Equipment selection guides, specification checklists and procurement resources for solar, storage and electrical projects. Browse by the decision you need to make.
Every guide below was written around a specific procurement decision — what to specify, what to check, what usually goes wrong — and each one links back to the equipment it refers to. If you would rather skip straight to a quote, send your requirements and we will work through the specification with you.
Equipment guides — what to specify before you buy
Core equipment and balance-of-system buying guides. Each one covers the specification fields that actually change the price or the delivery date, and the ones that are usually left blank and cause rework later.
Solar modules buying guide
Wafer format, power bin, degradation and what the flash test data actually tells you
Battery storage specification guide
Usable versus nameplate capacity, power-to-energy ratio, cycle life and warranty terms
Transformer specification guide
kVA rating, vector group, impedance, losses and cooling class
LV switchgear specification guide
Fault level, form of separation, fixed versus withdrawable construction
Mounting structure selection guide
Roof covering, foundation type, wind and snow region, corrosion class
Balance-of-system buying guide
Cabling, protection, earthing and the items that are usually ordered short
Procurement and compliance — what reviewers ask for
These cover the paperwork and the rules, which is where projects lose weeks rather than watts.
Import checklist for US buyers
documentation, classification and what delays a shipment
FEOC sourcing rules
what US projects have to evidence and how the documentation is assembled
Storage fire code compliance
UL 9540, UL 9540A and what the authority having jurisdiction asks to see
Module warranty claims
what a warranty covers, what voids it, and how a claim is evidenced
What moves solar equipment prices
the inputs that change a quotation, and which ones you can influence
Qualifying a supplier
what a factory audit looks at, the three inspections, and how to check a listing is real
Container loading and freight
what fits in a 40HQ, which limit binds first, and the packing specification to require
Letter of credit terms on equipment orders
Document terms, shipment milestones and banking fields to confirm before placing an equipment order.
Choosing a delivery term (Incoterms)
Delivery points, responsibilities and risk transfer to agree in the purchase contract.
Design, delivery and operations
From sizing through to year ten.
Inverter sizing
DC-to-AC ratio, string current limits and when clipping is intended
Grid connection requirements
interconnection studies, protection settings and commissioning tests
Microgrid controller: what it does and how to spec one
Operating modes, controller interfaces and transition requirements to define before ordering.
Commissioning checklist
what to verify before you sign off a project
Operations and maintenance
inspection intervals, spare parts holding and monitoring practice
What to define in an O&M contract
Response targets, spare parts, monitoring data and handover responsibilities to agree in writing.
Diagnosing underperformance
how to tell a fault from a normal seasonal variation
Hot spots: causes, detection and claims
Inspection methods, operating evidence and the records to prepare for a module claim.
Module selection and binning
matching modules to strings and to replacement arrays
What PID is and how to specify resistance
PID test evidence and the requirements to include in a module specification.
Site and structure — what to settle before the design is fixed
Resolve the site conditions that change equipment selection before the design is fixed. These guides cover structural, environmental and electrical questions that are costly to revisit later.
Roof life and roof warranty
how much remaining roof life an array needs, what voids the roof warranty, and what to get in writing
Wind and snow load calculation
what a project-specific calculation is issued against, and who signs it
Coastal and industrial corrosion
what a salt spray result actually proves, and where coated structure fails first
Ammonia corrosion on farm buildings
Site exposure, coatings and enclosure details for solar equipment on agricultural buildings.
Rapid shutdown requirements
the controlled conductor boundary, the two ways to comply, and what inspectors reject
Grounding and bonding: what to specify
Grounding, bonding and connection details to include in the equipment and installation scope.
Sizing and economics
Sizing solar plus storage for a facility
Load profiles, usable space, battery duty and electrical-service constraints to review together.
Choosing a DC/AC ratio and how far to oversize
Array and inverter capacity, current limits and clipping assumptions to compare during sizing.
Building a payback model
Tariff inputs, operating costs and project assumptions to make explicit in a payback model.
Calculating LCOE and which inputs belong in it
Energy yield, lifetime costs and discount-rate assumptions to document before comparing scenarios.
TOPCon versus PERC versus HJT
Module technology, operating conditions and specification evidence to compare for your project.
Application notes
Remote telecom sites
Critical loads, autonomy, site access and charge control to define for remote power.
Sizing a solar plus generator hybrid
Load behaviour, generator operating limits and storage control to coordinate in a hybrid system.
EV charging sites
Charger demand, site capacity and solar-plus-storage interfaces to define before procurement.
What installers should specify for homes
Home loads, backup scope and equipment interfaces to include in an installer brief.
