Which Appliances Work on Solar or an Inverter
The mistake that kills inverters is simple: people size them by adding up wattages and forget that motors demand two to three times their running power for the first second. An inverter has to survive the surge, not just the running load. This is which appliances work on solar or an inverter backup, which never will, and how to size for both numbers.
Running watts versus surge watts
Every appliance has two numbers. Running watts is what it draws steadily. Surge watts is the spike when a motor or compressor starts, typically two to three times running for a few hundred milliseconds.
A fridge drawing 150 W running may demand 450–900 W the instant its compressor kicks in. An inverter rated at exactly 150 W will trip. This is why "my inverter is big enough on paper" and "my inverter keeps cutting out" are usually the same installation.
What works, and what does not
| Appliance | Running | Surge | On solar / inverter? |
|---|---|---|---|
| LED lights | 7–12 W | None | Excellent |
| Phone / laptop charging | 5–90 W | None | Excellent |
| Router, decoder | 10–30 W | None | Excellent |
| Television | 50–150 W | Low | Excellent |
| Fan | 50–80 W | ~150–200 W | Good |
| Fridge / freezer | 100–200 W | 450–900 W | Good, if sized for the surge |
| Blender | 300–600 W | 900–1,500 W | Workable in short bursts |
| Washing machine (cold) | 500 W | 1,500 W+ | Possible on a larger system |
| Microwave | 800–1,200 W | ~1,500 W | Only on a large system |
| Electric kettle | 1,800–2,200 W | None (resistive) | Poor — huge steady draw |
| Iron | 1,000–1,800 W | None | Poor |
| Air fryer | 1,400–1,800 W | None | Poor |
| Cooker plate | 1,500–2,000 W | None | Not realistic |
| Instant shower heater | 3,000–4,500 W | None | No |
| Water heater / geyser | 1,500–3,000 W | None | No |
Notice the pattern. Heating elements have no surge but an enormous steady draw — they are the ones you simply do not put on battery. Motors have a modest steady draw but a violent surge — they are fine if you size for the spike. This distinction is the whole skill.
Sizing an inverter, properly
- List what must run at the same time. Not everything you own — what genuinely needs to be on during an outage.
- Add the running watts. Lights 60 W + router 20 W + TV 120 W + fridge 150 W = 350 W.
- Find the single biggest surge in that list — here the fridge, at up to 900 W.
- Your inverter must handle running total plus that surge: roughly 350 − 150 + 900 = about 1,100 W at the moment the fridge starts.
- Add 25–30% headroom. That points to a 1,500 W inverter for this modest load.
People size that same load at 400 W and then wonder why the inverter trips whenever the fridge cycles.
Battery capacity: how long it lasts
Inverter size decides what you can run. Battery capacity decides how long.
- Running 350 W for four hours needs about 1.4 kWh delivered.
- You cannot use a battery's full rating. Lead-acid batteries should not be drained past about half their capacity if you want them to last; lithium tolerates far deeper discharge.
- So 1.4 kWh of actual use needs roughly 2.8 kWh of lead-acid capacity, or around 1.6 kWh of lithium.
- Add losses — inverters are typically 85–90% efficient, so budget another 10–15%.
This is why people report their "2 kWh battery" lasting half as long as expected. It was never 2 kWh of usable energy.
Pure sine wave versus modified sine wave
Cheaper inverters output a modified (stepped) waveform. It runs simple loads but causes real problems with others:
- Fridges and motors run hotter and less efficiently, shortening their life.
- Anything with a compressor may buzz audibly or refuse to start.
- Some chargers and electronics whine, misbehave or fail early.
If a fridge is on your backup list, buy pure sine wave. It is the difference between a backup system and a slow way of destroying a compressor.
A realistic Kenyan outage plan
Rather than trying to run the whole house, split your load into tiers:
| Tier | What's on it | Why |
|---|---|---|
| Essential (always backed up) | Lights, phone charging, router, fridge | Low draw, high value, protects food |
| Comfort (if the system allows) | TV, fan, laptop | Modest draw, easy wins |
| Never on battery | Kettle, iron, shower heater, cooker, air fryer | Heating loads — keep a gas alternative instead |
Keep a gas burner and a flask. Boiling water on gas and storing it hot in a vacuum flask solves the tea problem for a whole outage without touching your battery. That single habit removes the biggest temptation to overload a system.
Five mistakes worth avoiding
- Sizing on running watts only. The surge is what trips the inverter.
- Putting a kettle or iron on backup. A 2,000 W heating load will flatten a domestic battery bank fast.
- Modified sine wave with a fridge. It works until the compressor does not.
- Draining lead-acid batteries flat. It shortens their life dramatically; treat half as empty.
- No headroom. A system running at its limit has no margin for the day you add one more thing.
Frequently asked questions
Can I run a fridge on an inverter?
Yes, if the inverter can handle the compressor surge — up to two or three times the running watts — and ideally if it is pure sine wave.
Can I run an electric kettle on solar?
Not practically. A kettle draws 1,800–2,200 W steadily. Boil on gas and keep the water in a vacuum flask instead.
What size inverter do I need for lights, a TV, a router and a fridge?
Around 1,500 W. The running load is only about 350 W, but the fridge's start-up surge plus headroom is what sets the size.
What is the difference between running watts and surge watts?
Running watts is the steady draw. Surge watts is the brief spike when a motor or compressor starts, typically two to three times higher.
Do I need a pure sine wave inverter?
If you are running a fridge, motors or sensitive electronics, yes. Modified sine wave shortens the life of compressors.
Why does my battery run out faster than expected?
Because usable capacity is less than rated capacity — lead-acid should not go below about half — and inverters lose 10–15% in conversion.
Which appliances should never go on battery backup?
Anything that makes heat: kettle, iron, air fryer, cooker plate, shower heater, geyser.
Plan your backup
Browse appliances and electronics, vacuum flasks for holding hot water through an outage, and outdoor and camping gear for lights and gas alternatives. Working out what your system can carry? Send us your appliance list on WhatsApp.