The 7 Hidden Exclusions in Commercial Solar EPC Tenders That Turn a $300k Project into a $480k Nightmare
You did the hard part. You got three commercial solar tenders, compared the headline prices, and picked the one that looked like the best value.
Then the variations started. A switchboard upgrade here. A DNSP fee there. A roof repair, a metering change, a protection upgrade, and suddenly the project your board approved at $300,000 is heading for $480,000, and nobody can quite explain why it was not in the original price.
This is not rare, and it is not usually a conspiracy. It is what happens when a tender is written around a solar array, while the real project includes a building, a switchboard, a network connection, an insurer, and a set of Australian Standards that do not care what the sales proposal said.
The array is often the easy part. The exclusions are where the money, the delay, and the risk live.
At EServices4U, our principal engineers bring 22+ years of Australian electrical and renewable energy experience and over 1 GW of audited project track record. Operating strictly as an Independent Owner's Engineer with zero installer commissions and zero hardware markups, we check the tender you already have, solely to protect your budget and your building.
1. What an EPC tender price usually means, and what it does not
EPC stands for engineering, procurement and construction. In a good commercial solar tender, the EPC price should cover the design, the equipment, the installation, the commissioning, and the handover documentation for a working, compliant system.
In a weak tender, the price covers the equipment and the labour to install it, and everything else is either assumed, excluded, or left as "to be confirmed".
The difference is rarely in the big print. It is in the exclusions schedule, the assumptions page, the single line diagram (SLD) notes, and the three words that should make any buyer pause: "by others", "excluded", and "subject to".
If your tender says the DNSP connection is "subject to approval", that is not a price. It is a risk. If it says switchboard works are "by others", someone still has to pay for them, and that someone is usually you.
An independent review does not make a tender more expensive. It makes the real price visible before you sign, when you can still negotiate it, stage it, or walk away from it.
2. The 7 hidden exclusions, in the order they usually bite
Switchboard capacity, protection, and arc flash: Your main switchboard was sized for the building, not for a solar inverter exporting into it. A tender may price the inverter and the cable to the board, but exclude new breakers, busbar work, protection coordination, or a full board upgrade. It may also exclude an arc flash study. Under AS/NZS 3000 and the principles in IEEE 1584, adding solar changes fault levels, and old arc flash labels can become invalid. That is a safety issue first and a cost issue second.
Roof structure, penetrations, and warranty: A warehouse roof has a structural capacity, a drainage fall, and a membrane or sheet warranty that a solar installer may never have seen. Tenders often exclude structural certification, reinforcement, penetration flashing, and any work needed to preserve the roof warranty. If the original roofer will not warrant penetrations made by someone else, you can be left with a leaking roof and two contractors pointing at each other.
DNSP connection, export limits, and protection settings: You cannot simply connect a commercial system and export at full power. Your DNSP, whether Energex or Ergon Energy in Queensland, AusNet or Powercor in Victoria, Ausgrid or Endeavour Energy in New South Wales, SA Power Networks, or Western Power, sets connection, protection, and export rules for your site. A tender may assume full export, while your site actually needs a network study, an export limit, or specific inverter protection settings under AS/NZS 4777.2. A system that cannot export as modelled will not deliver the financial return in the proposal, even if it generates exactly as promised.
Metering, current transformers, and monitoring: Commercial billing is not residential billing. Exclusions here include new meters, current transformers (CTs), metering panel work, export meters, sub-meters, and the monitoring platform itself. A system with no accurate interval data, in line with NMI interval modelling principles, cannot prove its savings, its warranty claim, or a tenant charge.
Cable runs, containment, voltage rise, and site conditions: The distance between the roof and the switchboard matters. AS/NZS 3008.1.1 governs cable selection, and AS/NZS 3000 governs installation, but a tender that prices a short, straight cable run will not cover a long run through a live warehouse, new cable tray, fire-rated penetrations, or out-of-hours work. Voltage rise is a particular trap: if the inverter trips on high voltage at midday, your best generation hours are lost.
Compliance, fire safety, labelling, and handover documentation: A compliant system needs design compliance with AS/NZS 5033 for PV arrays, AS/NZS 4777.2 for inverters, and AS/NZS 3000 for wiring, plus as-built SLDs, test results, and commissioning records that a future contractor, insurer, or buyer can actually use. Tenders sometimes exclude independent inspection or the full handover pack. That saves money on day one and costs money for years.
Performance, warranties, and who fixes it in year three: A headline performance guarantee may exclude soiling, shading changes, network outages, or degradation beyond a broad range. Equipment warranties may be manufacturer warranties, not installer warranties, and they may require you to diagnose the fault or pay for labour. Operations, cleaning, monitoring, and response times are often "available separately", which means they are not in the price you compared.
