Balcony solar kit: what is in the box

The phrase "balcony solar" arrived from Europe, where a renter hangs two panels on a railing, plugs a microinverter into a wall socket and offsets part of the household load. That product exists in the US in a small number of forms, and it is genuinely grid-tied.

The other product that uses the same words is an off-grid set: folding panels plus a portable power station. It works, it is useful, and it is not the same thing. Its output goes into a battery box, never into the house wiring, and it does nothing at all for a bill unless you plug appliances into the box.

The distinction is not marketing language, it is a different energy path. Grid-tied means the house wiring is the destination. Off-grid means the battery is the destination. Both are legitimate; only one of them is what most people mean when they search for a balcony kit.

Before comparing prices, check the box contents against four items. Listings routinely omit the one that costs the most, and a kit missing its inverter is not a discount, it is a different product.

Two details are worth checking on the inverter line specifically. First, whether the listing names a certification at all, and second, whether it gives a certificate number. A claim without a number is a claim; a number can be looked up.

For how the energy moves once it is connected, the guide on how plug-in solar works follows the whole chain from panel to meter.

Most kits in this class ship as one box with a microinverter already matched to the panels: a 800 W four-panel example (check current price).

An arithmetic check catches most incomplete kits. Four 200 W panels make 800 W; at 4.5 sun hours and 80 % efficiency that is about 2,880 Wh a day, which is more than a typical balcony household uses while the sun is up. If the box's microinverter is rated 800 W, panels and inverter match. If it is rated 600 W, the top 200 W of panel is clipped on clear days, and the kit is not the 800 W the name suggests.

A standard US wall circuit is 15 A at 120 V, which is 1,800 W. The continuous-load convention is 80 % of that, so 1,440 W is the practical ceiling for a load that runs for hours. A kit above that figure is asking the circuit to do something it was not sized for, and the listing's claim that it "plugs into any outlet" does not change the arithmetic.

This is why the very large kits in this category need a conversation rather than a purchase. An 800 W or 1,200 W kit sits inside the limit. A 1,600 W or 1,800 W kit does not, and the correct next step is a dedicated circuit or an electrician's assessment, not a longer extension cord.

One more practical point: the outlet you use is shared. A circuit already carrying a microwave and a kettle has less headroom than its rating suggests, and the kit is the load that pushes it over.

A balcony is not a roof. The railing is usually vertical, the view is often partly blocked, and the useful sun arrives at an angle. The table below applies the same 800 W kit to four mounting situations, using the sun hours published in the sun hours table.

Those factors are planning values, not measurements, and the exact loss depends on the season: a vertical panel is worst in summer, when the sun is high, and performs comparatively better in winter. That is the opposite of what most people expect, and it is why a balcony system's monthly production curve is flatter than a roof's.

Two panels on a railing also shade each other if they are stacked. Microinverters limit the damage to one panel each rather than one string, which is the main technical argument for them at this scale.

The arithmetic runs backwards from what you want to offset. Take a daily consumption figure in watt hours, divide by the sun hours for your location, divide again by system efficiency, and you have the array size in watts. Divide by the panel rating for the count.

Worked example. A household wants to offset 1,800 Wh a day. Its location has 4.5 sun hours, the balcony is vertical with a 0.75 factor, and system efficiency is 80 %. The usable sun hours are 3.4, so the array needs 1,800 divided by 3.4 and then by 0.8, which is about 660 W. At 200 W per panel, that is three panels, and a fourth if you want margin for winter.

The panel count calculator runs this with your own numbers, and the load calculator produces the daily figure in the first place. The most common mistake in this arithmetic is using the annual sun hours for a system that has to work in winter.

Three phrases appear in these listings and they mean different things. Reading them correctly is most of the due diligence.

This site does not assert that any particular standard is legally required, because that depends on the utility and the authority having jurisdiction. What can be said plainly is that a grid-connected product should be able to point to a certification, and a listing that cannot is asking you to take it on faith.

A grid-tied inverter must stop producing when the grid is absent. This is anti-islanding, and it exists so that a line worker repairing a conductor is not energized from a balcony. Every compliant inverter does it, including the ones sold as plug-in kits.

The practical consequence is worth stating without hedging: a balcony kit reduces a bill while the sun is up and provides nothing during an outage. If backup is the goal, the purchase is a battery, and the guide on adding a battery to plug-in solar explains why that is a different architecture rather than an accessory.

This is the part no product page covers, and it is usually the deciding one. A renter needs the lease to allow an exterior modification, and often the landlord's written agreement. A condo or co-op owner needs the association's rules, which frequently address anything attached to a balcony for fire and wind reasons.

There is also a utility process. A grid-connected system is an interconnection, and the utility has a form for it even when the system is small. Skipping that step does not make the system invisible; it makes it non-compliant, which matters at the moment of a sale or an inspection.

None of this is settled by the kit. It is settled before the kit is ordered, which is why the honest advice for a renter is to read the lease first and the product page second.

This is not a ranking, and it deliberately is not one: the honest description of this category in the US is that very few products exist, so an ordered list would be mostly noise. What follows is what is on the market, in the order a buyer should evaluate them, with the reason each one is interesting.

For the wider comparison of these systems on wattage, completeness and certification disclosure, see the plug-in panel comparison. If what you actually want is backup rather than a bill offset, the portable power station ranking is the better starting point.

The same three kits, put through the arithmetic that decides whether they are usable. None of these figures is a measurement; they are the calculations a buyer should run before ordering.

Those daily figures assume 4.5 sun hours and 80 % efficiency. Change the location and they move by a factor of two in either direction, which is why the sun hours table exists and why a kit without a location is an incomplete recommendation.

Buying panels without an inverter. The most common costly error here, and the checklist above is the whole defense against it.

Sizing on annual sun hours. A balcony panel already behaves worse in summer than in winter, and using the annual figure for a winter requirement doubles the shortfall.

Ignoring the circuit. Anything above 1,440 W continuous is a different conversation, regardless of what the listing promises about outlets.

Treating a title claim as certification. A standard named in a product title and a certificate number are not the same thing, and only one of them can be checked.

Buying it for outages. It will not run during an outage, by design. That is not a defect and no configuration of a grid-tied kit fixes it.

If a figure here disagrees with a calculator on this site, the calculator is the source of truth and the changelog records every correction.