After Dark | By Piotr Mikus
After Dark (Series): Browse the series: https://solarlightingnightshift.com/category/after-dark/ | Previous: Your Solar Panel Is Not the Wattage on the Label
(What to demand before award, while both sides can still walk away from the date):
- Irradiance dataset, years and plane named, with something better than a famous logo
- Battery chemistry, usable depth of discharge and charging temperature floor stated
- Load in watt hours for every programmed profile
- Hourly simulation files with the inputs attached
- One guaranteed number: unmet load in hours dark per year
- Definitions for autonomy and for “meets RP-8-25” that someone could actually fail
A solar lighting purchase is a blind date with a long lease attached. Most of the damage gets done before anyone gets on a call.
Every solar lighting project starts like a bad date: with a profile. The spec gets written, the submittal answers it, the sizing sheet makes promises, and somewhere in the middle a space agency gets name dropped for credibility. Nobody has talked to anybody yet.
Then commissioning day arrives, and the profile has to turn its camera on.
The Spec Writes the First Lie
A vague spec does not catch liars. It gives them room.
Five days of autonomy. Sounds like engineering. At what depth of discharge? At what temperature? On which battery chemistry? The buyer never said, the supplier never volunteered, and both walked into the date smiling.
“Meets RP-8-25” has the same problem. Meets it where? At what operating level, at what hour of the night, at the end of which winter? That sentence carries the confidence of a handshake and the enforceability of a weather forecast.
Then the submittal arrives, perfectly formatted, filled with datasheet numbers. Rated panel watts. Nominal load watts. Label battery capacity. All true in a laboratory, under conditions nobody asked about. That is the gym photo on the dating profile.
The Sizing Sheet Says the Sun Always Texts Back
The photos are from 2019 and the dataset has no years.
The sizing sheet promises hours of light, gray days of reserve and an array to load ratio that looks reassuring. Then it cites NASA, and the review ends, because nobody wants to argue with NASA. I took that apart in Nobody Argues With NASA. Your Battery Never Got the Memo. NASA measured the sun. Nobody at NASA sized your battery.
An unsupported irradiance claim names no dataset, no years, no plane. A miscalculated system balances only if a loss factor hides somewhere in the math. Both get signed, both ship, and the pole gets built exactly as designed. Whatever was wrong on paper is now standing in the ground.
Nobody shows up in January with an extra battery and an apology. The design is the design, and the only moment to check it is before award.
Commissioning Day: The First Video Date
The profile finally turns its camera on.
On commissioning day the assembled system gets connected to the app, usually remotely, and the customer takes control. Schedules, dimming, maintenance tools, everything the platform offers, handed over. RP-8-25 Section 6.10.4 describes commissioning as ensuring the system is designed, installed, tested, operated and maintained to the operational needs of the owner. Operated and maintained become the customer’s job from that minute.
It is also the first time the buyer and the manufacturer actually work together, and the first time the customer touches a system that the spec described and the sizing sheet promised. Every control they now hold moves the load. Raise a dimming level for an event, stretch a profile to answer a complaint, and the energy budget behind the sizing moves with it. If the sheet never stated its profiles in watt hours, the customer has no idea where the cliff is. They find it in January, in good faith, with admin rights.
In It for Good, or a Blind Date That Turns Sour
Some manufacturers stay on the call. Others drop off after the login works.
Commissioning happens over a screen now, which means the relationship gets one session to start well. A real solar lighting manufacturer treats that session as the beginning. Someone gets on the call with the customer, walks through the controls and the maintenance tools on screen, documents the programmed profiles against the sizing and hands over the as built record. They designed the system from real inputs, so a comparison between promise and performance is welcome. Winter becomes a reference, and support has something solid to stand on.
The other kind ships the boxes, sends a login and a PDF, and treats commissioning as the delivery receipt. The customer finds out what that manufacturer is really like when something breaks, and discovers the profile was a catfish. The sizing never stated its profiles. The irradiance never named its dataset. The guaranteed number was never guaranteed.
Solar did nothing wrong. The paper did.
Same poles. Same sun. One relationship lasts, and the other ends up with lawyers.
What to Require in a Specification
If it is not in the contract, it was small talk.
Keep it enforceable:
- Complete sizing package submitted with the bid and reviewed before award: dataset, resolution and years, the plane with tilt and azimuth, itemized derates, battery chemistry, voltage, usable depth of discharge, charging temperature floor
- Load in Wh for every programmed profile, so the customer knows what the controls can change
- A sequential hourly run in HOMER Pro with the input files attached
- One guaranteed number: unmet load in hours dark per year
- Conditions stated for every term in the spec, autonomy and “meets RP-8-25” included
- Commissioning handover written into the contract: system connected to the management platform, owner accounts with administrator access, a live training session on controls and maintenance, support contacts and response terms
- Data ownership and platform access terms for the owner
- As built record per pole: panel tilt and azimuth, battery chemistry, charging temperature limit, programmed profiles, firmware version
- What the supplier owes if the system misses its own stated number after the first winter, written before award
Three Questions to Ask Before You Sign
Ask now. The answers get shorter afterward.
Which dataset, which years and which plane produced the irradiance value in the sizing sheet, and can I have the input files?
What load in watt hours does each programmed profile assume, and what can I change in the app before I break the autonomy you quoted?
Who gets on the call with my team on commissioning day, how long do they stay on it, and who picks up the phone in January?
A supplier who built it right answers before the coffee gets cold.
Closing Thought
The spec writes the profile. Commissioning day is when the customer finds out whether it was true.
Everybody looks good before the first call.
Sources and Where to Verify
- ANSI/IES RP-8-25 (2025), Sections 5.4.10 (record drawings), 6.10.4 and 6.10.4.1 (integration and commissioning, interoperability)
- ANSI/IES LP-8-20, Lighting Practice: The Commissioning Process Applied to Lighting and Control Systems (cited in RP-8-25)
- NASA POWER, daily and hourly solar irradiance series: https://power.larc.nasa.gov/
- HOMER Pro documentation, time series simulation and imported resource data
- IEEE 1562, Guide for Array and Battery Sizing in Stand Alone Photovoltaic Systems
- Battery manufacturer datasheets for the stated chemistry (usable depth of discharge, cycle life, charging temperature range)
- Solar Lighting Night Shift, Nobody Argues With NASA. Your Battery Never Got the Memo.: https://solarlightingnightshift.com/2026/10/19/nobody-argues-with-nasa-your-battery-never-got-the-memo/
Piotr Mikus is a roadway lighting designer and specifier focused on solar powered street lighting and controls.
Quick FAQ
What happens on commissioning day for a solar street lighting system? The assembled system gets connected to the management app, usually remotely, and the customer takes control of the lighting controls, the maintenance functions and the other tools the platform provides. A real manufacturer uses that session to start working with the client.
Why is commissioning the start of the buyer and manufacturer relationship? It is the first day the customer operates a system defined by the spec, the submittal and the sizing sheet. Any misleading claim in those documents lands in the customer’s hands, and the manufacturer’s response sets the tone for every year after.
Can a manufacturer fix a sizing error after commissioning? The system has to be designed correctly from day one. A pole is built as designed, and nothing in the app corrects a miscalculated system. The sizing package, with hourly simulation files, belongs under review before award.
Continue reading the series: https://solarlightingnightshift.com/category/after-dark/
