A solar combiner box typically costs between $100 and $1,000, with several factors influencing this range, including the box's capacity, features, and manufacturer. Check each product page for other buying options. Hardcover Solar Combiner Box with 4 Strings, 80 A Circuit Breakers. This pv Combiner Box is Suitable for Off-Grid Solar Power High-Power Version Need help?Have you ever wondered why the price of solar combiner box can differ so much? You might see one model that costs twice as much as another. From robust constructions to user-friendly. If you have more than two solar panels, chances are you need a combiner box. It's the central hub that takes multiple PV source circuits and combines them into a single circuit – saving you wire, conduit, and headaches.