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robtheplod

Build a decent solar setup

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Budget?

 

You can get very powerful magnets, if at a cost, and they is conveniences in installation and being able to move them, cabling allowing. But they are not cheap, and can be overcome be a thief or high wind.

 

Drilling holes is easy, and the roof might well be thick enough to take a thread, but rain is very persistent and deckhead leaks are a bugger and can cause major internal damage. I would not drill holes in a roof to mount panels.

 

Welding on brackets sounds like major work, and reasonably permanent. But for anyone with the kit it's quick and easy and cheap, wouldn't pull off, can't leak, and can be much smaller and neater. Paint is easy to repair. You can also put in a doraded cable route while you're at it.

 

 

Daniel

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1 hour ago, DHutch said:

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

Good questions.. not sure if this is for me to ponder or you'd like a response but as you've very kindly replied here goes!

 

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?

We will eventually be living off grid and I may still do the odd bit of work via laptop etc

*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?

We are recreational currently, but the intention is to CC as soon as we can, so will have times without running engine/having shoreline

*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. Currently the boat is in a marina until we visit for long weekends/holidays. It would be nice to not have shoreline power when left if the solar can keep the fridge etc going?

 

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?

I'd like it to be fairly low profile but not the flexible panels due to issue with rust behind/cracking and damage to roof on removal etc

*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?

We intend to CC over the network so really keen the panels are below the mushroom vent height as we may go through low tunnels etc..

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

My preference is a DIY fit as want to understand it and find it interesting

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

No, I'd like it to be flat so they don't need adjusting. Happy to increase the number of panels to compensate slightly for this

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

Same as any boater really. Can't see how the mounting will impact on the likelihood of damage/being stolen - what will be will be!

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

We have an inverter, although just the laptop requires 240v at present, everything else on the boat is 12v (invertor isn't used much). Have a battery charger (currently always on when in marina), have a SmartGuage monitor, Gas cooker and 4 x 105ah leisure and 1 x 105ah starter battery.

Budget?

Budget isn't really too much of an issue as the sale of our boat share is paying for this! :)

ou can get very powerful magnets, if at a cost, and they is conveniences in installation and being able to move them, cabling allowing. But they are not cheap, and can be overcome be a thief or high wind.

Drilling holes is easy, and the roof might well be thick enough to take a thread, but rain is very persistent and deckhead leaks are a bugger and can cause major internal damage. I would not drill holes in a roof to mount panels.

Welding on brackets sounds like major work, and reasonably permanent. But for anyone with the kit it's quick and easy and cheap, wouldn't pull off, can't leak, and can be much smaller and neater. Paint is easy to repair. You can also put in a doraded cable route while you're at it.

I agree with you re drilling in the roof, and will try all other means before I do this as you say, water finds a way. I like the flexibility of moving panels and changing panels without having to have more brackets drilled. Having brackets seems limiting on having to replace like with like, i know this is a small point as they last X years but something to consider!

Edited by robtheplod

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On 19/06/2020 at 08:46, 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, think I've got this, does this look right?

 

Panel Layout.jpg

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3 minutes ago, robtheplod said:

Thanks, think I've got this, does this look right?

Perfik!

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On 19/06/2020 at 07:50, 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.

Careful I thought this , I have over panelled and have 6 x 270 w Perlight panels . I have a midnite classic for 96a and am testing one panel and In current light cloud with sunny intervals i am getting 250 watts very close to max and I think on  perfect day next week it could produce more that the max output . My old panels would not have got near 50 % of rated output so conclusion is new modern high efficiency perc panels will even in uk hit or exceed max rates output . 

 

Make sure your solar controller has a current limit if you over panel or it could end in tears 

 

 

Edited by RufusR
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1 hour ago, RufusR said:

Careful I thought this , I have over panelled and have 6 x 270 w Perlight panels . I have a midnite classic for 96a and am testing one panel and In current light cloud with sunny intervals i am getting 250 watts very close to max and I think on  perfect day next week it could produce more that the max output . My old panels would not have got near 50 % of rated output so conclusion is new modern high efficiency perc panels will even in uk hit or exceed max rates output . 

 

Make sure your solar controller has a current limit if you over panel or it could end in tears 

 

 

Plus we have VOC as well, I often see close to max amps and voltage with my setup. For me Midnite makes the best solar controllers in the world but of course I am biased as I have 2 of them on the boat

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5 hours ago, robtheplod said:

 

I agree with you re drilling in the roof, and will try all other means before I do this as you say, water finds a way. I like the flexibility of moving panels and changing panels without having to have more brackets drilled. Having brackets seems limiting on having to replace like with like, i know this is a small point as they last X years but something to consider!

