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robtheplod

Build a decent solar setup

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So, just starting to look around at solar panels and get as much info as I can so I end up with up (eventually) with the best I can get. On reading I can see lots of panels are designed for house installations so the voltage output is often quite high (~50v), so the Amps is lower, often 5amp as opposed to a some smaller panels which may be lower wattage, but the voltage is more like 18v so can push out theoretical ~9amp.... does this make sense?  I'm assuming the more actual amps they can supply is ultimate goal or is it not that clear cut?

 

Some panels I notice are quite old, such as 2010 etc... as solar is supposedly developing at a fast rate I would have assumed there would be far more newer panels about than there are.......

 

Obviously physical size is a factor being  a narrowboat, so 600mm or 800mm wide are much better suited?  Has anyone fitted the full sized panels and if so regretted it/recommend it?

 

I'm torn over the mounting. I had looked at this as being the answer:

https://midsummerenergy.co.uk/buy/solar-panel-kits/never-enough-cruising-3-panasonic-solar-charging-kit

which does look good, and also the tilting brackets. I'm struggling with the idea of drilling holes in the roof in case things change in the future and I need to move brackets, so end up having to fill holes etc.. really looking at a means of using magnets... this may be more hassle and i end up getting the drill out anyway but just looking so far...

 

I see people recommend fitting an isolator switch between the solar panels and MPPT controller so will certainly build that into it.... assume the positive to the battery needs to be fused also?

 

I notice many of the MPPT controllers are Victron or EPSolar Tracer makes - both look good although Victron seem pricier - any reason to choose one over the other?

 

thanks!!

 

 

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12 minutes ago, robtheplod said:

On reading I can see lots of panels are designed for house installations so the voltage output is often quite high (~50v), so the Amps is lower,

I have a 120volt panel (170w) "Low Light" so when the MPPT has converted it to 12 volts so in theory I can get 10x the current (at 12v) going into the battery that the panel is showing.

The way I see it is that if the sun is not very strong and I only get (say) 90 volts (ie 25% 'down), I still get a good input to the batteries. If I had a 12v panel and lost 25% I'd only be getting 9v and nothing going into the batteries.

 

Couple of examples

0.8 amps from the panel and 5.9 amps going into the battery at 14.7 volts

 

 

05-06-16.jpg

18-2-18.jpg

Edited by Alan de Enfield
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That kit seems expensive, is that the fitted price or diy install

 

have you tried bimble, I got a 1200w system from them last year for less money, did the install myself though.

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If you already have a Victron inverter, chances are you can use the Victron solar controller directly with this, thus saving on battery  cabling, and giving the BVM monitor a better chance of showing a good reading.

Those brackets are over engineered in my eyes, each panel will need 8 holes drilling in your roof for the feet. The new rails no longer come with end stops and the aluminium is cut rather roughly. You pay all that for a kit and they dont even give you an Allen key for all the bolts.....and worst of all, the legs are aluminium, so if one slides apart whilst you are lifting it into place....your sea searcher magnet will not find it in the depths.🙃

 

I've had large panels on my roof for the last 7 years, can still walk past them down one side so maximum bang for your buck.

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Another reason not to buy that kit is that the solar controller will not work with the panels wired in series, even 2 gave 109v, so 3 would be 160v.

In addition to the kit, you would need the MC4 connectors to parallel the panels.

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49 minutes ago, robtheplod said:

I'm torn over the mounting. I had looked at this as being the answer:

https://midsummerenergy.co.uk/buy/solar-panel-kits/never-enough-cruising-3-panasonic-solar-charging-kit

which does look good, and also the tilting brackets. I'm struggling with the idea of drilling holes in the roof in case things change in the future and I need to move brackets, so end up having to fill holes etc.. really looking at a means of using magnets... this may be more hassle and i end up getting the drill out anyway but just looking so far...

 

I was also originally interested in the Midsummer mounts but - aside from them being out of stock last time I looked - it has been pointed out to me that they are a rather complicated solution that wouldn't easily fit on my roof anyway.  I've since spoken to several folks who have large panels mounted on roof boxes with removeable hinge pins either side so you can choose which way to raise them and to whatever angle you like.  So long as they have air vents you can also stick them over mushroom vents.  In my case it's the ideal solution as it will also give me a large amount of wood storage and if I need to walk on the roof I can just raise or remove the solar lids beforehand.  I'm looking at having three large 140x100cm panels.  In theory I guess you could have hinge pins on all sides, providing a second plane to angle the panels, like the midsummer system.

