Hybrid, off-grid or grid-tied — which inverter is right for you?

The panels get the attention, but the inverter decides what your system actually does. Choose the wrong type and you can end up with a solar installation that switches itself off during a blackout — which is exactly what many Kenyan buyers discover, to their considerable surprise, the first time the grid fails.

There are three types. They do different jobs.

Grid-tied: cuts the bill, dies with the grid

A grid-tied inverter converts panel output to mains-quality AC and feeds it into your building's supply. Your appliances use solar first and draw from KPLC only for the shortfall. There is no battery.

What it is good at. It is the cheapest way per kilowatt to reduce a bill, because you are not paying for storage. For a business consuming most of its power during daylight, it is often the most economically efficient choice available.

The catch that surprises people. When the grid goes down, a grid-tied inverter shuts down too — even in bright sunshine, even though your panels are producing. This is not a fault. It is a mandatory safety function called anti-islanding: if the inverter kept exporting into a dead network, it could electrocute a lineman working on what he believes is a de-energised line.

So a grid-tied system reduces your bill and does absolutely nothing for you during an outage. If your reason for going solar includes blackouts, this is the wrong type on its own.

Off-grid: stands alone, ignores the grid

An off-grid inverter builds its own AC supply from panels and batteries. It does not need a grid connection and, in most configurations, cannot use one to charge.

What it is good at. Sites with no mains connection at all — remote homesteads, farm buildings, boreholes, camps, and anywhere a KPLC connection would cost more than the solar system. It is a complete, self-contained power supply.

The catch. Everything must be sized for the worst case, because there is no fallback. A run of overcast days with no generator means going without. Off-grid systems therefore carry more battery and more panel than a grid-connected equivalent, which makes them more expensive per useful kilowatt-hour.

Hybrid: both, and the reason most people buy one

A hybrid inverter manages solar, battery and grid together, deciding moment by moment where power should come from. Solar covers the load first, surplus charges the battery, and the grid fills any remaining gap. When the grid fails, the inverter disconnects from it and keeps running your backed-up circuits from battery and solar.

What it is good at. Almost every situation where a grid connection exists but is unreliable — which describes most of Kenya. It cuts your bill and keeps you running through outages.

The catch. It costs more than grid-tied, because you are buying storage and more sophisticated electronics. It is also the type most sensitive to being paired with the right battery.

Choosing, in three questions

1. Do you have a grid connection? No → off-grid. Yes → continue.

2. Do you need power during outages? No, you only want a smaller bill → grid-tied. Yes → hybrid.

3. Is the grid so unreliable that it is effectively absent? If you have more hours without mains than with, treat the site as off-grid regardless of the connection, and size accordingly.

For most Kenyan homes and small businesses, the answer lands on hybrid.

Sizing, and the mistake almost everyone makes

Inverters are rated in kilowatts, and that rating is about power — how much can flow at once — not about energy. It is decided by your peak load, not by your daily consumption.

The mistake is to size on running wattage alone and forget starting surge. Motors — fridge compressors, water pumps, washing machines, workshop tools — draw two to three times their running current for a moment as they start. An inverter that comfortably runs a 750W pump may trip the instant it starts if it has no surge headroom.

Look for the inverter's surge rating and its duration, not just its continuous rating. Many hybrid inverters will supply 200% for several seconds, which is what makes them tolerant of motor loads.

Single-phase or three-phase

Most Kenyan homes are single-phase, and a single-phase inverter is correct. Larger commercial premises, workshops with three-phase machinery and larger irrigation pumps need three-phase.

Do not assume you need three-phase because the system is large — plenty of substantial homes run happily on a large single-phase hybrid. Check what your supply actually is before specifying.

Battery voltage class: get this right or pay for it

This is where expensive mistakes happen. Hybrid inverters come in two battery classes:

• Low voltage (LV), typically 48V nominal / 51.2V actual. Single-phase and smaller three-phase systems.
• High voltage (HV), typically 300V and above. Larger three-phase systems.

They are not interchangeable. A 51.2V battery cannot be connected to a high-voltage input, and connecting either to the wrong class damages equipment and voids warranties. Every inverter product page on this site states its class, and our "Completes this system" suggestions only ever show batteries of the matching class — deliberately, because this is the mistake we see most often.

Features worth paying for, and features worth ignoring

Worth it:

• Generator input with automatic start/stop, if you own a generator. The inverter will run it only when solar and battery are exhausted, which usually cuts fuel consumption sharply.
• Dual backup ports, letting you separate critical from non-critical circuits so a heavy load cannot flatten your essentials.
• Proper monitoring, whether by app or portal. A system you cannot see is a system you cannot diagnose.
• AFCI (arc fault protection) on the DC side. DC arcs do not self-extinguish and are a genuine fire risk.

Less important than the marketing suggests: headline efficiency differences of a fraction of a percent, and interface polish. A well-matched, correctly sized inverter from a reputable manufacturer will outperform a flashier one that was specified carelessly.

Practical guidance

If you are unsure which type you need, work backwards from what failure you cannot tolerate. If you cannot tolerate a high bill, grid-tied. If you cannot tolerate darkness at 8pm, hybrid. If you have no grid at all, off-grid.

Then size the inverter on your genuine peak load with surge headroom, confirm the battery voltage class matches what you intend to buy, and check the surge specification if you run motors.

Our inverter range states the type, phase, battery class and key ratings on every product. If you would rather not work it out yourself, ask us for a quotation with your appliance list and an engineer will recommend a type and size — including which batteries it can legitimately be paired with.