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Old 16-04-2014, 23:34   #151
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Re: Solar Choices

Great info going here.

Jedi pretty much has me convinced that wiring in series is a good way to go, especially with an MPPT controller. So as I understand it, partial shading of the long axis results in lower voltage, but since it's way above 12v, the power continues into the batteries albeit at a lower rate. Right?

I am adding PV to my system. I have been running a Fourwinds Gen. for some years and it works pretty well most of the time, but I want solar to top off the batteries and supplement the charge system.

I am adding 2x85 watt panels to a 12v system. Vop is 22 and amps are 4.92 ea. I would like to control both the wind and PV's via MPPT (I think). The current controller is a flex controller (the kind that shuts off power when the batteries get to a certain level: about 14.5v or so) and I find it takes so long for the 880 Ah battery bank to come down to the restart voltage, that it's off more than it's on. As I understand it, an MPPT controller will modulate the power to allow higher rates of charge with the lower voltage associated with the absorption phase. Does that sound right? The current wind system uses a dump circuit with massive mercury switches to switch the power to a hot water heater. The wind controller has an PV input but if I hook up the new panels to it, I just get more of the same, more power going into the hot water heater, and batteries almost never get topped off

I'm concerned that the current wind system will interfere with the MPPT controller for just the PV and goof the whole works up. An integrated system would be preferable. Does anyone know of a good controller that can handle wind and solar and includes MPPT, without breaking the bank?

thanks

Buzz
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Old 17-04-2014, 01:16   #152
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Your wind generator needs a shunt type controller to keep a load on it. I have an MPPT controller and love it. But with only two panels and an existing controller I don't think it would be worth the extra money. you would be better off just buying another solar panel
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Old 17-04-2014, 07:57   #153
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Members with more technical knowledge please correct me if I'm wrong.

The way a three stage voltage regulator works

1) bulk. Allows maximum amperage until a set voltage is reached

2) absorption. Once this voltage is reached amperage is tapered off holding batteries at this voltage for a set amount of time

3) float. After the absorption cycle, amperage is cut off until float voltage is reached. Some regulators will hold the batteries at this voltage others will cycle between the float voltage and the charging voltage
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Old 17-04-2014, 12:49   #154
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Re: Solar Choices

Yes, you have it. The last sentence is a bit unclear - let me say it another way. Most regulators will control the current to maintain the float voltage, others will repeat the bulk/absorption steps occasionally (once a week to once a month typically). Just holding the batteries at float while they are being used (e.g. at the dock) will allow the charge level to drift down over time, and repeating the charge process tops them back up.

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Old 17-04-2014, 12:57   #155
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Re: Solar Choices

This is a long thread so my apologies if this has been covered. Make sure you have the correct size marine grade wiring. We had to use 10 AWG wire, which is larger than some might think, but is necessary when you take in to consideration the amp current and the length of our wire runs to the regulator and then to the fuse block by the batteries. You should also use heat shrink on all your terminals if possible. Everything is exposed out there and you will have long wire runs. And make sure your leads to the batteries are fused properly - as close to the batteries as possible. We used the small automotive style blade ones. They are handy when you want to work on the solar wiring between the regulator and the batteries. You can just turn off the regulator to work from it to the panels (if that is a feature - it should be).

Of course shading is a major issue but so is the angle of the sun to the panels. I am sure this is a "duh" piece of advice - no offense intended. BTW - we did have interference issues with our SSB and had to shut off the regulator when we used the radio. You might try using "chokes" on the solar wiring. These are often required on the power wiring and equipment interconnections for radios. They are cheap and easy to put on. It may not solve the problem 100% but it should help.
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Old 17-04-2014, 16:03   #156
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Re: Solar Choices

Quote:
Originally Posted by sparrowhawk1 View Post
Your wind generator needs a shunt type controller to keep a load on it. I have an MPPT controller and love it. But with only two panels and an existing controller I don't think it would be worth the extra money. you would be better off just buying another solar panel

Thanks for the suggestion: No room for another solar panel. So, i would like to extract all the energy I can from what I have. I have a shunt type controller that uses a "flexcharge" regulator. It is very ineffecient once the batteries come up to absorption. It's what happens after that, that makes MPPT attractive to me. (That and also the increased rate of charge in Bulk of course)
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Old 17-04-2014, 16:21   #157
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Re: Solar Choices

Quote:
Originally Posted by sparrowhawk1 View Post
Your wind generator needs a shunt type controller to keep a load on it. I have an MPPT controller and love it. But with only two panels and an existing controller I don't think it would be worth the extra money. you would be better off just buying another solar panel
Quote:
Originally Posted by sparrowhawk1 View Post
Members with more technical knowledge please correct me if I'm wrong.

The way a three stage voltage regulator works

1) bulk. Allows maximum amperage until a set voltage is reached

2) absorption. Once this voltage is reached amperage is tapered off holding batteries at this voltage for a set amount of time

3) float. After the absorption cycle, amperage is cut off until float voltage is reached. Some regulators will hold the batteries at this voltage others will cycle between the float voltage and the charging voltage

Yes, and that's the problem with these cheap so called regulators like my flexcharge ( I think that's what it's called). they don't really regulate, they turn the power on or off.

