Advice on buying solar panel and MPPT controller

V1nny

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I have two 90AH leisure batteries but don't have solar yet, and after much deliberation I have made the decision to get a flexible panel (because of space restrictions on the roof) with an MPPT controller. I'm thinking of a minimum panel size of 120W, but hopefully larger, and a 20W controller in case I want to upgrade batteries or panels in the future, and I would need to be able to keep the engine battery topped up too. I am looking for advice and recommendations for equipment and suppliers.

I have been looking online and have seen a 175W panel on renogy.com for £229.99
(https://uk.renogy.com/175-watt-12-volt-flexible-monocrystalline-solar-panel/)

and I have seen a potential dual battery 20A MPPT controller on Photonic Universe for £84.99
(https://www.photonicuniverse.com/en...-battery-system--520W-24V-battery-system.html)
I've just noticed this controller only trickle charges the engine battery at 1 amp. The last controller I had was adjustable for differing percentages of charging between the habitation and engine batteries, and I'm assuming that is a better option, so I'm open to suggestions.

Any thoughts or advice welcome.
 
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Cheap Flexible panes have a short life span, if you go Flexible consider ETFB aluminum backed . Many people go for victron controllers as they have good reputation. For output and quality, ,
 
V1nny said:
I have two 90AH leisure batteries but don't have solar yet, and after much deliberation I have made the decision to get a flexible panel (because of space restrictions on the roof) with an MPPT controller. I'm thinking of a minimum panel size of 120W, but hopefully larger, and a 20W controller in case I want to upgrade batteries or panels in the future, and I would need to be able to keep the engine battery topped up too. I am looking for advice and recommendations for equipment and suppliers.

I have been looking online and have seen a 175W panel on renogy.com for £229.99
(https://uk.renogy.com/175-watt-12-volt-flexible-monocrystalline-solar-panel/)

and I have seen a potential dual battery 20A MPPT controller on Photonic Universe for £84.99
(https://www.photonicuniverse.com/en...-battery-system--520W-24V-battery-system.html)
I've just noticed this controller only trickle charges the engine battery at 1 amp. The last controller I had was adjustable for differing percentages of charging between the habitation and engine batteries, and I'm assuming that is a better option, so I'm open to suggestions.

Any thoughts or advice welcome.
Click to expand...
As Molly stated cheap flexible panels don’t tend to last long. A single 120w panel will be fine during the summer period, but limited during spring and autumn. During winter months even with two panels whilst offline camping are extremely limited in what light can be harvested. But if you only want the panel to keep your vehicle battery and leisure batteries topped in winter whilst not camping, it will be fine. I also highly recommend the Victron MPPT controller, I use the one below for my two 120w panels. But if you only fit one 120w panel you could go for the the 100/15 model for around £115. I would contact wildebus on here, David is extremely knowledgeable and helpful on such issues.

www.ebay.co.uk

Victron Energy Smart Solar 20A MPPT 100/20 Charge Controller Regulator 12V 24V | eBay

Victron Energy. For remote installations – even when there is no internet connection or phone signal nearby – you may be able to monitor your MPPT by Bluetooth-pairing with a LoRaWAN (long-range wide area network) device, available optionally.
www.ebay.co.uk
 
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Short life with flexible, if you have small spaces go for 2 ridged units of 50/60 w each, me I would add a second battery and try for 200w and a votronic mppt reg which has a 1 amp bleed to the starter battery.
solar duel a.png
 
Very expensive semi flexible panels don’t seem to last long either. ;( I’ve found that they are only suitable to flex whilst fitting, after that and once fitted they need to remain stable. Mounting them also proves to be a problem with time to. My latest attempt is to cover the backs with butyl tape. Watch out though the moment it touches the roof it sticks. They should be easy to remove when the time cheese wire and some soap should do the trick.
 
As far as Flexible panels go, I do tend to avoid them when possible myself, but some folk do insist on them so have had to find some decent options over time ...

These Austrian made ones from Photonic are pretty good with the self-adhesive backing - for example - https://www.photonicuniverse.com/en...th-self-adhesive-backing-made-in-Austria.html
They are no cheap by any means though!

