I'm the person who signs the purchase orders, not the one selling generators. For the last six years, I've managed roughly $180,000 a year in electrical equipment and maintenance buying for a facilities company. That means I get pulled into two different searches: 'jackery solar generator near me' and 'perkins diesel generator set.' They both look like backup power requests. They are not the same request.
Both a solar generator and a diesel generator can make AC power. That is where the similarity ends. In this comparison I'm looking at total cost, realistic runtime, and the safe way to connect them to a building. I'll also answer the transfer switch question. No generator should be wired into a house through a dryer outlet, no matter how urgent the outage is.
1. Compare the machine class, not just the wattage label
The sticker price invites the wrong comparison. A solar generator has no fuel bill, but it has a finite battery life and a recharge limit. A diesel generator has fuel, oil, and filter expense, but it can also carry a larger continuous load. Measure both against the load you need to serve.
A Jackery solar generator is a portable battery station. A Perkins 20kW diesel generator is an industrial package: engine, alternator, radiator, base frame, controller, and output breaker. A Perkins diesel generator set is built to run for hours or even days in a permanent location. The solar generator is built to discharge stored energy more gently and quietly. Neither is bad. They are different tools.
In Q1 2024, I compared quotes for a small office. The solar generator was cheaper and quieter and had no fuel smell. The problem came when we added the real loads: refrigerator, network rack, lights, computers, and security panel. Startup surges ate into the battery reserve, and the recharge plan depended on sunlight we could not schedule. The diesel generator cost more upfront, but it was the only option that could carry that office through two days without a second unit.
Verdict: For small, intermittent loads, solar can win on total cost. For sustained loads or motor starts, a diesel generator set is usually cheaper over the life of the equipment, even after fuel and maintenance. That result surprises people, because the solar generator has no fuel bill. But the battery replacement cycle eventually shows up in the TCO.
2. 'Backup generator for apartment' means two different buyers
Searching for 'backup generator for apartment' can point you in opposite directions. A person in one apartment has a different problem than the company operating that apartment building.
If you are a resident, a Jackery solar generator can be a legitimate emergency battery. It is quiet, portable, and safe to use indoors. The rule is honesty about your loads. If the manufacturer's run-time table says your refrigerator will drain the battery in a few hours, assume it will drain it in a few hours. Use that number to decide if it is enough.
If you manage the building, your needs are different: corridor lighting, fire alarm panel, sump pumps, security cameras, maybe a few common-area receptacles. A portable solar generator is not designed for that duty cycle. A permanent Perkins 20kW diesel generator is a common starting point for small buildings. It also needs a concrete pad, fuel supply, exhaust, automatic transfer switch, and a maintenance schedule. That is not optional. If the building has code-required life safety loads, the electrical classification becomes even more serious.
Verdict: 'backup generator for apartment' is two separate purchases. Tenant: portable solar battery if the numbers cover your essential loads. Owner: permanent diesel generator set with proper transfer equipment and scheduled testing.
3. What happens on day three?
People assume a solar generator means free power in an outage. What they don't see is the battery behind the brand. If the clouds hang around or the panels are covered with snow, solar recharge slows down. For a small load, that can be fine. For essential building loads, it can turn a short inconvenience into a multi-day problem.
I am not anti-solar. I am anti-misapplication. And diesel has its own limits. A Perkins diesel generator set depends on fuel delivery and regular maintenance. It is not zero-maintenance, and nobody should pretend it is. But when the fuel supply is planned and the machine is tested under load, it can produce large amounts of power until the fuel is gone or the engine needs service.
Here is the embarrassing part. In 2022, I approved an emergency unit that had not been load-tested before the drill. It failed. The failure happened during a planned test, not a real storm, so the damage was limited to my pride and the after-action report. But it taught me the rule I now use everywhere: five minutes of verification beats five days of correction.
Verdict: The winner of the day three test is not the technology. It is the system that was tested for your actual outage profile. Battery, solar, diesel, or something else: if it is checked, it has a chance. If it is ignored, it will fail at the worst moment.
4. How to hook up generator to house with transfer switch
The exact question I hear is: 'how to hook up generator to house with transfer switch.' Here is the shortest safe version:
- List the circuits that matter. Skip the guest room and the patio heater. If you have a well pump, furnace fan, refrigerator, modem, and medical equipment, those are the ones that need power.
- Have a licensed electrician run a load calculation. The generator rating has to cover starting surge, not just running watts.
- Install a listed transfer switch, or an approved interlock kit where the local inspector accepts it. This prevents backfeeding, which is dangerous to utility crews and to your own equipment.
- Use a manual transfer switch for portable units. Use an automatic transfer switch for a stationary diesel generator set, so the generator starts when utility power disappears.
- Test the whole path under load, not just pushing the start button. Put the test on the calendar.
Under the National Electrical Code, backup generators are separate sources and need transfer equipment before they can be connected to a building. That is not a suggestion. In most areas, the local electrical inspector has to approve the installation. If you rent an apartment, do not modify the building panel without written permission. A portable solar generator is easier there, because it does not need a transfer switch if it is used only for cord-and-plug loads.
So which one should you buy?
Use the scenario, not the brand loyalty. If you need to keep a single apartment or small portable load alive, a solar generator can be the right answer. It is quiet, has no exhaust, and can be stored indoors. Just keep it matched to the load.
If you are protecting a house with a well pump or a building with common-area loads, a Perkins 20kW diesel generator with a transfer switch is the safer budget decision. It costs more upfront, but it is built to carry larger loads for longer periods. That's not a marketing opinion. It's a rating difference.
After six years of purchase orders, my final rule is simple: buy for the actual load, connect it legally, and test it before the lights go out. The cheapest generator gets expensive when it fails the first real test. The one that runs through the night is always worth what you paid for it.
