Solar Panel selection
- Thread starter Captain Rick
- Start date
Thanks @Captain Rick, i know it is close but I’m happy to give it a go. I only really use the van in the UK so the level of sun exposure won’t be as dramatic as if I was in Southern Europe for example.
My panel just arrived. I only ordered out yesterday, that is good service
That does seem very brave! I don't think the average level of sun exposure is much to do with it, I think panels generally reach operating voltage with any decent sun, and even if not, all it takes is one sunny day. Basically, you're betting on voltage losses in your cabling saving your ctek from frying.
I will take some measurements off the panel before I install it. Worst case I will take the CTEK out and sell it and replace it with a Renogy DCC30S which has a VOC of 25V.
OK, quick update, as it’s nice and sunny today I took the panel outside and opened the box so i could measure the voltage across the ends of the cables.
The good news is I measured 23.4V, that means the panel is pretty efficient as although it’s sunny, it’s not super bright today like it has been over the summer. I didn’t tilt it towards the sun or try to get the best output, just laid it flat on the ground in the box and stuck a meter across the ends of the cables.
The bad news is I measured 23.4V, that means I will definitely exceed the CTEK maximum.
I knew this might happen so had given some thought to what I might do. I think I have three options:
Below extract from the Renogy manual. In this regard, the Renogy appears to be much better than the CTEK as it seems to have some protection against the solar input voltage being exceeded:
The good news is I measured 23.4V, that means the panel is pretty efficient as although it’s sunny, it’s not super bright today like it has been over the summer. I didn’t tilt it towards the sun or try to get the best output, just laid it flat on the ground in the box and stuck a meter across the ends of the cables.
The bad news is I measured 23.4V, that means I will definitely exceed the CTEK maximum.
I knew this might happen so had given some thought to what I might do. I think I have three options:
- Replace the CTEK with another DC-DC with inbuilt MPPT controller. I’m thinking the Renogy DCC30S at this stage and this is my preferred option.
- Advantages:
- I can add the Bluetooth module and then I won’t have to crawl around the van to see if it is working.
- It seems to have a voltage limiter on the Solar input so won’t blow up if the VoC creeps over the 25V limit on a really sunny day
- Will charge both leisure, then starter once leisure is full in the same way the CTEK does
- it will replace the CTEK without any major wiring mods
- Disadvantages
- a single unit so if it fails I lose all charging capability - same as the CTEK
- it is a fraction bigger than the CTEK so I’ll need to do a minor rejig to get it to fit in the same place
- I’ll have to spend c£200 but should recoup some of that in selling the CTEK (which is only 6 months old)
- Advantages:
- Get a separate MPPT controller. If i do this I’d probably go fo the Victron 75/15 with Bluetooth.
- Advantages:
- two separate devices which gives a little more durability if one should fail
- 5 year warranty on the Victron
- plenty of headroom on the VoC side
- can manage the MPPT via Bluetooth so it can be installed out of the way
- Disadvantages:
- need a bit more space to fit the extra device in under the drivers seat
- I don’t think I‘d get my ideal setup which is for solar to charge leisure as priority and provide trickle to starter battery as the CTEK won’t do this without it’s own solar input - this is my main concern
- definite extra cost of about £120
- Advantages:
- Fit some kind of voltage limiter in line between the panel and the CTEK. I’m not sure how realistic this is. My instinct is telling me this would reduce the efficiency of the panel so it feels like a daft option to me.
Below extract from the Renogy manual. In this regard, the Renogy appears to be much better than the CTEK as it seems to have some protection against the solar input voltage being exceeded:
just for all though’s people with a Ctek system (and other systems ) you can fit a smart shunt that enables you to monitor the battery while charging ( solar) ...it’s easy to fit...even I did it
www.victronenergy.com
ps ...I do feel the pain in trying to maximise solar power to match your controller...
SmartShunt - Victron Energy
The SmartShunt is an all in one battery monitor, only without a display. Your phone acts as the display. The SmartShunt connects via Bluetooth to the...
ps ...I do feel the pain in trying to maximise solar power to match your controller...
