Can I design ground-mounted systems and solar farms, not just roofs?

Yes. The farm method lays tables in rows on an orthophoto with correct spacing, east-west or fixed-tilt structures, from 100 kWp to multi-megawatt sites.

Where do the irradiance and yield figures come from?

From the EasySolar AI calculation engine using irradiance data for the project location, roof azimuth and pitch, shading and system losses. The language model never generates a number.

Does it work in my country?

Fifteen markets are preconfigured with tariffs, incentives and metering rules. For any other market you define your own scheme in a few minutes and the interface runs in 25 languages.

Can I use my own module and inverter prices?

Yes. Pricing always comes from your component list and labour rates. Upload it once or sync it from Google Sheets via Zapier.

What happens if the aerial image is old or the building is new?

Switch to the photo method or upload a drone image or roof plan. One reference dimension sets the scale and you continue as usual.

Can the client see the design?

Yes. The client receives an interactive proposal by link and a personal panel with documents and project progress.

How does the free trial work?

3 days with full access. A card is required to start and nothing is charged before the trial ends. Cancel in one click from your account.

Solar Mounting Calculator

Solar Mounting Calculator: Rails, Clamps, Roof Hooks and Ballast for Your Roof

Choose your roof type, panel and row layout, and the solar mounting calculator counts the rails, connectors, clamps, roof attachments and small parts. Copy the bill of materials to Excel or your order in one click. Free, no registration.

See the full solar design software All design features

Try the solar mounting calculator

Add this calculator to your website

Installers and distributors can place the solar mounting calculator on their own website as a simplified tool for their clients, in their market's language, with traffic tagged to their company. The embed code is available in your EasySolar account: create a free account at web.easysolar-app.com, generate your code and paste it into any HTML block on your site.

The embedded calculator keeps the EasySolar attribution footer visible; this is the only condition of use.

Create a free account and get your embed code

On this page: embed the calculator on your website · how the calculation works · assumptions and limitations · example calculation · frequently asked questions · simplified vs. full version

How the solar mounting calculator works

The calculator counts a generic mounting structure: two rails under every row of panels, clamps in the gaps between panels and attachments chosen for the roof covering. Each row is calculated separately and the bill of materials is the sum of the rows.

1. Rail length per row

The rail runs from end clamp to end clamp with 50 mm to spare on each side:

L = n · Wp + (n − 1) · g + 2 · e

where n is the number of panels in the row, Wp the panel dimension along the row (width in portrait, length in landscape), g the clamp gap (20 mm by default) and e the rail extension beyond the last panel (50 mm).

2. Rail lengths, connectors, offcuts

A rail is made of stock lengths Lp (2.1 / 3.3 / 4.2 / 6.2 m):

lengths     = ⌈L / Lp⌉   per rail
connectors  = lengths − 1
offcut      = lengths · Lp − L

Each rail gets 2 end caps.

3. Roof attachments along the rail

Roof hooks, hanger bolts, standing seam clamps or flat-roof mounts, per rail:

m = max(2, ⌈(L − 2 · c) / s⌉ + 1)

where s is the maximum attachment spacing (1000 mm by default) and c the maximum rail overhang beyond the last attachment (400 mm by default, no more than ¼ of the rail on very short rails). Attachments are spaced evenly.

4. Attachments by roof type

Roof	Item	Quantity per row	Screws
Clay or concrete tiles	roof hook	2 · m	3 per hook
Metal roof tiles	hanger bolt with adapter and EPDM seal	2 · m	—
Trapezoidal sheet metal	trapezoidal mini rail (no long rails)	2 · (n + 1), two in each clamp line	6 per mini rail
Standing seam	standing seam clamp	2 · m	—
Flat roof	triangle mount under both rails + ballast	m	—

5. Clamps and small parts

Mid clamps: 2 · (n − 1) per row; end clamps: 4 per row.
T-head bolts: 1 per clamp plus 1 per attachment fixed to a rail (2 per flat-roof mount).
Grounding clips: 1 per panel.
Flat-roof ballast: number of panels × ballast per panel entered in the settings.

6. Summary

Area = longest rail × sum of row heights (without gaps between rows). Approximate structure weight = 1.4 kg per metre of rail + attachment weight (hook 1.0 kg; hanger bolt 0.35 kg; mini rail 0.25 kg; seam clamp 0.2 kg; triangle mount 3.0 kg) + 0.05 kg per clamp. Ballast is not included in the structure weight.