In Queensland, professional engineering work must be carried out or supervised by a Registered Professional Engineer of Queensland (RPEQ) under the Professional Engineers Act 2002 (QLD). In Victoria, the Professional Engineers Registration Act 2019 (VIC) sets a similar framework for RPEV engineers. If your project needs RPEQ or RPEV sign-off, that scope, and who holds it, should be in the tender, not discovered at handover.
3. A worked example: how $300,000 becomes $480,000
The figures below are illustrative, not a quote, and they will vary by site, size, and state. They show how ordinary exclusions add up, without any single item looking unreasonable on its own.
Exclusion | Illustrative variation | What it usually covers |
Switchboard upgrade and protection | $45,000 | New breakers, busbar work, protection coordination, arc flash study |
Roof structural certification and penetrations | $25,000 | Engineering certification, reinforcement, flashing, warranty work |
DNSP study, export limiting and protection | $20,000 | Network study, export controls, protection settings, fees |
Metering, CTs and monitoring | $15,000 | Meters, CTs, panel work, monitoring platform setup |
Cable, containment and voltage rise fix | $30,000 | Larger cable, tray, fire stopping, out-of-hours work |
Compliance, inspection and handover | $15,000 | Independent inspection, commissioning records, as-built SLDs |
Performance shortfall and O&M in year one | $30,000 | Cleaning, monitoring, response, and lost generation while issues are fixed |
Total variations | $180,000 | Original $300,000 + $180,000 = $480,000 |
None of these items means the original tender was dishonest. Together, they mean the original tender was incomplete as a project price. A buyer who sees the full scope before signing can negotiate a fixed price for the switchboard, stage the metering, or choose a smaller system that actually fits the board.
How This Works for Both Sides: Companies and Professionals vs. Everyday Australians
Tender & Contract Area | For Companies and Professionals (Facility Managers, CFOs, EPCs) | For Everyday Australians and Property Owners |
Tender comparison | Like-for-like comparison on a complete scope, with a defensible board paper and a clean SLD. | A plain-English list of what is included, what is excluded, and what each exclusion is likely to cost. |
Switchboard and DNSP risk | Fault-level and protection checks, DNSP connection and export modelling before construction. | No surprise switchboard or transformer bill after signing, and no system that cannot export as promised. |
Insurance and handover | A handover file that survives an insurer audit, a tenant dispute, or a building sale. | A system that can be insured, maintained, and sold because the documentation actually exists. |
Fixed-Fee EServices4U Solution |
Frequently Asked Questions (FAQ)
Should I get an independent review if I already have three tenders?
Yes, especially then. Three tenders with different exclusions are not three prices for the same project. An independent review turns them into a like-for-like comparison, so you are choosing on scope and value, not on who left the most out.
Does an RPEQ or RPEV review replace my EPC contractor's design?
No. It checks it. Your EPC contractor still designs and builds the system. The independent engineer verifies the design, the SLD, the protection, and the compliance scope, and flags gaps before they become variations or insurance issues.
What should I send for a commercial tender review?
Send all tenders, the SLD, your last 12 months of interval or billing data, and any DNSP correspondence together, rather than in separate emails. That is the fastest way to get a complete, like-for-like review.
Is a commercial assessment really from $495?
Commercial assessments from EServices4U start from $495, with the final scope and fee confirmed before work starts, based on system size, site complexity, and whether a site visit or SLD sign-off is required. Residential quote reviews start from $149, feasibility assessments from $299, and Home Owner's Engineer services from $599.
De-Risk Your Next Commercial Solar Tender: Contact Our RPEQ/RPEV Team Today
Not sure which review you need? Start with a free 15-minute consultation to talk through your tender, system, or project and find out which fixed-fee review fits, if any. Call/WhatsApp 0480 001 498 or email growthpartner@eservices4u.com.au. No obligation, and it does not include a written report.
For CFOs, Facility Managers and Property Owners: Reviewing a commercial solar tender or EPC contract? Email your tenders, SLD, and interval data to growthpartner@eservices4u.com.au or call/WhatsApp 0480 001 498 for an independent Commercial Infrastructure Assessment (From $495).
For Homeowners and Small Businesses: Comparing solar or battery quotes? Book a fixed-fee review (Packages from $149 to $599).
For EPC Contractors and Electrical Contractors: Need statutory RPEQ (QLD) or RPEV (VIC) SLD certification or independent tender review? Request priority service at www.eservices4u.com.au/quote.
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