Solar combiner

Disclaimer: This investigative report is engineered for educational and informational purposes only. The content presented herein is a synthesis of publicly available technical specifications, regulatory codes (specifically the National Electrical Code), third‑party certification databases (UL, ETL), and anecdotal field reports from user communities. It does not constitute professional engineering advice, legal counsel, or a formal recommendation for specific electrical installations.
Electrical codes, including the adoption of specific NEC revisions (2017, 2020, 2023), vary significantly by state, county, and municipality. Homeowners and installers are strictly advised to consult with their local Authority Having Jurisdiction (AHJ) and licensed master electricians to ensure full compliance with local statutes. References to specific brands, models, or manufacturers are for comparative analytical purposes and do not imply commercial endorsement. Discussion of potential safety hazards, including fire risks and thermal failures, is based on documented user experiences and theoretical application of electrical physics; these are illustrative of potential failure modes and do not represent definitive failure rates for any product line.
Scope: This analysis strictly targets "Solar Panel Combiner Boxes" and associated balance‑of‑system (BOS) components marketed to the United States residential market. The report evaluates technical architecture, code compliance, thermal thermodynamics, surge suppression efficacy, and manufacturing quality across a spectrum of market segments, ranging from direct‑to‑consumer import units to professional‑grade domestic enclosures.

1. Executive Summary: The Divergence of Safety and Cost

The residential solar industry in the United States currently stands at a crossroads defined by a stark bifurcation in component quality and regulatory adherence. At the center of this divide lies the photovoltaic (PV) combiner box, a device that serves as the "central nervous system" of a solar array’s direct current (DC) infrastructure. 1 While its fundamental purpose is elementary—consolidating multiple source circuits into a single output—the combiner box has become a focal point for complex discussions regarding fire safety, code compliance, and the economics of renewable energy adoption.
Our investigation identifies a critical tension between accessibility and integrity. On one side of the market, a flood of budget‑friendly, pre‑wired combiner boxes—typified by brands such as Eco‑Worth and Vevor—has democratized access to solar hardware, allowing DIY enthusiasts to construct off‑grid systems at a fraction of historical costs. However, rigorous analysis suggests that these "plug‑and‑play" solutions often rely on architectural choices, such as the integration of blocking diodes inside unventilated plastic enclosures, that introduce significant thermal hazards and potential code violations. 2
Conversely, the professional tier, represented by stalwarts like MidNite Solar and SolaDeck, adheres to a philosophy of modularity and rigorous third‑party listing (UL 1741). These products are designed not merely to function but to survive the harsh environmental realities of rooftop deployment for decades. Yet, their higher price point and assembly requirements often deter the entry‑level consumer, driving a wedge between code‑compliant best practices and the reality of many self‑installed systems. 3
This report provides an exhaustive deconstruction of these competing philosophies. Through detailed technical analysis, we explore why a $100 plastic combiner may function as a "70‑watt heater" on a rooftop, why a UL‑listed component does not guarantee a UL‑listed system, and how the evolution of the National Electrical Code (NEC) toward Rapid Shutdown (RSD) is fundamentally rendering the passive combiner box obsolete in grid‑tied applications.

2. The Role of the Combiner in Modern Photovoltaic Architecture

To evaluate the efficacy and safety of current market offerings, one must first establish the functional baseline of the device within the broader energy system. The solar combiner box is not merely a junction point; it is a critical control node that manages energy flow, protects against catastrophic overcurrent events, and facilitates system maintenance.

2.1 The Mechanism of Aggregation

In a typical residential solar array, photovoltaic modules are wired in series to create "strings." These strings increase voltage while keeping amperage constant. However, system inverters and charge controllers often have input limits that necessitate parallel connections to increase amperage. The combiner box is the physical location where these parallel connections occur.