 

That's why I used these, stuck on with Stixall.

 

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4 hours ago, RufusR said:

Make sure your solar controller has a current limit if you over panel or it could end in tears 

It won’t end in tears.
 

All controllers output up to their maximum current and no more. The panels don’t ‘push’ power into a controller, the controller finds the voltage that supplies the maximum current and then converts that to the correct charging voltage at whatever current the battery bank demands, up to the maximum that the controller can provide. 
 

In short, over-voltage can and will kill a controller in short order but there’s no such thing as ‘over power’. 

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So my statement was entirely correct when I wrote “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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On 19/06/2020 at 07:50, 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.

I recently fitted a 2 panel system on those brackets ordered as a kit from Midsummer.  I had advised a completely different controller, brackets and panels but hey ho, customer is always right and all that.

The panels had a Maximum Voc of 53.2v, so in series (as the kit had no MC4 parralelling connectors, I was expecting just over 100v(very warm afternoon in early April). I was very surprised to see 109.4v......less surprised to see the Victron 100/50 controller flashing over voltage and not working.

Covering 1/2 of 1 panel with a sheet of cardboard allowed the system to work properly, and that is how it stayed until the connectors to parralel the panels arrived from ebay a few days later.

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1 minute ago, matty40s said:

The panels had a Maximum Voc of 53.2v, so in series (as the kit had no MC4 parralelling connectors, I was expecting just over 100v(very warm afternoon in early April). I was very surprised to see 109.4v......

Yup, that doesn’t surprise me. A panel can easily exceed its stated Voc on a sunny but cool day (heat reduces the output somewhat). As with any electrical specifications you should always build in at least a 10% safety margin. 20% would be better. 


What you saw was less than 3% adrift from spec. 

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1 minute ago, WotEver said:

Yup, that doesn’t surprise me. A panel can easily exceed its stated Voc on a sunny but cool day (heat reduces the output somewhat). As with any electrical specifications you should always build in at least a 10% safety margin. 20% would be better. 

The temp on the day was over 25c!!

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Just now, matty40s said:

The temp on the day was over 25c!!

Yup you’d have seen a lot less at 35C. 

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Just now, WotEver said:

Yup you’d have seen a lot less at 35C. 

I wouldnt have been on a boat roof at 35c. 😁

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And anyway...

13 minutes ago, matty40s said:

The panels had a Maximum Voc of 53.2v...

Wired in series doesn’t really fit with the ‘well within’ part of...

13 minutes ago, matty40s said:

... configure them to be well within the maximum voltage of the controller

... if you have a max input voltage of 100V, now does it?

 

:P


 

Edited by WotEver

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6 minutes ago, WotEver said:

And anyway...

Wired in series doesn’t really fit with the ‘well within’ part of...

 

:P


 

I was a bit annoyed at getting the kit I hadn't specified delivered, and was even more annoyed when the Victron MPPt  was flashing I looked under the panels to see..

20200620_234258.jpg

 

You do expect a kit to come with everything you need and not have to order extra bits from somewhere else!

I didnt charge him for the cardboard however.

Edited by matty40s

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2 minutes ago, matty40s said:

You do expect a kit to come with everything you need and not have to order extra bits from somewhere else!

I agree completely. There’s a clue in the word ‘kit’...

4 minutes ago, matty40s said:

I looked under the panels to see..

... that they state that they can supply up to 10% more than spec. 

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8 hours ago, WotEver said:

It won’t end in tears.
 

All controllers output up to their maximum current and no more. The panels don’t ‘push’ power into a controller, the controller finds the voltage that supplies the maximum current and then converts that to the correct charging voltage at whatever current the battery bank demands, up to the maximum that the controller can provide. 
 

In short, over-voltage can and will kill a controller in short order but there’s no such thing as ‘over power’. 

There is some really useful info coming out here so thanks so much to those contributing, so much i need to learn!

 

So re the above, I noticed the Tracer MPPTs specifically mention:

 

These MPPT controllers have a limiting function on charging current to protect the components and circuits.  They will charge the battery(s) within the rated charging power even if PV input power exceeds this range, for example

1, If the PV array output power is less than or equal to the rated charge power above, the controller will charge the battery(s) at the actual maximum power point;

2, If the PV array output power is greater than the rated charge power above, the controller will charge the battery(s) at the maximum rated power.

