idol Dickens, who (Orwell says) "nowhere argues for a change in the existing system... but simply says that if people will behave decently to each other, the world will be decent." In Down and Out, Orwell implies that even those with good intentions are misguided in the way they deal with the poor. He observes, for instance, that people in general resent their benefactors, that people who are down and out really do not appreciate charity. In London, the system of taking care of homeless people is basically described as dysfunctional. In the shelters, the men are constantly coughing and yelling inarticulately (like the one Orwell describes as shouting "Pip!" for no apparent reason every couple of minutes). Earlier, in Part I of the book, the conditions in the kitchen of an upscale Paris restaurant are dirty and disgusting. Here the implication is that the management are thumbing their noses behind their backs at the rich patrons who dine there. It is another example of the lack of general decency in a society in which everyone is involved in a rat race to earn money. The extreme disparity between the lifestyle of the wealthy and that of the working poor—the economic polarization of Western Society—is thus the basis of the whole problem.
It would have been too easy, too pat, for Orwell to have proposed an explicit list of "solutions." Yet most of his writings from the 1930s were devoted to describing the unfair conditions of life for the majority of the European population. In The Road to Wigan Pier the subject is the coal mines in the north country, something most Londoners could not even imagine. In Homage to Catalonia it is the effects of a devastating civil war. In Keep the Aspidistra Flying the topic is the spiritual impoverishment a young writer experiences because he has refused to submit to or become a part of the money culture. Orwell is mostly preaching to the choir, and it's doubtful that his books would sway people not already politically on the left. But his implied answer—apart from the obvious one that socialism is the ideal system—is, again like that of Dickens, that if people will simply behave better to each other, the world will be a better, more decent place in which to live.