Trees and solar panels: planting for both

Know where the production actually is

In central Indiana, a roof-mounted array does most of its work between mid-morning and mid-afternoon, from the south. That is the window and the direction you protect. Early morning and late evening sun contribute far less, which means the east and west edges of a lot are much more forgiving than the south side.

Put shade where it saves you money instead

A tree on the west side cuts the afternoon heat load on the house through the hottest part of a summer day — that is real money off the cooling bill — while barely touching a south-facing array. East side is second best. South of the array is where you plant nothing tall, or you plant something that stays under the sight line permanently.

How far a shadow reaches in Indianapolis

Indianapolis sits at about 39.8° north. At solar noon the sun climbs to roughly 74° above the horizon at the June solstice, 50° at the equinoxes, and only about 27° at the December solstice. The length of a shadow is the height doing the shading divided by the tangent of the sun’s angle, which works out to:

Two things make this more forgiving than it looks, and one makes it worse. Measure from the height of the panels, not the ground: a 45-foot tree near a roof array sitting 15 feet up only has about 30 feet of height that can shade it. And winter days are short and the sun is weak, so December shade costs less production than June shade would. What makes it worse: those are noon figures. In the morning and late afternoon the sun is lower still and shadows run longer — which is part of why the south side is the one to keep clear.

Bare branches still cast shade

A deciduous tree to the south is not invisible in winter. A full crown of bare branches still blocks a real share of low winter sun, exactly when the array has the least to spare. And shade on part of a panel can cost more than its share of the output: on a system with a single string inverter, one shaded panel can drag down the panels wired with it. Panel-level electronics (microinverters or optimizers) reduce that penalty, which is worth knowing if you are still choosing a system for a partly shaded roof.

Plant for the mature height, not the nursery tag

The shade problem is never the tree you plant. It is that tree in eighteen years. Before you dig, look up the mature height and spread and picture it against your roofline. A tree that will top out at twenty feet is a different decision than one heading for sixty. As a rough guide, a redbud or serviceberry typically stays in the 15–30 foot range, a red maple commonly reaches 40–60 feet, and a tulip tree — Indiana’s state tree — can pass 80. Put the small ones where the sun matters and the giants where the shade does.

If they are already fighting

Often the fix is a reduction or a clearance prune rather than a removal — taking the height and the encroaching side down enough to clear the array through the production window, then keeping it there on a cycle. Panels also lose real output to leaf litter and shade from overhanging limbs even when the sun angle is fine, so the same visit usually helps twice. Just do not top the tree to get there; our pruning vs. removal guide explains why a proper reduction is not the same thing.

Before the panels go on

If you are planning solar, deal with the trees first. Removing or reducing a tree over an installed array means protecting the panels during the work, and sometimes means the installer has to come back. It is cheaper and simpler to clear the sky, then install.

We will walk the property, look at the array angle, and tell you whether this is a pruning problem or a removal problem. Start with the free sign-up.