Solar mounting structure costing is the work of finding out what each rail, leg, purlin and clamp really costs to make, from the metal you buy to the piece you ship. A structure factory buys aluminium or steel by the kilogram, cuts it by the millimetre and sells it by the piece, and most costing breaks somewhere between those three units. This guide stays on the shop floor. It shows how a single bar turns into pieces, kerf, trim and offcuts, where money leaks out of that process, what master data an ERP needs to track it, and how to test a vendor with your own numbers before you buy.
Key Takeaways
- Every structure part lives in three units at once. It is bought in kilograms, cut in millimetres and sold in pieces, and costing fails when the system holds only one
- Kerf, end trim, processing allowance and offcuts are metal you paid for. Estimates built on weight alone understate the true cost per piece
- A small change in piece length can change pieces per bar, which can move cost per piece by more than 15 percent
- Closing a production order should reconcile kilograms in against pieces, offcuts and scrap out, with a variance alert
Table of Contents
- Why Costing Breaks for Solar Structure Makers
- One Part, Three Units
- Where the Cost Leaks
- How an ERP Handles Solar Mounting Structure Costing
- Master Data That Makes Conversion Work
- Closing a Production Order
- Pricing and Quoting From Real Cost
- Vendor Evaluation Checklist for Structure Makers
- Preparing Data Before the Demo
- FAQs
Why Costing Breaks for Solar Structure Makers
Most structure makers already have some kind of software for solar manufacturers in place, usually for sales and billing. That software rarely sees the factory floor, where cost is decided.
- Billing software sees invoices, not metal. Many structure makers run on a GST billing app. It records what was sold, but not how many kilograms went into each piece or how much came back as offcuts.
- Standard weights hide real usage. A price list built on theoretical weight per piece ignores what the saw, the trim and the leftover lengths consume.
- Metal prices move every week. Without live costing, margin stays a guess until the month closes.
The symptom is a margin that looks fine on every quote and thin at year end. The gap is usually metal that was bought, cut and lost, but never costed.
One Part, Three Units
Every structure part is counted in a different unit depending on who touches it. Solar mounting structure costing only works when the system can move between those units without anyone doing the arithmetic in a spreadsheet.
| Stage | Unit | Who Uses It | What Goes Wrong Without Conversion |
|---|---|---|---|
| Purchase | Kilograms | Purchase and accounts | Supplier bills cannot be matched to bars received |
| Stock and cutting | Bars and millimetres | Stores and production | Stock in kilos says one thing and the rack says another |
| Sale and dispatch | Pieces, sets or kilograms | Sales and dispatch | Invoices priced per piece cannot be traced back to metal cost |
The Link That Holds It Together
- Weight per metre, stored on each profile. It converts kilograms to length and back, for every bar, piece and offcut.
- Standard bar length. Profiles usually arrive in fixed lengths.
- Pieces per set. A structure kit for one table or one kWp is a fixed count of each part.
Where the Cost Leaks
Metal you paid for that never reaches a customer
- Kerf. The saw blade removes a few millimetres on every cut. Thousands of cuts a month add up to real kilograms.
- End trim. Bar ends are often squared off before cutting begins.
- Processing allowance. Extra length kept on each piece for drilling, punching or finishing.
- Offcuts. The leftover length after the last full piece. Whether it is reused or scrapped changes the cost.
- Weight drift. Actual weight per metre can differ from the catalogue figure.
- Job work losses. Material sent to anodisers or galvanisers can come back lighter or short. Getting subcontracting valuation and stock ownership right keeps that loss visible.
Small leaks compound. A loss of one or two percent per bar looks harmless. Across tonnes of aluminium a month, it eats real margin.
How an ERP Handles Solar Mounting Structure Costing
The cut plan is the core of solar mounting structure costing. Every bar is split into five parts, and those parts must add back to the bar length exactly.
The Cut Plan in Plain Arithmetic
- Usable length equals bar length minus end trim.
- Length consumed per piece equals piece length plus processing allowance plus kerf.
- Pieces per bar equals usable length divided by length consumed per piece, rounded down.
- Offcut equals usable length minus pieces per bar multiplied by length consumed per piece.
- Balance check. Finished pieces, allowance, kerf, trim and offcut together must equal the bar length. If they do not, the plan is wrong.
Worked Example With One Aluminium Bar
These illustrative values use a 6,000 mm bar weighing 1.2 kg per metre, so 7.2 kg per bar. Metal costs ₹280 per kg, which makes the bar worth ₹2,016. Kerf is 3 mm, end trim is 20 mm and the processing allowance is 5 mm per piece. Scrap is credited at ₹150 per kg.
| Item | 1,450 mm Piece | 1,500 mm Piece |
|---|---|---|
| Pieces per bar | 4 | 3 |
| Finished length | 5,800 mm | 4,500 mm |
| Allowance, kerf and trim | 20, 12 and 20 mm | 15, 9 and 20 mm |
| Offcut | 148 mm | 1,456 mm |
| Yield | 96.7% | 75.0% |
| Cost per piece by weight alone | ₹487.20 | ₹504.00 |
| Real cost with offcut scrapped | ₹495.00 | ₹582.00 |
| Real cost with offcut returned to stock | ₹489.23 | ₹506.29 |
Every part in both columns adds back to 6,000 mm. A piece just 50 mm longer drops the bar from four pieces to three. If the 1,456 mm offcut is scrapped, the real metal cost per piece is 15.5 percent above the weight based figure. If the offcut goes back to stock for a later order at full metal value, the gap almost disappears.
