Solar Geyser vs Solar PV: Where Should You Start?

Two different technologies, two different jobs

What a solar geyser does

A solar geyser (solar water heating) uses the sun's heat directly. Panels or evacuated tubes on the roof warm water — or a fluid that transfers heat to your water — which is then stored in an insulated tank. There's no electricity being generated anywhere in the process. It's a heat machine, pure and simple, and it does one job: giving you hot water using free sunshine instead of your geyser's electric element.

Because it targets water heating specifically, a solar geyser attacks what is, for most South African households, the single hungriest appliance in the house. Your electric geyser quietly accounts for a big slice of your monthly bill. Displace most of that with sunshine and the saving on your water-heating costs is substantial.

What solar PV does

Solar PV (photovoltaic) panels make electricity. That power can run everything in your home — lights, plugs, the fridge, the TV, the wifi — and, when paired with a battery and a hybrid inverter, it keeps those things running when Eskom drops. PV is the general-purpose solution: it doesn't just tackle one appliance, it addresses your whole electricity supply and your load-shedding problem at once.

The trade-off is that PV is a bigger, more expensive system, because it's doing a much bigger job.

The key difference: load-shedding

This is the fork in the road, and it's worth being blunt about it. A solar geyser does absolutely nothing for load-shedding. When the grid goes down, a solar geyser home still loses its lights, wifi, fridge and everything else — you'll have hot water, but you'll be enjoying it in the dark.

Only solar PV with a battery keeps your home powered through a blackout. If the thing that makes you grind your teeth is the grid going off during dinner, the kids' homework and your work-from-home calls, then no amount of solar water heating will fix that. You need PV. This single distinction resolves most people's decision on its own.

Cost and savings compared

The geyser: cheap, focused, fast

A solar geyser is far cheaper than a full PV system because it's a smaller, simpler, single-purpose install. It also targets your biggest electrical load, so the saving relative to its cost is excellent. For a household whose only real goal is to cut the bill — and who can live with load-shedding — a solar geyser is one of the highest-return solar purchases available. It's often the sensible first move for a tight budget.

PV: bigger spend, bigger job

Solar PV costs more because it's replacing far more of your grid dependence and adding backup power. But it also does far more: whole-home savings plus load-shedding immunity. You're not really comparing like with like on price — you're comparing a focused tool with a complete solution. The right lens isn't "which is cheaper" but "which problem am I actually trying to solve".

Don't forget the heat pump

There's a third option worth knowing about: a heat pump, which heats water using electricity but far more efficiently than a standard element — think a fraction of the energy for the same hot water. Heat pumps pair especially well with a PV system, because they let you heat water electrically without hammering your panels and battery. For many homes going the PV route, a heat pump is a smarter partner than trying to heat water with an old-fashioned element running off the battery.

How to decide your first step

Ask yourself what's really driving you:

• "My bill is too high, but I can cope with load-shedding." Start with a solar geyser (or a heat pump). It's the cheapest way to knock down your biggest single load, and you can always add PV later.
• "Load-shedding is ruining my life." Go straight to solar PV with a battery. A geyser won't touch this problem — you need electricity and backup.
• "I want the bill down and the lights to stay on." You want PV, and you should decide how to handle hot water as part of that design — often a heat pump or a dedicated solar geyser alongside the PV, so you're not wasting battery energy heating water.

Where to start with PV

If PV is your answer, you don't have to buy the biggest system on day one. Alumo's most popular Silver "Eishkom Ex" package (a Sunsynk 3.6kW inverter, 3.8kWh battery and four panels, from around R2,035/month) covers the essentials — lights, wifi, fridge, TV — through load-shedding, and is a sensible entry point for many homes.

A larger home, or one that wants more backup runtime and headroom to add loads later, might step up to the Gold "Power Bae" (a Sunsynk 5kW inverter, 5.32kWh battery and six panels, from around R2,423/month). The right size depends on your usage and how much of the house you want to keep alive during an outage. Get a free quote → and let a proper assessment match the system to your home.

The honest bottom line

Neither technology is "better" — they answer different questions. A solar geyser is a cheap, brilliant way to slash your hot-water bill if load-shedding isn't your main gripe. Solar PV is the complete answer if you want whole-home savings and to stay powered through blackouts. Plenty of households end up with both, and the smartest PV designs think about water heating from the start. Figure out which pain is louder for you, and your first step becomes obvious. Get a free quote → if you'd like help weighing it up for your home.

Frequently asked questions

Will a solar geyser help during load-shedding?

No. A solar geyser only heats water using the sun's heat — it generates no electricity, so it can't keep your lights, wifi or fridge on when the grid goes down. If load-shedding is your main concern, you need solar PV with a battery, not a solar geyser.

Which saves more money, a solar geyser or solar PV?

It depends what you're measuring. A solar geyser is cheaper and targets your biggest single electrical load (water heating), so its saving relative to cost is excellent. Solar PV costs more but cuts your whole-home electricity use and adds load-shedding backup, so it saves across everything. They're really solving different problems, so compare them by the problem you want fixed, not by price alone.

Can solar PV heat my water too?

Yes, but heating water with battery-stored PV can be wasteful. A far more efficient approach is to pair PV with a heat pump, which heats water electrically using a fraction of the energy of a standard element, or to add a dedicated solar geyser alongside the PV. That keeps your battery free for lights, electronics and other essentials.

What's the difference between a solar geyser and a heat pump?

A solar geyser uses the sun's heat directly to warm water, with no electricity involved. A heat pump uses electricity but very efficiently — extracting heat from the surrounding air — to heat water for a fraction of what a standard geyser element uses. Heat pumps work day or night and pair well with a PV system; solar geysers rely on sunshine but have no running cost at all.

Who supplies and installs these systems?

Alumo supplies, installs, finances and warrants the systems, and can advise on the best combination of PV, battery and water heating for your home. SolarGuide is an independent referral partner — we help you compare options and get a free quote. All pricing is indicative and subject to a site assessment and credit approval.