Proudly shipping to·Accra, Ghana·Acton, MA·Adams, MA·Agawam, MA·Albany, NY·Amherst, NH·Ashburnham, MA·Ashland, MA·Athol, MA·Atlanta, GA·Attleboro, MA·Auburn, CA·Auburn, IN·Ayer, MA·Aztec, NM·Barrington, NH·Baton Rouge, LA·Bear Lake, MI·Becker, MN·Bedford, MA·Bedford, NH·Bellingham, MA·Bessemer, AL·Bethel, VT·Beverly, MA·Billerica, MA·Birdsboro, PA·Bisbee, AZ·Bolton, MA·Boston, MA·Boulder, CO·Bound Brook, NJ·Boxborough, MA·Braintree, MA·Branford, CT·Brattleboro, VT·Brenham, TX·Brentwood, CA·Bridgewater, ME·Brighton, MI·Bristol, ME·Bristol, RI·Brooklyn, NY·Brunswick, ME·Bryceville, FL·Bumpass, VA·Burlington, MA·Burlington, ME·Buxton, ME·Carlisle, MA·Carver, MA·Cary, NC·Cedar Park, TX·Chebeague Island, ME·Chelmsford, MA·Chelsea, MI·Chesapeake, VA·Chicago, IL·Chico, CA·Cincinnati, OH·Clinton, IL·Clover, SC·Cocoa Beach, FL·Cohoes, NY·Colchester, VT·College Park, MD·Colorado Springs, CO·Concord, MA·Concord, NH·Cortez, CO·Dakota City, NE·Dallas, TX·Davie, FL·Daytona Beach, FL·Derry, NH·Detroit, MI·Dorchester, MA·Dover Foxcroft, ME·Dracut, MA·Dry Ridge, KY·Dublin, NH·Durango, CO·Duxbury, MA·Eagle River, AK·Eden, VT·El Dorado Hills, CA·El Paso, TX·Ellijay, GA·Ellettsville, IN·Elk Grove Village, IL·Elkton, MD·Emmaus, PA·Enfield, CT·Englewood, OH·Erving, MA·Everett, MA·Fairmont, WV·Farmington, ME·Farmington, NM·Fitchburg, MA·Fitzwilliam, NH·Fort Myers, FL·Fort Worth, TX·Franklin, MA·Frederiksted, USVI·Freedom, NH·Gaffney, SC·Georgetown, TX·Girard, PA·Gloucester, MA·Grand Rapids, MI·Greensboro, NC·Greenfield, MA·Groton, CT·Groton, VT·Guaynabo, PR·Hamden, CT·Hampstead, NH·Hancock, MI·Hancock, NH·Harding, PA·Hartford, CT·Harvard, MA·Heber City, UT·Helena, MT·Hemet, CA·Henrico, VA·Herndon, VA·High Point, NC·Holyoke, MA·Hopkinton, MA·Houghton, MI·Houlton, ME·Houston, TX·Huntsville, UT·Hutchinson, KS·Istanbul, Turkey·Ithaca, NY·Jersey City, NJ·Kahului, HI·Kingman, AZ·Lake Mary, FL·Lancaster, PA·Larez, PR·Laurel, MD·Lebanon, NH·Leominster, MA·Lincoln, MA·Lincoln, NH·Long Island City, NY·Lorton, VA·Los Gatos, CA·Louisville, CO·Lynnfield, MA·Madison, VA·Manchester, ME·Manchester, NH·Manchester, TN·Manistee, MI·Marietta, OH·Marion, SC·Marlborough, MA·Marquette, MI·Marshall, NC·Marshfield, MA·Maynard, MA·Medford, MA·Medford, OK·Melbourne, FL·Metairie, LA·Miami, FL·Middletown, DE·Montego Bay, Jamaica·Monticello, KY·Monticello, ME·Moretown, VT·Moriarty, NM·Moss Town, The Bahamas·Mountain View, CA·Nashua, NH·Nevada City, CA·New London, CT·New Orleans, LA·North Bergen, NJ·North Conway, NH·Northborough, MA·Northfield, VT·Oberlin, OH·Odon, IN·Ogden, UT·Ojai, CA·Oklahoma