More commercial buildings have rooftop solar now than don’t. And LED lighting is often the single largest daytime electrical load in an office building. So why aren’t we talking more about integrating them?

I’ve been involved in several projects where clients want to maximise self-consumption of their solar generation through intelligent lighting. Here’s what I’ve learned.

The Basic Opportunity

A typical commercial office might have:

• 100kW rooftop solar array
• Peak generation around midday
• LED lighting consuming 15-25kW during business hours
• Significant lighting load coinciding with solar generation hours

The maths seems simple. Solar generates during the day. Lights operate during the day. Match them up and avoid buying grid electricity.

Reality is more complicated.

The Grid Export Problem

Most commercial solar installations in Australia were designed around grid export. Generate as much as possible, export what you don’t use, receive a feed-in tariff.

But feed-in tariffs have dropped dramatically. In many jurisdictions, commercial rates are now 2-5 cents per kWh for export—versus 25-35 cents to buy electricity back. The arbitrage has flipped.

This changes the optimisation target. Instead of maximising generation, you want to maximise self-consumption. Use every kilowatt you generate before it goes to the grid.

How Lighting Fits In

Lighting is interesting for solar integration because:

Predictable load: Unlike HVAC, lighting demand doesn’t swing wildly based on weather. You know roughly what your lighting will draw.

Discretionary timing: Some lighting isn’t time-critical. Car parks, common areas, external lighting can often be shifted.

Dimmable loads: Modern LED systems can modulate output, providing a variable load that can track solar generation.

Control infrastructure: If you have a DALI or Bluetooth mesh system, the control capability already exists.

Practical Integration Approaches

Strategy 1: Schedule Alignment

The simplest approach. Shift discretionary lighting loads to solar generation hours.

Car park lighting is a common example. Many facilities keep car parks lit continuously for security. But during peak solar generation, you might boost levels beyond minimum. Pre-condition common areas with brighter light when solar is abundant.

This doesn’t require sophisticated control—just thoughtful scheduling.

Strategy 2: Load Following

More sophisticated. Lighting levels modulate in response to real-time solar generation.

When solar output is high, boost lighting levels in areas that can use it. When a cloud passes and generation drops, dim back to baseline.

This requires integration between your solar inverter monitoring and your lighting control system. Not trivial, but achievable with the right equipment.

Strategy 3: Battery Buffering

If you have on-site battery storage (becoming more common), the integration changes. Batteries absorb excess solar during the day and discharge during evening peaks.

Lighting becomes part of the overall load profile that batteries serve, rather than directly tracking solar. The optimisation happens at the building level, not the lighting level.

The Integration Challenge

Here’s where projects often stumble. Solar systems, lighting controls, and building management systems typically come from different vendors with different protocols.

Your solar inverter speaks Modbus. Your lighting speaks DALI. Your BMS speaks BACnet. Getting them to cooperate requires integration work.

For sophisticated energy management involving multiple building systems, that’s where specialists who understand the broader technology picture add value. AI consultants Melbourne working on intelligent building systems often deal with exactly this kind of multi-system integration.

But for simpler approaches—schedule-based optimisation or basic load monitoring—your building automation contractor should be able to handle it.

What Actually Saves Money

Let me be realistic about the savings.

If your lighting consumes 20kW during peak solar hours, and you shift 50% of that consumption from grid to solar, you’re saving:

10kW x 8 hours x $0.25/kWh x 250 business days = $5,000/year

That’s meaningful, but not transformative. It doesn’t pay for a sophisticated control system on its own.

The value compounds when lighting is one piece of a broader self-consumption strategy including HVAC, hot water, EV charging, and batteries. The integration investment serves multiple loads.

The Dimming Consideration

Some solar-lighting integration schemes propose continuous dimming to track solar output. In theory, this maximises self-consumption moment by moment.

In practice, I’m skeptical. The savings from precise load following versus simple scheduling are marginal. And constantly varying light levels aren’t great for occupant comfort.

I’d rather have steady, predictable lighting with bulk scheduling adjustments than lights that flicker with every passing cloud.

DC Distribution: The Longer-Term Answer

Here’s something that might change the picture: DC distribution.

LEDs run on DC power internally. Solar panels generate DC. Batteries store DC. Converting everything to AC and back to DC loses 10-15% at each step.

A DC-native building would connect solar directly to lighting with fewer conversion losses. Several pilot projects are exploring this.

It’s not mainstream yet. Standards, products, and installer training need to catch up. But it’s where the physics suggests we should go eventually.

Practical Recommendations

If you’re considering solar-LED integration:

Start with data: Understand your actual solar generation profile and lighting consumption patterns before designing solutions.

Begin with scheduling: Simple time-of-use optimisation captures most of the value without complex integration.

Design for the future: If upgrading lighting controls, choose systems that can integrate with building energy management even if you don’t connect them immediately.

Consider the whole building: Lighting is one load. HVAC is usually larger. EV charging might be significant. Optimise at the building level.

Check the export rates: The business case depends heavily on your specific electricity contract. What are you actually paid for export?

Looking Ahead

As feed-in tariffs continue declining, self-consumption becomes more valuable. The buildings that can absorb their own solar generation—through intelligent loads, batteries, and smart control—will have lower energy costs than those that export cheap and buy expensive.

Lighting is one piece of that puzzle. Not the biggest piece, but a readily controllable one. The integration capability exists if you’re prepared to invest in it.

James Thornton has been working in commercial lighting for 18 years and is based in Australia.