calculate_home_battery_payback
ClaudePayback time of a home battery with the calculator of jeroen.nl, for five ways of using it: self-consumption of solar surplus at night, self-consumption plus charging from the grid at low prices, trading only on days with a large enough price spread, trading at fixed times, and trading every day at the best hours. Trading uses the real Dutch day-ahead prices of the last 12, 24 or 36 months; self-consumption uses how full a battery of this size gets per day in real measured households with about the same yearly solar production. Savings in EUR per year incl. 21% VAT, energy tax and supplier fees. With a fixed or variable contract only self-consumption applies. Battery wear is in the cycle budget; the full nominal capacity is used.
check_grid_congestion
ClaudeGrid congestion in the Netherlands for a postcode (4 digits, or 4 digits plus 2 letters), a place, a municipality or a province. Two sources: (1) voltage problems in the neighbourhood that Stedin, Enexis and Liander reported per postcode when every postcode was checked between January and May 2024 (other grid operators had no check, so their postcodes are "not checked"); (2) the transport capacity map of the Dutch grid operators (Partners in Energie) for the supply area: whether there is a queue for withdrawal (consumption) and for injection (feed-in), on the regional grid and on the TenneT high-voltage grid, in MW, and when it is expected to be solved. For a place or municipality the supply area of its most populated postcode is used. Includes what it means for a household with a heat pump, home charger, solar panels or home battery.
compare_ere_providers
ClaudeDutch ERE booking service providers (inboekdienstverleners) for home charging of an electric car, as compared on jeroen.nl: commission and how it works, all fixed costs, payout frequency, contract terms, confirmed charger brands, benefits, the jeroen.nl score (1 to 10) and the expected net revenue per year in EUR for a given number of kWh charged at home, at the current ERE market price. Give kwh_per_year (kWh charged at home) or km_per_year (converted like the site: 18 kWh per 100 km, 80% charged at home, so 14.4 kWh per 100 km). Without either, 10,000 km per year is used. The net revenue uses the commission of the first contract year and all yearly costs; it is an estimate, the real payout follows the market price.
compare_p1_meters
ClaudeThe P1 meter (smart meter dongle) comparison of jeroen.nl: every active P1 meter with its rating out of 10 and the five components behind it (local control 2.25, app 2.25, subscription 2.0, update rate 1.5, community 2.0; unknown data scores 0), the lowest current shop price in EUR incl. VAT, the monthly subscription cost, update interval, local API, support for Home Assistant, Homey and Domoticz, connection types and how many jeroen.nl profiles have that meter. A shop price counts when it was updated in the last 45 days; otherwise the oldest known price is shown with price_date. Default order is the same as on the site: highest rating first. Filters only keep meters where the property is known.
compare_plug_in_batteries
ClaudeThe home battery comparison of jeroen.nl: active batteries that are sold in at least one shop, with the lowest current shop price, price per kWh of gross capacity, gross and usable capacity, charge and discharge power (for plug-in batteries the power allowed back through the socket), round-trip efficiency, depth of discharge, warranty, cycle life, chemistry, purposes and how many jeroen.nl profiles have that model. Prices are consumer prices in EUR including VAT. A shop price counts for the lowest price when it was updated in the last 45 days; only when no shop has a recent price, an older one is used and price_date shows its date. Default order is the same as on the site: most profiles first, then lowest price per kWh. The profile count only includes batteries whose model could be identified with certainty.
get_electricity_price_forecast
ClaudeForecast of Dutch day-ahead electricity prices for today and the coming days (up to 7), made by jeroen.nl with a weather-driven model. Per quarter hour or hour: the known market price where the auction already happened, otherwise p10, p50 and p90 in EUR/kWh excluding VAT.
get_electricity_prices
ClaudeDay-ahead electricity prices for the Netherlands (EPEX/ENTSO-E bidding zone NL) from 2013 until tomorrow once published (around 13:00). Market price in EUR/kWh excluding VAT, per quarter hour, hour, day, month or year. Optionally an indicative all-in consumer price including energy tax, average supplier fee and 21% VAT (only for dates from 2023). Maximum period per call: 31 days per quarter hour, 92 days per hour, 10 years per day.
get_energy_saving_tips
ClaudeEnergy saving tips for Dutch households from jeroen.nl, as published on https://jeroen.nl/energie/besparen: per tip the topic, its number within the topic, title, explanation, the personal example of Jeroen, the saving as a quantity (kWh electricity and/or m3 gas per year, only when a source gives one), effort, cost, source and a link to the tip on the page. savings_eur_per_year_incl_vat is calculated by jeroen.nl with the average price of the last 12 months: day-ahead market price plus average supplier fee plus energy tax of the current year plus 21% VAT (the prices used are in the answer). Tips without a quantity have no amount, because the saving depends too much on the house. Amounts are rounded estimates for an average household.
