Problems do not buy solutions, people do.
Whether your solution is needed by individuals, companies, non-profit organizations, or the government, some person will ultimately decide whether your product is worth buying, or not. It is imperative to understand who that person is, because they are your potential customer.
Whose problem I am solving?
Who is this person? What is his or her role in their organization? Is this problem important to them? Do they know this problem exists? Do they already have a solution to this problem? If they want your product, do they have the authority and budget to buy your product?
Bird Watch—[Whose problem?]: Animal psychologists, wildlife conservationists, and others who research wildlife need a better/faster/cheaper solution for monitoring wildlife. Ranchers and farmers might have similar needs to track their livestock. Looking at tagging humans, retailers may have analogous problems tracking the behaviors of shoppers in their stores. Urban planners, too, might want to track the flow of people around cities.
Concrete Battery—[Whose problem?]: Wind and solar manufacturers could use ways to provide a continuous and steady supply of electricity from their installations. The product managers at these companies would be the best people to talk to about this issue. Electricity providers may want to install centralized or distributed storage “farms” to balance the alternative energy production across their electric grids. The buyers of alternative energy at the electric companies would know if this is a problem.
Close to Home—[Whose problem?]: Survivors of natural disasters whose houses are unlivable need somewhere to stay. For large-scale natural disasters, there are often not enough hotel rooms, vacant apartments, and available home rentals within the affected community. And even when the hotels exist, most survivors do not want to live in a hotel for the twelve to twenty-four months it typically takes to rebuild a home after it has been destroyed.
Ensibuuko—[Whose problem?]: Rural farmers, the majority of the population of East Africa, share the problem. We could call this group poor rural farmers, but that would be redundant. These are often subsistence farmers who generate a small surplus of produce they sell in their local markets. It is a population who has the knowledge of farming and access to land but insufficient access to capital to maximize the output from that land.
In the case of Bird Watch, the animal psychology teams tend to be small, and thus it would be obvious who within those teams would know about the problem and could provide you with feedback.
For Close to Home, the problem is shared not only by individuals but often by whole families and, when a large-scale disaster hits, by whole communities all on the same day.
In the case of Concrete Battery, the two potential types of customers are actually very large organizations, and it would take further research to determine the organizational structures and associated job titles and roles of the people who would be aware of the problem.
For Ensibuuko, the problem is shared by the majority of the population of whole countries. Tens of millions of people in East Africa.
Note again, like before, these examples focus only on the people and problem, without even a hint of a solution. To best understand the opportunity, focus first on the problem and people involved. Once these are clear, you can return to your solution with confidence.