What can your roof produce? A guide to the government solar calculator

Start with the official tool, understand its inputs, and turn an estimate into better questions for an installer.

Select an underlined term for a short explanation.

A roof can look large from the street and still leave its owner with a small question: where should I begin? Israel’s Ministry of Energy and Infrastructure provides an official rooftop calculator. Its value is as a starting point for investigation. An estimate can help organise a conversation, but the number on a screen should be read together with the information entered and the assumptions behind it.

Open the official calculator linked below. Choose the building type: detached, shared or other. Enter the address or cadastral block and parcel, then choose the matching search result. The separate government solar map credits the Ministry with defining the information and the Survey of Israel with processing it. A location-based estimate connects the question to a particular roof; it is still useful to check that the selected building is the one you mean.

The calculator asks whether you already have an installer’s quote. Choosing yes reveals fields for installed system power and total system cost including VAT. Enter the corresponding figures from the proposal, keeping the units consistent. This lets you ask a more precise question than “Is solar profitable?”: what does this particular proposal assume about the equipment and its cost? The distinction between a model input and a confirmed project specification matters.

Two units help make the numbers readable. A kilowatt measures power, while a kilowatt-hour measures energy over time. In a simplified example, a device supplying one kilowatt steadily for three hours delivers three kilowatt-hours. This is an illustration of the units, not a forecast for your roof. A solar system’s rated power cannot be multiplied by every hour of the year as though its output stayed constant.

Finally, treat any estimate as an invitation to compare assumptions. Imagine two proposals with the same installation price: they can still differ in what maintenance, monitoring or later replacement is included. Keep those questions beside the calculator result and ask the installer to explain any difference between their proposal and the model. The useful outcome is a clearer discussion of the roof and the offer, rather than a number detached from the conditions that produced it.