What is an Inverter? A Complete Guide for Solar Power Beginners

When people start exploring solar power systems, the first device they come across is the inverter. It’s often called the heart (and the brain) of the system — and for good reason. Without it, all the DC energy from your solar panels and batteries can’t power your AC appliances. In this guide, we unpack what an inverter does, how it works, the different types, how to size one correctly, and what to look for when buying — especially for South African homes and businesses.

What Is a Solar Inverter?

A solar inverter converts DC (direct current) from solar panels and batteries into AC (alternating current) for your plugs, lights, fridges, servers, and machinery. Most buildings in South Africa run on 230 V AC single-phase or 400 V AC three-phase; the inverter is the bridge that makes solar usable day-to-day.

Many modern systems pair a quality hybrid inverter with a solar panel array and a matching lithium battery bank to deliver both savings and backup power.

What Else Does an Inverter Do?

Optimises panel output via MPPT (Maximum Power Point Tracking).
Manages battery charging and discharging (hybrid/off-grid models).
Provides system monitoring via app or web dashboards.
Handles load management and automatic changeover during outages.

How Do Inverters Work? (Simple 3-Step View)

DC Input: Solar panels (and/or batteries) feed DC power into the inverter.
Conversion: High-frequency electronics switch the DC rapidly to create a clean AC sine wave.
Output: The inverter supplies your building’s circuits or exports to the grid (where permitted).

Modern units keep the sine wave clean and stable to protect sensitive electronics like IT equipment, compressors, medical devices, and point-of-sale systems.

If you’d like a deeper technical overview, you can also read how inverters fit into complete systems in our article on choosing inverter size.

Types of Solar Inverters

1) Off-Grid Inverters

Designed for sites with no grid or extremely unreliable supply.
Always paired with batteries; often include a generator input.
Common for farms, lodges, remote telecom sites, or critical backup rooms.

2) Grid-Tied Inverters

Connect directly to the utility grid and can export surplus energy (where allowed).
No backup during outages unless combined with special additional equipment.
Best for businesses focused on daytime bill reduction where grid power is relatively stable.

For pure grid-tie savings in commercial environments, you’ll often see larger units like a 110 kW grid-tie inverter feeding energy straight into the distribution board.

3) Hybrid Inverters (Most Popular in South Africa)

Combine grid-tied efficiency with battery backup.
Provide seamless switchover during load-shedding and power failures.
Can export (if your municipality allows it) while still protecting against outages.
Ideal for homes and SMEs wanting both reliability and savings.

Hybrid models like the 8 kW Sunsynk hybrid inverter or 8 kW Deye hybrid inverter are popular choices for larger homes and small businesses.

Voltage Ratings: 12 V, 24 V, 48 V & High-Voltage DC

12 V: Very small systems (campers, tiny UPS). Typically under 1 kW.
24 V: Small homes or backup-only systems; more efficient than 12 V for modest loads.
48 V (Standard): The go-to for most residential and SME systems — lower currents, smaller cables, cooler operation.
High-Voltage (HV) DC Buses: Used in larger residential and commercial sites for higher efficiency and longer string lengths. These must be designed and protected by qualified professionals.

Many modern hybrid systems pair a 48 V inverter with a compatible 5 kWh lithium battery and then scale up in steps as needs grow.

Single-Phase vs Three-Phase Inverters

Single-phase (1Ø): Used in most homes and smaller offices. Common sizes range from 3–12 kW.
Three-phase (3Ø): Used in larger homes, guesthouses, workshops, and businesses with 3Ø supply. Typical sizes are 8–30 kW+ (with parallel options for larger needs).
If you have 3Ø supply, it’s best to choose a three-phase hybrid inverter (or multiple 1Ø units configured per phase) to balance loads and avoid nuisance trips.

For serious commercial loads, you may look at three-phase hybrids like a 15 kW Deye three-phase inverter or similar units in the same class.

Quick Sizing Guide (Rule-of-Thumb)

Goal: Choose an inverter that can run your simultaneous loads, handle startup surges, and then size batteries and panels to match your autonomy and savings goals.

1) Calculate Your Running & Surge Loads

Running load (kW) = sum of all appliances you expect to run at the same time.
Surge load (kW) = motors/compressors (fridges, pumps, air-cons) can pull 3–6× their running power for a few seconds.

Example (small office):

6 desktops @ 180 W each = 1.08 kW
Printer/laser peak = 0.8 kW (intermittent)
Networking/UPS/modems = 0.2 kW
LED lighting = 0.3 kW
Small fridge (running 120 W; surge up to ~600 W)

Likely simultaneous: ≈2.0–2.5 kW running, with surge capacity of ≥4–5 kW recommended.

2) Choose Inverter Size

Pick an inverter with headroom: typically 30–50% above your continuous load.
Ensure the surge rating covers worst-case starts (fridges, pumps, compressors).

For many homes in Gauteng, a well-planned 5 kW hybrid solar kit already covers the main critical loads comfortably.

3) Battery Sizing (for Backup)

Battery energy (kWh) ≈ (critical load in kW × backup hours) ÷ usable DoD.
For LFP batteries, usable DoD is typically 0.9–0.95.

Example: 2.5 kW critical load for 6 hours → 2.5 × 6 = 15 kWh / 0.9 ≈ 16.7 kWh battery storage.

4) PV Array Sizing (for Savings + Recharging)

Start with your daytime kWh use and roof space.
In Gauteng, a rough thumb-rule is that 1 kWp of panels yields around 4–5 kWh/day (season and roof dependent).
If you want batteries to refill during the day, size PV to cover daytime loads plus some surplus to charge the batteries.

