About Will It Shade
This site exists because of a question I could not answer about my own back yard.
Why it exists
I was working out where to put vegetable beds, and I kept getting stuck on something that sounds simple: which parts of the yard actually get enough sun? Not today — through the year. A bed that bakes in midsummer can sit in shadow for the whole of winter, and what decides it is usually a fence, a tree, or the neighbour’s roof rather than which way the garden faces.
You can find that out by standing in the garden every hour for a day and writing down what is in sun. That works, but it only tells you about the day you did it. To know about June you have to wait for June.
I looked for something that would just show me, and could not find it. So I had a go at building it.
How it works
You type an address. The planner finds the real building outlines around that point from OpenStreetMap, the free map of the world that anyone can contribute to, and stands them up as 3D shapes over an aerial photo. You can correct any of them, set how many storeys they are, and add the things no map records — fences, and trees.
Then it puts the sun where it genuinely was. The position is calculated from your latitude, longitude, the day of the year and the time of day using the standard solar position formulas, not a lookup table or an approximation. Drag the sliders and the shadows move the way they really move.
It runs entirely in your browser. There is no account, no sign-up and no email required, and nothing you trace is sent anywhere or stored by me — see the privacy policy for the detail.
What it cannot do
Worth saying plainly, because a tool that overstates itself is worse than no tool.
Roofs are flat blocks. Buildings are drawn as simple extruded shapes, so shadow length is accurate but the shape cast by a pitched or gabled roof will not be exact.
Clock times are approximate. The time zone is worked out from longitude rather than real time zone data, so daylight saving is not accounted for. The shape and direction of the shadows are right; do not rely on the clock reading to the minute.
Map coverage varies. OpenStreetMap has excellent coverage in some places and very little in others, so a rural or newly built address may return few surrounding buildings. You can always draw them yourself.
It does not calculate power. For solar, it answers whether and when shade reaches a roof. It does not model panel efficiency, weather or output in kilowatt hours — an installer’s quote does that, and this is meant to be the thing you check first.
Who made it
Michael. I am not a solar company, a landscaper or a nursery. Nobody pays me for a referral, there is nothing on this site to buy, and no one is quoted or recommended. It is free to use and paid for by the adverts on the page.
If it got something wrong about your property, or there is something it should do and does not, I would genuinely like to hear it — [email protected].