5 Costly Mistakes South African Business Owners Make When Going Solar
I've been installing commercial solar systems for over a decade. I've worked on everything from a 5 kWp system for a small tuckshop to a 2 MWp ground-mounted array for a logistics park. In all those years and hundreds of installations, I keep seeing the same mistakes from business owners — mistakes that either cost them money upfront, reduce their system's long-term performance, or leave them with no recourse when something goes wrong.
I'm writing this because informed clients make better decisions, and better decisions mean better installations. The solar industry's reputation depends on clients being satisfied. So here are the five mistakes I see most often, and how to avoid them.
Mistake 1: Choosing on Price Alone
This is number one by a distance. A business owner gets three quotes, picks the cheapest, and six months later calls me to ask why their system isn't performing as promised — or worse, why a component has failed and the installer has gone out of business.
The solar industry in South Africa has some outstanding installers and some genuinely terrible ones. They often look identical on the surface. The way to tell them apart is not by their price — it's by their accreditation (SAPVIA membership, CEC accreditation), their track record (ask for three reference clients with working systems you can call), their component specifications (brand names, model numbers, warranty terms), and their workmanship warranty (minimum 5 years from a serious company).
I have gone back and rectified installations by cheaper competitors on behalf of their clients' insurers. The remediation work costs more than the saving from the cheap quote. Pick on quality, not price.
Mistake 2: Undersizing the Battery Bank
The most common technical mistake I see in commercial installations. The client says "I just want basic load shedding protection," the salesperson sizes the battery for one 2.5-hour block to keep the price competitive, and the client calls after the first week of Stage 6 asking why the power goes off at 8pm when the third load shedding slot hits.
Load shedding in South Africa is not a single 2.5-hour event per day. During high-stage load shedding, a business can experience three to four blocks per day. If you're only covered for one, you're exposed for the other three. When I size a system, I ask the client to tell me which loads cannot go off, and I size the battery to carry those loads for the maximum number of consecutive hours they could experience load shedding in their schedule. Often that's 4–6 hours per daily cycle, sometimes more.
The additional cost of going from a 20 kWh battery to a 40 kWh battery is significant — but so is the cost of the second and third block of load shedding you now have no protection for.
Mistake 3: Not Doing a Proper Load Analysis Before Quoting
Sizing a commercial solar system correctly requires understanding not just how much electricity you use in total, but when you use it, how it's distributed across different loads, and what your critical versus non-critical loads are. A business that runs 200 kWh/day but does 80% of that consumption between 8am and 5pm on weekdays has a very different solar opportunity to one that runs refrigeration, security systems, and network infrastructure through the night.
Some installers — particularly those running high-volume, low-touch operations — will size a system purely from a 12-month electricity bill average without ever analysing the load profile. This almost always results in either an undersized or oversized system that doesn't perform as expected.
Ask your installer to explain how they determined the system size. If they can't point to a specific load analysis, be cautious.
Mistake 4: Ignoring Roof Condition
I've arrived on site to install a system and found an IBR roof that's 25 years old with corroded fasteners, stress fractures in the sheeting, and no waterproofing treatment in years. Installing solar on that roof is a bad idea — not because solar is the problem, but because in 3 years when the roof needs replacement, you're going to have to remove the solar panels, re-roof, and reinstall. That costs more than fixing the roof before installation.
Any installer worth their salt will flag obvious roof condition issues during the site assessment. If yours doesn't, either they didn't look carefully enough or they're prioritising the sale over your long-term interest. Address roof condition first. Your panels are expected to last 25 years — make sure the roof they're sitting on can last that long too.
Mistake 5: Not Setting Up Monitoring Properly at Commissioning
Every modern commercial solar system includes a monitoring platform — cloud-based, app-accessible, showing real-time and historical production and consumption data. I am constantly amazed by how many clients never set it up, never download the app, and have no idea whether their R700,000 system is performing as designed.
A system that has a shading problem, a failed string, a loose connector, or a battery cell fault can lose 15–30% of its designed output without making any obvious noise or producing any visible symptom. The monitoring system catches it. But only if someone is watching.
At every commissioning I do, I walk the client through the monitoring app, show them what healthy performance looks like, and set up email alerts for fault conditions. Then I tell them to check it once a week for the first three months. Most of the time this catches small issues before they become expensive ones.
The Common Thread
What these five mistakes have in common is that they all flow from rushing or cutting corners. Going solar is a 25-year commitment. The extra time and money spent on a proper load analysis, a quality installer, a correctly sized battery, a sound roof, and properly configured monitoring are the difference between a system that delivers its promised return and one that disappoints.
Choose slowly. Install once. Enjoy the savings for 25 years.
Read: What to expect during a commercial solar installation | How to size a solar system | More articles