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One thing to potentially check, is point 3.3 just past where your screenshot cuts off. It reads as though, when the solar input is hooked up, the alternator input is only able to use half the rated current of the unit. It's not exactly clear but definitely something to check with Renogy if you care about the alternator input getting past 15A.
My general inclination would be to go with a dedicated solar controller. You could check whether the CTEK trickle charges in this scenario by sticking it on EHU now and seeing whether the voltage at the starter battery goes up slightly (this is how both my votronic DC-DC/solar boxes work) but, even it it doesn't, stand-alone trickle charging boxes are very cheap as the previous poster says.
That’s exactly what it says. I’m not too worried by this TBH. With a panel permanently on the roof I’ll be getting much longer hours of charging than I do just now so in all probability the leisure will be pretty full most of the time unless I’m using the fridge heavily in which case I likely won’t be driving so the alternator won’t come into the equation anyways.
It doesn’t. I’ve tested this previously. It will only trickle charge the starter if solar is connected and leisure is fully charged. I’ve tested this as well
. I know its only small but the trickle charger is another unit to fit into a pretty busy spaceThere's another thread about this issue somewhere, their wording is confusing but that's the gist of it, that's why I ended up using a Votronics trickle charger off my Victron MPPT to do this. Not quite sure how I'm going to trickle charge my starter battery when I fit lithium, at the moment I've set the MPPT load output to trickle charge when the leisure battery is over 12.9v - but the Valence is going to be above that nearly all the timeConfused...The Ctek will charge the leisure battery via alternator.....The Ctek will charge the leisure battery via solar ( Mppt) and once the battery is charged will trickle charge the starter battery
but due to the limitations of the inputs to the Ctek ...a suggestion to fit along side and use the Victron system that can take higher inputs
But the Ctek can’t trickle charge without solar ......i Must have miss read this
Captain Rick
Member
Just fitted (squeezed!) the Victron 100/20 solar controller under the seat with the 120aH AGM leisure battery and the Ctek D250SE. The Ctek is dealing with the dc to dc starter battery to leisure battery management while the Victron, connected directly to the leisure battery, is looking after my 250watt Photonics Universe semi-flexible roof mounted panel. The Load output of the Victron feeds to the starter battery (as described by @andys in a separate feed) to keep it charged.
What I've yet to do is 1. permanently fix the panel on the roof, and 2. set the Load output on the Victron via my iPhone's already established bluetooth connection to it. @andys suggested switching on at 13v and off at 14.7v but I can't figure out how to do that as the available algorithms all seem to switch OFF at a lower voltage to the level to switch ON. Advice would be welcome but otherwise all seems to be performing OK - so far!
Oh, and while I was at it I fitted a Clipper BM2 battery monitor that I had hanging about left over from my boating interest. It monitors the leisure and starter batteries so complements the bluetooth info from the Victron.
What I've yet to do is 1. permanently fix the panel on the roof, and 2. set the Load output on the Victron via my iPhone's already established bluetooth connection to it. @andys suggested switching on at 13v and off at 14.7v but I can't figure out how to do that as the available algorithms all seem to switch OFF at a lower voltage to the level to switch ON. Advice would be welcome but otherwise all seems to be performing OK - so far!Oh, and while I was at it I fitted a Clipper BM2 battery monitor that I had hanging about left over from my boating interest. It monitors the leisure and starter batteries so complements the bluetooth info from the Victron.
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Can't remember what numbers I finally settled on as it was ages ago, I'll have a look tomorrow. But yes it would be on above 12.9 and off if it dropped below 13, then the top would be set to cut off at 14.7v in that example.
Hi @Captain Rick,
Just read the thread! Very interesting... I have had no end of issues with my solar (had my T6 converted in March, and it has not worked properly since then). The converter has agreed to replace the MPPT controller and panel, which he is doing on the 4th Jan (so time is short for me to consider any options!). The current plan is he will just replace like with like. This is what I currently have.