Current Summation: The primary electrical function is the summation of current. If four strings of panels each produce 9 Amps, the combiner box aggregates this into a single output of 36 Amps. 1
Wiring Transitions: The combiner also serves as a transition point for wiring types. Solar panels utilize PV Wire, a specialized conductor with thick, UV‑resistant cross‑linked polyethylene insulation. However, running multiple runs of PV Wire to a distant inverter is cost‑prohibitive and inefficient. The combiner allows for the transition to standard building wire (THHN/THWN‑2), which is run through conduit to the final equipment location. 6

2.2 The First Line of Defense

Beyond aggregation, the combiner box houses the system's primary overcurrent protection devices (OCPD).

Fault Protection: In the event of a short circuit or a ground fault, current from the battery bank or parallel strings can backfeed into the faulted circuit. Without fuses or breakers, this massive reverse current can melt conductors and ignite fires. The combiner box fuses each string individually, isolating faults before they propagate. 7
Surge Suppression: As the component electrically closest to the rooftop array, the combiner box is the logical location for Surge Protection Devices (SPDs). These components shunt high‑voltage transients—caused by nearby lightning strikes or grid switching—to ground, protecting sensitive downstream inverters. 9

3. The Regulatory Framework: A Landscape of Strict Compliance

The design and installation of combiner boxes are governed by a complex web of codes and standards. In the United States, the National Electrical Code (NEC) is the supreme authority, while Underwriters Laboratories (UL) provides the testing benchmarks. Understanding this framework is essential for distinguishing between "safe" and "compliant" equipment.

3.1 NEC Article 690: The Evolution of Solar Safety

Article 690 of the NEC specifically covers Solar Photovoltaic Systems. Over the past decade, this article has undergone radical revisions, primarily driven by the need to protect first responders from electrical shock hazards during structural fires.

3.1.1 The Rapid Shutdown (RSD) Mandate (NEC 690.12)

The most transformative change in recent history is the introduction and tightening of Rapid Shutdown requirements.

NEC 2014: Introduced the concept, requiring that conductors more than 10 feet from the array be de‑energized to 30 V within 10 seconds.
NEC 2017/2020/2023: The requirement became significantly more stringent. Now, conductors within the array boundary (1 foot from the array) must be de‑energized to 80 V or less within 30 seconds. 10

Implications for Combiner Boxes:
This regulatory shift has profound implications for the traditional combiner box. A standard, passive combiner box containing only fuses and busbars cannot meet the "inside the array boundary" shutdown requirement on its own. It has no mechanism to stop the solar panels from producing voltage when the sun is shining.

The "Smart" Shift: Compliance now requires Module Level Power Electronics (MLPE) or specialized disconnects. Consequently, the combiner box is evolving from a simple aggregation point into a housing for RSD initiators or "keep‑alive" signal transmitters, such as those used by Tigo Energy. 12
The Compliance Gap: Many budget combiner boxes marketed today (e.g., Eco‑Worth, Vevor) make no mention of RSD compatibility. Installing these on a residential rooftop in a jurisdiction enforcing NEC 2017 or later would result in an immediate inspection failure. 13

3.2 Grounding and Bonding Requirements (NEC 690.43)

Grounding is the foundational safety mechanism for any electrical system. NEC 690.43 requires that all exposed non‑current‑carrying metal parts of PV module frames, electrical equipment, and conductor enclosures be grounded and bonded to the equipment grounding conductor. 1

Metal vs. Plastic: Professional‑grade metal enclosures (like those from MidNite Solar) offer inherent advantages here. The enclosure chassis itself can serve as part of the bonding path, provided paint is scraped away at contact points or bonding washers are used. Plastic enclosures, common in the budget tier, are non‑conductive. They must rely entirely on internal grounding bars and wire‑to‑wire continuity, which introduces more points of potential failure if a connection loosens. 1

3.3 UL 1741: The Gold Standard for Equipment

While the NEC dictates how equipment is installed, UL standards dictate how it is built. UL 1741 is the standard for "Inverters, Converters, Controllers and Interconnection System Equipment for Use With Distributed Energy Resources". 15