City, OK·Orlando, FL·Oswego, IL·Paauilo, HI·Panama City, FL·Parker, CO·Payson, AZ·Penn Laird, VA·Pepperell, MA·Petersham, MA·Pewaukee, WI·Philadelphia, PA·Pickens, SC·Pinson, TN·Pomfret, CT·Ponce, PR·Port Wing, WI·Portland, ME·Princeton, MA·Providence, RI·Queens, NY·Raleigh, NC·Readstown, WI·Redwood City, CA·Rochester, VT·Rockaway, NJ·Rockford, MI·Rockland, ME·Roseburg, AK·Round Rock, TX·Rowlett, TX·Salisbury, CT·San Juan, Puerto Rico·San Luis Obispo, CA·San Marcos, CA·San Tan Valley, AZ·Savannah, GA·Scarborough, ME·Searsport, ME·Sebastopol, CA·Shirley, MA·Silvana, WA·Simi Valley, CA·Smithfield, RI·Smithfield, UT·Smyrna, GA·South Londonderry, VT·Sparta, NJ·Spring Creek, NV·Springfield, VT·St. Petersburg, FL·Stoddard, NH·Sun City West, AZ·Swanzey, NH·Tampa, FL·Temple, NH·Titusville, FL·Tonasket, WA·Vega Baja, PR·Wakefield, MA·Waterbury Center, VT·Watertown, MA·Waupaca, WI·Wauseon, OH·Webster, MA·West Hartford, CT·West Hempstead, NY·West Palm Beach, FL·Westborough, MA·Westford, MA·Weston, MA·Willits, CA·Willington, CT·Wilmington, MA·Winchendon, MA·Winchester, MA·Windham, NH·Winston Salem, NC·Wolcott, VT·Woodstock, CT·Worcester, MA·Williamstown, VT·Charlotte, NC·Yarmouth, ME·and more across 49 states and worldwideProudly shipping to·Accra, Ghana·Acton, MA·Adams, MA·Agawam, MA·Albany, NY·Amherst, NH·Ashburnham, MA·Ashland, MA·Athol, MA·Atlanta, GA·Attleboro, MA·Auburn, CA·Auburn, IN·Ayer, MA·Aztec, NM·Barrington, NH·Baton Rouge, LA·Bear Lake, MI·Becker, MN·Bedford, MA·Bedford, NH·Bellingham, MA·Bessemer, AL·Bethel, VT·Beverly, MA·Billerica, MA·Birdsboro, PA·Bisbee, AZ·Bolton, MA·Boston, MA·Boulder, CO·Bound Brook, NJ·Boxborough, MA·Braintree, MA·Branford, CT·Brattleboro, VT·Brenham, TX·Brentwood, CA·Bridgewater, ME·Brighton, MI·Bristol, ME·Bristol, RI·Brooklyn, NY·Brunswick, ME·Bryceville, FL·Bumpass, VA·Burlington, MA·Burlington, ME·Buxton, ME·Carlisle, MA·Carver, MA·Cary, NC·Cedar Park, TX·Chebeague Island, ME·Chelmsford, MA·Chelsea, MI·Chesapeake, VA·Chicago, IL·Chico, CA·Cincinnati, OH·Clinton, IL·Clover, SC·Cocoa Beach, FL·Cohoes, NY·Colchester, VT·College Park, MD·Colorado Springs, CO·Concord, MA·Concord, NH·Cortez, CO·Dakota City, NE·Dallas, TX·Davie, FL·Daytona Beach, FL·Derry, NH·Detroit, MI·Dorchester, MA·Dover Foxcroft, ME·Dracut, MA·Dry Ridge, KY·Dublin, NH·Durango, CO·Duxbury, MA·Eagle River, AK·Eden, VT·El Dorado Hills, CA·El Paso, TX·Ellijay, GA·Ellettsville, IN·Elk Grove