Specialist work
System design and engineering, as a standalone service
The engineering on its own: SLDs, string layout, cable and protection sizing, structural loading — for owners who have a contractor but no engineer.
HV
Substation background
Electrical engineer, high-voltage substations before solar
IEC 62116
Anti-islanding verified at commissioning
Standard applied on commissioned projects
Design-only
Available without procurement
You keep your contractor; I supply the engineering
Whether this fits
Work out whether you should be talking to me at all
This is for you if
You have a contractor you trust but no engineering oversight
Installation skill and design competence are different things. A good crew building to a bad design produces a neat installation that underperforms for twenty years.
You have been handed a quotation with no SLD
If nobody has drawn the system, nobody has designed it. The drawing is where the protection, the string layout and the cable sizing are decided.
Your roof is structurally uncertain
Array dead load and wind uplift on an old industrial roof is a real question, and it is one that gets skipped because it is inconvenient.
You need a design a distribution company will accept
A drawing that does not match the installation is the most common reason net metering files come back.
This is not for you if
Owners who want a drawing to legitimise a system already installed incorrectly. I will inspect and report honestly, but I will not draw a compliant SLD for a non-compliant installation.
Anyone wanting a design they can shop around to get a cheaper build of the same thing — that is a fine use of it, but say so, because it changes what the deliverable needs to contain.
Very small domestic systems where a competent installer working to standard practice is genuinely sufficient.
Scope
What is included, as deliverables rather than adjectives
- 01 Single-line diagram
- The full electrical schematic from array through protection to the point of connection.
- 02 String layout and array configuration
- String sizing against inverter MPPT windows, including temperature extremes at both ends of the range.
- 03 Cable sizing
- DC and AC cross-sections calculated for voltage drop and current-carrying capacity at actual ambient temperatures, not at datasheet conditions.
- 04 Protection design
- DC isolators, fusing, surge protection, AC protection and discrimination.
- 05 Earthing design
- Array earthing, equipotential bonding and lightning protection where the site warrants it.
- 06 Structural loading
- Dead load and wind uplift checked against the roof structure, with mounting and penetration detail.
- 07 Bill of materials
- Specified to model number so that a substitution is visible rather than invisible.
Not every client needs me to run their project. Some have a contractor they have used for years and trust, and what they are actually missing is the engineering — the drawings, the calculations and the specification that the contractor was never going to produce because nobody asked them to.
This is that engagement. I design the system to model-number specificity, you build it with whoever you like, and the design is yours.
If nobody drew it, nobody designed it
A striking number of systems in Pakistan are built from a quotation and a rule of thumb. There is no single-line diagram, so there is no record of what protection was intended; no string calculation, so string sizing was decided by what fitted; no cable calculation, so cross-sections were chosen by habit.
None of that is visible in a finished installation. All of it is visible in year eight, in generation that is quietly below what the array should produce, or in a fault that turns out to have no isolation point.
Structural loading, the check that gets skipped
An array adds dead load to a roof and, more importantly, adds a surface for wind uplift. On an old industrial shed with unknown purlin condition, that is a real question. It gets skipped because checking it is inconvenient and because nothing bad happens on day one.
I check it, and where the roof cannot take the array I say so — which occasionally kills a project I would otherwise have been paid for, and is precisely why the check is worth having from someone with no equipment margin at stake.
A bill of materials specified to model number
"550W panels" is not a specification. "JA JAM72D40 715W N-Type bifacial" is. The difference matters because the second one makes substitution visible: if something else arrives on site, you can see that it did.
That is most of the practical value of a design document to an owner who is not an engineer. It converts an unverifiable purchase into a checkable one, whoever ends up building it.
Earthing, and why it is the first thing to go
Earthing and surge protection are omitted from a startling share of quotations in Pakistan, and the reason is straightforward: they cost money, they are invisible once installed, and leaving them out has no effect whatsoever on day-one generation. Nothing about the finished system looks different.
What they do is determine what happens on the day something goes wrong — whether a fault is a service call or a fire, and whether a nearby lightning strike takes out an inverter that was otherwise fine. An array is a large metallic surface on the highest part of a building, connected to expensive electronics. Treating its earthing as optional is not a cost saving; it is a deferred cost with an unknown due date.
A design from me specifies array earthing, equipotential bonding and, where the site warrants it, lightning protection — and it specifies them in a form your contractor can be held to rather than as a line saying "proper earthing to be provided".
Design review of someone else’s proposal
A shorter version of this engagement is reviewing a design or quotation you have already been given, and telling you what is missing from it. It is a small piece of work and it is frequently the highest-return money spent on the whole project — particularly where three quotations differ by amounts nobody can account for.
Questions
What clients ask before they commit
- Can I hire you only for the design and use my own contractor?
- Yes. You receive the single-line diagram, string layout, cable and protection sizing, earthing design, structural loading check and a bill of materials specified to model number. You build it with whoever you like. The bill of materials being model-specific is what lets you verify that what arrives on site is what was designed.
- What is included in a solar single-line diagram?
- The full electrical schematic from array through to the point of connection: string configuration, combiner arrangement, DC isolation and fusing, inverter, AC protection, earthing and bonding, and the metering point. It is also the document your distribution company will compare against the physical installation, which is why it has to reflect what was actually built rather than what was originally intended.
- Will you review a design or quotation I have already been given?
- Yes, and it is often the best-value work I do. It is a short engagement that tells you what is missing — usually protection detail, cable sizing justification, string sizing at temperature extremes, or structural verification. Where three quotations differ by amounts nobody can explain, a review normally explains them.
- Do you check whether my roof can take the array?
- Yes, as part of the design. Dead load and wind uplift are checked against the roof structure and the mounting arrangement. Where the roof cannot take it I will tell you, including when that means the project should not go ahead in its proposed form — I have no equipment margin riding on the answer.
- Why does string sizing need to consider temperature?
- Because open-circuit voltage rises as cells get colder. A string sized only against summer conditions can push the inverter beyond its MPPT window — or its maximum input voltage — on a cold winter morning. Sizing must hold at both extremes of the local temperature range, and designing at one temperature is among the most common errors I find on existing installations.
Next step
A site assessment, before anything is quoted
It starts with twelve months of your bills and a visit. If the numbers do not justify the work, that is what I will tell you — and you will have the analysis either way.
Or call 0312 4945198