This is the solar: FLEXi SUN – 150W Flexible Solar Panel | CampervanCulture.com
This is the MPPT (bluetooth enabled): Midsummer Energy
But, I am now considering getting him to upgrade the setup, and for me to pay him the difference in cost. I was also thinking of a panel around 250W or so.
I understand you went for the Victron 100/2 and also 250W Photonic Universe panel. Was it this one? 12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine
I just wanted to know how you have got on with it? Would be really interested (if you were able / prepared) to see the info you have from your Victron bluetooth app. On mine, I can get an output for the last 30 days (its just a spreadsheet), and also see the "current" figures on the screen. Would be really useful if you could post the last 30 days on here if possible? And also a current screenshot of the bluetooth app perhaps in the middle of the day today. Would really help me in deciding whether to upgrade or not.
Final thing (for anyone really), I am really happy with the Victron MPPT, so I will just get the correct one to match the panel. But in terms of panel makes, if I am going for a 250W, are there any other makes apart from Photonic Universe that I should consider? Ones which are a good blend of quality and value for money.
Many thanks in advance!
Just read the thread! Very interesting... I have had no end of issues with my solar (had my T6 converted in March, and it has not worked properly since then). The converter has agreed to replace the MPPT controller and panel, which he is doing on the 4th Jan (so time is short for me to consider any options!). The current plan is he will just replace like with like. This is what I currently have.
This is the solar: FLEXi SUN – 150W Flexible Solar Panel | CampervanCulture.com
This is the MPPT (bluetooth enabled): Midsummer Energy
But, I am now considering getting him to upgrade the setup, and for me to pay him the difference in cost. I was also thinking of a panel around 250W or so.
I understand you went for the Victron 100/2 and also 250W Photonic Universe panel. Was it this one? 12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine
I just wanted to know how you have got on with it? Would be really interested (if you were able / prepared) to see the info you have from your Victron bluetooth app. On mine, I can get an output for the last 30 days (its just a spreadsheet), and also see the "current" figures on the screen. Would be really useful if you could post the last 30 days on here if possible? And also a current screenshot of the bluetooth app perhaps in the middle of the day today. Would really help me in deciding whether to upgrade or not.
Final thing (for anyone really), I am really happy with the Victron MPPT, so I will just get the correct one to match the panel. But in terms of panel makes, if I am going for a 250W, are there any other makes apart from Photonic Universe that I should consider? Ones which are a good blend of quality and value for money.
Many thanks in advance!
Captain Rick
Member
Hi there. I’m tied up this morning but will answer when things are quieter this afternoon
Captain Rick
Member
Hello @monsteruk
You are right that I eventually went for the Victron 100/20 solar controller with the 250watt Photonics Universe panel. Here's a view of the panel finally stuck to the roof:
In my post of 19 Oct 2020 you'll see a photo of the blue Victron in the bottom left squeezed under the drivers seat with the 120Ah AGM battery and the Ctek D250SE which is doing the battery to battery management. I went for this set up as I wanted a decent sized leisure battery and after quite a bit of research and lots of helpful advice from this forum worked out that the Ctek couldn't cope with a solar panel more than about 150watts (because of the voltage limit to the Ctek) while I wanted a panel of at least 200watts. That took me to having a separate solar controller and while I might have liked a panel of maybe 300watts (see the photo from @Martin Gibson near the start of this thread) the Victron Controller to accommodate that would have been too big for the under seat space that I had left. So I looked at the next size down (the 100/20) and found that it could cope with up to 280 watts. So the best panel I could find just less that 280watts was the 250watt PU panel that I bought and fitted. (Note: the first Victron 100/20 that I ordered arrived as the 48 volt version even though the description and picture of it on the vendors web-site showed the 12/24v so I had to get it changed!)
I finally completed this set up about 3 weeks ago, (doing it all by myself which was sometimes rather challenging) and since then the weathers been rather grotty. I've only had the 'van out once since then and it was a rather miserable day so expected little performance from the panel. This is what was showing on my phone by bluetooth:
So its working fine - I just need a better day to try it on! Meanwhile I've had it in the garage as I'm busy fitting furniture in it with a Thetford C262-CWE cassette loo, a 50litre fridge and a combined 2 gas burner and sink unit. Its all just taking a long time as I have so much else to do.
