Removing old panels

[agb83]

Hi - funster newbie here. Recently purchased MH - came with dual 110ah life4po (lifos go) batteries, pvlogic mppt and a couple of roof mounted panels. Prior owner had it all fitted 2.5y ago. He suggested combined panel rating of 400w - have cleaned them but not convinced they’re rated at 200w each - max charge of 120w experienced in near perfect conditions. They also look a bit small for 200w each. Anyhow, thinking about a phased upgrade - starting with pv… my question is how to safely remove the existing ones. I’ve had a brief look on the roof - but can’t tell if they’re bonded or screw/bolt fixed. Suspect the former. If that’s the case, what is the best way of removing them without damaging the roof? Solvent? Steel scraper? Combo?

Help appreciated. Cheers, ab

 

[Speve]

A photo would be very helpful to us to be in a position to give sensible & practical advice

 

[agb83]

Fair point - I’ll snap one when it’s light and update original post.

 

[Russ N Tracey]

If just bonded I find a length of piano wire and 2 chunky dowels does the trick (its still hard work though)

 

[Guigsy]

At this time of year in Blighty, you won't get anywhere near peak power, particularly on flat mounted panels. Assuming the battery wasn't charged and there were zero shadows (even a finger), 120w from 400w of solar is low. But it's way more than I get from my 175w. I use my van through most of the year, so solar isn't that useful for several months regardless.

Before you go nuts... Do you actually need more? It's almost a fashion trend at the moment to add excessive amounts of panels. I bet many people are full by 11am and the rest if the time it's a waste.

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[Nigel Crompton]

Dental floss is kinder than piano wire, and easier to get; does break but it works ....
Braided, not monofilament, fishing line works too ...

 

[headlight]

agb83 I have 2 x 115 watt panels in parallel and a Victron MPPT.
I've just been away for 18 days in the UK, Gower Peninsula Wales, and even on the best sunny days the most I saw from my 230 watts was 150 watts.
The most I've ever seen from them in the UK was 197 watts.

 

[agb83]

Ok - thanks everyone for the replies; perhaps I’m just being overly optimistic with performance. Prior to purchasing MH, I was using foldable 200w BLUETTI panel to charge a portable power station - that gave me 165w at peak. I guess the panel was at an angle though.

 

[agb83]

At this time of year in Blighty, you won't get anywhere near peak power, particularly on flat mounted panels. Assuming the battery wasn't charged and there were zero shadows (even a finger), 120w from 400w of solar is low. But it's way more than I get from my 175w. I use my van through most of the year, so solar isn't that useful for several months regardless.

Before you go nuts... Do you actually need more? It's almost a fashion trend at the moment to add excessive amounts of panels. I bet many people are full by 11am and the rest if the time it's a waste.

Do I need more: right now, no. Longer term (summer 26) yes. The plan is to have hab Aircon fitted (for use in southern Europe) and be able to run that for 6/7hrs overnight, off grid. That use case will need around 900-1000ah of lithium, as much solar as I can squeeze in, larger b2b charger(s). Backstop being mains to charge when needed.

 

[Raul]

Hi - funster newbie here. Recently purchased MH - came with dual 110ah life4po (lifos go) batteries, pvlogic mppt and a couple of roof mounted panels. Prior owner had it all fitted 2.5y ago. He suggested combined panel rating of 400w - have cleaned them but not convinced they’re rated at 200w each - max charge of 120w experienced in near perfect conditions. They also look a bit small for 200w each. Anyhow, thinking about a phased upgrade - starting with pv… my question is how to safely remove the existing ones. I’ve had a brief look on the roof - but can’t tell if they’re bonded or screw/bolt fixed. Suspect the former. If that’s the case, what is the best way of removing them without damaging the roof? Solvent? Steel scraper? Combo?

Help appreciated. Cheers, ab

Before you remove the panels, I would change the pvlogic to a real world mppt from victron.

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[Guigsy]

Do I need more: right now, no. Longer term (summer 26) yes. The plan is to have hab Aircon fitted (for use in southern Europe) and be able to run that for 6/7hrs overnight, off grid. That use case will need around 900-1000ah of lithium, as much solar as I can squeeze in, larger b2b charger(s). Backstop being mains to charge when needed.

To me that sounds a little excessive. A/C won't need continuous draw.

But if you are dedicated to the cause, then yes, pull off those existing solar panels and tessellate as many panels together as you can. Might even be worth getting bifacial panels to get a bit extra from each square metre.

 

[Raul]

To me that sounds a little excessive. A/C won't need continuous draw.

But if you are dedicated to the cause, then yes, pull off those existing solar panels and tessellate as many panels together as you can. Might even be worth getting bifacial panels to get a bit extra from each square metre.

Bifacials do not benefit of the back side facing the roof close up. It needs to be ground mount, car port, or vertical fence.

 

[Guigsy]

Bifacials do not benefit of the back side facing the roof close up. It needs to be ground mount, car port, or vertical fence.

I thought that being over a shiny white roof would help... But yeah, I think you're right. It needs light to get under it to have a significant difference.

 

[MisterB]

Do I need more: right now, no. Longer term (summer 26) yes. The plan is to have hab Aircon fitted (for use in southern Europe) and be able to run that for 6/7hrs overnight, off grid. That use case will need around 900-1000ah of lithium, as much solar as I can squeeze in, larger b2b charger(s). Backstop being mains to charge when needed.

Might be cheaper to book a hotel ....

 

[CAB96]

Can you slide your phone underneath while videoing to see what the panel is!

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[Lizbiebrowne]

If you have an iPhone and an Apple Watch you can slide the iPhone under your panel whilst viewing its camera picture on your watch and press a button on the watch to take the picture. Don’t know if that works with other brands.

 

[Nigel Crompton]

agb83 I have 2 x 115 watt panels in parallel and a Victron MPPT.
I've just been away for 18 days in the UK, Gower Peninsula Wales, and even on the best sunny days the most I saw from my 230 watts was 150 watts.
The most I've ever seen from them in the UK was 197 watts.

If you can change the wiring to series, that will improve the efficiency a bit. The greater the voltage into the controller in relation to the battery voltage the better MPPT works. AFAIC.

 

[Lee Fryer]

 

[Guigsy]

If you can change the wiring to series, that will improve the efficiency a bit. The greater the voltage into the controller in relation to the battery voltage the better MPPT works. AFAIC.

Putting them in series will double the voltage (and half the current). Generally, the output in the middle of a summer's day will be roughly the same. The advantage is you lose a bit less from voltage drop, although it'll only be a percent or two. And when the light is low, you get above the required 13v to start charging your battery a bit quicker, so you'll get a bit more juice at the beginning and end of the day. The downside is if one panel gets in the shade, it drags down both of them. Even small shadows across the corner of a panel can have a large difference.

 

[headlight]

If you can change the wiring to series, that will improve the efficiency a bit. The greater the voltage into the controller in relation to the battery voltage the better MPPT works. AFAIC.

Swings and roundabouts as Guigsy has said.
Slightly better output first thing in the morning and evening but more affected by shade/shadow.
The couple of days I saw 150 watts it was bright sunshine but the sky wasn't haze free.

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[Raul]

Series in 12v systems is not great, the efficiency is only improved from panel to controller transmission, that's it. Then the controller has to double tripe or quadruple work on high voltage to buck it down to 12-14v.
Series has its advantages where the run from panels is long, and output is considerably higher than 12v. Like 500vdc down to 230v is only double the output.
On 12v output, ideal incoming voltage for efficiency is 1.5 to 2 times the output. Any higher the controller will produce allot of heat, wasted energy.