The right inverter for how your property really uses power.
FoxESS and Sigenergy only, sized to your panels and your real load, with a 10-year swap-out warranty.
Start an assessmentAre you sure you're buying the right inverter, or just guessing?
Does this sound familiar?
The right inverter is chosen once, from your property's real numbers, not guessed at twice.
We help South African businesses and homes choose the inverter that actually fits
An inverter turns the direct current (DC) electricity your solar panels make into the alternating current (AC) electricity your home or business runs on. Panels only ever produce DC. Lights, plugs, geysers and almost every appliance need AC, so without an inverter your panels cannot power your property at all.
A good inverter does two other jobs. Maximum power point tracking (MPPT) constantly adjusts the inverter to pull the most power it can from your panels as the sun moves and clouds pass. Anti-islanding protection stops the inverter feeding power into the grid whenever the grid supply is switched off, so it cannot send power down the line while a utility worker may be on it.
There are three main types: hybrid, grid-tied and off-grid. Most South African homes and businesses choose a hybrid inverter, because it manages a battery and lets you choose when to use your own stored power and when to draw from the grid: control over your own supply. The table below sets out how the three compare.
Most buyers are told a size and a brand and have no way to check either.
ZenSolar designs every system in house, using FoxESS and Sigenergy inverters only, matched to your property and sized to your panels and real load. At EFJS Printing, a 30 kW FoxESS three-phase hybrid inverter with a 12 kWh battery and 27 x 550 W panels paid back its investment in 2.5 years.
And we can do the same for you.
Hybrid vs grid-tied vs off-grid, at a glance
| Type | Battery | Use your own stored power, on your terms | Cost level | Best for |
|---|---|---|---|---|
| Hybrid | Yes, manages a battery | Yes, you choose when to use it and when to draw from the grid | Medium to high | Most homes and businesses that want control over their own supply |
| Grid-tied | No battery | No, it can only use power the moment the panels make it | Low to medium | A site that wants solar now and has no need to store power yet |
| Off-grid | Yes, sized to carry the whole load | Yes, it is the property's only supply, so it runs on its own stored and generated power | Medium to high | Remote sites and farms with no grid connection at all |
A hybrid inverter can start without a battery and have one added later, without swapping the inverter out. See how battery sizing works on Solar Power Backup.
What size inverter, for what kind of property
| Property type | Typical inverter size | Phase | What it runs |
|---|---|---|---|
| Typical home | 6 to 10kW | Single phase | Lights, plugs, a geyser, a TV and fridge, often a pool pump or borehole pump |
| Large home | 10 to 16kW | Single phase, sometimes three phase | Everything above plus air conditioning, a larger geyser, and more appliances running at once |
| Small business | 30 to 100kW | Three phase | Retail or office lighting and power, air conditioning, small equipment, one or two motors such as a compressor or pump |
| Factory | 100 to 300kW | Three phase | Production equipment, several motors running together, larger HVAC plant |
| Medium to bigger business | 300kW and up | Three phase, often several inverters paralleled | Heavy industrial motors, multiple production lines, large cold storage or refrigeration plant |
ZenSolar's typical system sizes are 6 to 16kW on average for homes, 30 to 300kW for businesses, and 300kW and up for medium to bigger businesses. The split inside each band above is a guide, not a fixed rule: see Residential and Commercial Solar. The free energy assessment measures your property's real usage and sizes the actual system.
kW, kWh and kVA, in plain words
kW (kilowatt) measures the rate of power: how fast something uses or makes electricity, like a car's speed. kWh (kilowatt hour) measures energy used over time: how far the car travelled, which is what your bill charges for. kVA (kilovolt-ampere) is how an inverter's capacity is usually rated: the size of the pipe the power flows through. On a well-designed system the kW and kVA figures sit close together, so you can treat them the same for sizing.
The inverter is sized from your power (kW): the most your property draws at once, plus headroom. The panels are sized from your energy (kWh): how much you use in a day, and how much roof you have. Panels are often rated a little above the inverter, because they rarely make their full rated power in real sun. How far above is limited by each inverter model, and is checked in the design.
A worked example: a home on single phase supply
This is an example only, to show the method. The free energy assessment measures your real appliances and sizes your actual system.
Typical loads for a home like this:
Add the running loads together: 400 + 150 + 200 + 3,000 + 750 = 4,500W, or 4.5kW.
Add 20 percent headroom for the kettle, microwave or iron that will switch on sooner or later: 4.5kW x 1.2 = 5.4kW.
Now check the start-up surge. A borehole pump, like a fridge, draws far more power for a second or two when it switches on, often about three times its running wattage: 750W x 3 = 2,250W, which is 1,500W more than its running load. So for a moment the load jumps to 4,500W + 1,500W = 6,000W, or 6kW.
ZenSolar's single-phase range runs 5kW to 10.5kW. The home needs 5.4kW with headroom and can spike to 6kW, both more than the 5kW unit gives. So a 10.5kW FoxESS single-phase hybrid inverter fits best, with room for a second heavy appliance.
