More Solar Panel Q's

[Serenity Malc]

Yello,

 

If I fitted 2 x solar panels (£125 a throw NEW !!) with nominal wattages of 250W a piece, max voltage of 34.9V each and max current of 7.18A each, would I be able to purchase an MPPT controller to deal with them to feed a 12V battery bank of 400Ahr ?

 

I'm assuming their output voltages is a variable ? The MPPT controller is the important piece of kit ?

 

Sorry for the abstract questions, but I understand basic electricals but am unaware of the control processes to feed a 12V battery bank.

 

MPPT = ? .... and why are they so much better ?

 

 

Thanks muchly .... Malc.

Edited February 3, 2013 by Serenity Malc

[Ex- Member]

Yello,

 

If I fitted 2 x solar panels (£125 a throw NEW !!) with nominal wattages of 250W a piece, max voltage of 34.9V each and max current of 7.18A each, would I be able to purchase an MPPT controller to deal with them to feed a 12V battery bank of 400Ahr ?

 

I'm assuming their output voltages is a variable ? The MPPT controller is the important piece of kit ?

 

Sorry for the abstract questions, but I understand basic electricals but am unaware of the control processes to feed a 12V battery bank.

 

MPPT = ? .... and why are they so much better ?

 

 

Thanks muchly .... Malc.

 

Yeah 50 Ampt MPP controller would be fine 42 Amp minimum, bear in mind if you might want to upgrade your solar in the future so buying a bigger rated controller can cope wih expansion of solar array.

 

£125.00 sounds a bargian for new panels, are these on e-bay?

Edited February 3, 2013 by Julynian

[Serenity Malc]

Yello,

 

Thanks Julynian ..... I'll let you know if they're a runner.

 

I'll have to research MPP controllers now and also a some deck chair fixings for 1610 x 861 x 35 panels. Fortunately I have a widebeam roof to house them on.

 

Many thanks Malc.

[matty40s]

Yello,

 

Thanks Julynian ..... I'll let you know if they're a runner.

 

I'll have to research MPP controllers now and also a some deck chair fixings for 1610 x 861 x 35 panels. Fortunately I have a widebeam roof to house them on.

 

Many thanks Malc.

This is the one I am currently looking at to replace the Tracer units 40A MPPT also do a 60A and 80A unit, and you can also buddy them up so you can cover the whole of your roof with panels!!

[GoodGurl]

we have 570watts of panels and they run fine on a 45a mppt controller, wired in parallel as opposed to series, if wired in series you wont get the full benefit if one of the panels is in the shade, whereas in parallel it don't matter.

[Ex- Member]

This is the one I am currently looking at to replace the Tracer units 40A MPPT also do a 60A and 80A unit, and you can also buddy them up so you can cover the whole of your roof with panels!!

 

 

 

That's a good price for a MPP controller, but from that seller bear in mind that here will likely be tax due on the item. I've ordered lots of stuff from China and never had any problems or additional taxes, this ittem is located in Tiawan and the fact the seller is stating it, there's clearly a risk that duty will be charged on the ittem.

Edited February 3, 2013 by Julynian

[matty40s]

That's a good price for a MPP controller, but from that seller bear in mind that here will likely be tax due on the item. I've ordered lots of stuff from China and never had any problems or additional taxes, this ittem is located in Tiawan and the fact the seller is stating it, there's clearly a risk that duty will be charged on the ittem.

all my previous solar purchases from the Far East have arrived tax free, and usually been labelled "samples".......simples

[CV32]

I have been looking at regulators v MPPT's - many regulators do manage 2 battery banks, can an MPPT do the same ?

 

Sorry if its a dumb question, just trying to get my head round solar to keep my battery's topped up.

[Mat B]

I have been looking at regulators v MPPT's - many regulators do manage 2 battery banks, can an MPPT do the same ?

.......

 

I have not come across a mppt controller that can charge 2 banks.

 

However, it is not usually necessary to charge the starter battery between boat runs, the alternator will normally bring it up to full charge each time the engine is run. If you do want to top up the starter battery a separate, small (say 10W) panel will do the trick.

 

If you are using 34.9V panels then a mppt is necessary as it will sort out the mismatch between the panel voltage and your battery voltage, you will not get so much of an advantage if you are using 12V panels (open circuit about 18V ish)

 

m@

[Paul C]

If you really wanted the engine starter battery charged too, you could buy a smartbank or a separate small solar panel for it.

[GoodGurl]

Edited February 3, 2013 by GoodGurl

[Serenity Malc]

This is the one I am currently looking at to replace the Tracer units 40A MPPT also do a 60A and 80A unit, and you can also buddy them up so you can cover the whole of your roof with panels!!

 

Yello Matty,

 

I was looking at the MPPT in the link and both the 40A and 60A units when set to a 12v battery pack say that the minimum input voltage is 40V. The two different types of panels I'm looking at have Max Power voltages of 43.70v and 34.90v respectively. If I wired 2 of them in series then I could potentially see either 87.40v or 69.80v. But if I wired them in parallel, and I doubt I would see any where near Max Power most of the time, they would be under the minimum input voltage.

 

1) Does the unit simply not MPPT under 40 volts ?

 

2) Why wouldn't you purchase the 60A version anyway since it's almost the same price and would allow for future expansion ?

 

3) Series v parallel connections ..... series would allow for less volt drop per given cable size. Whereas It's been suggested that parallel connection is better for shaded or partial cloud conditions ?

 

Many thanks Malc.

