Which solar combiner box belongs in your balance-of-system? The choice often comes down to two layouts: a 4-string 63A model and a 2-in/2-out 20A model. Both are new and use ABS/PC enclosures, but their input counts, breaker ratings, and surge protection point to different array sizes and current demands.
Quick verdict
For a multi-string array that needs one high-capacity output, the 4-String 63A Solar Combiner Box is the straightforward pick. For a setup where per-string current needs are higher and you want a box with layered circuit protection in one enclosure, the 2-in/2-Out 20A PV Combiner Box brings more integrated protection.
Comparison at a glance
| Feature | 4-String 63A Combiner | 2-in/2-Out 20A Combiner |
|---|---|---|
| Listed price | $62.54 | $125.82 |
| Input strings | 4 | 2 |
| Per-string fuse | 10A rated | 20A |
| Circuit breaker | 63A, 550V | 20A DC500V |
| Surge protection | 2 SPDs plus lightning arrester | DC500V 40kA Class T2 SPD |
| Enclosure material | ABS and PC | ABS and PC |
| Condition | New | New |
Where each product wins
The 4-String 63A Solar Combiner Box is the choice when your array needs more inputs combined into a single heavy-duty output. The 2-in/2-Out 20A PV Combiner Box is the choice when every input needs more generous current handling and you value a fully integrated protection package.
Product notes
4-String 63A Solar Combiner Box
This combiner takes in four PV strings, each protected by a 10A rated fuse, and funnels them to a 550V 63A circuit breaker. A high-voltage lightning arrester and two surge protection devices cover surge defense. The ABS and PC housing is impact- and corrosion-resistant, with natural cooling. At $62.54, it is the less expensive way to combine multiple panel strings, and the 63A breaker provides a higher output current ceiling than the 20A breaker on the other box. The tradeoff is the per-string fuse rating: at 10A per string, it suits panels that stay below that current. If your panels exceed 10A per string, the 2-in/2-out 20A model's per-string capacity is a better match.
2-in/2-Out 20A PV Combiner Box
This box is built around a 2-in/2-out layout: two PV panel inputs feed two output circuits, with each string capped at 20A and a 20A DC circuit breaker on the output. A triple protection scheme brings together a 20A DC500V miniature circuit breaker, a DC500V 40kA Class T2 surge protective device, and a 20A DC500V fuse, so overvoltage, overload, and short-circuit risks are addressed in one enclosure. Support goes up to 20kW in a 500V system. The enclosure is ABS and polycarbonate. Choose it when your panel strings stay at or under 20A and you want a single box that bundles MCB, SPD, and fuse protection. The flip side is that you get two input strings, and the $125.82 price is roughly double the four-string model's.
Final choice by use case
For a multi-string array with panels that produce modest per-string current and a desire to keep spend down, go with the 4-String 63A Solar Combiner Box. For a two-input setup with higher per-string current-or a preference for having circuit breaker, surge protector, and fuse in a single enclosure-the 2-in/2-Out 20A PV Combiner Box is the better buy.