 

 

So going on WotEvers reply above this behaviour is quite normal in MPPT controllers and Tracer just happens to mention it? I can't find any equivalent statement from Victron about the Victron Energy Smart Solar MPPT 100V/50A - (12/24V) that I'm hoping to use, but maybe they just assume this is a known?

 

So the 50A on the controller spec is what it can supply to the batteries as opposed to what it can handle from the panels?

 

So it looks like I need to focus on the voltage more when speccing?  The panels I have in mind are:

 

Max Power. 185W ± 3%
Max Power Voltage. 18V
Max Power Current. 10.3A
Open Circuit Voltage. 21.6V
Short Circuit Current. 11.2A
Normal Operating Cell Temp. -45 to 80°C
Max System Voltage. DC600V
Dimensions. 1470 x 660 x 35mm

 

so that's 21.6v (thanks Tony!) per panel, so with four of them wired in the series/parallel setup as shown earlier that's 86.4v? (or is that 43.2v... not sure!!)- under the 100v capability of the controller by about 15% (if 86.4v) - is this cutting it a little fine or ok since the variation on the panels is small (about 3%)? I don't want to have to worry about frying the controller if possible - does the Victron close down in these circumstances or just give off a smell!

Edited by robtheplod

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On 19/06/2020 at 08:46, 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.

I have four 170w panels wired this way, not complicated and gives good outout.

1 hour ago, robtheplod said:

There is some really useful info coming out here so thanks so much to those contributing, so much i need to learn!

 

So re the above, I noticed the Tracer MPPTs specifically mention:

 

These MPPT controllers have a limiting function on charging current to protect the components and circuits.  They will charge the battery(s) within the rated charging power even if PV input power exceeds this range, for example

1, If the PV array output power is less than or equal to the rated charge power above, the controller will charge the battery(s) at the actual maximum power point;

2, If the PV array output power is greater than the rated charge power above, the controller will charge the battery(s) at the maximum rated power.

 

 

So going on WotEvers reply above this behaviour is quite normal in MPPT controllers and Tracer just happens to mention it? I can't find any equivalent statement from Victron about the Victron Energy Smart Solar MPPT 100V/50A - (12/24V) that I'm hoping to use, but maybe they just assume this is a known?

 

So the 50A on the controller spec is what it can supply to the batteries as opposed to what it can handle from the panels?

 

So it looks like I need to focus on the voltage more when speccing?  The panels I have in mind are:

 

Max Power. 185W ± 3%
Max Power Voltage. 18V
Max Power Current. 10.3A
Open Circuit Voltage. 21.6V
Short Circuit Current. 11.2A
Normal Operating Cell Temp. -45 to 80°C
Max System Voltage. DC600V
Dimensions. 1470 x 660 x 35mm

 

so that's 21.6v (thanks Tony!) per panel, so with four of them wired in the series/parallel setup as shown earlier that's 86.4v? (or is that 43.2v... not sure!!)- under the 100v capability of the controller by about 15% (if 86.4v) - is this cutting it a little fine or ok since the variation on the panels is small (about 3%)? I don't want to have to worry about frying the controller if possible - does the Victron close down in these circumstances or just give off a smell!

Wired in series pairs the voltage will be 43.2.

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1 hour ago, robtheplod said:

So going on WotEvers reply above this behaviour is quite normal in MPPT controllers and Tracer just happens to mention it? I can't find any equivalent statement from Victron about the Victron Energy Smart Solar MPPT 100V/50A - (12/24V) that I'm hoping to use, but maybe they just assume this is a known?

 

So the 50A on the controller spec is what it can supply to the batteries as opposed to what it can handle from the panels?

Yes. And yes. :)

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1 hour ago, robtheplod said:

so with four of them wired in the series/parallel setup as shown earlier that's 86.4v? (or is that 43.2v... not sure!!)

As above - 43.2V (+10% or thereabouts)

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19 hours ago, robtheplod said:

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

 

Search for Magpads and Aluminium U channel on eBay.

 

 

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On 20/06/2020 at 14:28, DHutch said:

 

Excellent thanks so much for all the replies.

 

I'm looking at wiring and thought as the panels have 4mm i probably need to go for 6mm for the main wiring along the roof. Not sure on the voltage drop as it will go a fair way along the boat - would i need to go larger?

 

Also cant seem to find a solar 3 way cable junction box that will need to go under the first lot of panels. Would these be ok?

https://www.amazon.co.uk/gp/product/B01N30QTDA/ref=ox_sc_act_title_2?smid=A1IX7WRB7J03LQ&psc=1

 

thanks!!

 

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