[IainW]

another mppt option for you - clicky

[Serenity Malc]

Yello,

 

Thanks IainW.

 

Typical newbie ! Didn't do a thorough search on the forum before asking lots of Q's !

 

So if I parallel fit 2 x 240watts rated panels and assume a constant voltage of around 43.7v, I=P/E.

 

480/43.7 = 11.0A for calculation purposes.

 

I hadn't cottoned on that the controllers are rated in the output side. D'oh !

 

So 480/14.2 = 33.8A. On a VERY good day.

 

Does that sound right ?

 

So to answer my own previous question, an input voltage of >40v is fine even when the panels are wired in parallel.

 

 

Many thanks Malc.

Edited February 4, 2013 by Serenity Malc

[Justme]

 

 

So 480/14.2 = 33.8A. On a VERY good day.

 

Does that sound right ?

 

 

 

You will get the most power when the bats are at their lowest SOC / voltage so you would be better using 12 - 12.2v as your base line. By the time your bank hits 14.2v it will already be reducing the max amperage it can accept.

 

480 / 12 = 40 amps.

 

Oh & it does not have to be a very good day to hit that level.

[matty40s]

Yello Matty,

 

I was looking at the MPPT in the link and both the 40A and 60A units when set to a 12v battery pack say that the minimum input voltage is 40V. The two different types of panels I'm looking at have Max Power voltages of 43.70v and 34.90v respectively. If I wired 2 of them in series then I could potentially see either 87.40v or 69.80v. But if I wired them in parallel, and I doubt I would see any where near Max Power most of the time, they would be under the minimum input voltage.

 

1) Does the unit simply not MPPT under 40 volts ?

 

2) Why wouldn't you purchase the 60A version anyway since it's almost the same price and would allow for future expansion ?

 

3) Series v parallel connections ..... series would allow for less volt drop per given cable size. Whereas It's been suggested that parallel connection is better for shaded or partial cloud conditions ?

 

Many thanks Malc.

 

1. I am looking into this, the Tracer shute off at around 36V, however, this is usually after the sun has gone down so I do not see 40V as being a worry.

 

2.Because not all narrowboats have 3 acres to install solar panels like you wide beams malc

 

another mppt option for you - clicky

 

 

IanW, that is the controller I was using last year, however, am struggling to find them at a reasonable price (£160) and I believe from the suppliers that a new model is coming out shortly.

Edited February 4, 2013 by matty40s

[Serenity Malc]

You will get the most power when the bats are at their lowest SOC / voltage so you would be better using 12 - 12.2v as your base line. By the time your bank hits 14.2v it will already be reducing the max amperage it can accept.

 

480 / 12 = 40 amps.

 

Oh & it does not have to be a very good day to hit that level.

 

 

Excellent point ! .... Many thanks.

 

Malc.

[lewisericeric]

This is the one I am currently looking at to replace the Tracer units 40A MPPT also do a 60A and 80A unit, and you can also buddy them up so you can cover the whole of your roof with panels!!

Looks very much like an outback!

 

We have 690w of solar and have an 80amp outback MPPt controller which gives that little bit of room if we did want to add another panel, not that we have any such plans at the moment.

 

Definately agree with getting an MPPT controller though that has a higher capacity than your current setup Incase you do want to expand!

 

And can't we tell that spring is on its way....12 amps as I speak right now which is the most I've had for a long time!

[Grifter]

£125 for 250W is very cheap! Could you post a link to the supplier?

 

Cheers, Joe

[Serenity Malc]

Yello,

 

I will post a link as soon as I'm sure he's fit to trade with .... I've emailed him without response so far, and I'm very keen to purchase. I will collect as he's localish to me .... I wouldn't want to be giving the forum a bogus lead.

 

Malc.

[matty40s]

Yello,

 

I will post a link as soon as I'm sure he's fit to trade with .... I've emailed him without response so far, and I'm very keen to purchase. I will collect as he's localish to me .... I wouldn't want to be giving the forum a bogus lead.

 

Malc.

I can't even ask him a question, the first time I have come across that.

[Justme]

£125 for 250W is very cheap! Could you post a link to the supplier?

 

Cheers, Joe

 

What about 235 watts for £120 inc vat linky

 

 

Or 275 watts for £165 linky

Edited February 4, 2013 by Justme

[Serenity Malc]

I can't even ask him a question, the first time I have come across that.

 

 

Yello,

 

Definitely no offence meant Matty ! I've just got off the phone to the vendor. I've only just found out that they are actually a solar installation company getting rid of a few pieces of spare kit before moving warehouse. NOT a supplier by any means and I was also quite keen to snap up 2 x Sanyo HIT-N240 SE10 panels myself. So please don't take me wrong. The last 2 x 240's and 1 x 250 are on Ebay and available to everyone who can be bothered to research and read a spec sheet as opposed to being told a panel's nominal value.

 

Regards Malc.

 

Not the 'supplier' mentioned in Justme's post either. I'm paying £240 for my 480watts of solar by picking them up.

Edited February 4, 2013 by Serenity Malc

[Grace and Favour]

Malc - - - I'm using Sanyo HIT-N240 SE10 panels . . . they are excellent!!!!! - you should be 'well 'appy'

[Serenity Malc]

Yello,

 

Well that's very comforting to know Grace and Favour !! .... still a big outlay when you add another £200 for a controller, but thanks for the endorsement of my purchase.

 

Malc.

Edited February 4, 2013 by Serenity Malc