The number of panels is then worked out from how much energy (kWh) the home uses each day and how much roof it has, and checked against what the inverter can take. Battery size is also worked out from your actual usage, not the inverter's rating. See Solar PV Panels and Solar Design Calculations for the full method.
Single phase or three phase: what a business buyer needs to know
Phase describes how electricity is delivered from the grid. Single phase carries power on one live wire and is what almost every home uses. Three phase carries power on three live wires, spaced evenly so heavy equipment gets a smoother, more constant supply, and is common on business and industrial sites.
To check which supply a property has, look at the breakers at the DB board where the municipal or Eskom cable comes in. One large main breaker usually means single phase; three breakers of the same size usually means three phase.
A three-phase site needs a three-phase inverter. A single-phase inverter only feeds the one phase it is wired to, which can unbalance the supply if other loads are not spread evenly, tripping breakers or straining the heavier phase. National rules also limit the size: under NRS 097-2-3, a system bigger than 4.6kVA should connect on a three-phase supply, and the power on the three phases may not differ by more than 4.6kVA.
Businesses with motors, compressors, pumps or large air conditioning nearly always sit on three phase, since a heavy motor starting alone would place a sudden load on one phase only. See Commercial Solar for how ZenSolar sizes a business system.
A worked example: a small factory or printing works on three phase
This is an example only, using typical figures, not a real client's numbers.
Typical daytime loads for a small factory:
Add the running loads together: 6 + 5 + 10 + 4 = 25kW.
Add 20 percent headroom so the inverter is never pushed to its limit: 25kW x 1.2 = 30kW.
Now check the motor start-up surge. The press motor can briefly draw two to three times its running power when it switches on: 10kW x 3 = 30kW for a moment, which is 20kW above its running load. Inverters can carry a short overload for a moment, and the exact limit is on each model's data sheet, so the design checks that the biggest single surge fits inside it. Where two big motors could start together, the design staggers them rather than buying a much bigger inverter.
A load of 25kW with 20 percent headroom is why a FoxESS 30kW three-phase hybrid inverter suits a site like this. The electrician splits single-phase loads, lighting and sockets, evenly across the three phases, while the three-phase motors, the press and the compressor, already draw evenly across all three by design.
The panels are then sized from the factory's daily energy use and roof space. A daytime business like this uses most of its power while the sun shines, so more of its solar goes straight into running the machines. See the full sizing method on Solar Design Calculations and how ZenSolar plans an install on Solar Installations.
FoxESS and Sigenergy: the two brands we fit
ZenSolar installs FoxESS and Sigenergy only. FoxESS is a wide range of separate inverters and high-voltage batteries across single and three phase, suited to a home or a factory alike. Sigenergy is a different design: an all-in-one stack combining the inverter, battery and energy management in one unit, with optional EV charging on select models. ZenSolar fits every model of both it sells.
FoxESS and Sigenergy, side by side
| FoxESS | Sigenergy | |
|---|---|---|
| Design | Separate inverter and battery units, mixed and matched to the site | One all-in-one stack: inverter, battery and energy management together |
| Phase range | Single and three phase models | Single and three phase models |
| Battery | High-voltage LiFePO4 batteries, sized and added separately | Battery sizes from 5kWh up to 16kWh, stacked on one controller |
| EV charging | A separate EV charger, fitted alongside | An optional DC EV charging module, 12.5kW as standard and upgradeable to 25kW, that fits into the stack |
| Bought as | Quoted after the free energy assessment | Quoted after the free energy assessment |
| Weather rating | IP65 | IP66 on the energy controller |
| Best for | Homes and businesses that want separate units they can add to over time | Homes and businesses that want one neat stacked unit, with the option of built-in EV charging |
Still weighing FoxESS against Sigenergy for your site?
See which one fits your propertyCost control: demand charges, time of day and battery voltage
Many business bills carry two charges: a kWh charge for energy used, and a separate kVA demand charge for the highest rate of power drawn at any one point. A hybrid inverter can draw on the battery during that peak instead of the grid, lowering the demand charge without changing how much the business runs.
Some tariffs also cost more at certain times of day. A hybrid inverter can be set to use stored power during the priciest hours and recharge when grid power is cheaper: cost control, not just storage.
FoxESS's three-phase high-voltage batteries run at 150 to 800V, well above a standard 48V bank. Higher voltage moves the same power at lower current, meaning thinner cable runs, fewer losses, and easier expansion or linking on a bigger site.
ZenSolar can also connect a new system to a site's existing diesel generator.
The South African rules, in plain steps
Any grid-connected solar system must clear these steps before it can switch on, whichever installer does the work.
1
Register the system. Any solar system connected to the grid must be registered as a Small-Scale Embedded Generation (SSEG) system with whichever supplier serves the property, Eskom or the local municipality, before or when it connects.
