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Old 02-02-2014, 20:46   #1
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Solar Choices

Hello Cruisers,

I am tossing up between two solar options, after getting good prices on both the Kyocera 140W 12V panels and the 215W 18V panels.

In summary, I can fit a pair of panels up on our davits, and according to my calculations, a pair of 140W panels would be adequate, whereas a pair of 215W panels would be a bit generous in their power production. (We have light power consumption with the backup of an Aerogen 6, plus we have shore power and are unlikely to do much more than week long hops for the foreseeable future. Adelaide is VERY sunny pretty well all year round, the davits are rarely shaded. I plan on a 300AH - 400AH Lithium battery bank. Finally, I do have plenty of other places on the boat I could put panels, but I am keen to see if I can avoid putting panels anywhere they might get in the way, such as the old pair currently ont he cabin roof.)

I need to replace my current regulator, no matter which I choose, but I will need a MMPT reg for the 215s, whereas I would only need a PWM for the pair of 140s.

The cost for the panels are practically the same, so economically, its a no brainer when it comes to the panels themselves. The cost of the regs are very different, of course, but ASIDE from the extra cost of the MMPT regulator, are there other concerns I should factor in to the equation?

I have read of interference from the MMPT regs with SSB radio, but I don't have one of those any more, all we have at the moment is VHF and AM.

Thoughts or cautions on the above...?

Matt
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Old 03-02-2014, 00:02   #2
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Re: Solar choices

I got two 80 watts going to replace with 245 watts my MPPT can handle both go big

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Old 03-02-2014, 00:37   #3
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Re: Solar choices

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Originally Posted by GILow View Post

Thoughts or cautions on the above...?

Matt
I would go for the 215w panels. More power is always useful. Your batteries will last longer and/or you can get away with fewer AHrs. The 280w of the smaller option is not a great amount of power even if you are light on consumption especially over winter (in South Australia)


There is not much difference in price between good MPPT controllers and non MPPT controller. (There is at the cheap end) For lithium batteries you will need controller which is very adjustable which means a good quality one.
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Old 03-02-2014, 01:29   #4
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Solar choices

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I would go for the 215w panels. More power is always useful. Your batteries will last longer and/or you can get away with fewer AHrs. The 280w of the smaller option is not a great amount of power even if you are light on consumption especially over winter (in South Australia)


There is not much difference in price between good MPPT controllers and non MPPT controller. (There is at the cheap end) For lithium batteries you will need controller which is very adjustable which means a good quality one.

Good points. Is there a mppt controller you would choose for this sort of application?

Matt
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Old 03-02-2014, 06:25   #5
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Re: Solar choices

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Good points. Is there a mppt controller you would choose for this sort of application?

Matt
Unfortunately at this level you are just getting out of the level of the Rogue and the new Midnite Kid.

The best controllers for this size are the Outback 60 and the larger Midnite range. The Midnite series has easily adjustable firmware which is a bonus when the ideal parameters for charging lithium are still debatable. The outback is still very adjustable and has a longer track record. They are both very good.
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Old 03-02-2014, 12:15   #6
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Re: Solar choices

That is two 245 watt pannels for total of 490 watt Canadian solar panels are what I looking at

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Old 03-02-2014, 14:37   #7
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Re: Solar choices

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Originally Posted by noelex 77 View Post
Unfortunately at this level you are just getting out of the level of the Rogue and the new Midnite Kid.

The best controllers for this size are the Outback 60 and the larger Midnite range. The Midnite series has easily adjustable firmware which is a bonus when the ideal parameters for charging lithium are still debatable. The outback is still very adjustable and has a longer track record. They are both very good.
Thanks Noelex77, I did not know about the adjustable firmware on the Midnite series, that's a bit of a deal maker for me for the very reason you mention about the relative unknowns of Lithium. And I was planning to buy something with capacity expand the system if I need to, which the Midnite Classics certainly do.

Matt

P.S. Typical... the controller will cost more than the panels. Sigh.
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Old 03-02-2014, 15:01   #8
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Re: Solar choices

Quote:
Originally Posted by GILow View Post
Hello Cruisers,

I am tossing up between two solar options, after getting good prices on both the Kyocera 140W 12V panels and the 215W 18V panels.

In summary, I can fit a pair of panels up on our davits, and according to my calculations, a pair of 140W panels would be adequate, whereas a pair of 215W panels would be a bit generous in their power production. (We have light power consumption with the backup of an Aerogen 6, plus we have shore power and are unlikely to do much more than week long hops for the foreseeable future. Adelaide is VERY sunny pretty well all year round, the davits are rarely shaded. I plan on a 300AH - 400AH Lithium battery bank. Finally, I do have plenty of other places on the boat I could put panels, but I am keen to see if I can avoid putting panels anywhere they might get in the way, such as the old pair currently ont he cabin roof.)

