Fixing solar panels

[SusieC]

I want to mount my panels at 15 deg, and don’t want to drill or screw into the roof, any examples of brackets etc that make that possible?

(Don’t want to make any holes in roof as they are just an invitation to a leak at some point)

[GUMPY]

Angling the panels will gain you from memory about 12% over having them flat provided they are facing the sun.

Unless you are always moored in the same spot with the boat facing East/West it's not worth the faff. Far better/easier to add 20% more panels.

My panels are fixed to the roof with M6 security Torx and after 5 years they don't leak🥱

Edited October 29, 2022 by Loddon

[Jen-in-Wellies]

Plus, flat panels you have much less to worry about from wind loading, which can be substantial in a gale on angled panels. With flat panels, an easy way to fix them down is with Neodymium magnets to some steel angle bolted to the panels. This is assuming your boat has a steel roof!

I use this on my boat. There are eight of 15mm x 5mm size Nd magnets holding each 80W panel. This has survived all that the weather has thrown at it for a good number of years.

Edited October 29, 2022 by Jen-in-Wellies

[PaulD]

I glued some angle brackets on the roof using Stixall. Still there after 3 years.

[David Mack]

I fitted mine flat using these brackets, glued to the roof with Stixall. Been fine for over 3 years. 

https://www.bimblesolar.com/extras/mounting/solar-abs-mount-kit. Also available from other suppliers. EBay may be a bit cheaper.

Edited October 29, 2022 by David Mack

[jonathanA]

I'm with loddon. I just don't see what t5he issue is with drilling and tapping holes. I used 6mm brass set screws with a dab of copper grease. Job done.

Seen plenty of folks rescuing their panels out of cut after the wind blew them off one with there stuck on brackets...

[MtB]

5 hours ago, SusieC said:

I want to mount my panels at 15 deg, and don’t want to drill or screw into the roof, any examples of brackets etc that make that possible?

(Don’t want to make any holes in roof as they are just an invitation to a leak at some point)

 

 

Basically, no there aren't any. 

 

Why not just lay them flat and buy one more with the money you saved on complicated brackets?

 

 

[matty40s]

7 hours ago, SusieC said:

I want to mount my panels at 15 deg, and don’t want to drill or screw into the roof, any examples of brackets etc that make that possible?

(Don’t want to make any holes in roof as they are just an invitation to a leak at some point)

How many mushroom vents, chimneys, windows, potholes, plank racks etc etc etc have you, where they are screwed in....and dont leak.

Do it properly, it wont leak.

[peterboat]

I have 15 large panels on the roof I wouldn't trust anything other than 4 brackets bolted and glued down with sicaflex. I have seen flying panels in a high wind not pleasant and dangerous 

[blackrose]

On 29/10/2022 at 15:40, Loddon said:

Angling the panels will gain you from memory about 12% over having them flat provided they are facing the sun.

Unless you are always moored in the same spot with the boat facing East/West it's not worth the faff. Far better/easier to add 20% more panels.

My panels are fixed to the roof with M6 security Torx and after 5 years they don't leak🥱

 

From what Chris W tells me that's the figure for summer:

 

To calculate the sun angle affect, the loss owing to the panels’ *not* being pointed at the sun is:

[1 - cosine(90 - A)], where A is the angle of the sun at any moment. 

An example: in the height of summer at our latitude (say, 52 degrees N), the sun never gets higher than 60 degrees at solar noon. 

Ergo, the loss of power by having your panels horizontal is:

[1 - cos(90 - 60)] = 13% surprisingly small. 

However, in mid winter, when the sun never gets above 14 degrees at solar noon, at our latitude, the loss is [1 - cos(90-14)] = 76%, which is massive. 

 

At the moment, the sun is not getting above about 28 degrees in mid-October. So, the loss on a sunny day, for horizontal panels is around 53%. That is to say, you’d have to tilt your panels by (90 - 28) = 61 degrees to be perpendicular to the sun today. (What sun!)

 

Here’s a sun angle calculator for any time, any day, any place.

 

https://keisan.casio.com/exec/system/1224682277

Edited November 3, 2022 by blackrose

[blackrose]

On 29/10/2022 at 19:04, jonathanA said:

I'm with loddon. I just don't see what t5he issue is with drilling and tapping holes. I used 6mm brass set screws with a dab of copper grease. Job done.