get_ere_market_price
ClaudeCurrent market price of an ERE (emissiereductie-eenheid, the Dutch renewable energy unit for charging an electric car) in EUR per ERE, and the weekly history with bid, ask and mid price on the LRE-E spot market. Also the gross revenue per kWh charged at home. One quote per week at most, history from 2026. Source Joulo (CC BY 4.0).
get_expected_average_prices
ClaudeExpected average market prices for the coming 12 months that Dutch suppliers of dynamic contracts must use in their cost estimates: electricity without solar panels, electricity with solar panels, solar feed-in and gas. Excluding VAT, taxes and supplier fees. Useful when comparing fixed and dynamic contracts. Without dates it returns the latest values; with date_from it also returns one snapshot per day (history from 2026-07-09).
get_gas_prices
ClaudeDaily dynamic gas prices for the Netherlands from 2018, in EUR/m3 excluding VAT, per day, month or year. Optionally an indicative all-in consumer price including energy tax, average supplier fee and 21% VAT (only for dates from 2023).
get_grid_operator_costs
ClaudeMonthly grid operator costs (netbeheerkosten) in the Netherlands per grid operator and connection size, for electricity and gas, for 2026 and 2027 when published. Amounts include VAT. Grid operator costs are identical for every energy supplier.
get_historical_weather
ClaudeMeasured weather in the past for a place in the Netherlands, per day or per hour: mean, minimum and maximum temperature, heating degree days (base 18 °C, plain and weighted the way Dutch energy suppliers do), sunshine hours, solar radiation, precipitation and wind. Give a Dutch postcode (1934AA or 1934) or a latitude and longitude. On https://jeroen.nl/mcp/account, use_my_home uses the location of the signed-in account's house instead (needs the woning permission). Use it to explain energy use: gas and heat pump consumption follow degree days, solar production follows radiation and sunshine. Available from 2000-01-01 up to yesterday. Maximum 1100 days per call per day, 31 days per hour. Source: Open-Meteo archive (ERA5 reanalysis), on a grid of about 10 km.
get_quiz
ClaudeOne open knowledge quiz from jeroen.nl with all questions and answer options, plus the sources the quiz is based on. By default the correct answers and explanations are left out, so the questions can be asked first. With include_answers=true every question also gets the correct option, the explanation and how often it is answered correctly on jeroen.nl. Ask the questions one by one and only fetch the answers after the user has answered. This tool cannot submit answers or award energy points.
get_solar_bonus
ClaudeSolar feed-in bonuses of Dutch dynamic suppliers: the rules, when the bonus applies and what it pays right now, or for a given market price. Amounts in EUR/kWh, excluding and including VAT.
get_solar_bonus_analysis
ClaudeBackground data behind the jeroen.nl article on solar bonuses: the average market price per hour over the last 12 months (April to September, 07:00-21:00, positive prices), what each supplier with a solar bonus pays per kWh at that price, the best paying supplier per hour, averages for south, east and west facing panels, and a month by hour grid. Refreshed daily.
get_solar_forecast
ClaudeSolar panel yield forecast for a location in the Netherlands for today and the coming days, per kWp and for a given system size, with an uncertainty band (p10, p50, p90) from a weather ensemble. Azimuth: 0 = south, -90 = east, 90 = west. Tilt in degrees from horizontal. Model: irradiance on the panel plane, temperature derating and a performance ratio of 0.85.
list_dynamic_energy_suppliers
ClaudeDynamic (hourly or quarter-hourly priced) electricity and gas suppliers in the Netherlands with their fees: purchase fee per kWh, feed-in fee per kWh, fee per m3 gas and monthly costs, excluding and including VAT, plus whether they offer a solar bonus. Each supplier has an information link and a signup link on jeroen.nl. The order is alphabetical or by the chosen sort, not a ranking.
list_electric_cars
ClaudeElectric cars (source EV Database) or plug-in hybrids (source Autoweek) sold in the Netherlands, as listed on jeroen.nl: brand, model, list price in EUR incl. VAT, usable battery kWh, real-world and WLTP range, consumption, AC and DC charging power, and bidirectional charging: V2L (to appliances), V2H (to the home), V2G (to the grid), each with status yes, announced, no or unknown, whether it works via AC (the car converts) or DC (the charger converts) and the power in kW. Announced is not yes: it only counts in the bidirectional filter with include_announced. Also how many jeroen.nl profiles have the model.
list_quizzes
ClaudeLists the open knowledge quizzes on jeroen.nl about energy (electricity prices, solar panels, home batteries, heat pumps and more): title, level, categories, number of questions, the maximum energy points a first attempt earns on jeroen.nl, how many people completed it and the share of answers given on the site that were correct. Use get_quiz with the slug to go through a quiz with the user. Energy points are only earned by doing the quiz on jeroen.nl itself.