Village, IL·Elkton, MD·Emmaus, PA·Enfield, CT·Englewood, OH·Erving, MA·Everett, MA·Fairmont, WV·Farmington, ME·Farmington, NM·Fitchburg, MA·Fitzwilliam, NH·Fort Myers, FL·Fort Worth, TX·Franklin, MA·Frederiksted, USVI·Freedom, NH·Gaffney, SC·Georgetown, TX·Girard, PA·Gloucester, MA·Grand Rapids, MI·Greensboro, NC·Greenfield, MA·Groton, CT·Groton, VT·Guaynabo, PR·Hamden, CT·Hampstead, NH·Hancock, MI·Hancock, NH·Harding, PA·Hartford, CT·Harvard, MA·Heber City, UT·Helena, MT·Hemet, CA·Henrico, VA·Herndon, VA·High Point, NC·Holyoke, MA·Hopkinton, MA·Houghton, MI·Houlton, ME·Houston, TX·Huntsville, UT·Hutchinson, KS·Istanbul, Turkey·Ithaca, NY·Jersey City, NJ·Kahului, HI·Kingman, AZ·Lake Mary, FL·Lancaster, PA·Larez, PR·Laurel, MD·Lebanon, NH·Leominster, MA·Lincoln, MA·Lincoln, NH·Long Island City, NY·Lorton, VA·Los Gatos, CA·Louisville, CO·Lynnfield, MA·Madison, VA·Manchester, ME·Manchester, NH·Manchester, TN·Manistee, MI·Marietta, OH·Marion, SC·Marlborough, MA·Marquette, MI·Marshall, NC·Marshfield, MA·Maynard, MA·Medford, MA·Medford, OK·Melbourne, FL·Metairie, LA·Miami, FL·Middletown, DE·Montego Bay, Jamaica·Monticello, KY·Monticello, ME·Moretown, VT·Moriarty, NM·Moss Town, The Bahamas·Mountain View, CA·Nashua, NH·Nevada City, CA·New London, CT·New Orleans, LA·North Bergen, NJ·North Conway, NH·Northborough, MA·Northfield, VT·Oberlin, OH·Odon, IN·Ogden, UT·Ojai, CA·Oklahoma City, OK·Orlando, FL·Oswego, IL·Paauilo, HI·Panama City, FL·Parker, CO·Payson, AZ·Penn Laird, VA·Pepperell, MA·Petersham, MA·Pewaukee, WI·Philadelphia, PA·Pickens, SC·Pinson, TN·Pomfret, CT·Ponce, PR·Port Wing, WI·Portland, ME·Princeton, MA·Providence, RI·Queens, NY·Raleigh, NC·Readstown, WI·Redwood City, CA·Rochester, VT·Rockaway, NJ·Rockford, MI·Rockland, ME·Roseburg, AK·Round Rock, TX·Rowlett, TX·Salisbury, CT·San Juan, Puerto Rico·San Luis Obispo, CA·San Marcos, CA·San Tan Valley, AZ·Savannah, GA·Scarborough, ME·Searsport, ME·Sebastopol, CA·Shirley, MA·Silvana, WA·Simi Valley, CA·Smithfield, RI·Smithfield, UT·Smyrna, GA·South Londonderry, VT·Sparta, NJ·Spring Creek, NV·Springfield, VT·St. Petersburg, FL·Stoddard, NH·Sun City West, AZ·Swanzey, NH·Tampa, FL·Temple, NH·Titusville, FL·Tonasket, WA·Vega Baja, PR·Wakefield, MA·Waterbury Center, VT·Watertown, MA·Waupaca, WI·Wauseon, OH·Webster, MA·West Hartford, CT·West Hempstead, NY·West Palm Beach, FL·Westborough, MA·Westford, MA·Weston, MA·Willits, CA·Willington, CT·Wilmington, MA·Winchendon, MA·Winchester, MA·Windham, NH·Winston Salem, NC·Wolcott, VT·Woodstock, CT·Worcester, MA·Williamstown, VT·Charlotte, NC·Yarmouth, ME·and more across 49 states and worldwide