Seen plenty of folks rescuing their panels out of cut after the wind blew them off one with there stuck on brackets...

 

Yes I agree. Drilled and tapped holes will only leak if they aren't sealed properly. Most mushroom vents are bedded in with sealant and screwed down. I stuck my aluminium solar brackets down with the Screwfix equivalent of Stixall (Sticks like Sh*t) and then drilled and tapped with a blob of the same sealant on the screw threads. It's always a mistake to use silicone to bed in and seal any fittings which are meant to be permanent, but it's surprising the number of people on boats who don't realise there are much better flexible sealant/adhesives around.

On 29/10/2022 at 14:52, SusieC said:

I want to mount my panels at 15 deg, and don’t want to drill or screw into the roof, any examples of brackets etc that make that possible?

(Don’t want to make any holes in roof as they are just an invitation to a leak at some point)

 

Renogy do some angled aluminium brackets for about 30 quid but they were too small for my panels and it looks like they only work on flat roofs.

 

Renogy Adjustable Solar Panel Tilt Mount Brackets RV Roof Flat Surface Aluminum Mounting Set https://amzn.eu/d/f4fiSxf

[David Mack]

11 minutes ago, blackrose said:

However, in mid winter, when the sun never gets above 14 degrees at solar noon, at our latitude, the loss is [1 - cos(90-14)] = 76%, which is massive. 

But the amount of solar you will get at noon in mid winter is trivial anyway, so losing 76% of it makes no difference. The only time of year when angling the panels might make sense is in Spring and Autumn when it might be worth squeezing a few extra % out of a moderate amount of solar energy.

[blackrose]

5 minutes ago, David Mack said:

But the amount of solar you will get at noon in mid winter is trivial anyway, so losing 76% of it makes no difference. 

 

Really? But I thought on a cold clear sunny winter day the panels could be producing quite a lot if you can angle them towards the sun? They will work more efficiently in cold temperatures.

Edited November 3, 2022 by blackrose

[GUMPY]

15 minutes ago, blackrose said:

 

Really? But I thought on a cold clear sunny winter day the panels could be producing quite a lot if you can angle them towards the sun? They will work more efficiently in cold temperatures.

My 4.3kW array which faces due south has been producing 6-7 kWh a day over the last week (its not been raining all day down here) compared to 25-30kWh in July. I have had to resort to charging the battery from the grid 

Even on a sunny day at this time of year I am only getting about 11kWh 

It will get less until next year

[MtB]

9 minutes ago, Loddon said:

My 4.3kW array which faces due south has been producing 6-7 kWh a day over the last week (its not been raining all day down here) compared to 25-30kWh in July. I have had to resort to charging the battery from the grid 

Even on a sunny day at this time of year I am only getting about 11kWh 

It will get less until next year

 

There are lots of credible figures on the next showing angled roof panels deliver about 10% of their rated energy in mid winter, but my own personal experience of panels flat on my boat roof is it's closer to 1%. 

 

I put this down to the panels lying flat in the winter when the sun is particularly low, coupled with my boat always being around trees which reduce the "amount of sky" my panels can "see" on cloudy days when the sun is not actually visible i.e. most of them. 

[blackrose]

1 hour ago, Loddon said:

My 4.3kW array which faces due south has been producing 6-7 kWh a day over the last week (its not been raining all day down here) compared to 25-30kWh in July. I have had to resort to charging the battery from the grid 

Even on a sunny day at this time of year I am only getting about 11kWh 

It will get less until next year

 

But your panels are flat and can't be tilted. On dull winter days I agree with you and David that tilting panels will get you 76% of not a lot extra so won't be significant. But on bright sunny winter days (and we do get plenty of them) I don't see why tilting panels wouldn't be more beneficial. After all, most solar farms I've seen don't have horizontal panels and don't stop tilting their panels towards the sun in winter.

 

Anyway, I will soon find out for myself how significant the difference is as I'll be able to have my panels flat or tilted.

Edited November 3, 2022 by blackrose

[GUMPY]

22 minutes ago, blackrose said:

 

But your panels are flat and can't be tilted. On dull winter days I agree with you and David that tilting panels will get you 76% of not a lot extra so won't be significant. But on bright sunny winter days (and we do get plenty of them) I don't see why tilting panels wouldn't be more beneficial. After all, most solar farms I've seen don't have horizontal panels and don't stop tilting their panels towards the sun in winter.