The "Listing" vs. "Component" Trap: A critical distinction exists between a "UL Listed Assembly" and an assembly made of "UL Recognized Components."
- Listed Assembly: The entire box, as a unit, has been tested for heat dissipation, water ingress, and electrical safety. It bears a holographic UL label on the outside. 16
- Recognized Components: A manufacturer might buy UL‑listed breakers and put them in a non‑listed plastic box. They then market the product as "UL Compliant." This is deceptively common in the budget import market. Most U.S. electrical inspectors will reject a device that lacks a listing for the entire assembly. 17

4. Technical Architecture and Deep‑Dive Component Analysis

The reliability and safety of a combiner box are defined by the physics of its components. We will now deconstruct the device into its constituent parts to understand the stark differences between market segments.

4.1 Enclosure Physics: Thermal Dynamics and Material Science

The enclosure is more than a bucket for wires; it is a thermal management system.

4.1.1 Polycarbonate/ABS (The Budget Standard)

Brands like Eco‑Worth and Vevor predominantly utilize ABS or Polycarbonate plastics for their enclosures. 19

Thermal Conductivity: Plastic is a thermal insulator (0.2 W/m·K). Heat generated by internal components (fuses, diodes, wire resistance) is trapped inside the enclosure.
UV Degradation: While often stabilized, plastics are susceptible to UV radiation. Over 10‑20 years of rooftop exposure, they can become brittle, yellow, and prone to cracking, compromising the NEMA/IP rating. 20
Flammability: While "flame retardant" additives are used, plastic will ultimately melt and consume fuel in a fire scenario, unlike metal.

4.1.2 Powder‑Coated Steel/Aluminum (The Professional Standard)

Brands like MidNite Solar and Watts247 utilize metal enclosures. 21

Thermal Conductivity: Aluminum (205 W/m·K) and Steel (50 W/m·K) act as effective heatsinks. They radiate internal heat into the ambient air, keeping internal components cooler.
Durability: Metal enclosures are essentially immune to UV degradation. Powder coating provides corrosion resistance, and materials like stainless steel or aluminum are preferred for coastal environments. 23
EMI Shielding: Metal enclosures block Electromagnetic Interference (EMI), which can be crucial if the combiner box houses communication equipment for rapid shutdown systems.

4.2 The "Blocking Diode" Controversy: A Thermal Hazard?

One of the most significant findings of this investigation is the prevalent use of integrated blocking diodes in budget‑tier combiner boxes. This design choice represents a critical divergence from professional engineering standards.

The Theory: Blocking diodes are intended to prevent reverse current flow—stopping a battery from discharging into a solar panel at night, or preventing one parallel string from backfeeding into a shaded string. 24
The Physics of Failure: A silicon diode has a forward voltage drop (ΔV) of approximately 0.7 Volts. Power dissipation (P) is calculated as P = I × V.
- Scenario: A 6‑string Eco‑Worth box running at its rated 10 Amps per string.
- Calculation: 10 A × 0.7 V = 7 Watts of heat per diode.
- Total Heat Load: 6 diodes × 7 W = 42 Watts of continuous heat generation inside a sealed, insulated plastic box. 2
The Consequence: User reports and teardowns confirm that these diodes act as localized heaters. Temperatures can rise high enough to soften the plastic enclosure, degrade wire insulation, or cause the diode itself to fail. A failed diode often fails "open" (cutting power) or "short" (defeating its purpose), but the heat generated prior to failure is a verified fire risk. 2
Professional Approach: High‑end combiners (MidNite, SolaDeck) do not use blocking diodes. They rely on the MPPT charge controller to prevent night‑time reverse current and use fuses/breakers for fault protection. The elimination of the diode removes a significant heat source and failure point. 23

4.3 Overcurrent Protection: Fuses vs. Breakers

The choice between fuses and circuit breakers is often dictated by system voltage and user preference.