Assumptions and limitations

The structure is generic. Item names are not tied to any manufacturer's system. The final kit is matched to the catalogue of the chosen system.
Attachment spacing is an input, not a result. In practice it depends on the snow and wind load zone, the rafter spacing (hooks, hanger bolts) or seam spacing, and the system manufacturer's guidelines.
No structural calculation. Ballast per panel is a value you enter, not one calculated from standards; on flat roofs it is set by the designer.
Rail lengths without cut optimisation. Each rail is counted separately: the calculator does not reuse offcuts between rows or between the two rails of the same row, and does not check where connectors fall relative to attachments. The actual purchase may be smaller.
Landscape orientation. With rails running along the row, the clamps hold the short side of the panel; many panel manuals allow this only with reduced loads. The calculator shows a warning in that case.
Panels longer than 2.2 m. Check the clamping zones and permitted loads in the manufacturer's manual.
Trapezoidal sheet metal. Clamp lines have to fall on the trapezoid ribs; with a different rib spacing the panel layout must be adjusted.
Approximate result. Check the bill of materials with the mounting system manufacturer before ordering. For the wider installation context, see installation of PV panels on the ground, roof, balcony and façade and proper grounding of photovoltaic panels.

Example calculation (tiled roof, 16 panels)

Tiled roof, 1722 × 1134 mm · 430 W panels in portrait, three rows of 6, 6 and 4 panels. Default settings: attachment spacing 1000 mm, 3.3 m rails, 20 mm gap, 400 mm overhang.

Row	Panels	Rail length	Lengths per rail	Hooks per rail
1	6	6 · 1134 + 5 · 20 + 2 · 50 = 7004 mm	⌈7004 / 3300⌉ = 3	max(2, ⌈6204 / 1000⌉ + 1) = 8
2	6	7004 mm	3	8
3	4	4 · 1134 + 3 · 20 + 2 · 50 = 4696 mm	2	max(2, ⌈3896 / 1000⌉ + 1) = 5

Item	Qty	Notes
Mounting rails	16 pcs	37.4 m · 3.3 m lengths · offcuts 15.4 m
Rail connectors	10 pcs	1 per rail joint
Mid clamps	26 pcs	2 · 5 + 2 · 5 + 2 · 3
End clamps	12 pcs	4 per row
Roof hooks	42 pcs	2 · (8 + 8 + 5)
Fixing screws	126 pcs	3 per hook
T-head bolts	80 pcs	38 for clamps + 42 for hooks
Rail end caps	12 pcs	2 per rail
Grounding clips	16 pcs	1 per panel

Summary: 16 panels · 6.88 kWp · area 7.0 × 5.2 m · structure weight approx. 96 kg (37.4 m · 1.4 kg + 42 · 1.0 kg + 38 · 0.05 kg). To check how much this roof will produce, continue in the solar system sizing calculator or the azimuth and tilt calculator.

Frequently asked questions

How many roof hooks do I need per solar panel?

It depends on rail length and attachment spacing, not on the panel count directly. With a 1000 mm spacing and two rails per row, a row of six portrait panels (about 7 m of rail) needs 16 hooks, roughly 2.7 per panel. In high snow or wind zones the spacing drops to 600–800 mm and the number rises accordingly; the manufacturer's load tables decide.

How many mid clamps and end clamps are needed?

Per row: 4 end clamps (two on each rail at the row ends) and 2 mid clamps for every gap between panels, so 2 · (n − 1). A row of six panels uses 4 end clamps and 10 mid clamps.

How much mounting rail do I need for solar panels?

Two rails per row, each as long as the row of panels plus the clamp gaps plus 50 mm at each end. For six portrait panels 1134 mm wide that is 7.0 m per rail, 14 m per row, bought as stock lengths (2.1, 3.3, 4.2 or 6.2 m) with connectors at every joint. Expect 20–40% offcut if lengths are not optimised across rows.

What attachments are used on metal, trapezoidal and flat roofs?

Metal roof tiles: hanger bolts with an adapter and EPDM seal screwed into the rafters. Trapezoidal sheet: short mini rails screwed to the ribs in every clamp line, with no long rails. Standing seam: seam clamps, no roof penetration. Flat roof: triangle mounts under both rails, held by ballast rather than screws.

How much ballast does a flat-roof solar system need?

The calculator multiplies the number of panels by the ballast per panel you enter; it does not compute it. The value comes from the system manufacturer's wind-load calculation for the building height, roof edge zone and tilt, typically 20–60 kg per panel, and must be checked against the roof's load capacity.

Can I mount solar panels in landscape orientation?

Yes, but with rails running along the row the clamps hold the short side of the panel. Many panel manuals allow this only with reduced snow and wind loads, or require clamping within a specific zone. The calculator warns about it; confirm the permitted loads in the panel datasheet.

Simplified vs. full version

The solar mounting calculator gives a quick, approximate bill of materials for rectangular rows of panels. Full EasySolar designs the system on the real roof shape from aerial imagery or a 3D model, takes obstacles and shading into account, selects the inverter and cabling, and turns the design into a wiring diagram and a customer quote.

	Calculator	Full EasySolar
Panel layout	rectangular rows	any roof shape, obstacles
Mounting	generic bill of materials	designed on the customer's roof
Electrical, inverter	—	selection and diagram
Customer quote	—	ready-made document

Create a free EasySolar account and design the system on the real roof