 

Anyway, I will soon find out for myself how significant the difference is as I'll be able to have my panels flat or tilted.

Those figures are for the house panels which are  angled at 30deg.

The thing I have noticed about flat panels is that though they produce less they do it for longer. At this time of year the house panels work from about 9am until 4pm as the sun passes, if they were flat this time would be extended.

[MtB]

13 minutes ago, Loddon said:

Those figures are for the house panels which are  angled at 30deg.

The thing I have noticed about flat panels is that though they produce less they do it for longer. At this time of year the house panels work from about 9am until 4pm as the sun passes, if they were flat this time would be extended.

 

I suspect the whole thing is really marginal. On boats if one tilts to catch the sun, as the day progresses the sun moves and the tilted panels eventually point the wrong way and collect less than flat ones do, with their 'always working albeit less than optimally' property. 

 

House roof panels are obviously gonna be sloping as the roofs slope. I would not mid betting there are loads of flat solar installations out there on top of factories, warehouses and office buildings that we never see from the ground. I'm always vaguely surprised solar farms have sloping panels as they too could collect more energy at the start and end if the day if laid flat. 

 

For the grid managers solar farms with their peak output around midday must be a headache to manage, as they increase the 'lumpiness' of demand on the 'always on' gas turbine and nuclear generators. 

 

 

[Tony1]

57 minutes ago, Loddon said:

Those figures are for the house panels which are  angled at 30deg.

The thing I have noticed about flat panels is that though they produce less they do it for longer. At this time of year the house panels work from about 9am until 4pm as the sun passes, if they were flat this time would be extended.

 

For me, the thing about tilting panels on narrowboats is that it's nice to have the option, but from Nov to Feb inclusive, they are limited even on good days.

So if its an overcast day in November, its not worth tilting. But if the side of the boat happens to be facing south, and its a day when it happens to be a bit sunny, then its worth tilting them. But for me, its not worth trying to seek out open-aspect moorings (or ones where the panels face south) just to gain an extra 20-40 Ah per day. I'd rather stay in a mooring that is convenient and pleasant, and just run the engine for an extra 20 or 30 mins to make up the meagre 30Ah that I would have gotten from solar in a more open mooring.

As an example, I tilted my rear panels this morning because they were facing south east, and the sun was out. 

So for about 2 hours (at most), the rear panels were yielding about 20 amps, and the front panels (flat), were yielding about 10 amps. But then the sun passed into the south and southwest, so I laid them flat again.

But then it got cloudy anyway, and the sun went behind some trees, so I got very little during the afternoon. 

I did meet a boater with a broken engine at Whixall Moss last spring, who said he'd been stuck there for 3 months waiting to complete a major engine repair. His sides faced almost due south and he had two panels angled at 60 degrees on the roof, and one panel hanging on the side of the superstructure, and he said he'd managed to get enough electricity from those throughout the winter. But what is considered enough electricity for one person may be a nightmare scenario for someone else. 

 

 

Edited November 3, 2022 by Tony1

[GUMPY]

There is one house round here that has East><West facing solar panels  12 on each elevation so produces the same as mine does  but morning and evening instead of at midday. I think that overall he will be generating more than I do. 

[blackrose]

My boat more or less points E-W at the mooring so the for a large part of the day tilted panels will be more perpendicular to the sun than flat panels. But I'll experiment and see how it goes. It's got to be worth having the option.

[Tony1]

17 minutes ago, blackrose said:

My boat more or less points E-W at the mooring so the for a large part of the day tilted panels will be more perpendicular to the sun than flat panels. But I'll experiment and see how it goes. It's got to be worth having the option.

 

I would add a note of caution re the wind. 

I was in Ellesmere Port basin, I think last February, and I tilted the panels up almost every morning- it seemed to be fairly sunny most mornings if I recall correctly. 

Things was, there was one morning it was forecast for I think 25mph winds, blowing from behind the tilted panels, and although I realised the panels ought to be lowered to avoid damage, I didn't do it straight away and then I forgot, and sure enough, an hour or two later there was a banging noise as one of the tilted panels was caught by the wind coming from behind it, blown off, and deposited on the grass beside the boat. Thankfully I got away with minor damage to the clamps on the mountings, and I was able to remount the panel later. 