Fuses (Touch‑Safe Holders): Commonly used for higher voltage systems (up to 600 V or 1000 V DC). They are simple, reliable, and have high Interrupting Ratings (AIC), meaning they can safely break massive fault currents without exploding. 27 However, they are "one‑time use" devices.
DC Circuit Breakers: Preferred for lower voltage systems (150 V‑300 V) and for their utility as a disconnect switch.
- Polarity Danger: Many DC breakers are polarized, meaning they rely on magnets to push the electrical arc into a chute to extinguish it. If wired backward (reverse polarity), the magnet will pull the arc into the mechanism, leading to catastrophic failure and potential fire. 8
- Quality Variance: A MidNite Solar breaker is rated for millions of cycles and rigorous environmental conditions. Generic "125 A" breakers found in import boxes often lack credible AIC ratings, raising questions about their ability to actually stop a fault current in a high‑power array. 28

4.4 Surge Protection Devices (SPD): The Silent Sentinel

Surge protection is critical for protecting the inverter from lightning‑induced transients.

MOV Technology: Most SPDs rely on Metal Oxide Varistors (MOVs). When voltage exceeds a threshold, the MOV clamps the voltage by shunting current to ground.
Failure Mode: MOVs degrade over time. A quality SPD (like MidNite’s MNSPD) includes thermal fusing to disconnect the MOV if it overheats and a visual indicator (LED or mechanical flag) to show it has failed. 29
Budget Reality: Cheaper combiner boxes often use replaceable "cartridge" SPDs. While convenient, the quality of the MOV inside is often unknown. Crucially, some "lightning protection" features in ultra‑budget models may just be simple MOVs soldered to a board without proper thermal disconnects, creating a fire hazard if the MOV goes into thermal runaway. 20

5. Market Segmentation and Brand Analysis

To provide actionable insights for the consumer, we have categorized the market into three distinct tiers: The Budget Import Tier, The DIY Mid‑Range, and The Professional Domestic Tier.

5.1 The Budget Import Tier: Eco‑Worth and Vevor

Target Demographic: Cost‑conscious DIYers, small off‑grid cabins, RVs.

Product Profile: These units are ubiquitous on marketplaces like Amazon and eBay. They are typically pre‑wired, plastic‑enclosed, and feature‑rich on paper (lightning protection, breakers, fuses included) for a price of $50‑$120. 30
Critical Findings:
- Enclosure: The IP65 rating is often claimed but physically questionable due to poor gasket quality and limited door swing radius (<90 degrees), which hinders installation. 2
- Diodes: As discussed, the inclusion of anti‑backflow diodes is a major thermal liability. Users frequently report "plastic cooking smells" or high heat output. 2
- Compliance: While individual components (like the breaker) might carry a UL symbol, the assembly as a whole is rarely UL Listed. This makes them fundamentally unsuitable for any installation requiring a building permit or electrical inspection. 13
- Verdict: Acceptable only for small, non‑critical, 12 V/24 V systems mounted in non‑flammable locations (e.g., pole mount away from the house). Dangerous for high‑voltage or rooftop usage.

5.2 The DIY Mid‑Range: Watts247

Target Demographic: Serious DIYers, Solar enthusiasts, "Grandfathered" systems.

Product Profile: Watts247 offers a step up in build quality, utilizing metal enclosures (powder‑coated steel) that mimic professional gear. 22
Technical Edge: The shift to metal resolves the thermal dissipation and UV degradation issues of the budget tier. They also typically avoid the use of integrated diodes, relying on proper OCPD instead.
The Inspection Trap: Despite better build quality, these units occupy a "gray zone" regarding certification. Marketing materials may state "UL Listed Components" or reference a UL file number for the breaker. Field reports indicate that inspectors have failed these units because the box itself lacks the UL 1741 holographic label required for the assembly. 17
Verdict: A robust hardware solution for off‑grid applications where strict code enforcement is not a factor, but a risky gamble for permitted grid‑tied projects.