Edited by The Gravy Boater

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2 hours ago, robtheplod said:

I'm assuming the more actual amps they can supply is ultimate goal or is it not that clear cut?

A solar panel produces power.  Power is measured in watts.  So a 200W panel could produce 2A at 100V, or 100A at 2V, or anything in between.

 

Clearer?

 

 

Edited by WotEver
added a comma... just because I could.
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I have full size panels 4 in series 3 times. My controller is a midnite classic 200 , I have MCBs between panels and controller plus same again to batteries. Solar is a great product for most of the year (for me all year) but you will need another power source for winter. Now all you need is LifePo4s batteries..............👹

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Thanks for all the replies..... does anyone have any photos of how they attached their panels with magnetic mounts?

 

Looking at these currently: 

 

https://e-magnetsuk.com/magnet_products/work_holding_magnets/pot_magnets/external_threaded_stud.aspx


https://e-magnetsuk.com/magnet_products/work_holding_magnets/pot_magnets/surface_protecting_slide_resist_clamp_magnet.aspx

 

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10 hours ago, WotEver said:

A solar panel produces power.  Power is measured in watts.  So a 200W panel could produce 2A at 100V, or 100A at 2V, or anything in between.

 

Clearer?

 

 

 

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23 hours ago, robtheplod said:

Thanks for all the replies..... does anyone have any photos of how they attached their panels with magnetic mounts?

 

I bolted aluminium u channel to the panel then magnetic pads to the u channel. The bolts holding the channel to the panel are lossened slightly to allow some movement for curvature of the roof. 6 pads per panel. About 4 years in service and they can be removed to clean the roof beneath. Obviously they could be stolen.

 

Screenshot_20200616-232520_Gallery.jpg

Edited by Cas446
Changed photo
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I've been looking around for smaller (narrow) panels with a decent output and originally found these:

 

https://www.photonicuniverse.com/en/catalog/full/183-160W-monocrystalline-solar-panel-with-5m-cable.html

 

Then I found these, which seem a higher output in the same ideal size - can anyone see any flaws in this panel?:

 

https://www.sunshinesolar.co.uk/Item/SSP185MS 

Edited by robtheplod

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1 hour ago, robtheplod said:

I've been looking around for smaller (narrow) panels with a decent output and originally found these:

 

https://www.photonicuniverse.com/en/catalog/full/183-160W-monocrystalline-solar-panel-with-5m-cable.html

 

Then I found these, which seem a higher output in the same ideal size - can anyone see any flaws in this panel?:

 

https://www.sunshinesolar.co.uk/Item/SSP185MS 

They seem ok to me, don't buy the PWM controller though 

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9 hours ago, peterboat said:

They seem ok to me, don't buy the PWM controller though 

Thanks, It'll be a Victron MPPT. Just trying to see which would be most appropriate. Thinking about 4 of the 185w panels, so 740w but the Victron I had in mind is 700w (https://www.sunshinesolar.co.uk/Item/SCC110050210)  so might need to make the leap up to the next one, which seems to be far more expensive..:(    its only just over and the 185w on the panels is likely to be overstated so would this suffice anyone???

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30 minutes ago, robtheplod said:

Thanks, It'll be a Victron MPPT. Just trying to see which would be most appropriate. Thinking about 4 of the 185w panels, so 740w but the Victron I had in mind is 700w (https://www.sunshinesolar.co.uk/Item/SCC110050210)  so might need to make the leap up to the next one, which seems to be far more expensive..:(    its only just over and the 185w on the panels is likely to be overstated so would this suffice anyone???

You're never likely to see anything like full output from the panels, and as long as you configure them to be well within the maximum voltage of the controller, that one would be fine.

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4 minutes ago, WotEver said:

You're never likely to see anything like full output from the panels, and as long as you configure them to be well within the maximum voltage of the controller, that one would be fine.

Thanks, as the panels are low at 18v each, 4 of them is 72v and the controller is 100v so that all looks good on that front unless I've overlooked anything?

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2 minutes ago, robtheplod said:

Thanks, as the panels are low at 18v each, 4 of them is 72v and the controller is 100v so that all looks good on that front unless I've overlooked anything?