Balance of System

Shop solar BOS components — PV wire, combiner boxes, DC disconnects, breakers, fuses, surge protection, and conduit. Wholesale pricing on NEC-compliant balance of system hardware for professional installers.

1/0 Busbar Cover

Products

1/0 Busbar Cover

SKU: MN1/0LBBC

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10/3 SEOOW Portable Cord, 600V UL/CSA, Power Cables

Products

10/3 SEOOW Portable Cord, 600V UL/CSA, Power Cables

SKU: SEOOW-CORD

$1.99
1000v 10mm X 38mm Fuses

Products

1000v 10mm X 38mm Fuses

SKU: MN1000FUSE-xx

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125VDC Panel Mount Breaker - 3/8" studs 1.5"

Products

125VDC Panel Mount Breaker - 3/8" studs 1.5"

SKU: MNEDC175250

$142.00
150VDC Panel Mount Breaker

Products

150VDC Panel Mount Breaker

SKU: MNEDC

$27.00
150VDC din rail mount breaker - non polarized

Products

150VDC din rail mount breaker - non polarized

SKU: MNEPVxx-150-1PNP

$26.00
16 Amp 600 VDC Din Rail mount breaker.

Products

16 Amp 600 VDC Din Rail mount breaker.

SKU: MNEPV16-600RT

$152.00
180 amp Busbar

Products

180 amp Busbar

SKU: MNTBB

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2/0 Busbar, Insulator And Cover with 5 Wire Locations

Products

2/0 Busbar, Insulator And Cover with 5 Wire Locations

SKU: MNTBB2

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2/0 Busbar, insulator and cover with 9 wire locations

Products

2/0 Busbar, insulator and cover with 9 wire locations

SKU: MNTBB2-9

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300 VDC panel mount breaker

Products

300 VDC panel mount breaker

SKU: MNEDC-300

$54.00
300A 75mV Shunt Resistor

Products

300A 75mV Shunt Resistor

SKU: SHUNT300A75MV

$9.99
300VDC Din Rail Mount Breaker, Single Pole, Polarized

Products

300VDC Din Rail Mount Breaker, Single Pole, Polarized

SKU: MNEPV##-300-1PP

$65.32
300VDC din rail mount breaker - Polarized

Products

300VDC din rail mount breaker - Polarized

SKU: MNEPV-300

$46.00
400amp Copper Bus Bar - 4x M10 Positive and 4x M10 Negative

Products

400amp Copper Bus Bar - 4x M10 Positive and 4x M10 Negative

SKU: BUSBAR400AMP8XM10RB

$49.95
50 amp 300VDC ground fault protector din rail mount

Products

50 amp 300VDC ground fault protector din rail mount

SKU: MNDC-GFP50-300

$153.00
600VDC din rail mount two pole breaker

Products

600VDC din rail mount two pole breaker

SKU: MNEPVxx-600-2PP

$63.00
600v 10mm X 38mm Fuses

Products

600v 10mm X 38mm Fuses

SKU: MN600FUSE

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63 amp 150VDC din rail mount DC ground fault protector

Products

63 amp 150VDC din rail mount DC ground fault protector

SKU: MNDC-GFP63

$88.00
6AWG Bare Copper Wire

Products

6AWG Bare Copper Wire

SKU: BCW-AWG6

$2.24
80 Or 100 Amp Din Rail Mount Breaker

Products

80 Or 100 Amp Din Rail Mount Breaker

SKU: MNEPV80or100

$65.00
80 Volt DC breaker

Products

80 Volt DC breaker

SKU: MNEPVxxx-80-1PNP

$45.00
80 amp 150VDC panel mount DC ground fault protector

Products

80 amp 150VDC panel mount DC ground fault protector

SKU: MNDC-GFP80

$88.00
AP Smart Transmitter Single Core

Products

AP Smart Transmitter Single Core

SKU: TRANSMITTER-PLC-1P

$35.45
Best Value Solar Cable

Products

Best Value Solar Cable

SKU: RS-Cable-Parent

$9.95
Burndy BIBS4-3 Multiple Wire Terminal

Products

Burndy BIBS4-3 Multiple Wire Terminal

SKU: BIBS43

$42.44
Burndy Insulated Multitap Connector

Products

Burndy Insulated Multitap Connector

SKU: BIT04

$34.99
Busbar, insulator and cover with 15 wire locations

Products

Busbar, insulator and cover with 15 wire locations

SKU: MNTBB2-15

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Bussmann Fusetron Dual-Element Class Rk5 Fuses

Products

Bussmann Fusetron Dual-Element Class Rk5 Fuses

SKU: BUSSMANNXXXAMPXXXVAC

$10.00
CableLoc Wire Management

Products

CableLoc Wire Management

SKU: CableLoc

$0.99
Delta Lighting Arrestor

Products

Delta Lighting Arrestor

SKU: DELLA

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Din Rail Mount 277VAC Triple Pole Breaker

Products

Din Rail Mount 277VAC Triple Pole Breaker

SKU: MNEAC-3P

$70.50
Generic Y Branch Solar Connectors

Products

Generic Y Branch Solar Connectors

SKU: GEN-SC-Y

$13.99
GripClip Wire Management

Products

GripClip Wire Management

SKU: GripClip

$0.75
MNEAC

Products

MNEAC

SKU: MNEAC

$21.75
MNEACQZD

Products

MNEACQZD

SKU: MNEACQZD

$21.75
MNEACQZD-2P

Products

MNEACQZD-2P

SKU: MNEACQZD-2P

$45.50
Mamba general duty junction box

Products

Mamba general duty junction box

SKU: MAMBA

$100.00
Mersen's HP10M Photovoltaic (PV) Fuse

Products

Mersen's HP10M Photovoltaic (PV) Fuse

SKU: MN1000FUSE

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MidNite PV Combiners

Products

MidNite PV Combiners

SKU: MNPV

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MidNite Prewired Combiners

Products

MidNite Prewired Combiners

SKU: MNPVX-MC4

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MidNite Solar Hawks Bay Breaker Box 125