1. 1st Stage: Bulk They connect to the batteries full power until the batteries come up to 14.5 volts.
2. 2nd Stage: "Absorption". They disconnect the power to the batteries until the resting voltage drops to somewhere around 13.5v then they turn on until the batteries are back up to 14.5v. This cycle repeats.
3. There is no 3rd stage. See number 2.

It appears that the MPPT controllers would help with the output of the wind gen because the V/I curve is non-linear? I think it was Dave who pointed that out in another thread. But what wind gens need apparently is to shunt the power at disconnect to some load to prevent incineration or overspeed. At lease that is conventional wisdom. It seems to me that a MPPT or PWM controller would not require a shunt because it never disconnects the generator from the batteries. Excess power is sent to the mosfet transistors for conversion to heat? Right experts? So that leaves overspeed when the power to the batteries is insufficient to slow the generator down. I have a centrifugal governor on the generator that prevents overspeed. It works very well so maybe I don't really need a shunt controller? I would hate to spend the money for a MPPT controller and have it burn up. Although I could get a cheap chinese controller to see if it works Ok.
My main concern and question relates to how 2 MPPT controllers will interact with each other as the PV's are relatively constant output versus the wind gen that varies it's output alot over short time window. The PV controller will see these varying voltages on the battery side and be constantly hunting for the right V/I power point?
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Old 17-04-2014, 17:03   #158
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I'm surprised the experts haven't chimed in. not that it really matters what you call it but your two stage regulator is bulk and float. floating between 13 5 and 14 5 its kinda high in my opinion and I would think the problem wouldn't be keeping the battery topped up electrically but keeping them topped up with water. Both MPPT and PWM regulators work by connecting and disconnecting the battery which I think would be bad for your wind generator.
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Old 17-04-2014, 18:24   #159
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Re: Solar Choices

MPPT is an obsolete technology at 1$/Watt solar panels it was even at 5$/Watt but it was a great idea when solar PV where over 10$/Watt not that long ago.
I'm not going to explain how it works since is obsolete but if you want I can do that.
I live offgrid and use 3x 240W panels (60 cells) work great with 24V LiFePO4 battery 8 cell x 100Ah
My usage is around 60 to 90kWh/month most of that during the day for cooking.
I also have a small 300W wind turbine that helps in cloudy days is quite windy here.
I designed my own Solar BMS charge controller probably the first ever. I did not see anything like that up to now.
It was designed almost as a replacement for existing 12V and 24V Lead Acid charge controller.
It has an graphic LCD to display individual cell voltage, charge and discharge current, SOC and much more. Is also fully programmable so it can work with any type of Lithium battery (for energy storage I recommend LiFePO4 it has the best price over the life of the battery).
I now on Kickstarter so you can see much more details there or on my youtube channel if you search for Solar BMS.
Charge is 40A and discharge 80A so 1000W charging ad 2000W discharging with 8 cells or half this power with 4 cells.
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Old 17-04-2014, 21:56   #160
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Re: Solar Choices

I followed the link and found this:


From my experience, he's exactly right.
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Old 08-05-2014, 08:13   #161
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Re: Solar Choices

I have several questions based on the installation and hope someone would answer them. I tend to like to have a plan and full understanding of what is going to happen before I spend a dime so please bare with me.

I haven't fiscally looked at any of the pieces but here is what I hope to install on the davits of my Catamaran.
2-240W panels, moncrystalline by Kyocera. Probably 24V
I also like the Solarworld SW 255 but am concerned about them going into bankruptcy. They seem to be very strong and have a high rate of efficiency. Comments or concerns on these would be appreciated.

MPPT Controllers:
My first choice is the Morningstar TriStar 45. Unlike the Outback it has a remote display. I also see it doesn't have a fan and conformal coated.

Installation:
I plan on running them in series to a fused junction box 10 feet away then to the MPPT another 6 feet away. The batteries will be within 3 feet of the MPPT unit.

Installation questions:
I see that most solar panels have a Jbox at each panel. There are (2)whip wires I believe have an MC4 connector at the ends. So you plug the first panel to the next one in the solar Jbox correct?
Now at the last one (the one that is going to the fused Jbox) can't use the MC4 connector. Is there normally a terminal strip within the Solar Panel Jbox to convert to standard marine wire?
If there was a "power out" MC4 wire is this just removed from terminals at the SP jbox?

I plan on running the wires inside the davits and assume it's just 3 (probably a minimum of #10) a hot, neutral and ground. If I wanted to convert these to parallel in the future would I need to run 4 wires (2 hots) back to the fused Jbox in the davits? separate grounds or neutrals wouldn't be necessary correct?
I may run an extra wire "just in case" anyway.
Also I assume for a parallel arrangement that the panels are wired only separately to the fuse jbox? after the Jbox they can run to the MPPT controller on the same wires?

Honestly I have searched many sites and the installation instructions are hard to find and no straight info available unless someone can point me in the right direction.

Any and all help on this is appreciated!

Steve in Solomons MD
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Old 10-05-2014, 18:58   #162
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Re: Solar Choices

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