5.3 The Professional Tier: MidNite Solar and SolaDeck

Target Demographic: Licensed Electricians, Grid‑Tie Residential, Long‑term reliability focus.

5.3.1 MidNite Solar (The MNPV Series)

MidNite Solar is widely regarded as the industry benchmark for DC combiners. 35

Architecture: The MNPV3, MNPV6, and MNPV12 utilize NEMA 3R aluminum enclosures. Aluminum is chosen for its superior heat dissipation and immunity to rust. 21
Modularity: Unlike the pre‑wired imports, these are sold as chassis systems. The installer selects the specific busbars and breakers/fuses needed for the project. This prevents the "square peg in a round hole" problem of pre‑configured boxes. 37
RSD Integration: MidNite offers specific "Disco" (Disconnect) versions with big red handles that can be integrated with their "Birdhouse" emergency shutdown switch, providing a clear path to NEC 690.12 compliance. 38
Certification: These units carry full UL 1741 Listing for the US and Canada. There is no ambiguity for inspectors. 21

5.3.2 SolaDeck (The Rooftop Specialist)

SolaDeck solves a specific problem: getting wires from the roof into the attic without an ugly conduit run over the eave.

Design: The enclosure is designed to be installed under the roof shingles, flashed into the roofing system like a vent.
Function: It acts as a combiner and a pass‑through, allowing the transition from PV Wire to building wire (THHN) inside the enclosure, which is then routed directly into the attic. 41
Verdict: The only professional choice for aesthetic, stealthy wiring penetration on composite shingle roofs.

6. Comparative Analysis: Data and Specifications

To visualize the disparities discussed, the following table contrasts key specifications of the market leaders.

Table 1: Combiner Box Specification Comparison

Feature	Eco‑Worth 6‑String	Watts247 4‑String	MidNite Solar MNPV6	SolaDeck 0783‑41
Enclosure Material	ABS/Polycarbonate Plastic	Powder Coated Steel	Powder Coated Aluminum	Galvanized Steel
NEMA / IP Rating	IP65 (Claimed)	IP65	NEMA 3R (Verified)	NEMA 3R (Verified)
Thermal Mgmt	Insulated (Traps Heat)	Radiative (Metal)	Radiative (Aluminum)	Radiative (Steel)
Blocking Diodes	Yes (Integrated)	No	No	No
Voltage Rating	250 V DC (Limited)	1000 V DC	150 V / 300 V / 600 V	600 V DC
UL Certification	Components only (Ambiguous)	Components only (Ambiguous)	UL 1741 Listed Assembly	UL 1741 Listed Assembly
Rapid Shutdown	No Support	No Support	Birdhouse Compatible	Pass‑through only
Price Point	~$100 (Pre‑wired)	~$150 (Pre‑wired)	~$190 (Box Only) + ~$150 Parts	~$275 (Box Only)
Warranty	1 Year	1 Year (Implied)	5 Years	Variable

Insight: The price delta between Eco‑Worth and MidNite Solar is not merely a "brand tax." It reflects the cost of aluminum vs. plastic, the cost of UL testing and listing, and the removal of hazardous components like integrated diodes.

7. System Integration Challenges: Tigo, Victron, and The Future

The combiner box does not exist in a vacuum; it must integrate with inverters and modern safety electronics.

7.1 The Tigo Energy Factor (Rapid Shutdown)

As NEC 690.12 mandates module‑level shutdown, Tigo's TS4 platform has become a standard solution.

