Solar & battery
Solar Installation Time Calculator
Estimates install time, where the electrical work and the roof conditions dominate.
Result
Install time here covers the physical work only. Permitting, utility interconnection approval, inspection scheduling and any required electrical service upgrade routinely take far longer than the installation and are what actually determines how long a customer waits.
Get a Free Business AuditHow the calculation works
Hours by task: roof attachment and racking, module setting, DC and AC electrical, inverter and equipment mounting, and commissioning, with crew size converting hours into elapsed days. The electrical portion and the roof access conditions account for most of the variation between otherwise similar jobs.
What moves the number
- Roof pitch, height and access.
- Distance from array to inverter and service.
- Number of roof planes and layout complexity.
- Whether a service upgrade is required.
Where this one goes wrong
A service panel upgrade turns a one-day install into a multi-visit job with a utility coordination dependency, and discovering the need on install day is the most expensive way to find out, so the panel assessment belongs in the site survey. Roof access and pitch also drive hours more than module count does: a steep three-storey roof takes substantially longer per module than a low single storey, and the fall protection that steep work requires is both a legal obligation and a time cost to plan for.
Before you quote
- Assess the service panel at survey, not on install day.
- Rate hours by roof pitch, height and access.
- Plan fall protection time into the estimate.
Where the rules come from
Questions
About this calculator
What makes one install take twice as long as another?
Roof access and the electrical work, far more than module count. A steep three-storey roof with a long run to the service takes substantially longer than a low single-storey roof with the panel nearby, for the same array size.
What derails an install schedule?
A service panel upgrade discovered on install day, which turns a single visit into a multi-visit job with utility coordination. Assessing the panel during the site survey is the cheapest possible time to find out.
Should fall protection time be in the estimate?
Yes, because it is required rather than optional on the roof work solar involves, and setting it up and working within it takes real time. An estimate that assumes crews work unprotected is estimating a job nobody should perform.
The formula
hours = kW x base hours per kW x roof factor x plane factor, plus battery time
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How to use this calculator
- System size (kW). Enter your own figure; the page starts at 7.2.
- Crew size. Enter your own figure; the page starts at 4.
- Roof type. Enter your own figure; the page starts at Composition shingle (baseline).
- Roof planes. Enter your own figure; the page starts at 2.
- Base labour hours per kW. Enter your own figure; the page starts at 7.
- Battery included. Enter your own figure; the page starts at No.
The result updates as you type, so you can try a figure, see what it does to crew days, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| System size (kW) | 7.2 |
| Crew size | 4 |
| Roof type | Composition shingle (baseline) |
| Roof planes | 2 |
| Base labour hours per kW | 7 |
| Battery included | No |
What comes out
| Result | Value |
|---|---|
| Crew days main result | 1.8 |
| Total labour hours | 56.4 |
| Hours per person | 14.1 |
| Effective hours per kW | 7.8 |
About 56.4 labour hours, which is 1.8 days for a crew of 4. That is 7.8 hours per kW once roof type and 2 planes are counted.
How sensitive the answer is
Holding everything else steady and changing only system size (kw), this is what happens to crew days. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| System size (kW) | Crew days |
|---|---|
| 3.6 | 0.9 |
| 5.4 | 1.3 |
| 7.2 example above | 1.8 |
| 10.8 | 2.6 |
| 14.4 | 3.5 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- System size (kW)
- A number, between 0 and 5000, starting at 7.2.
- Crew size
- A number, between 1 and 40, starting at 4.
- Roof type
- Choose from Composition shingle (baseline), Tile (about 40% slower), Standing seam metal (about 15% faster), Flat, ballasted (about 20% faster).
- Roof planes
- A number, between 1 and 20, starting at 2.
- Base labour hours per kW
- A number, between 0 and 40, starting at 7.
- Battery included
- Choose from No, Yes, add about 12 hours.
What the results tell you
| Result | What it is |
|---|---|
| Crew days | The headline result. A decimal figure. |
| Total labour hours | A decimal figure. |
| Hours per person | A decimal figure. |
| Effective hours per kW | A decimal figure. |
A design still needs a site visit
Output and sizing figures use the assumptions you enter, not measured irradiance, shading or roof orientation at your address. Real production depends on all three, plus inverter behaviour and local interconnection rules.
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