How prices per 100 Wp are computed
The price on the box says little about what solar power costs. A 440 W module at €89 is cheaper per watt than a 100 W panel at €39, and a balcony set sold as “800 W” usually carries 880 W of modules without its title saying so. This site turns every Amazon solar listing into the price of the same thing — one watt-peak of module power, quoted per 100 Wp — and ranks by that.
The price column
Every category is quoted per 100 Wp of module power. Rigid, flexible and portable panels and balcony sets are never ranked against each other: a set includes an inverter and a foldable panel a bag and cables, so each is compared with its own kind.
| Category | Ranked by | Example |
|---|---|---|
| Solar panels (rigid glass modules) | price per 100 Wp | €179 for 2 × 440 Wp = €20.34 per 100 Wp |
| Flexible panels | price per 100 Wp | €139 for 200 Wp = €69.50 per 100 Wp |
| Portable panels (foldable, USB chargers) | price per 100 Wp | €199 for 160 Wp = €124.38 per 100 Wp |
| Balcony kits (modules + micro-inverter) | price per 100 Wp of their modules | €299 for 2 × 440 Wp with an 800 W inverter = €33.98 per 100 Wp |
| Balcony kits with storage, off-grid kits | listed by package price, not ranked | the battery, inverter or controller decides the price |
Watt-peak at STC, front side only
A module’s watt-peak (Wp; Wc in French) is its power at standard test conditions: 1,000 W of sunlight per square metre at a cell temperature of 25 °C. Every label states it, so it is the one figure that compares across brands. Real output on a roof or balcony is lower and depends on orientation, shade, heat and season. A bifacial module also collects light on its back; that extra is not counted, and neither are “up to 550 W” figures that include it — a 440 Wp module is priced as 440 Wp.
The “800 W” trap
“Balkonkraftwerk 800W” names the inverter, not the modules. 800 W is the feed-in limit for plug-in sets in Germany and elsewhere; the modules behind it usually add up to 820–900 Wp, and “2000W” sets are four 500 Wp modules behind the same 800 W inverter. A set is priced over the sum of its modules: “880W/800W” and “2x440W + 800W inverter” are both 880 Wp. A title that only says “800W” or “600W” states no module power at all, so the set is listed by its package price, without a price per watt-peak, until its product page names the modules. Inverter watts never enter the price per watt-peak.
Sets versus panels
A balcony set costs more per watt-peak than a bare module because its price includes the micro-inverter, cables and often a mount: compare sets with sets. Sets with a battery are battery purchases first — a 2 kWh store can cost more than the modules — and off-grid kits carry a charge controller, sometimes a battery or a power station. Ranking either per watt-peak of modules would reward a weak battery, so both are listed by package price, with the modules, inverter and battery in each row’s details. Balcony sets appear only in the storefronts that sell them as such (Germany, France, Italy and Spain).
The Efficiency column and the highlights
Efficiency is the module efficiency the listing states (the share of sunlight a module turns into electricity at STC, usually 20–23 %). It is shown beside the price and never changes the ranking: a more efficient module needs less space for the same power, which matters on a balcony, not on a field. Best value marks the lowest price per 100 Wp among in-stock listings in the selected category that match your filters, across all result pages; Most efficient marks the highest stated efficiency. Tied winners share the highlight, and a lone listing gets no badge.
What is estimated, and what never is
Module power is never invented. A listing without a module figure, or with several different ones in its title, is listed by package price. Two things make a price an estimate, marked ~ and removed by “Hide estimates”: a module count assumed to be one because the title says “Set” or “Stück” without a number, and a listing whose stated total contradicts its modules (“2x 400W, 880W”), where the modules win.
Never estimated:
- module power from an inverter, a power station or a USB output — “800W Wechselrichter” is not a module;
- module power from watt-hours — a battery’s 1.6 kWh is storage;
- module power from an “up to” or bifacial maximum;
- efficiency, which is shown only where the listing states it.
Implausible figures are not ranked
Amazon carries “1000W” folding panels that weigh 2 kg. A rigid glass module weighs about 1 kg per 20 Wp, so module power heavier per kilogram than physics allows (30 Wp/kg for rigid modules, 150 for flexible and 100 for portable panels) is refused, and so is a price per watt-peak far below or above the market for its category. Such listings stay visible by package price, marked as unranked, and the row says why. “Solar generators” are power stations: batteries, not panels.
What is not listed
Inverters on their own, mounts and brackets, cables and MC4 connectors, charge controllers on their own, solar lamps, fountains and pumps, power banks, power stations without a panel, solar film, bare cells and solar thermal products are never listed, even when their titles name a wattage.
Where the numbers come from
Module power, counts and efficiencies are read from the listing itself: the title (“Jinko Tiger Neo 440W Solarmodul bifazial, 2 Stück” → 2 × 440 Wp), and, where the product page has been read, the description and product information. Every number read from a product page must come with the exact words it was read from, or it is dropped.
Prices, VAT and freight
Prices are the item prices Amazon shows, with the VAT Amazon applies. In Germany solar modules and balcony sets are often sold at 0 % VAT, and the prices here are as Amazon shows them, never adjusted. Large modules may ship by freight or on a pallet, and a listing may charge that delivery separately: it is not part of the price here, so check the delivery cost at checkout.
Data freshness & countries
Prices are refreshed weekly for each of ten Amazon storefronts, each a separate catalog in its own currency; the date above the table shows the last update. Prices and availability change at any time — what Amazon shows at checkout is what applies.
Affiliate disclosure
Product links carry an Amazon Associates tag. As an Amazon Associate, this site earns from qualifying purchases, at no extra cost to you. Rankings are computed from the numbers alone and are never sponsored.
Installation and local rules are your check
The cheapest watt-peak is only a bargain if you may and can use it. This site gives no installation advice. Plug-in sets follow local rules: in Germany an 800 W inverter limit, up to 2,000 Wp of modules and registration in the Marktstammdatenregister; in France a self-consumption agreement with Enedis. Fixed wiring belongs to a qualified electrician, and a balcony railing has to carry the module safely in a storm. Check with your grid operator, your landlord or a qualified installer before you buy.