Pass‑Through Functionality: When using Tigo TS4‑A‑F (Fire Safety) modules, the rapid shutdown logic happens at the solar panel. The combiner box's role shifts to becoming a transparent pass‑through for the Power Line Communication (PLC) signal that controls the Tigo units. 42
Interference Risks: Some budget combiner boxes with poorly designed internal circuitry or noise‑generating components (like cheap LED indicators) can interfere with the PLC signal, causing "crosstalk" or signal loss. Professional combiners with clean, direct busbars are preferred to ensure the "keep‑alive" signal reaches the roof. 42

7.2 The Victron Energy / Off‑Grid Paradigm

Victron Energy, a giant in the off‑grid space, typically does not market a traditional combiner box for the U.S. market. 43

MPPT Architecture: Victron MPPT charge controllers often feature multiple sets of PV input terminals (e.g., MC4 terminals directly on the unit). This allows installers to run separate string wires all the way to the controller, effectively using the controller itself as the combiner. 44
The "Combiner‑less" Design: For arrays located close to the equipment room, avoiding a combiner box reduces connection points (points of failure) and voltage drop. However, for long runs (e.g., ground mounts 100 ft away), a combiner at the array is still necessary to transition to larger gauge wire to minimize transmission loss. 45

8. Installation Guidelines and Safety Best Practices

For homeowners proceeding with an installation, adherence to best practices is the final barrier against failure.

8.1 Thermal Management

Shade is King: The single most effective way to extend the life of a combiner box (especially a plastic one) is to mount it in the shade. The north side of a pole mount or the shaded eave of a house can reduce operating temperatures by 20 °C or more compared to direct sun exposure. 46
Diode Removal: If utilizing a budget box for a non‑critical application, knowledgeable users often surgically remove or bypass the internal blocking diodes, relying instead on the MPPT controller for reverse current protection. This immediately eliminates the primary internal heat source. 24

8.2 Wiring and Torque

The Torque Spec: Copper wire "cold flows" (deforms) under pressure over time. A connection that is tight today may be loose in a year. Using a torque screwdriver to tighten terminals to the manufacturer's exact specification is not optional; it is critical for preventing high‑resistance arcs and fires. 31
Strain Relief: Cable entry points must be sealed. Using generic "knockouts" without proper UL‑listed liquid‑tight cord grips allows moisture ingress, which leads to corrosion and ground faults. Professional boxes usually have concentric knockouts designed for standard conduit fittings. 47

8.3 The Inspection Reality

The "Sticker" Check: Before purchasing, ask the vendor for a photo of the product label. If it does not explicitly say "UL Listed" (not just "Certified" or "Compliant") with a file number for the assembly, assume it will fail a formal electrical inspection. 13

9. Conclusion: The Verdict on Value vs. Safety

The investigation into the U.S. residential solar combiner market reveals a landscape defined by "you get what you pay for."
The Budget Tier (Eco‑Worth, Vevor) represents a functional but compromised solution. These products prioritize low upfront cost over longevity and thermal engineering. The inclusion of heating elements (diodes) inside insulated plastic boxes is a fundamental design flaw that limits their safe use to low‑amperage, intermittent, or non‑critical off‑grid applications. They are the "temporary spare tire" of the solar world—functional in a pinch, but not designed for the highway.
The Professional Tier (MidNite Solar, SolaDeck) represents the gold standard. These products are engineered with a clear understanding of thermal thermodynamics, arc physics, and regulatory compliance. The use of aluminum and steel, the modularity of DIN rail components, and the rigorous UL 1741 listing make them the only viable choice for grid‑tied residential structures where safety and insurance coverage are paramount.
The Middle Ground (Watts247) offers a compelling hardware value—metal enclosures at a reasonable price—but stumbles on the bureaucratic hurdle of system‑level certification, making them a "buyer beware" option for permitted projects.
Final Recommendation: For the U.S. homeowner, the "savings" of a $100 plastic combiner box evaporate instantly in the face of a single failed inspection, a melted enclosure, or a rooftop fire. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong place to economize. In the context of a solar energy system costing thousands of dollars, the combiner box is the wrong...

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