Plug-in solar panels, with or without a battery: what they produce
One or two panels plugged into a household socket: how much they produce on a balcony or in the garden, and how long they take to pay for themselves.
A plug-in solar panel, sold in France as a “kit prêt à brancher” or “plug and play” kit, is a small set of one or two modules fitted with a micro-inverter that you connect to an ordinary socket in your home. It powers whatever appliances are running while it produces; anything extra flows to the grid without payment. In Paris, an 800 Wp kit fixed vertically on a south-facing balcony produces about 648 kWh a year according to PVGIS, against 905 kWh if it stands on the ground tilted at 30°. For a household using 4,500 kWh, almost all of it is used: the saving reaches €129 a year on the balcony and €176 on the ground. At the average price found in January 2026 (€424, an estimate excluding the mount), the kit pays back in 3.3 yrs in the first case and 2.4 yrs in the second. Even plugged into a socket, it must be declared to Enedis, the grid operator.
Does a plug-in solar kit pay off where you live?
Pays for itself in
3.3 years
| Output per year, due south | 648 kWh |
| Saving per year | €129 |
| Average kit price found | €424 |
Household using 4,500 kWh a year, surplus not sold. Average prices found in January 2026, excluding mount and delivery.
Checked by Radif Partners · Editorial policy · Method and sources
What a kit produces by size and mounting
Two things decide a kit’s output: its peak power and its position. Fixed vertically on a railing, a panel catches the sun at an angle for much of the year. In Paris, a vertical south-facing position gives 71 % of the output of a panel at the best tilt, and 50 % if the balcony faces east.
| Kit | Mounting | kWh per year | Saving per year | Average price found | Pays back in |
|---|---|---|---|---|---|
| 400 Wc | Balcony, vertical | 324 | €65 | €245 | 3.8 yrs |
| 400 Wc | Ground, tilted 30° | 453 | €91 | €245 | 2.7 yrs |
| 800 Wc | Balcony, vertical | 648 | €129 | €424 | 3.3 yrs |
| 800 Wc | Ground, tilted 30° | 905 | €176 | €424 | 2.4 yrs |
| 1,000 Wc | Balcony, vertical | 809 | €159 | €514 | 3.2 yrs |
| 1,000 Wc | Ground, tilted 30° | 1,132 | €206 | €514 | 2.5 yrs |
| 2,000 Wc | Balcony, vertical | 1,619 | €251 | €926 | 3.7 yrs |
| 2,000 Wc | Ground, tilted 30° | 2,263 | €284 | €926 | 3.3 yrs |
Prices are averages found across hundreds of kits in January 2026, excluding the mount and delivery: they are estimates, and your kit may cost more or less. The table assumes the household uses at least as much power during the day as the kit produces, which is almost always true below 1,000 Wp.
Why a kit’s surplus is lost
A plug-in kit has no purchase contract with EDF Obligation d’Achat, the body that buys solar surplus in France: whatever it exports when the home uses less than it produces feeds the grid for nothing. For an 800 Wp kit and an average household this loss stays small; it becomes significant at 2,000 Wp or more, especially if nobody is home during the day. Beyond a few panels, a grid-connected kit with surplus sales or a professionally fitted system makes more sense.
How much do you lose with your roof’s facing?
Output vs due south at 35°
81 %
| Loss (or gain) | −19 % |
| For 3 kWp in Paris | 2,776 kWh |
Factors calculated with PVGIS 5.3 for seven reference cities.
The paperwork
- Enedis: the self-consumption agreement without export (CACSI), free and online, before you switch on.
- Planning: no formality on the ground under 3 kWp and 1.8 m (article R421-2), outside protected areas; on a balcony or façade, ask the mairie.
- Flats: the co-ownership rules may restrict what can be fixed to balconies and railings.
The formalities for a larger system are on the installation and paperwork page.
Plug-in panels with a battery
Some plug-in kits are sold with a battery. It only helps if there is surplus to store. In Paris, an 800 Wp kit on a south-facing balcony is 100 % self-consumed by a household using 4,500 kWh: there is almost nothing to store, and a battery would earn next to nothing. With 2,000 Wp on the ground at 30°, the surplus rises to 843 kWh, a 2 kWh battery recovers 410 and its break-even price rises to €1,642. Hour-by-hour calculation at the current Tarif Bleu, with no rise assumed.
Kit or rooftop system?
The kit wins on price and simplicity; the roof wins on output and yearly saving. At €129 a year for 800 Wp on a Paris balcony, a kit covers a small part of an average bill, whereas a 3 kWp rooftop system covers far more. The calculator on the home page lets you compare both for your commune.