Products

MidNite Solar Hawks Bay Breaker Box 125

SKU: MNHAWKSBAYBB125

$299.00
MidNite Solar Surge Protector Device

Products

MidNite Solar Surge Protector Device

SKU: MNSPD

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Mini DC Disconnect

Products

Mini DC Disconnect

SKU: MNDC

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Passthrough Box

Products

Passthrough Box

SKU: PTB-ALPHA-ONE

$1013.00
Product Photo

Products

Protocol-D V01

SKU: PD-V01

$2000.00
Pure Copper Battery Cable Wire

Products

Pure Copper Battery Cable Wire

SKU: BATCABLE

$15.70
Samlex Inverter Installation Kit

Products

Samlex Inverter Installation Kit

SKU: DC-XXXX-KIT

$99.00
Short Busbar

Products

Short Busbar

SKU: MNSBB

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Small Breaker Boxes

Products

Small Breaker Boxes

SKU: MNBABY

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Soladeck Outdoor Pass-thru Enclosure

Products

Soladeck Outdoor Pass-thru Enclosure

SKU: SD

$79.94
Solar Cable made with Stäubli Original MC4 connectors

Products

Solar Cable made with Stäubli Original MC4 connectors

SKU: SOLARCABLE-

$90.24
Product Photo

Products

Strain Relief

SKU: GENSR

$4.50
Tigo MLPE accessories

Products

Tigo MLPE accessories

SKU: TIGO-ACC

$50.00
Transfer Switch for the Big Baby

Products

Transfer Switch for the Big Baby

SKU: MNTRANSFER

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Two pole din rail mount 120/240 VAC breaker

Products

Two pole din rail mount 120/240 VAC breaker

SKU: MNEAC-2P

$45.50
Ultimate PV Junction Box

Products

Ultimate PV Junction Box

SKU: JB

$48.66
Wire Management Tray for Sol-Ark

Products

Wire Management Tray for Sol-Ark

SKU: SOL-ATRWTR-15

$646.12

Balance of System (BOS) Buying Guide

Balance of system components are everything between the panels and the inverter output — wire, overcurrent protection, disconnects, combiners, and surge protection. Properly specified BOS hardware protects the system, satisfies code, and passes inspection the first time.

Combiner Boxes

A DC combiner box serves as the central hub when a system has more than two or three panel strings. Each string connects through its own overcurrent protection device (fuse or breaker) before feeding into a common busbar. This isolates a faulted string and prevents backfeed from the remaining strings. Key internal components include string fuses or breakers, positive and negative busbars, a DC disconnect or isolator switch, a surge protection device (SPD), and a grounding bar. For residential systems a 2–4 string combiner is typical; commercial arrays may use 12–24 string boxes with integrated string-level monitoring.

Wire, Conduit & Connectors

PV wire (USE-2 / PV Wire) is rated for direct sunlight exposure and higher temperatures than standard building wire. Size conductors to keep voltage drop under 3 % over the full run from combiner to inverter — the three factors are amperage, voltage, and distance. Module-level connections use MC4 or equivalent locking connectors rated for the system voltage. All exposed wiring on rooftops must be secured in conduit or approved cable management per NEC Article 690. Use copper conductors for all DC circuits; aluminum is acceptable on the AC side for larger feeders where cost savings justify the larger conduit size.

Fuses, Breakers & Disconnects

Overcurrent protection devices must be DC-rated — standard AC breakers cannot safely interrupt a DC arc. Size string fuses at 1.56 times the panel short-circuit current (two NEC 1.25x multipliers stacked). DC disconnects are required between the array and the inverter and between the inverter and the grid, giving firefighters and technicians visible isolation points. Use fuses where cost matters and replacement is simple; use breakers where frequent resets are expected, such as on commercial arrays where nuisance trips during commissioning are common.

Surge Protection & Grounding

A Type 2 DC surge protection device (SPD) at the combiner box protects against lightning-induced transients and switching surges. SPDs should be installed with the shortest possible lead length to the grounding bar — long leads reduce clamping effectiveness. Equipment grounding connects all metallic racking, enclosures, and frames to the grounding electrode system per NEC 250. Verify that all BOS components carry the appropriate listings: UL 248-19 for PV fuses, UL 489B for DC breakers, and UL 1449 for SPDs.

Need help choosing?

Our team can help you select the right balance of system for your project.