2
Use an approved inverter. The inverter must meet NRS 097-2-1, the national safety standard for small generators connecting to the grid. Some cities keep their own list of approved inverters.
3
Get a Certificate of Compliance. A registered electrician must issue a CoC confirming the electrical installation is safe and meets the rules.
4
Get municipal or Eskom approval. The supplier reviews the application and, for systems that export power, may require a meter change.
ZenSolar's promise here is simple: CoC and SSEG application handled for you.
Where to install your inverter
How long an inverter lasts, and what the warranty covers
A typical string or hybrid inverter lasts about 10 to 15 years, shorter than the 25 years or more most solar panels last, so most systems need at least one inverter replacement over the panels' lifetime. Heat is the main reason an inverter fails early: a hot, poorly ventilated spot ages its components faster, which is why placement matters as much as the brand.
ZenSolar backs every FoxESS and Sigenergy inverter and battery with a 10-year swap-out warranty. In plain terms: if the inverter or battery fails within that period, it gets swapped out, not sent away for a lengthy repair and not left as your problem to solve.
How we get you the right inverter
1
Book your free energy assessment
We look at your property's usage, roof or site, and your biggest loads, so we know what your system actually needs.
2
We match and size your inverter
Hybrid, off-grid or grid-tied, FoxESS or Sigenergy, sized to your panels and your biggest load, so it fits your property, not a generic spec sheet.
3
Installed and monitored
Installed by our team and preferred, vetted installers approved by the brands, with a 10-year swap-out warranty. You see your system in an app and get pop-up notifications.
A real job: EFJS Printing
"ZenSolar was excellent in all that they did. The installation at my Printing Shop and home was done to the highest standard."
Bernard Synman, Director, EFJS Printing.
How is this different from buying an inverter online?
With us
- Matched to your property after a free energy assessment
- FoxESS and Sigenergy, with a 10-year swap-out warranty
- We install and maintain your system
- CoC and SSEG application handled for you
With them
- Guess the size yourself
- A brand with no local stock or warranty backup
- Self install and hope it is compliant
- No help with paperwork
Frequently asked questions
A solar inverter converts the direct current (DC) electricity your solar panels make into the alternating current (AC) electricity your home or business runs on. Panels only produce DC, but lights, plugs, geysers and most appliances need AC. The inverter also manages how power moves between your panels, any battery and the grid, and lets you monitor your system's output.
There is no single best inverter: it depends on your property, your usage and whether you want a battery. ZenSolar fits FoxESS and Sigenergy, both hybrid capable and both able to give you control over your own supply. We choose between them based on your usage, battery needs and phase supply, not a brand ranking.
A grid-tied inverter sends your solar power into your home and the grid, with no battery. A hybrid inverter adds a battery and gives you control over your own supply: you choose when to use stored power and when to draw from the grid. Most South African homes and businesses now choose hybrid.
A 5kW inverter can run most everyday loads, lights, plugs, a TV and a fridge, but usually not everything at once. If several heavy items switch on together, an oven, a kettle and air conditioning, it can reach its limit. What it can carry depends on your property's real usage, checked against your actual appliances.
A 5kW solar system can often run a geyser during the day, depending on what else is running. A geyser element typically draws about 2 to 4kW, so it can run in good sun if few other appliances are on. Many homes put the geyser on a timer so it heats mainly during sunny hours.
Add up the loads that run at the same time, add 10 to 20 percent headroom, then check the start-up surge of any pump or motor. For example, 4.5kW of running load becomes 5.4kW with headroom, so a 5kW inverter is too small. A business on three phase needs a three-phase inverter. A free energy assessment checks your actual usage and sizes it correctly.
Yes, a hybrid inverter can run without a battery. It works grid-tied, drawing power from your panels and the grid directly, switching between the two as needed. Most modern hybrid inverters let you add a battery later without replacing the inverter, so you can start with panels now and add storage when it suits you.
A typical solar inverter lasts about 10 to 15 years, shorter than the 25 years or more most panels last, so most systems need at least one replacement over the panels' lifetime. ZenSolar backs its FoxESS and Sigenergy inverters and batteries with a 10-year swap-out warranty: if one fails within that period, it gets swapped out.
It depends on your supply, not your preference. Check the DB board: one large main breaker usually means single phase, three equal breakers usually means three phase. A three-phase supply needs a three-phase inverter, since a single-phase inverter can only go on a three-phase connection if its capacity is 4.6kVA or less. Sites with motors or heavy air conditioning almost always need three phase.
Neither is simply better, and both suit homes and businesses. The two are similar, with a few small differences. FoxESS is a wide range of separate inverters and batteries across single and three phase, while Sigenergy is an all-in-one stack with the inverter, battery and energy management built together, with EV charging on select models. ZenSolar fits every model of both; the right one depends on your phase supply, battery needs and whether you prefer separate units or one stack.
Not ready for a full assessment? Contact us and we will answer your questions first, or see everything ZenSolar offers on Services.