This week I was involved in two commercial solar projects. People will almost certainly be printing money for decades. The other one looked promising at first glance, but fell apart when we climbed onto the roof.
The contrast between the two was a useful reminder that, despite the current obsession with batteries and “three free” business electricity plans, old-fashioned solar panels are still extremely effective.
In many ways, enterprises are still the cleanest use case for solar energy for two main reasons.
Reason #1: In contrast to private households, companies usually use the most electricity when the sun is shining. Their demand tends to rise throughout the morning, peak in the early afternoon and decline overnight. Solar power generation fits perfectly into this profile.
Reason #2: Once your meter is connected to a business unit, all 3-free hour plans will disappear. In fact, as far as I know, there isn’t even a small business tariff that offers particularly cheap daily rates. The best thing I found on Energy Made Easy was the Origin Business Sunshine Special at 28.6c per kWh from 10am to 3pm. Unfortunately at all other times it was knocked out of the race by a stunning 58c[1SQbelongstoOrigin–butthatwashonestlythebestdaytimerateIcouldfind–letusknowinthecommentsifImissedatrickhere[1SQisownedbyOrigin–butthiswasoneofthebestdaytimeratesIcouldfind–letusknowinthecommentsifI’vemissedatrickhere[1SQgehörtOrigin–aberdaswarehrlichgesagtderbesteTagestarifdenichfindenkonnte–lassenSieesunsindenKommentarenwissenwennichhiereinenTrickverpassthabe[1SQisownedbyOrigin–butthiswashonestlythebestdaytimerateIcouldfind–letusknowinthecommentsifI’vemissedatrickhere
A tale of two roofs
The first project included a large commercial property with several tenants: a brewery, a café, a boxing gym, laboratories and several offices. Electricity for the entire building flows through a single NMI, using an embedded network and submeters to distribute consumption among individual tenants. The total consumption is almost 1,000 kWh per day, and about eighty percent of this occurs during daylight hours. From a solar perspective, this alignment is almost perfect.
So the solution was obvious. The building has a large, north-facing roof, so the plan followed long-standing SQ advice: “Fill your roof!” The final design included 250kW Longi 650W modules feeding a 110kW Sungrow hybrid inverter as well as an additional 50kW inverter, with 100kWh of battery storage as a finishing touch. Even without claiming STCs for solar energy – systems over 100kW are not eligible – the numbers still work well. The expected payback is just over four years.
The landlord was happy to invest because the incentives were clear. It pays the grid electricity bill and charges customers further. Once the system has paid for itself, the building effectively has a large, inexpensive daytime power source on the roof. Some of these savings can be passed on to tenants while improving operational economics and the value of the property.
The second project could hardly have been more different. It was a small but extremely busy cafe/restaurant in the Adelaide CBD. Their electricity consumption is astonishing: around 165 kWh per day. This corresponds to a constant load of 7 kW running 24 hours a day.
What makes this number even more surprising is the fact that the kitchen itself isn’t heavily electric. Cooking is done with wood and gas, and cooling is usually done using a large evaporation system. The building footprint is only about fifty square meters. Still, the cafe’s electric bill is about $6,000 per quarter, and the landlord was eager to install a solar system at his own expense to provide some relief for the tenants.
This all sounded promising until we inspected the roof.
Unexpected complications
It turned out to be a labyrinth of penetrations. Refrigerator compressors, hoods, evaporative coolers, parapets, pipes and other obstructions covered almost every available section of space. After trying everything we could, the maximum system power that could be installed without the job turning into a major construction project was around 4.75 kW.
A system of this size would likely achieve about eighty percent self-consumption and save about $2,000 per year. On the surface, that still sounds reasonable. In reality, it hardly hurts the bill; it would cover less than ten percent of their electricity costs.
At this point the obvious question arises: why not install it anyway? A payback period of three years is still attractive. Unfortunately, there is a complication.
The cafe is currently connected to a mechanical meter and has a relatively low flat rate electricity charge. Installing solar energy would require a smart meter upgrade, and this upgrade would result in a different tariff structure with a higher average energy price. Your consumption would decrease slightly, but your electricity bill would increase.
Adding a huge battery is pointless – because there is no cheap energy to charge it.
Where is the energy used?
So what are your options? The first thing to do is check their efficiency, and even that is difficult. Because they don’t have a smart meter, they only get insight into energy consumption from a quarterly electricity bill.
The sensible first step is the correct measurement. Installing 5 to 5 minute resolution monitoring on the main circuits would quickly identify where the energy is flowing. In cafes, the answer is often refrigeration: cold rooms, fridges, under-counter cabinets, ice machines and compressors sitting outside in the heat, working harder than they should.
A compressor on this particular roof is completely exposed, its condenser coils visible from the street and there is no shading or protection whatsoever. That alone could result in tens of kWh being wasted per day.
Once we know where the energy is being used, we can start making improvements and also be prepared to optimize their tariff when they are inevitably forced into a usage schedule.
The two projects illustrate a simple point. Solar energy remains one of the best investments a business can make, but only if the basic requirements are right: a usable roof and significant daily consumption. When these ingredients are present, the results can be spectacular. When this isn’t the case, the smartest energy upgrade goes back to basics – good old-fashioned energy efficiency.
Phase Shift is a weekly opinion column from SolarQuotes founder Finn Peacock. Subscribe to SolarQuotes’ free newsletter to have it emailed to your inbox each week along with our other home electrification coverage.
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