How to Mount Solar Panels
Built by Jeremy Panasuk. Published October 3, 2026.
Orientation comes from the Department of Energy. The hardware limits come from Canadian Solar's installation manual for its standard modules. The wattage example is this site's calculator.
Direction and tilt
DOE's system-design page says a PV array needs a stable, durable structure that can support the array and withstand wind, rain, hail, and corrosion over decades. For the highest annual energy output, modules in the northern hemisphere are pointed due south and inclined at an angle equal to the local latitude. Rack mounting, DOE says, is currently the most common method. Ground-mounted trackers move the panels to follow the sun. One-axis trackers typically follow the sun from east to west. Two-axis trackers keep the modules pointed at the sun through the day. DOE says tracking provides more energy and involves more up-front cost, and that sophisticated systems are more expensive and require more maintenance.
The Canadian Solar manual says the highest yields are achieved when sunlight shines perpendicularly onto the modules, and that even minor partial shading, including dirt, reduces yields. It treats a module as unshaded only when its entire surface is free from shading all year, including the shortest day. Constant shading, it says, can affect service lifetime because of accelerated ageing of the encapsulation and thermal stress on the bypass diodes.
Clearance, bolts, and fire rating
The same manual requires at least 10 cm (3.94 in) between the module frame and the mounting surface so cooling air can circulate around the back and so moisture can dissipate. It requires a minimum of 6.5 mm (0.25 in) between modules for thermal expansion of the frames. Bolting, in the method it qualifies, goes through the mounting holes in the rear frame flanges only. Each module is fastened at a minimum of 4 points on two opposite sides. The manual says not to drill additional holes or modify the frame. It says the fire rating is valid only when the product is installed as specified in the mechanical mounting instructions, and it says any clearance a UL 1703 system fire rating requires should prevail over that 10 cm figure. Workers and third parties, it says, shall wear or install fall arrest equipment.
What a bad mount does to the calculator
The solar size calculator does not compute tilt. It asks for sun hours. sizeSystem divides daily watt-hours by those hours and by 0.75, then rounds up to the next 100 W. The file's comment describes 0.75 as wiring, controller, battery round-trip, and panel heat and soiling. Rear clearance is the manufacturer's cooling instruction. The 0.75 factor is the calculator's lump. They sit next to each other because a mount with no air gap is a heat problem the manual calls out, and heat is one of the words in the calculator's comment. The number 0.75 is not a measurement of a 10 cm gap.
Take Battle Born's 2,400 Wh example, sun hours 4, autonomy 2, depth of discharge 80%. Array watts are 2,400 ÷ 4 ÷ 0.75 = 800, which is already on a 100 W step. The same function has a winter line that substitutes 2.5 sun hours: 2,400 ÷ 2.5 ÷ 0.75 = 1,280, which rounds up to 1,300 W. If the array is pointed away from the direction DOE describes, the sun-hours input is the number that changed, and both lines move with it. Shade that the manual says cuts yield is the same kind of change: fewer effective sun hours than the 4 you typed.
A cabin load list that already produced a panel count still has to be mounted. The count itself is on how many solar panels for a cabin and in the off-grid cabin guide.
One common mistake
Flushing the frame to the roof and skipping the rear gap. The manual's cooling clearance is at least 10 cm (3.94 in), and it says a fire-rating clearance from the racking supplier prevails when that clearance is larger. Drilling new holes in the frame is the paired mistake: the bolting method uses the rear-flange mounting holes only, and extra holes void the warranty the manual describes.
Limits
This page is not a mount design. The manual says a registered professional engineer certifies the mounting design, that design loads are the responsibility of the racking supplier or a professional engineer, and that the module is considered in compliance with UL 1703 and IEC 61215 only when it is mounted in the manner the manual specifies. Do not install modules in strong wind. Fall arrest is required by the manual's mounting section. A licensed electrician makes the electrical connections. How the series fuse relates to parallel strings is a separate page, how to fuse a solar panel array.
FAQ
Which way does DOE aim modules for the highest annual energy?
In the northern hemisphere, due south, inclined at an angle equal to the local latitude. DOE says rack mounting is the most common method. One-axis trackers typically follow the sun east to west, and two-axis trackers keep modules pointed at the sun, with more energy, more up-front cost, and more maintenance.
What clearance does the Canadian Solar manual require behind the frame?
At least 10 cm (3.94 in) between the module frame and the mounting surface, so air can cool the back of the module. It also requires at least 6.5 mm (0.25 in) between modules. A UL 1703 system fire-rating clearance prevails when the racking supplier requires more than 10 cm.
What array does 2,400 Wh produce in this calculator at 4 sun hours?
2,400 ÷ 4 ÷ 0.75 = 800 W. The winter line in the same function uses 2.5 sun hours and prints 1,300 W. The calculator does not compute tilt; a mount that misses DOE's south-and-latitude aim changes the sun-hours input those lines divide by.
Compiled with AI assistance from the sources below. Spot an error? Email [email protected].
Sources
- U.S. Department of Energy, Solar Photovoltaic System Design Basics — accessed Oct 3, 2026.
- Canadian Solar, Installation Manual of Standard Solar Modules, EN-Rev IM/GN-AM-EN/2.2, July 2020 — accessed Oct 3, 2026.
- Battle Born Batteries, How to Size a Deep Cycle Battery Bank, May 22, 2026 — accessed Oct 3, 2026.
- SolarSizer calculator, assets/app.js (sizeSystem) — accessed Oct 3, 2026.