Plug-in solar or a power station?

The confusion is understandable, because both are sold as ways to "use solar power". In practice one is a generation device and the other is a storage device, and neither replaces the other.

A plug-in solar array is panels plus a microinverter that feeds a wall outlet. It produces while the sun is up and puts that power onto a circuit immediately. Whatever the house is using at that moment gets it; the rest is exported to the grid. There is no tank.

A portable power station is a battery with an inverter. It stores energy from the wall, from panels, or from a car, and gives it back when you plug something into it. It produces nothing on its own.

That asymmetry decides the whole comparison. If the house is empty all day and nobody is home to use generation, the panels' output goes to the utility for whatever credit your state offers, which may be nothing. If the grid fails at night, the battery is the only one of the two that can answer.

The first-year return is generation multiplied by the share of it you use while it is being made, multiplied by your price per kWh. Generation is easy: panel watts times peak sun hours times system efficiency, times 365. The self-consumption share is the part people get wrong.

If nobody is home between nine and five, self-consumption might be 20 %. If someone works from home, runs a fridge, a router and air conditioning, it can be 60 %. The same array is worth three times as much in the second house, and no datasheet tells you which house you have.

Exported energy is the part that depends on policy rather than physics. States with full net metering credit it near retail; states with avoided-cost compensation credit it far below. This page prices self-consumption only, so the numbers below are the floor, not the ceiling, for someone with a good export rate.

For the panel-count side of the same question, the panel count calculator works out how many panels a given daily energy needs.

A station's return is not a bill offset, it is hours of continuity. Usable energy divided by the load gives runtime, and the honest way to value that is to ask what an hour without power costs you: spoiled food, a missed work call, a sump pump that does not run.

Two numbers decide whether a given station is enough. The first is the running load you would keep alive, which is usually far smaller than total house load: a fridge, lights, a router and a phone charger come to roughly 300 W of average draw. The second is how long an outage typically lasts where you live.

That makes the station the only one of the two products with a measurable outage value, and it makes it the correct first purchase for anyone whose reason for looking is a storm rather than a bill.

If you already know the running load, the fridge runtime calculator turns capacity into hours for the most common case.

Grid-tied inverters must stop producing when the grid disappears. This is called anti-islanding, and it exists so that a lineworker repairing a downed conductor is not energized from the far end. It applies to every compliant microinverter, including the ones sold for balconies.

So a plug-in array provides zero backup hours. Not few, not reduced: zero, physically. Any page that suggests otherwise is either describing an off-grid inverter with a transfer switch, or it is wrong.

The practical consequence is the reverse of what most buyers assume. The panels save money; the station saves the evening. A house that wants both outcomes needs both devices, and the order to buy them in depends purely on which loss is larger today.

Two details are worth knowing before you price either route. First, a microinverter that shuts down in an outage is not faulty, and swapping it for a different brand will not change the behavior; the shutdown is in the firmware because the standard requires it. Second, a station connected to a house circuit through a proper transfer switch can run the house, but a station plugged into a wall outlet cannot backfeed a circuit for the same anti-islanding reason. The switch is what separates the two arrangements, and it is the part an electrician installs.

The table holds self-consumption at 40 % and power at 0.17 USD per kWh, a planning figure in the range of recent US residential rates. Both inputs are editable in the calculator, so treat this as a reference point rather than a verdict.

The dollars look small next to the hardware, and that is the honest finding. A plug-in array is not a wealth machine; it is a modest, predictable offset that pays back slowly. Anyone expecting a dramatic bill change from 800 W should see these numbers first.

What improves the picture is self-consumption, not array size. Moving a dishwasher or a dryer into the middle of the day can lift the share from 20 % to 50 % without buying any hardware, which is the cheapest upgrade in this entire comparison.

Run the comparison with two concrete arrays. A 400 W array at 4.5 sun hours and 80 % efficiency makes 1,440 Wh a day; at 40 % self-use, 576 Wh is kept and 864 Wh is exported. Doubling to 800 W makes 2,880 Wh, keeps 1,152 Wh and exports 1,728 Wh. Both columns double, which is why the bill only moves when the kept column does. Moving one 1,500 W appliance from the evening into the middle of the day keeps 1,500 Wh that would otherwise have been exported, and that is more than the 576 Wh a second 400 W panel adds.

On the station side the arithmetic is a division. A 300 W average load for a given number of hours needs that many watt hours, and nameplate has to be larger than usable because depth of discharge is not 100 %. The table below uses 300 W and 85 %.

Read the last column down and the category boundary appears. Sixteen kWh does not come in a suitcase, so a two-day outage is the point where the conversation moves from a portable box to a fixed battery and an electrician. Knowing that in advance prevents a purchase that only covers the first night.

If the load you care about is a fridge specifically, the runtime page uses the real compressor duty cycle rather than a flat 300 W.

A renter with a balcony and a small bill. Panels, and probably only panels. The outage exposure is a few hours a year and the goal is a lower bill. Start with an 800 W array and revisit storage only after a real outage.

A homeowner who lost power for two days last winter. The station, sized to the eight-hour row at minimum. Panels can wait; they cannot help during the event that motivated the purchase, and buying them first would have been the expensive mistake.

Someone who wants both and has one budget. Station first, panels second. The station works without panels, while panels do not work without the grid. The second purchase then reduces how often you recharge from the wall, which is the cheapest way to extend the first one.

The pattern is consistent: buy the device that solves today's loss, then add the other one when the budget allows. The wrong order costs a year of the exact protection you were trying to buy.

One more case is worth naming because it is common and badly served by both products: a household that wants a lower bill and has no daytime load at all. Panels alone return very little there, and a station cannot create savings without a time-of-use rate. The honest advice is to change the load pattern first, moving laundry and dishwashing into the middle of the day, and only then decide whether hardware adds anything.

Fourteen units in the current US market, ordered by what they can cover. The first group is for short outages and bill shifting, the middle covers a full day, and the last is the only single box that carries a two-day load at reduced draw. For a wider view of the category, see the portable power station ranking.

None of these is a panel. If the bill is the problem, the purchase is on the solar side and the plug-in panel comparison covers what is actually sold in the US.

Buying panels for backup. The most common error in this comparison. Panels do not run during an outage, so a storm-motivated buyer who starts with solar has bought the wrong thing for the event that prompted the purchase.

Buying a station for the bill. A station moves energy in time; it does not create any. Without a time-of-use rate, it saves nothing on a bill, and it costs more per kWh than the grid does.

Pricing exported kWh at retail. If the state does not have net metering, exported production may be credited at zero. The array then only earns what the house uses while it produces.

Sizing the station to the whole house. Total house load is not the backup load. A fridge, lights, a router and a phone charger are around 300 W of average draw; sizing to the panel's total rating is how people buy a system built for a house that is not running during an outage.

Every number on this page is recomputable from the two formulas: generation equals array watts times sun hours times efficiency, and runtime equals usable energy divided by load. If a value here disagrees with the calculator, the calculator is the source of truth, and the changelog records each change.

For the specific case of adding storage to an array that already exists, see adding a battery to plug-in solar.

For the panel-to-battery side of the same wiring, size the charge controller before comparing systems.