Solar & battery
Solar Crew Size Calculator
Works crew size, where the tasks are not equally divisible.
Result
Crews do not scale linearly. On a residential roof there is a practical limit set by how many people can work safely on one plane, and past four or five the extra hands spend their time waiting. A roof with only one access point is limited further still.
Get a Free Business AuditHow the calculation works
Total hours divided by crew size gives elapsed time, with the practical minimum and maximum crew noted. Solar installation divides unevenly: module setting benefits from more hands, electrical termination and commissioning do not, so adding people past a point stops reducing the schedule.
What moves the number
- Total hours by task.
- Which tasks parallelise and which do not.
- Licensed electrical work, which limits who can do it.
- Roof size, which limits how many can work safely.
Where this one goes wrong
The licensed electrical work is a hard constraint on crew composition rather than crew size, since adding general labour does not help with terminations and commissioning that require a qualified person. Plan the crew around that. Roof area is the other limit, because a small roof cannot be worked safely by a large crew and crowding creates both inefficiency and risk, which is a reason the optimum crew is smaller than the arithmetic suggests.
Before you quote
- Plan crew composition around the licensed electrical work.
- Check how many can work the roof safely at once.
- Identify which tasks genuinely parallelise.
Questions
About this calculator
Does a bigger crew finish faster?
Up to a point. Module setting benefits from more hands, while electrical termination and commissioning do not, so beyond a certain crew size the schedule stops improving and the labour cost keeps rising.
What limits crew composition?
The licensed electrical work, which requires a qualified person and cannot be absorbed by additional general labour. Planning the crew around that constraint rather than around total hours is what makes the schedule realistic.
Can a large crew work a small roof?
Not safely or efficiently. Roof area limits how many people can work at once, and crowding creates both inefficiency and real risk, which is why the practical optimum crew is usually smaller than the hours arithmetic suggests.
The formula
crew grows until crew x effective hours x days covers the total, where efficiency falls as the crew grows
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How to use this calculator
- System size (kW). Enter your own figure; the page starts at 7.2.
- Labour hours per kW. Enter your own figure; the page starts at 7.
- Days to complete. Enter your own figure; the page starts at 1.5.
- Working hours per day. Enter your own figure; the page starts at 8.
- Coordination loss per extra person (%). Crews do not scale perfectly: more people means more waiting.
The result updates as you type, so you can try a figure, see what it does to crew needed, 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 |
| Labour hours per kW | 7 |
| Days to complete | 1.5 |
| Working hours per day | 8 |
| Coordination loss per extra person | 4% |
What comes out
| Result | Value |
|---|---|
| Crew needed main result | 5 |
| Total labour hours | 50.4 |
| Effective hours per person per day | 6.7 |
| Days that crew actually takes | 1.5 |
5 installers completes 50.4 hours of work in 1.5 days. Each person contributes 6.7 effective hours a day once coordination losses are counted, which is why doubling a crew never halves the time.
How sensitive the answer is
Holding everything else steady and changing only system size (kw), this is what happens to crew needed. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| System size (kW) | Crew needed |
|---|---|
| 3.6 | 3 |
| 5.4 | 4 |
| 7.2 example above | 5 |
| 10.8 | 10 |
| 14.4 | 28 |
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.
- Labour hours per kW
- A number, between 0 and 40, starting at 7.
- Days to complete
- A number, between 0 and 60, starting at 1.5.
- Working hours per day
- A number, between 0 and 16, starting at 8.
- Coordination loss per extra person (%)
- Crews do not scale perfectly: more people means more waiting.
What the results tell you
| Result | What it is |
|---|---|
| Crew needed | The headline result. A number. |
| Total labour hours | A decimal figure. |
| Effective hours per person per day | A decimal figure. |
| Days that crew actually takes | 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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