I also tried some Lensun Panels on a VW Installation - the customer wanted panels that were as invisible as possible.
1661543522170.png

These were fitted over 3 years ago and are still providing good harvesting when checking on the VRM system :)

SquirrellCook said:
.... Watch out though the moment it touches the roof it sticks....
Click to expand...
This is very true. On the Lensuns I used 3M VHB tape and as soon as the tape touched it would not shift - and I was about 2 degrees out annoyingly. Not enough to anyone to really notice except me though.


Something to watch out for with "Flexible" panels ... many, especially the ones with ETFE backing are anything but flexible and great care needs to be taken to avoid bending too much. For example, the Lensum semi-flexible ones must not flex more than 5% and I had to take great care in supporting them when lifting onto the roof. I would regard them as a low-profile frameless panel to be fixed on a flat surface - and that is what most people do want when they are looking at flexi panels I reckon.

Controller wise, the Votronic Duos are pretty good but I would still go with a Victron Solar Controller and a separate Starter Battery trickle that will work on both Solar AND Hookup for better flexibility.
Having said that, the MPPT linked to from Photonics site looks good value. On the minus side, the 1A divert to Starter could be a bit low depending on parasitic loads and a lot of these dual-battery units are not well-regulated in terms of their output and are pretty indiscriminate (you may not want 1A constantly going to the Starter Battery for example).
 
V1nny said:
I have two 90AH leisure batteries but don't have solar yet, and after much deliberation I have made the decision to get a flexible panel (because of space restrictions on the roof) with an MPPT controller. I'm thinking of a minimum panel size of 120W, but hopefully larger, and a 20W controller in case I want to upgrade batteries or panels in the future, and I would need to be able to keep the engine battery topped up too. I am looking for advice and recommendations for equipment and suppliers.

I have been looking online and have seen a 175W panel on renogy.com for £229.99
(https://uk.renogy.com/175-watt-12-volt-flexible-monocrystalline-solar-panel/)

and I have seen a potential dual battery 20A MPPT controller on Photonic Universe for £84.99
(https://www.photonicuniverse.com/en...-battery-system--520W-24V-battery-system.html)
I've just noticed this controller only trickle charges the engine battery at 1 amp. The last controller I had was adjustable for differing percentages of charging between the habitation and engine batteries, and I'm assuming that is a better option, so I'm open to suggestions.

Any thoughts or advice welcome.
Click to expand...
Well timed that man. 🙏

I’ve just come by one of these Here 325watt panel and I’m trying to work out how best to put it to use.

I have a spare 230ah agm battery and a 2kw inverter Here kicking around and no idea what best use to put them all too.

I also have an ECOflow river max but don’t think it will work with the solar panel as ECOflow say 220w solar is the max it will take.

Therefore I think I need a solar controller but have no idea where to start In all honesty.

Any help/advise would be appreciated
 
Boris7 said:
Well timed that man. 🙏

I’ve just come by one of these Here 325watt panel and I’m trying to work out how best to put it to use.

I have a spare 230ah agm battery and a 2kw inverter Here kicking around and no idea what best use to put them all too.

I also have an ECOflow river max but don’t think it will work with the solar panel as ECOflow say 220w solar is the max it will take.

Therefore I think I need a solar controller but have no idea where to start In all honesty.

Any help/advise would be appreciated
Click to expand...

Seems a bargain for the panel Kev.

I shall watch with interest.
 
Boris7 said:
Well timed that man. 🙏

I’ve just come by one of these Here 325watt panel and I’m trying to work out how best to put it to use.

I have a spare 230ah agm battery and a 2kw inverter Here kicking around and no idea what best use to put them all too.

I also have an ECOflow river max but don’t think it will work with the solar panel as ECOflow say 220w solar is the max it will take.

Therefore I think I need a solar controller but have no idea where to start In all honesty.

Any help/advise would be appreciated
Click to expand...

Would it be feasible to charge the Ecoflow indirectly from the solar, ie. via the inverter?

I'm sure some will say "what's the point? use the inverter for your power needs" but a combination of both would give a very flexible system in my opinion.
 
Robmac said:
Seems a bargain for the panel Kev.

I shall watch with interest.
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I didn‘t pay anything for the panel Rob, just right place, right time (unusual for me) the battery and inverter we left over from an event I worked on.

Seems if I can just get the panel to charge the battery I can use 12v to charge the Ecoflow f.o.c. and with a fully charged battery and an inverter I can survive longer off grid.
 
