The technical meaning of outsourcing is "obtaining services from other companies or individuals rather than employing full-time members of staff to provide them." (See BBC, Learning English, General & Business English [→])
However, if we admit that panels are goods¹, strictly speaking, we could say "Company A outsources panels from company B" only if "A" can produce panel by itself; that is, "A" has the necessary know-how to produce panel, but choose to outsource because of the advantages it offers as compared to the traditional process of production. If not, we might say "Company A buys panels from company B".
¹ Oxford Dictionary of English | outsource: "obtain (goods or a service) by contract from an outside supplier."