Running Your Borehole and Pool Pump on Solar

Why pumps and solar are a natural fit

The timing lines up

The single biggest factor in how much a load benefits from solar is when it runs. Loads that draw power at night lean heavily on expensive battery storage. Loads that run in the middle of the day can be fed straight off the panels, no battery required. Pool pumps and daytime borehole pumping fall squarely into the second camp — which makes them some of the most cost-effective things you can move onto solar.

The savings add up quietly

Because pumps run for long stretches, their consumption is larger than people expect. A pool pump cycling for hours a day, every day, is a steady, predictable draw. Shifting that load off Eskom and onto free midday sun removes a chunk of your bill that you'd otherwise never think about. And unlike lights or a TV, a pump doesn't care whether it runs at 11am or 8pm — so you can freely schedule it for peak sun.

The one thing everyone gets wrong: start-up surge

What surge actually is

An electric motor doesn't sip power evenly. At the instant it starts, it pulls a large inrush of current — commonly several times its normal running draw — for a fraction of a second before settling into its steady state. A pump that hums along at, say, a modest running load might briefly demand a multiple of that at the moment of switch-on.

Why it matters for solar

Your inverter has a maximum instantaneous output. If the pump's start-up surge exceeds what the inverter can deliver in that instant, the inverter protects itself and trips — even though it could easily handle the pump once it's running. This is the classic failure mode of an under-designed pump-on-solar setup, and it's entirely avoidable. A proper design sizes the inverter (and, where relevant, a soft-starter) to swallow the surge. This is exactly why a site assessment that looks at your specific pump motor beats guessing from a spec sheet.

The simplest approach: a timer and the midday sun

For most homes, the cheapest and most elegant way to run a pool or borehole pump on solar is to schedule it for peak generation. Set a timer so the pump does its daily work between roughly mid-morning and mid-afternoon, when your panels are producing their most. During those hours the sun feeds the pump directly, and you've effectively taken that load off the grid for free — no extra battery capacity spent.

This works beautifully for pool pumps, which don't need to run at any particular time as long as they complete their daily cycle. Borehole pumps that fill a storage tank are similar: pump into the tank during the day, draw from the tank whenever you need water. In both cases you're using the tank or pool as a kind of "battery" for water, which is far cheaper than storing electricity.

Do you need a battery for your pump?

Often, no

Here's the liberating part: if your pump only needs to run during the day, you may not need any extra battery for it at all. Direct solar during daylight covers the load. Adding battery capacity purely to run a pump at night is usually poor value, because you're paying to store expensive electricity to power a job you could simply schedule for daytime instead.

Sometimes, yes

There are exceptions. If your borehole is your only water source and you need pressure on demand at any hour — including through the night and during load-shedding — then some storage, or a pressurised tank, keeps water flowing when the sun's down. Likewise, if the pump is on a circuit you want backed up during outages regardless of time, it factors into your battery sizing. The right call depends on how essential round-the-clock pumping is for your household, which is a good thing to talk through during an assessment. Get a free quote → to work out whether your pumps need storage or just daytime sun.

Fitting it into a whole-home system

Pumps rarely go solar on their own — they're usually part of a broader home system that also covers lights, wifi, the fridge and load-shedding backup. When you size that system, the pump's running load and its start-up surge both need to be in the calculation so the inverter is comfortable with everything switching on together.

For a typical household adding pumps to the mix, a mid-range system like Alumo's Silver "Eishkom Ex" (a Sunsynk 3.6kW inverter, 3.8kWh battery and four panels, from around R2,035/month) covers everyday essentials, while a larger home with a big pool pump and a borehole might step up to the Gold "Power Bae" (a Sunsynk 5kW inverter, 5.32kWh battery and six panels, from around R2,423/month) for the extra inverter headroom the motors want.

The honest way to get this right is to let an installer look at your actual pumps and usage. Get a free quote → and have the system sized so your borehole and pool pump run on sunshine without a single nuisance trip.

Frequently asked questions

Can I run my pool pump entirely on solar?

In most cases, yes — and often without any extra battery. Because a pool pump doesn't care what time of day it runs, you simply set a timer to run it during peak sun, when your panels feed it directly. As long as it completes its daily filtration cycle in daylight hours, you've moved that whole load off the grid for free.

Why does my pump trip the inverter?

Almost always because of start-up surge. When a pump motor switches on it draws a brief inrush of current several times its running load, and if that spike exceeds the inverter's instantaneous limit, the inverter trips to protect itself. The fix is designing the system — inverter size, and sometimes a soft-starter — around your specific motor, which a site assessment sorts out.

Do I need a battery to run a borehole pump on solar?

Not necessarily. If you pump into a storage tank during the day and draw from the tank when you need water, daytime solar can run the pump directly with no extra battery. You only need storage if you require pumping or water pressure on demand at night or through load-shedding — for example, if the borehole is your sole water source.

Is it cheaper to run pumps during the day?

Yes, considerably. Running a pump in daylight lets it feed off direct solar generation instead of drawing from the grid or discharging your battery. Storing electricity to run a pump at night is usually poor value — it's far cheaper to schedule the pump for peak sun and, where needed, store the water rather than the power.

Who designs and installs the system?

Alumo supplies, installs, finances and warrants the system, including sizing the inverter to handle your pump's start-up surge. 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.