Documentation by equipment and project scope
The required documents depend on the selected equipment, destination market and agreed engineering scope. Confirm availability, responsible parties and the delivery schedule in the quotation. The following documents may be relevant to procurement, installation, inspection or a later claim:
- Equipment datasheets and mechanical drawings for every item on the order
- Product listings and test reports matched to the selected equipment and destination-market requirements; confirm the applicable standards, issuing body and covered model
- Serial-level records — flash test data per module, battery cell traceability where applicable
- Structural calculation for mounting and racking, issued per project and per roof or ground zone
- Single-line diagram and torque specification for electrical equipment
- Packing list, commercial invoice and delivery documentation
The exact set depends on what you are buying — a module order and a switchgear order do not produce the same file — and the list is confirmed in writing on the quotation rather than being discovered at delivery.
Everything we have published
Browse the full article library
Equipment Guides
Ammonia Corrosion on Solar Equipment: Farm Sites
Why a salt spray result does not answer an agricultural site, what ammonia attacks first, and the coating, fastener and enclosure items to specify.
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Equipment Guides
Solar Module Hot Spots: Causes, Detection and Claims
Why a small shadow costs more than its area, how hot spots are actually found, and the distinction that decides whether a claim is a product claim at all.
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Off-Grid & Telecom Power
Microgrid Controller: What It Does and How to Spec One
Grid-forming versus grid-following, the four operating modes, why the transition is where projects fail, and the eight items to settle before ordering.
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Equipment Guides
Solar Array Grounding and Bonding: What to Specify
Equipment grounding and bonding are two different jobs, why surge protection fails without the earth path beneath it, and what belongs in the specification.
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Commercial & Industrial Solar
Solar O&M Contract: What to Define Before You Sign
Response versus resolution time, how availability is counted, who owns the spares and the data, and the handover clause most contracts leave out entirely.
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Procurement & Compliance
Incoterms for Solar Equipment Orders: How to Choose
What a trade term actually decides about risk, cost and customs, why EXW and DDP cause trouble, and the items to settle before the order goes out.
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Procurement & Compliance
Letter of Credit for Solar Equipment: What to Specify
Why banks deal in documents rather than goods, where solar equipment orders run into discrepancies, and the fields to settle before you instruct a credit.
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Equipment Guides
Solar Module PID: Causes, Testing and Specification
What PID is, why it shows up as a gradient along the string, how PID resistance is tested rather than claimed, and what belongs in the specification.
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Commercial & Industrial Solar
How to Calculate LCOE for Commercial Solar + Storage
Which inputs belong in a commercial solar LCOE calculation, which get left out, and why a figure without a stated discount rate cannot be compared.
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Off-Grid & Telecom Power
Solar + Generator Hybrid: Sizing and Integration Guide
How to size a solar + generator hybrid: generator minimum load, motor inrush, battery autonomy and SoC setpoints. Checks to run before you request a quote.
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Equipment Guides
Solar DC/AC Ratio: How Much Oversizing Actually Pays
How to pick a DC/AC ratio for a solar plant: which range fits each site type, what moves it up or down, and how to check the number a supplier gives you.
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Procurement & Compliance
How Much Solar Equipment Fits in a 40HQ Container
40HQ dimensions, payload limits and loading quantities for solar modules, inverters, batteries and racking, plus which of the two limits binds first.
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Equipment Guides
Coastal Solar Mounting: Salt Spray and Coatings
What a salt spray test does and does not prove, where coated mounting structure actually fails, and how to specify coastal corrosion resistance in writing.
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Equipment Guides
Solar Rapid Shutdown: What US Projects Need
Rapid shutdown explained for solar installers and EPCs: the array boundary, module-level versus array-level control, and the four questions to settle first.
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Procurement & Compliance
Solar Supplier Audit: Factory and Inspection
How to qualify a solar equipment supplier: what a factory audit looks at, which inspection catches what, and how to check a listing is current and in scope.
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Commercial & Industrial Solar
Commercial Roof Solar: Roof Life and Warranty
Check roof life, waterproofing and roof warranty before a commercial array goes on. What to confirm in writing, and what usually voids coverage.
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Commercial & Industrial Solar · Equipment Guides
Solar Mounting Load Calculation
Procurement guide7 min readGTP SolarThe number that governs your racking is almost never the regional wind speed. It is which roof zone or which array row the equip…
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Commercial & Industrial Solar · Equipment Guides
Solar Plant Operations and Maintenance
Procurement guide6 min readGTP SolarOperations and maintenance is usually specified after handover, which is the wrong end of the project. The inspection intervals,…
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Commercial & Industrial Solar · Equipment Guides
Solar Inverter Sizing Guide
Procurement guide6 min readGTP SolarInverter sizing looks like a simple division - array kilowatts divided by something - and it is not. Two arrays of the same rati…
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Commercial & Industrial Solar · Equipment Guides
Solar Mounting Structures: How to Specify the Right System
How to choose a solar mounting system: roof type and attachment, ballast vs penetration, ground foundations, ASCE 7 loads, coating class, tilt and spacing.
