Your grow lights, finally in sync with the sun.
FairGrow measures the natural light and only tops up what your crops are missing. Through the open Horti Lighting Protocol, without an expensive climate computer.
Light on a timer, not on the plant
Most grow light setups have no idea what the sun has already done that day.
A fixed timer, even when the sun shines
Your lights switch on at a set time, bright day or not. You end up paying for light your crop already had.
On a grey day nobody knows
How much light is still missing after a day of cloud? Without a measurement it is guesswork, and guessing costs either yield or power.
Every brand speaks its own language
Lights and controls talk differently from one supplier to the next. Connecting them turns into custom work, and custom work is expensive.
Measure, calculate, top up exactly
One day in the greenhouse, in five steps. Pause the animation or walk through it step by step.
Animation of one day in a greenhouse. The sun climbs and a PAR sensor between the crop measures the light. The readings travel over ESP-NOW to the HLP node, which stays connected to FairGrow over wifi all day. At 16:00 the daily light integral turns out to be behind target. The node has the LED lights top up through the lighting gateway until the target is met exactly. Then the lights switch off, FairGrow receives the report over wifi, and the lighting network stays separated from the internet.
- The PAR sensor measures the sunlight your crop actually receives.
- Every reading goes to the HLP node locally. No internet is needed for that.
- At 16:00 the node does the sums: today’s target will not be met.
- The node tops up with exactly the light that is still missing.
- Done. FairGrow gets the report over wifi. Nothing ever travels from the internet to your lights.
Not how bright, but how much light per day
Plants count in light per day, not in watts. That daily light integral, or DLI, is expressed in moles per square metre per day. From sunrise onwards the PAR sensor adds up all the light your crop can use for growth.
If the total at, say, 16:00 is still below the target you set for your crop, the HLP node tops up with LED light until the target is reached. If the sun delivers enough, the lights simply stay off.
The grow light calculator works out which target suits your crop.
The sun delivers about 11 mol. The node tops up 6 mol, roughly 7 LED hours.
Illustrative values: target 17 mol/m²/day, LED light at 250 µmol/m²/s. Your crop and installation set the real numbers.
Your lighting network never touches the internet
The HLP node itself is connected to FairGrow over wifi. Your lights and the cable to them never are: the node talks to FairGrow over wifi and to your lights over a cable, and passes nothing from one network to the other.
Two networks, one bridge that stays shut
Wifi upwards, cable to your lights. No traffic runs from the internet to your lighting network, not even through the node.
If the internet drops
Your rules keep running locally. The node has its own clock and receives the PAR readings directly.
If the node fails
Your lights fall back to the power-on light level you set yourself for each light group.
You decide who is in charge
You always start in read mode. Control is a separate, deliberate step.
Read: your climate computer controls the lights, FairGrow only watches.
Read
You already have a climate computer. It stays in charge of your lights. FairGrow only watches: consumption, realised light, faults and alarms. In this mode the node writes nothing to your lights.
Control
FairGrow is your only control. You set the rules in the automation editor and the node carries them out. When you switch over you confirm that no other system is controlling the lights, and you set the power-on light level for each light group.
A rule you can read yourself
Automations are written in YAML, the same shape as in Home Assistant. This rule tops up at 16:00 until today’s daily light integral is reached, but only if the sun fell short and power is affordable at that moment.
# Supplement on a grey day, not on a sunny onealias: Top up DLI greenhouse 1description: Top up to 17 mol/m² per daymode: single triggers: - trigger: time at: "16:00:00" conditions: # Only if the sun fell short today - condition: numeric_state entity_id: sensor.gh1_dli_today below: 17 # And only if power is affordable right now - condition: numeric_state entity_id: sensor.power_price_now below: 0.30 # euro per kWh actions: - action: hlp.top_up_dli target: light_group: bay_1 data: target_dli: 17 channels: [red, blue] max_power: 80 # percent no_later_than: "20:00:00" - action: notify.grower data: message: "Greenhouse 1 topped up to 17 mol/m²"- triggerswhen the rule looks
- conditionsonly if this holds
- actionswhat happens then
Rather not type it yourself? The “help me” button in the editor lets you describe what you want in plain words, and you get a proposal you see first, before it does anything. Already running automations in Home Assistant? Bring them across.
The node at a glance
| Protocol | Horti Lighting Protocol (HLP) v1.1.0, Stichting Hortivation |
|---|---|
| Connection to lights | Modbus TCP (Ethernet, port 502) or Modbus RTU (RS-485) |
| Connection to FairGrow | Wifi |
| Local sensors | ESP-NOW (including PAR), see ESP-NOW sensors |
| Supported HLP modules | Basic, System status, Power. Exact Light Control and Preferred Setpoints will follow. |
| Capacity | Up to 100 light groups, 8 channels per group (the limit of the protocol) |
| Without internet | Rules keep running locally, with their own clock |
| Power supply | 12V DC |
What growers ask us
Does it work with my lights?
With lighting gateways that support HLP v1.1.0. Ask your supplier whether your installation does.
I already have a climate computer. Is this still useful?
Yes. You use the node in read mode: FairGrow keeps an eye on consumption, realised light and faults, and your climate computer stays in control.
What happens if the internet goes down?
Nothing special. The rules live on the node and keep running locally, with their own clock. Once the connection is back, FairGrow receives the report after all.
And if the node itself fails?
Then your lights fall back to the power-on light level you set for each light group. You have to set it before FairGrow is allowed to control anything.
Do I need the FairGrow PAR sensor?
No. Any connected PAR source works. Without a PAR reading, rules based on time and power work as usual; only topping up to a daily light integral does not.
What is HLP, exactly?
The Horti Lighting Protocol is a publicly available communication standard from Stichting Hortivation for controlling grow lights. How it works, with light groups, channels and modules, is explained in What is the Horti Lighting Protocol?
Is the HLP node connected to the internet?
Yes, to FairGrow over wifi. That is how your rules reach the node and how you see readings and reports in FairGrow. Your lights and the cable to them sit on a separate network that never gets internet: the node passes nothing from wifi to that network. If the wifi drops, the node simply keeps measuring and topping up.
Keep me posted
Tell us who you are and what your greenhouse looks like. We will let you know as soon as you can order the HLP node. If your crop is a good fit for the test phase, you will hear from us sooner.
The Horti Lighting Protocol is a standard of Stichting Hortivation.