That basin is a bit of a wind trap and it behaves unpredictably when it blows hard because of the high buildings nearby, but one of the things about tilting mounts is you have to remember to always lower them if the forecast is for strong winds, or just lower them every night as a default procedure. 

In the summer you dont need to tilt them anyway as the sun is so strong, so most of the time they stay flat. Its the spring and autumn when you want to tilt, and they can be quite windy as we know. 

 

 

[blackrose]

8 hours ago, Tony1 said:

 

I would add a note of caution re the wind. 

I was in Ellesmere Port basin, I think last February, and I tilted the panels up almost every morning- it seemed to be fairly sunny most mornings if I recall correctly. 

Things was, there was one morning it was forecast for I think 25mph winds, blowing from behind the tilted panels, and although I realised the panels ought to be lowered to avoid damage, I didn't do it straight away and then I forgot, and sure enough, an hour or two later there was a banging noise as one of the tilted panels was caught by the wind coming from behind it, blown off, and deposited on the grass beside the boat. Thankfully I got away with minor damage to the clamps on the mountings, and I was able to remount the panel later. 

That basin is a bit of a wind trap and it behaves unpredictably when it blows hard because of the high buildings nearby, but one of the things about tilting mounts is you have to remember to always lower them if the forecast is for strong winds, or just lower them every night as a default procedure. 

In the summer you dont need to tilt them anyway as the sun is so strong, so most of the time they stay flat. Its the spring and autumn when you want to tilt, and they can be quite windy as we know. 

 

 

Yes, it's windy here a lot of the time so I will be careful. 

[Tony1]

17 minutes ago, blackrose said:

 

Yes, it's windy here a lot of the time so I will be careful. 

 

One other thing I found with the tilting mounts (from midsummer energy) was that although they will hold my 1m wide panels (and they are well made), they need extra support to hold them tilted upwards, because the sheer weight and the width of the panels means the allen bolt holding mechanism (within the legs) doesnt feel 100% secure.

 

https://midsummerenergy.co.uk/buy/solar-panel-mounting/Narrowboat-Tilt-Mount

 

That said, I'm sure they'd work very well with say 80cm panels (which were the ones I saw on the youtube vlog) 

The idea is that you tilt them up and then tighten the allen bolts to hold them in place, but I found it necessary to add support. I bought a small aluminium work platform (the type that has a short ladder on each end of a platform).

I took the two ladders off of the platform, and I use the ladders to help prop up the side of the mounting frame when the panels are tilted up. 

A neater solution would be to put hinges on the end of the ladders (or similar legs), and attach the hinge to the mounting frame itself, so the support legs drop down when you lift up the side of the panel. Its aluminium so its no problem doing a bit of heath robinson adaptation.

 

Re the tilting, bear in mind that if you have two lines of say 80cm or 1m panels running along the roof, the panel that is nearest the sun- when tilted up- will tend to cast a shadow on the panel behind it, so in some situations you actually want to leave the 'sunny side' panel flat, and only tilt up the one behind it. 

 

You will have seen the odd boat with panels hung almost vertically on the sides of the superstructure. For off grid purists it probably works pretty well, but aesthetically some might not be keen on the look of it. For the hard core types, I do think with that sort of setup, and not running the fridge, you could probably get 90% through the winter just on solar. 

 

I think the ideal world mount would be something based on a rotatable or movable base, so you could adjust it every hour or so to follow the sun (and with that, you don't have to face the sides southwards). But that's a lot of designing (and cash) for what would probably be not too many extra amp hours of charge during winter. 

 

 

[IanD]

14 hours ago, blackrose said:

 

Really? But I thought on a cold clear sunny winter day the panels could be producing quite a lot if you can angle them towards the sun? They will work more efficiently in cold temperatures.

 

The efficiency drop-off with temperature is very small, typically about 0.4%/C. So in midwinter compared to midsummer you might gain at most 10% (for 25C temperature difference) of a power output that was very small anyway... 😉

 

Whether tilting is worth it is another tradeoff where there's no "right" answer; you do get some extra output (assuming the boat/panels face the right way), and this is bigger in winter -- but again, this is when there's not much output anyway. However flat-mounted panels can be more robust (and thief-proof!) and less obtrusive and cheaper to install, and it might be possible to get more in without the hardware/clearance for tilting. YMMV... 😉