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Commercial & Industrial Solar · Procurement & Compliance
Battery Storage Fire Safety and Code Compliance: The Submittal Checklist
What a US battery storage submittal needs: UL 9540 and UL 9540A, NFPA 855 separation, siting rules, detection and suppression, and where review fails.
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Equipment Guides · Procurement & Compliance
Solar Module Warranty: What It Covers and How Claims Work
How module warranties actually work: product vs performance cover, what voids a claim, how output is measured, and the evidence pack that gets a claim paid.
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Equipment Guides · Procurement & Compliance
Why Solar Equipment Prices Vary: What Actually Moves the Quote
What drives solar equipment pricing in 2026: module price bands, power bins, BOS and installation, storage cell costs, quantity tiers and compliance.
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Commercial & Industrial Solar · Equipment Guides
LV Switchgear: How to Specify a Board That Passes Inspection
How to specify LV switchgear: rated current, short-circuit rating, form of separation, protection discrimination, IP rating and IEC 61439 type testing.
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Commercial & Industrial Solar · Equipment Guides
Distribution Transformers: How to Specify One Correctly
How to read a transformer nameplate: rating, vector group, impedance, losses, cooling and the IEC vs ANSI choice that decides the test report.
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Commercial & Industrial Solar · Equipment Guides
Residential Solar + Battery: What Installers Should Specify
Residential storage is sold on backup and bought on self-consumption. Getting the specification right means designing for the second and explaining the first.
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Commercial & Industrial Solar · Equipment Guides
Solar and Storage for EV Charging Sites: What to Specify
On an EV charging site, the grid connection is usually the constraint, not the chargers. Here is what to specify before the utility quote arrives.
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Equipment Guides
Solar Plant Underperformance: A Diagnostic Sequence
Before assuming a fault, establish whether the plant is actually underperforming. Then work the causes in the order that finds them fastest.
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Commercial & Industrial Solar · Procurement & Compliance
Commercial Solar Payback: How to Model It Honestly
A payback figure is an output of a model, not a fact about a system. Here is how to build the model so the number means something.
Read article →Procurement & Compliance
FEOC Sourcing Rules: What US Solar Buyers Must Document
From 2026, equipment sourcing affects federal tax credit eligibility. Here is what US buyers should require from suppliers before issuing a PO.
Read article →Equipment Guides
TOPCon vs PERC vs HJT: What B2B Buyers Should Specify
Module efficiency is the least useful number on the datasheet. Here is what actually separates TOPCon, HJT and PERC in 2026.
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Equipment Guides · Procurement & Compliance
Balance of System: The B2B Equipment Buying Guide
Modules and inverters get the attention; balance of system is where budgets break. A practical BOS guide for commercial projects.
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Equipment Guides · Procurement & Compliance
Solar Project Commissioning: What to Check Before Sign-Off
Most commissioning delays trace back to the week the container arrived. The sequence EPC teams should run before sign-off.
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Equipment Guides
Solar Inverters and Grid Connection: A B2B Checklist
The inverter is the component most likely to be wrong on a first specification. Here is what to confirm before grid-connected equipment is ordered.
Read article →Commercial & Industrial Solar · Equipment Guides
Battery Energy Storage: How B2B Buyers Should Specify a BESS
Two batteries with the same kWh rating can behave nothing alike. This is the specification checklist B2B buyers should send before comparing storage quotations.
Read article →Procurement & Compliance
What to Check Before Importing Solar Equipment into the US
Most import problems are documentation problems. What B2B buyers should confirm before solar and battery equipment leaves the factory.
Read article →Equipment Guides
Solar Modules: What B2B Buyers Should Check Before Ordering
Module datasheets are easy to skim and easy to misread. The checklist B2B buyers should run before committing to a PV module order.
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Equipment Guides · Off-Grid & Telecom Power
Off-Grid Solar for Telecom Sites: What Remote Operators Actually Need
Remote sites fail for mundane reasons - undersized autonomy, wrong enclosure rating, no service margin. A practical equipment checklist for off-grid and telecom power.
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Commercial & Industrial Solar · Equipment Guides
How to Size a Commercial Solar + Battery System for Your Facility
Sizing a commercial system starts with the load, not the roof. This guide walks through the sequence we use before putting a B2B equipment list together.
Read article →Questions, specifications and quotes
The procurement FAQ covers the questions that come up on almost every order — lead times, minimum quantities, mixing models on one delivery, certification, and how claims are handled.
If you have a specification to price, send it here. Send the single-line diagram, the site location, and your target date if you have them; we confirm the specification, the documentation set and the delivery date in writing.
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