Short answer: To mount a commercial string or hybrid inverter on a flat roof without drilling into the membrane, use a ballasted, non-penetrating inverter stand. It is a steel frame that sits on rubber pads and is held down by concrete blocks, so nothing goes through the roof. In Canada, a professional engineer (P.Eng) licensed in your province should confirm the ballast and the roof load for your site before you install.
Why the inverter is a problem on flat commercial roofs
On a house, the inverter usually goes on a wall in the garage or basement. On a commercial flat roof, the array can be far from any wall, and long cable runs back down to the electrical room add cost and voltage drop. Putting the inverter on the roof next to the array solves that, but then you need something to hang it on.
Bolting a stand through the roof means cutting the membrane and flashing every attachment. Each penetration is a possible leak, and something your roofer, the building owner and the roof warranty holder will want to approve.
Your options for mounting an inverter on a flat roof
| Option | How it works | Watch out for |
| Wall or parapet mount | The inverter bolts to a building wall, a rooftop structure or a parapet near the array. | Only works where a solid wall is close by. Parapets are not always strong enough. |
| Penetrating stand | A frame anchored through the roof with flashed attachments. | Membrane cuts, flashing work, leak risk and roof warranty sign-off. |
| Mount on the array racking | Some inverter makers offer brackets or kits for mounting under the array. | Only for approved inverter and racking combinations. Service access can be tight. |
| Ballasted, non-penetrating stand | A free-standing frame on rubber pads, held down by concrete ballast. | Needs engineering for the ballast, sliding and roof load, and adds weight to the roof. |
For most commercial flat roofs without a wall near the array, a ballasted stand is the simplest choice: no holes, no flashing, and it can go almost anywhere the roof structure and your engineer allow.
How a ballasted inverter stand works
- Frame: galvanized steel strut channel, bolted together on the roof.
- Roof contact: rubber blocks spread the load and protect the membrane.
- Ballast: concrete blocks on ballast rails hold the stand down against wind uplift and sliding.
- Inverter rails: two adjustable rails that take the inverter's own wall bracket, so one stand fits many inverter models.
Step by step: installing an inverter on a flat roof without penetrations
- Pick the spot. Close to the array and the roof access, away from roof edges and corners where wind loads are highest, with the clearances your inverter manual asks for and the working space the Canadian Electrical Code requires in front of electrical equipment.
- Get your roofer's approval. The stand puts load on its bearing points. Ask the roofer or roof warranty holder to approve the layout, and whether they want protection pads or a slip sheet under the blocks.
- Get the engineering done. Wind and snow loads in Canada depend on where the building is, its height and its parapet. A P.Eng licensed in your province sets the ballast amount and layout and checks sliding and the roof structure. Building departments and building owners often ask for a stamped design.
- Assemble the frame on the roof. A bolt-together strut frame needs no cutting or welding on the roof.
- Load all the ballast first. Weigh one block before you start, because hollow or lightweight blocks weigh less than you might expect. Never hang the inverter on an empty frame.
- Hang the inverter and disconnect. Two people to lift the inverter onto its bracket. Torque the bolts to the inverter manual. An AC disconnect or combiner can go on the same strut frame with standard strut fittings.
- Book the inspection. Your electrical inspector (for example, ESA in Ontario) checks the installation to the electrical code that applies in your province.
How much ballast does a rooftop inverter stand need?
It depends on wind exposure, building height, the friction of the roof surface and the inverter's weight and shape. As an example, the assembly guide for our Maple Leaf stand starts with 22 solid concrete blocks (about 106 kg) as a layout only, while an engineered version of a similar stand needed 233 to 322 kg. That is why your engineer, not a rule of thumb, should set the number. A shade awning catches more wind, so it raises the ballast needed.
Which inverters fit on a ballasted stand?
Most wall-bracket commercial string and hybrid inverters can hang on adjustable strut rails. Weight is the main limit. Our stand is built around a 50 kg inverter such as the Solis S6-GC25K to 60K, and it also fits the SMA Sunny Tripower X, SolarEdge SE30K and SE40K, Huawei SUN2000-30KTL to 50KTL-M3 and Fronius Symo. Heavier units such as the Sungrow SG36CX and SG60CX, CPS (Chint) SCA36KTL to 60KTL, Sol-Ark 30K and 60K and Fox ESS H3 Plus fit the rails but should go with a stamped design. Inverters that stand on their own feet, like the SMA Sunny Tripower CORE1, don't need a wall-mount stand.
What does a rooftop inverter stand cost in Canada?
- Maple Leaf Universal Rooftop Inverter Stand: from $2,859 CAD
- Shade awning: +$699
- P.Eng stamped design for your site: +$900
- Concrete ballast blocks: bought locally, not included
- Freight: the stand ships in 2 to 3 packages, about 68 kg (150 lb)
Checklist before you order
- Inverter make, model and weight
- Roof type, membrane and age
- Your roofer's or roof warranty holder's approval
- Building height, parapet height and the distance from the stand to the roof edge
- The ballast block you plan to use, and its weighed mass
- Who is doing the engineering, and the electrical permit
The Maple Leaf Universal Rooftop Inverter Stand
We designed the Maple Leaf Universal Rooftop Inverter Stand for exactly this job: a bolt-together galvanized strut frame on six rubber blocks, held down by concrete ballast, with adjustable rails that take most commercial string and hybrid inverters. It is made to order by Solar Power Store Canada in Barrie, Ontario, and the datasheet, assembly guide and full compatibility table are on the product page. Questions? Email hello@solarpowerstore.ca or call 1-888-421-5354.
Frequently asked questions
Can I put an inverter on a flat roof without drilling?
Yes. A ballasted, non-penetrating stand sits on rubber pads and is held down by concrete blocks, so nothing goes through the membrane. Have an engineer confirm the ballast and roof load for your building.
Is a ballasted inverter stand allowed under the building code?
Ballasted equipment is common on commercial roofs, but the design has to meet the building code where the building is. A P.Eng licensed in your province confirms the ballast, sliding and roof structure for your site.
Can the inverter sit in direct sun on the roof?
Most commercial inverters are rated for outdoor use, but heat and direct sun can make them reduce their output. Check your inverter manual. A shade awning keeps direct sun and rain off the inverter.
Does a ballasted stand void my roof warranty?
It makes no penetrations, but it does put load on the roof. Ask your roofer or the roof warranty holder to approve the layout before install.