Polymer solar cells are considered as very promising candidates for development of photovoltaics of the future. They are cheap and easy to fabricate, however, up to now, they possess fundamental drawback: low effectiveness. In the most popular BHJ (bulk heterojunction) architecture the actual long-standing top effciency is about 12%. One ask the question how fundamental this limitation is, as certain theoretical considerations suggest that it should be two times higher. We describe our simulations on possible influence of so called 'geometric factor' on total efficiency, sketch possible influence of some other factors, and argue that limitations of BHJ architecture are inevitable. We speculate also on perspectives of development of organic solar cells using other ideas.