Solar Panels Is Panel Angle REALLY That Big of a Deal? (My Installers Were Pretty Relaxed...)

[Leo Breydon]

So we just had our solar panels installed last week – super exciting! But one thing that's been bugging me is the panel angle. The installers weren't super precise, saying it would only make a small difference... but now I'm second-guessing everything!

I've been doing some research on the Internet, but I am not sure whether should I follow them or not and meanwhile I'm worried we're missing out on precious energy! Especially in winter when the sun is lower.

Here's the deal:

Our roof is pretty standard, slight south-facing slope.

The panels are basically flat on the roof, maybe a tiny tilt.

Have I messed up by not demanding a steeper angle? Help a nervous solar newbie out!

What I want to know from YOU:

How much difference does panel angle ACTUALLY make in your experience?

Did you obsess over it during installation, or go with the flow?

Pics of your setup (and maybe even energy output data) would be awesome!

Maybe I'm stressing over nothing, but I want to make sure we're getting the most out of our investment!

 

[littlespark]

As long as the roof has a standard slope, (around 45 degrees) I don’t think it matters too much.

It’s only when it’s a flat roof, or on the ground, that panels are fixed to a sloped frame.

There is a limit to how much a panel can put out… so even at optimum angle, no shade and no clouds… the panels can’t make more than they’re capable of…

Likewise, the AC inverter can only put out a certain amount of kW….


Whatever the angle, or size of inverter… you are now enjoying free electricity during the day.
The investment cost will pay back in energy company savings.

 

[UNG]

While panel angle can affect performance, so does the latitude of the property the panels are installed on, roof orientation, shading from trees and chimneys to list a few factors that need to be considered when designing a system to give the optimum maximised output

 

[Dan]

I saw on a documentary about the sun and it had a small bit on them where people had them following the sun and the amount of money they'd spent on it they'd never claw the extra back.

Spoke to a bloke on a canal boat who would move it every few hours and he swore it'd double it's usefulness doing it. Would have been a basic thing for charging phones and things mind I don't think it was wired to the boat CU (did I use that right, consumer unit? Lol - I try). Was probably 3x6' on a 10-20% slope.

 

[UNG]

I fitted a solar panel on a 10m sailing boat a few years back for my brother's brother in law other than shading from the sail occassionally he reports that it is working well and maintains the batteries charge and runs all the electronics without having to run the engine when as sea. The other advantage is he doesn't need to remove the batteries from the boat during the season to recharge them

 

[Dan]

I wish I needed a solution to me keep needing get batteries out my 6m boat!

 

[wookey]

So we just had our solar panels installed last week – super exciting! But one thing that's been bugging me is the panel angle. The installers weren't super precise, saying it would only make a small difference... but now I'm second-guessing everything!

I've been doing some research on the Internet, but I am not sure whether should I follow them or not and meanwhile I'm worried we're missing out on precious energy! Especially in winter when the sun is lower.

Here's the deal:

Our roof is pretty standard, slight south-facing slope.

The panels are basically flat on the roof, maybe a tiny tilt.

Have I messed up by not demanding a steeper angle? Help a nervous solar newbie out!

What I want to know from YOU:

How much difference does panel angle ACTUALLY make in your experience?

Did you obsess over it during installation, or go with the flow?

Pics of your setup (and maybe even energy output data) would be awesome!

Maybe I'm stressing over nothing, but I want to make sure we're getting the most out of our investment!

There is obviously an optimum slope, which actually varies with the time of year, but there is also one best average for the year, but of course that is rarely the same as the angle of your roof. In practice PV panels are always fixed at the same angle as the roof unless it's actually flat, because as soon as you do anything different you have to space the panels further apart to avoid shading (a much worse problem than non-optimum angles) and most people are constrained by roof space (or export limitations) so filling the roof is the best strategy.

You can calculate how much difference it actually makes (not much (a few percent) for typical roof angles and latitudes) by using PVGIS or easy-pv (there are no doubt other tools).

So in short, don't worry about it - 'aligned to the roof' is the right answer in all cases except flat roofs.The optimum angle for where I am in the UK is 43 degrees, but my roof is 30 degrees. My panels have nevertheless done very well for the last 15 years, giving typically 930kWh/kWp which is fine for 52 degrees lattitude.