I need to replace my current regulator, no matter which I choose, but I will need a MMPT reg for the 215s, whereas I would only need a PWM for the pair of 140s.

The cost for the panels are practically the same, so economically, its a no brainer when it comes to the panels themselves. The cost of the regs are very different, of course, but ASIDE from the extra cost of the MMPT regulator, are there other concerns I should factor in to the equation?

I have read of interference from the MMPT regs with SSB radio, but I don't have one of those any more, all we have at the moment is VHF and AM.

Thoughts or cautions on the above...?

Matt
Dear Matt.
I am in the middle of a solar project on my cat, and have been checking many specialists around.
Important issues in Norway where I am based is that the panels can be tilted in all directions, and that more unstable weather makes polychrystalline panels more efficient. I have ordered a pole mount system from the US, and I am about to order a Solara 140 W panel for it.

First I am not sure that you are comparing apples with Apples. The Kyocera panel may be 12 Volts nominal voltage, but I am sure it has some 17-19 volts output.
And I do not understand why you do not want an MPPT Controller for the larger panels.
I have been strongly adviced to use one Genasun GC 10 MPPT Controller for each panel (Max 140 W panel). Thus you will always have a back up if one system is out of function or shaded. And we all know things break down on a boat....
I would like to have your's and other' views on this
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Old 03-02-2014, 15:13   #9
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Re: Solar choices

Interesting ideas here. But I am not against mppt controllers, just comparing options. I accept that the 215 panels need the mppt controller but I believe that the 140 panels only need pwm.

Tilting panels at our latitude would be of less benefit than your latitude and monos lean so much I believe there is even less benefit still. Also I am trying to keep things simple. (At home I do track the sun actively with my 2kw array of kaneka panels and get a good 20% more power as a result)

Very good point about multiple controllers for redundancy. I will certainly give that idea some serious thought. Thank you for the suggestion.

Matt
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Old 03-02-2014, 15:37   #10
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Re: Solar choices

Dear Matt,
Just wish to add that the smaller size and cost of the Genasun combined with the fact that it is sized for one panel , could justify the use of multiple MPPTs.
I am going to make space for three on the board in the engine room, even if I am starting off with one.
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Old 03-02-2014, 15:45   #11
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Re: Solar choices

I thought most of the benefit of MPPT was when used with more than one panel? Anyone confirm.
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Old 03-02-2014, 15:47   #12
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Re: Solar choices

Also a 20 volt panel can be shaded in an emergency to deliver lower voltage and charge without a controller.
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Old 03-02-2014, 15:54   #13
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Re: Solar choices

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I thought most of the benefit of MPPT was when used with more than one panel? Anyone confirm.
No the benefits of MPPT are for converting the excess voltage so the principal is the same for a single panel.
The gain can be more for a single panel because there is only one Vmp.

Against this MPPT circuitry requires a reasonable amount of self consumption (to track well) so it is not optimum for a small single panel.

There can be some extra gains in reducing wire losses when wiring multiple panels in series, but this is not applicable to marine systems.
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Old 03-02-2014, 16:22   #14
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Re: Solar choices

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I thought most of the benefit of MPPT was when used with more than one panel? Anyone confirm.
What Noelex said +1 and a little more.

Solar panels (in our application) should really be rated by current rather than power. The current changes very little with voltage. So, the 140W panel is rated at 17.7V and 7.91A. If you run it at 13.6V (on a PWM controller or unregulated) it will produce about 8A (the current does go up a little). You end up with a 109W panel because you are not running it at optimum voltage.

The 215W panels are rated at 26.6V and 8.09A. You could easily still run these at 13.6V, although you would only go up to about 8.5A, losing 100W in the process.

The MPPT controller can allow even a single panel to run at its optimum voltage, and rather than just losing the power the DC-DC converter in the MPPT controller can increase the current while dropping the voltage, maintaining the total power output (with mid- to high-90s efficiency). All of the example maths above use rated conditions, real-world conditions are far different and so the gains of MPPT won't be nearly so dramatic, especially after factoring in the energy costs as mentioned by Noelex.
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Old 03-02-2014, 16:29   #15
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Re: Solar choices

Our 14 year old Kyocera 125 watt panels produce 19.3 V into an open circuit so the 12V nominal rating is very misleading and confusing.

Each panel produced 8.0 amps at 14.4V with the sun directly overhead at 22 degrees North and the system has worked flawlessly since June 2000.

Our 20 year old Trace C-40 controller has no problem modulating the power and voltage with our four panels into 625 amp hours of battery capacity (6xT105)

More power is better.
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