18V is not the maximum voltage. 21.6 volts is for Peter's  second option but that is still 87 volts so still OK. Look for the open circuit voltage, not the peak power voltage.

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12 minutes ago, Tony Brooks said:

18V is not the maximum voltage. 21.6 volts is for Peter's  second option but that is still 87 volts so still OK. Look for the open circuit voltage, not the peak power voltage.

Thanks Tony, I'm learning everyday... :)

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46 minutes ago, robtheplod said:

Thanks, as the panels are low at 18v each, 4 of them is 72v and the controller is 100v so that all looks good on that front unless I've overlooked anything?

 

41 minutes ago, Tony Brooks said:

18V is not the maximum voltage. 21.6 volts is for Peter's  second option but that is still 87 volts so still OK. Look for the open circuit voltage, not the peak power voltage.

If you're fitting 4 then I'd consider wiring them in two parallel series pairs.  If that sounds complicated, it's not :)  Basically, two panels in series, plus another pair in series, then parallel the two pairs. That way, if one panel is in shade you only lower half of the output instead of the whole thing, and the voltage is still high enough for the MPPT to achieve a decent output.  It's always worth arranging the wiring such that you can experiment in the future - do they work better all in series, all in parallel etc.

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11 minutes ago, WotEver said:

 

If you're fitting 4 then I'd consider wiring them in two parallel series pairs.  If that sounds complicated, it's not :)  Basically, two panels in series, plus another pair in series, then parallel the two pairs. That way, if one panel is in shade you only lower half of the output instead of the whole thing, and the voltage is still high enough for the MPPT to achieve a decent output.  It's always worth arranging the wiring such that you can experiment in the future - do they work better all in series, all in parallel etc.

Thanks WotEver. I do intend to experiment with these and will do as you suggest. They will be mounted on magnets to start with and if that doesn't work then will have to screw in, but trying this first. They will be flat rather than on any tilting device (again, trialling!) and the wires will come into the boat via the grill on the stern, so initially no holes drilled. I had thought of the following layout. My thoughts are to pop two on either side of the boat so they will be angled slightly working in pairs, so your wiring idea will work well here:

 

Panel Layout.jpg

Everything is moveable so will be interesting to see what works... :)

Edited by robtheplod

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With that layout since the two pairs of panels are at different angle, due to the curved roof,  you need to wire them as two pairs in parallel each pair in series. As well as the different angle producing different outputs, partial shading is more likely because they are a long way apart. If your roof is very curved it may even be beneficial to have two smaller controllers, one for each pair. 

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On 16/06/2020 at 23:20, Cas446 said:

I bolted aluminium u channel to the panel then magnetic pads to the u channel. The bolts holding the channel to the panel are lossened slightly to allow some movement for curvature of the roof. 6 pads per panel. About 4 years in service and they can be removed to clean the roof beneath. Obviously they could be stolen.

 

Screenshot_20200616-232520_Gallery.jpg

Thanks, where did you get the aluminium mounting that your magnets connect to?

 

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Having got a grasp of some of the options, the thing you need to think about is what do you want out of them and what are the compromises you are willing to take, how do you use the boat etc.

 

Power Requirements:

*Are you trying to live off grid without a shore connection, or moving much, throughout winter, maybe working from home, and therefore need about as much power output as possible?

*Are you using the boat recreationally, or as a continuous cruisers, but want to be able to stop somewhere for a week or so during summer without having to turn the fridge off?

*Are you basically already self sufficient because your only on the boat weekends and holidays when you run the engine 8h a day for propulsion, and just want a bit to top the batteries up if you leave it a month.

 

Compromises:

*Do you want solar that you basically can't tell is there, it is of for the boat to look like a solar farm?

*Is it a floating home that never moves, or so you mainly use it for boating around so need the roof clear for lines etc. Any low tunnels near you?

*Do you want something DIY fit easy to fit, or are you prepared to get more involved?

*Do you want to just leave it be, or are you happy to adjust the angle each time your moor? Or even daily?

*How likely is you will moor somewhere a bit rough where panels might get broken or stolen?

 

What other equipment do you have onboard? Inverter, Charger, battery monitor? Cooker? Size of battery bank.

 

Etc

 

Daniel

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