I have fitted semiflexible on 2 campers now this one still working after 5 years and the other after 9 years. I got both from photonic universe. I think they were German made. I think the important thing is to fit them with little and even curvature, cylinder or cone curves but shallow. I supported mine off the ribs of my doblo roof with layers of butyl tape to get an even curve but allowing 100 to 150mm of space between intermittent strips of butyl for maximum ventilation at the back. I used stixall on the long sides as I can reach the edges to cut through that,, if replacement is needed. Back ventilation is important to cool the panels. What you must NOT do is seal any air pocket under the panel as expansion can blow the pocket and kill the panel.
I too have a victron mppt from David,After trying a Ring b2b which failed.
 
Derekoak said:
I have fitted semiflexible on 2 campers now this one still working after 5 years and the other after 9 years. I got both from photonic universe. I think they were German made. I think the important thing is to fit them with little and even curvature, cylinder or cone curves but shallow. I supported mine off the ribs of my doblo roof with layers of butyl tape to get an even curve but allowing 100 to 150mm of space between intermittent strips of butyl for maximum ventilation at the back. I used stixall on the long sides as I can reach the edges to cut through that,, if replacement is needed. Back ventilation is important to cool the panels. What you must NOT do is seal any air pocket under the panel as expansion can blow the pocket and kill the panel.
I too have a victron mppt from David,After trying a Ring b2b which failed.
Click to expand...

For the Lensun panels mentioned earlier, this is a photo of the fixing method I used when attaching the panel to a GRP poptop ...
1661589485986.png

3M VHB Tape to attach the sides and centre of the panel to the raised ribs.
Strips of Perspex the same thickness to match the rib height attached between the long strips to give extra support as a precaution, with VHB tape again to attach.
At the front, added Perspex and Tape to stop airflow underneath the panel. I wanted to avoid the possibility of the panel getting any lifting strain from air pressure. Not sure if this is really needed but more of a precaution as the pressure of lift can be very high.
At the rear the ends are left open for the reasons Derek mentions to allow ventilation and pressure relief if needed.

This VHB tape REALLY grabs very hard (it is used for sticking panes of glass to the side of skycrapers!) and before selecting the type of VHB to use, I checked with the manufacturer of the GRP Roof and with Lensum to confirm compatibility as always nervous about non-mechanical fastenings!
 
wildebus said:
For the Lensun panels mentioned earlier, this is a photo of the fixing method I used when attaching the panel to a GRP poptop ...
View attachment 112157
3M VHB Tape to attach the sides and centre of the panel to the raised ribs.
Strips of Perspex the same thickness to match the rib height attached between the long strips to give extra support as a precaution, with VHB tape again to attach.
At the front, added Perspex and Tape to stop airflow underneath the panel. I wanted to avoid the possibility of the panel getting any lifting strain from air pressure. Not sure if this is really needed but more of a precaution as the pressure of lift can be very high.
At the rear the ends are left open for the reasons Derek mentions to allow ventilation and pressure relief if needed.

This VHB tape REALLY grabs very hard (it is used for sticking panes of glass to the side of skycrapers!) and before selecting the type of VHB to use, I checked with the manufacturer of the GRP Roof and with Lensum to confirm compatibility as always nervous about non-mechanical fastenings!
Click to expand...
With the last ones I fitted, I covered the back of the panel with as much butyl tape as possible to evenly conduct the heat away. Expensive, but what the hell.
I doubt even if you wanted to you'd trap air, it will come out long before it could rupture a panel.
 
SquirrellCook said:
With the last ones I fitted, I covered the back of the panel with as much butyl tape as possible to evenly conduct the heat away. Expensive, but what the hell.
I doubt even if you wanted to you'd trap air, it will come out long before it could rupture a panel.
Click to expand...
Photonic universe Web site had a warning about it and a picture of a blown bubble in a kaput flexible panel that someone had tried to totally glue down but missed a section. When the sun shines air trapped behind will expand rapidly.
As far as David stopping air flowing under when driving. You cannot rely on air being forced under when driving to cool a panel because the worst case is when parked up in full sun, with no or minimum air flow under or over the panel.. however I have not had any lift off even though my panels are curved following the roof, a bit like the top of a wing. I left mine open as heat kills panels by a function of higher temperatures for longer times so I feel any cooling is an improvement? Anyway no flexible panel failures here.
 
Many flexy panels have been fitted to yacht cabin roofs, they last at best 3/5 years, think its because no free air gets under them and they cook.
 
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