So, a long story and do let me know if you need any more info. Hope everything works out OK for you
You are right that I eventually went for the Victron 100/20 solar controller with the 250watt Photonics Universe panel. Here's a view of the panel finally stuck to the roof:
In my post of 19 Oct 2020 you'll see a photo of the blue Victron in the bottom left squeezed under the drivers seat with the 120Ah AGM battery and the Ctek D250SE which is doing the battery to battery management. I went for this set up as I wanted a decent sized leisure battery and after quite a bit of research and lots of helpful advice from this forum worked out that the Ctek couldn't cope with a solar panel more than about 150watts (because of the voltage limit to the Ctek) while I wanted a panel of at least 200watts. That took me to having a separate solar controller and while I might have liked a panel of maybe 300watts (see the photo from @Martin Gibson near the start of this thread) the Victron Controller to accommodate that would have been too big for the under seat space that I had left. So I looked at the next size down (the 100/20) and found that it could cope with up to 280 watts. So the best panel I could find just less that 280watts was the 250watt PU panel that I bought and fitted. (Note: the first Victron 100/20 that I ordered arrived as the 48 volt version even though the description and picture of it on the vendors web-site showed the 12/24v so I had to get it changed!)
I finally completed this set up about 3 weeks ago, (doing it all by myself which was sometimes rather challenging) and since then the weathers been rather grotty. I've only had the 'van out once since then and it was a rather miserable day so expected little performance from the panel. This is what was showing on my phone by bluetooth:
So its working fine - I just need a better day to try it on! Meanwhile I've had it in the garage as I'm busy fitting furniture in it with a Thetford C262-CWE cassette loo, a 50litre fridge and a combined 2 gas burner and sink unit. Its all just taking a long time as I have so much else to do.
So, a long story and do let me know if you need any more info. Hope everything works out OK for you
Thanks for coming back to me @Captain Rick.
Looks great on the van. I was kinda hoping it would have been on your drive for a few days to get some numbers! But thanks for the screenshot, and it looks like the project is coming on well.
The panel looks ace on the van. I can see there are two options on the PU site for 250W
12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine
12V solar panel solar charging kits for motorhome caravan boat campervan yacht marine off-grid
www.photonicuniverse.com
12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine
12V solar panel solar charging kits for motorhome caravan boat campervan yacht marine off-grid
www.photonicuniverse.com
Both are the same price, and I have to confess I am not entirely sure what the difference is! It looks as if the connector is on the panel for the one, and separate for the other?
Which of the two did you get?
Thanks.
Roy
Captain Rick
Member
I had the one with the connector on the top face, shown in the first link that you sent. I understand that the other has the connector underneath and it sticks out so that you have to make a big hole for it in the roof of the van. Of course that avoids the use of a separate 'blob' on the roof to the rear of the panel which covers the two cables going through the roof. I've only seen photos of this second style (panel + 'blob') and I've not heard of anyone using the other - but I bet someone has? Photonics Universe were only able to supply a white 'blob' so I sourced a black one from Amazon Offgridtec 006415 Roof Duct Dual Black For Motor Home Caravan Boat Solar Cable Duct ABS: Amazon.co.uk: Business, Industry & Science
I’ve got the box on the underside. It is neater looking once installed but you really do have to cut a pretty substantial hole in the roof to fit it in!
Some of the newer ones have a nice round underside fitting you can do with a hole saw but I haven’t seen a 250w flavour of those.
Interesting. What ever I get will need to replace the existing panel (so hole already in pop top roof for that).
This is the one fitted now, which is being replaced: FLEXi SUN – 150W Flexible Solar Panel | CampervanCulture.com
So I am hoping the one @Captain Rick has (12V solar panels charging kits for caravans, motorhomes, boats, yachts, marine) will be a reasonable replacement and re-use the same hole!
I hope!