Master Data That Makes Conversion Work
Set these up before the first production order
- Profiles. Weight per metre, standard bar length, alloy and temper, and supplier die reference for every profile.
- Saws and work centres. Kerf per blade, standard trim per bar and hourly cost.
- Finished parts. Cut length, processing allowance, operations such as punching or drilling, and finish.
- Offcut rule. A minimum reusable length per profile. Anything shorter is scrap.
- Scrap rates. Credit per kilogram by alloy or material, reviewed whenever scrap buyers change their rates.
- Process costs. Anodising, powder coating or galvanising rates, per kilogram, per metre or per square metre, the way your job workers bill.
- Kits and structures. Pieces per structure set or per kWp, including fasteners and clamps. In most systems this lives in bills of materials and work orders.
Bad master data produces confident wrong numbers. Weigh sample bars from each supplier before going live, because a wrong catalogue weight skews every cost.
Closing a Production Order
Solar mounting structure costing is only as good as the way each production order is closed. This is where planned yield meets what the saw actually did.
- Record what was issued. Number of bars, plus any offcuts drawn from stock.
- Record what came out. Good pieces, rejects, offcuts returned to stock with their length, and scrap weighed on a scale.
- Reconcile in kilograms. Weight issued should equal pieces, offcuts, scrap and expected process loss combined. Anything left over is unexplained variance.
- Flag exceptions. Set a variance threshold per profile. Orders above it go to a supervisor before they close.
- Post the cost. Record actual metal, process and labour cost per good piece against the quoted standard cost.
Alerts beat surprises at month end. An automatic flag on orders with high variance catches a worn blade or a wrong cut plan within days.
Pricing and Quoting From Real Cost
- Quote from replacement cost. Price metal at today's purchase rate, not the cost of bars already in stock.
- Build up from the piece. Go from cost per piece to per set, per kWp or per tonne, as the customer buys.
- Use actual yield, not theoretical. Feed the last few months of real yield per profile into the quote, so wastage is priced in.
- Keep validity short. For longer projects, agree a metal price adjustment clause linked to a published rate.
Imported material needs landed cost. Duty, freight and clearing charges belong in the metal rate.
Vendor Evaluation Checklist for Structure Makers
Use this together with the broader solar ERP evaluation checklist. The checks below are specific to solar mounting structure costing on the factory floor.
| Check | Ask the Vendor to Show | Red Flag |
|---|---|---|
| Kilogram to length conversion | Purchase in kg, stock in bars and cut in mm, using weight per metre for each profile | One global conversion factor for all profiles |
| Cut plan | Pieces per bar with kerf, trim, allowance and offcut | Pieces calculated from weight only |
| Offcut stock | Offcuts returned with length and reused on a later order | Offcuts lumped into scrap |
| Order close | Weight reconciliation with a variance alert | Only finished quantity recorded |
| Costing | Actual versus standard cost per piece, per order | Average cost only, after the month closes |
| Upgrade safety | How custom costing logic survives new versions | No answer, or a promise to rewrite it |
Expect some of this to be built, not bought. Cut plans and weight reconciliation are rarely standard features. Understanding customization versus configuration helps you ask which parts are settings and which are new code.
Preparing Data Before the Demo
What to Bring
- Your ten highest volume profiles with measured and catalogue weight per metre, and standard bar lengths.
- Three real orders with part lengths, quantities and finishes.
- Saw kerf, standard trim and your offcut reuse rule.
- Last month's metal purchase, scrap sale and finished dispatch totals in kilograms.
What to Ask the Vendor
- Build a cut plan for one order and show the balance check adding back to bar length.
- Close a production order with rejects, an offcut and weighed scrap.
- Show the real cost per piece against the cost in your quotation.
- Reconcile last month's kilograms in against kilograms out.
Your own numbers expose weak systems fast. A functional consultant can prepare the data pack and run the comparison.
Structure Costing
Want to Know Your Real Cost per Piece Before the Next Quote?
Tatvamasi Labs sets up ERP for solar structure manufacturers with weight to length conversion, cut plans, offcut stock and production order reconciliation, so every quote starts from real cost.
Get a Costing Review →Frequently Asked Questions
Solar mounting structure costing is the method of finding the true cost of each rail, leg, purlin or clamp a factory makes. It follows metal from the kilograms bought to every cut, offcut and scrap kilogram, then adds process costs.
Take the cost of the bar issued, subtract the value of reusable offcuts and the credit for scrap, and divide by the number of good pieces produced. Then add finishing, labour and overheads.
Kerf is the width of metal the saw blade removes with every cut. Across thousands of cuts a month it becomes real kilograms of metal you paid for and never sell.
Set a minimum reusable length for each profile. Longer offcuts go back to stock for a later order. Offcuts below it are scrap, credited at the scrap rate.
Most ERPs convert units within one category, but not weight to length. Each profile needs its own weight per metre, used in purchasing, stock and production.
Quote from the current replacement cost of metal, not the cost of old stock, and keep validity short. Longer projects need a metal price adjustment clause.
Yes. Steel channels and purlins are also bought by weight, cut by length and sold by count. The same cut plan, offcut rule and scrap reconciliation apply.
Prefer a quick chat? Talk to Tatvamasi Labs about solar mounting structure costing.
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