If you are unsure where to start, you can always browse ready-made solar kits and then adjust the design to your exact loads and roof size.

Key Features to Look For (Buyer’s Checklist)

True hybrid operation (PV + battery + grid + backup outputs).
High surge capability (2× for 10 seconds or better if you have heavy starts).
Battery flexibility (compatibility with common LFP brands via CAN/RS485).
Scalability (parallel options, single- or three-phase variants).
Strong MPPT range (supports your planned string lengths and roof configuration).
Monitoring & control (app/web dashboards, load graphs, alerts, remote diagnostics).
Protection (correct AC and DC isolators, fuses, RCD/RCBO integration, surge protection).
Compliance & sign-off (installed to SA electrical standards with a valid CoC).

Quality inverters from brands such as Sunsynk, Deye and Solis tick many of these boxes when paired with a professional installation.

Typical Packages (Examples You Can Tailor)

A) Home/Office Critical-Load Backup (5–8 kW, 10–15 kWh, 6–10 kWp PV)

Runs PCs, lights, networking, fridges, point-of-sale, and selected plugs.
Provides 6–10 hours autonomy depending on actual loads.
Expandable battery stack for longer outages.

A popular option in this range is an 8 kW Sunsynk solar kit that balances backup and savings for family homes.

B) SME Mixed-Load Hybrid (10–12 kW, 15–20 kWh, 10–14 kWp PV)

Suited to small factories, workshops, medical practices, and retail.
Balanced between bill savings and strong resilience during outages.
Three-phase options where the supply or machinery requires it.

Many SMEs choose flexible systems built around a 12 kW hybrid inverter or similar capacity.

C) Business-Grade 3-Phase (15–30 kW+, 20–40 kWh+, 15–30 kWp PV)

Handles compressors, selected cold rooms, server rooms, and large lighting banks.
Uses demand-management and staged startups to reduce surges.
Can be paralleled for future growth or additional roof/ground-mount arrays.

For very large commercial or industrial sites, Enerlux also offers bespoke generator and solar integrations where required.

Installation & Compliance in South Africa

A safe, reliable system needs correct AC and DC protection, correct earthing, clear labelling, lightning and surge protection where applicable, and a proper Certificate of Compliance (CoC). Three-phase boards, neutral-earth configurations, and generator integration must be designed and tested by qualified professionals.

Enerlux works with vetted installers and electrical teams to ensure neat workmanship and standards-compliant sign-off on every project.

Common Mistakes to Avoid

Under-sizing surge capacity for fridges, air-cons, and pumps.
Too small batteries for the required backup runtime.
PV strings outside MPPT range (string voltage too low or too high).
Ignoring roof details (wrong mounting kits for tile vs IBR/corrugated roofs).
No sub-DB split (critical vs non-critical loads), which leads to nuisance trips.
Skipping monitoring — you can’t optimise what you can’t see.

For example, a home that keeps an electric stove and geyser on the backup side without redesigning the system will often overload even a good inverter.

Real-World Example (Johannesburg)

Example: 15 kW three-phase hybrid with 2 × 14 kWh LFP (28 kWh total) and 24 × ~590 W panels (~14.2 kWp)

Runs a medium office plus refrigeration and lighting, with capacity to stage heavy starts.
Provides reliable backup during load-shedding, while PV slashes daytime bills.
Installed with full AC/DC protection, correct earthing, and a valid CoC.

Larger commercial clients may also combine such systems with high-capacity storage like a 215 kWh high-voltage battery bank for deeper resilience.

FAQ: Quick Answers

Q: Can I start small and expand later?
A: Yes. Choose a hybrid inverter that supports parallel expansion and add batteries or PV modules later as your budget and needs grow.

Q: Will solar run my stove or geyser?
A: It can, but those are heavy loads. Most clients keep them on non-critical circuits, or design a larger system and battery bank specifically to include them — sometimes switching to a solar geyser to reduce demand.

Q: Do I need three-phase?
A: Only if your property already has a three-phase supply or your machinery requires it. Otherwise, single-phase is usually sufficient.

Q: How long will the batteries last?
A: Modern LFP batteries are often rated for 6,000–10,000 cycles depending on brand and depth of discharge — typically 8–15+ years in normal home or office use.

Q: Can I export to the grid?
A: This depends on your municipality and metering rules. Even without export, a well-designed hybrid system offers excellent backup and daytime savings.

Final Thoughts

A solar inverter is more than a DC-to-AC converter — it’s the control centre of your energy system. The right choice ensures performance, safety, and long-term value. Whether you need quiet backup for load-shedding, serious daytime savings, or a scalable three-phase solution, a correctly sized hybrid inverter with quality batteries and panels will transform your energy resilience.

If you’re still deciding between options, you can also explore broader topics like the true cost of going solar or hybrid power systems for a bigger-picture view.

Get a Tailored Quotation from Enerlux

Tell us your loads and roof: we’ll map out options with clear runtimes, savings estimates, and a bill of materials — installed with a valid CoC.

You can reach us via the Enerlux contact page or send your details over WhatsApp or email.

Share These Details to Get Started

Property location (Johannesburg/Gauteng/other)
Single-phase or three-phase supply
Your critical loads and required backup hours
Approximate roof type (tile/IBR/corrugated/flat) and available area
Photos of your main DB board and the proposed inverter wall (if possible)

From there, Enerlux will recommend a practical system size — whether that’s a compact 5 kW backup bundle or a larger three-phase solution — with clear pricing and upgrade paths.

What is an Inverter? A Complete Guide for Solar Power Beginners