LONGi Solar — China

Hi-MO X 420W A All-Black

The LONGi Solar Hi-MO X 420W A All-Black is a 420W PERC solar panel with 20.2% efficiency. Backed by a 25-year warranty.

Standard TierFEOC: Restricted

420W

Wattage

20.2%

Efficiency

PERC

Cell Type

25 years

Warranty

Full Specifications

Brand
LONGi Solar
Model
Hi-MO X 420W A All-Black
Series
Hi-MO X
Wattage
420W
Module Efficiency
20.2%
Cell Type
PERC
Dimensions
66-80" x 39-41"
Weight
48 lbs
Warranty
25 years
Est. Price Per Watt
$2.14
Est. 7kW System Cost
$14,980
Est. 10kW System Cost
$21,400
Temperature Coefficient
-0.35%/°C
Bifacial
No
Origin
China
FEOC Status
fail

Other LONGi Solar Panels

ModelWattageEfficiencyCell$/W
Hi-MO 480W D480W22.1%N-Type TOPCon$2.67
Hi-MO X 480W D480W22.1%N-Type TOPCon$2.67
Hi-MO 5 480W D480W22.1%N-Type TOPCon$2.67
Hi-MO 6 480W D480W22.1%N-Type TOPCon$2.67
Hi-MO 7 480W D480W22.1%N-Type TOPCon$2.67

Similar Wattage Panels (Competitors)

PanelWattageEfficiency$/W
Maxeon Maxeon 3 450W D Plus450W23.3%$4.61
Maxeon Maxeon 6 450W D Plus450W23.3%$4.61
Maxeon Maxeon 7 450W D Plus450W23.3%$4.61
Maxeon Maxeon Air 450W D Plus450W23.3%$4.61

Frequently Asked Questions

How much does a 420W LONGi Solar Hi-MO X 420W A All-Black cost?
The LONGi Solar Hi-MO X 420W A All-Black costs approximately $899 per panel ($$2.14/W). A typical 7kW system using this panel would cost around $14,980 before incentives.

⚠ The 30% Federal Solar Tax Credit (48E/ITC) expired July 4, 2026.

Selecting 30% ITC assumes you began construction before this deadline. Most new purchases no longer qualify.Learn about your options after the deadline →

Is the LONGi Solar Hi-MO X 420W A All-Black a good solar panel?
The LONGi Solar Hi-MO X 420W A All-Black has 20.2% efficiency and a 25 years warranty, placing it in the standard tier. This is a solid mid-range panel suitable for most residential installations.
How many LONGi Solar Hi-MO X 420W A All-Black panels do I need?
For a typical 7kW residential system, you'd need approximately 17 panels. For a 10kW system, plan for about 24 panels. The exact number depends on your roof space, energy usage, and local sun hours.

Written & reviewed by

Jeremy Wolfe — Senior Solar Energy Analyst

Jeremy Wolfe is a solar energy analyst specializing in residential photovoltaic economics, federal and state incentive policy, and return-on-investment modeling for homeowners. He leads EnergyTools' solar research program and methodology.

  • 10+ years analyzing residential solar economics and payback modeling
  • Lead researcher for EnergyTools' 50-state solar cost-per-watt database
  • Author of 100+ solar ROI, payback, and incentive analyses

Methodology & data sources:NREL PVWatts, EPA FuelEconomy.gov, state utility commissions— updated 2026.