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groingo
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# Posted: 12 May 2014 10:41pm
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The setup was supposdd to be 3 250 watt Sharp 250 panels, 1 Tri Star mppt 60 controller, connector cable but then the said I would need this as well.
1 Combiner box for 3 150 VDC or 600 VDC breaker
2 Din rail 150 VDC breaker
1 Din rail 150 VDC breaker
1 Big baby box enclosure 1-4 Din Breakers
1 Short terminal bus bar for Big Baby box enclosure
Is this legit?
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suburbancowboy
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# Posted: 13 May 2014 12:19am
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This is pretty much the same system I have at my cabin. You will need more than this though. Cables, batteries, invertor, grounding rods, etc. mtndon did a similar system and he has a very good schematic floating out on the web some where. I used it when I designed my system. Take the extra time and money to do it right.
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MtnDon
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# Posted: 13 May 2014 09:51am - Edited by: MtnDon
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Quoting: groingo Is this legit?
Pretty much. Not to mention a lightning arrestor at the PV panels and combiner box.
With a 100 foot distance from PV and combiner to the balance of the system it is also helpful to have a disconnect / DC breaker at both the combiner and the wire where it connects to the CC. And one from the CC to the batteries.
I can locate the link to the schematic later when I have time if wanted. I do believe it is listed here someplace. It does not include the type T fuse at the batteries as it should (error of omission)
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MtnDon
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# Posted: 13 May 2014 10:33am - Edited by: MtnDon
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Quoting: groingo 3 250 watt Sharp 250 panels, 1 Tri Star mppt 60 controller,
Are you still planning on series connections for the panels to keep the wire size minimized?
I believe three of those panels in series are too high a voltage for the Tristar. And if you are planning on a 12 VDC battery system you are close to the wattage limit for 12 volts.
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groingo
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# Posted: 13 May 2014 10:54am
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At this time I'm going to re-evaluate the whole solar thing, I have one money pit I'm getting out of don't want to jump into another and this one just keeps getting bigger.
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MtnDon
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# Posted: 13 May 2014 01:28pm - Edited by: MtnDon
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If the folks that recommended 3 of those panels in series did not do the voltage calcs you should find someone else to talk with, IMO. That combination should never have even been priced out for you, if you asked for them as a system, or especially if it was their recommendation.
If you want we can go through it here..... Good solar, meaning dependable solar that will run safely with no glitches takes lots of planning and will probably cost more than you think when it is all totaled up.
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groingo
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# Posted: 14 May 2014 11:25am
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Don:
Mis information seems to be the norm these days, at this point I'm going to do a complete re think on the solar, that is why I keep coming back here to get confirmation because many here actually use the stuff, these phone jockies are only interested in the bottom line.
Am moving on to plan B, soon as I figure that out I will let you all know.
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MtnDon
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# Posted: 14 May 2014 01:24pm
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FWIW, thesolarbiz.com iand backwoodssolar.com have in my experience always had knowledgeable people and are honest. Prices may be a little higher than the bargain basement folks who have less knowledge. Affordable-solar.com has also been good IMO. And for small but necessary stuff solarseller.com is reliable and honest.
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creeky
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# Posted: 14 May 2014 02:05pm
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hey groingo hang in there.
it's all the little things that surprise you. and make it seem more difficult than it really is.
You need to combine your panels. You can do that with the mc4 connectors (they sell two into one connectors. I don't know about three into 1). Then send the combined power to a panel that lets you disconnect your panels from the charge controller.
So a combiner box with breakers. As you're combining at the panels you only need one 150v 15 amp breaker. Make your own box (search online) or buy one. Up to you.
What is the exact panel? Is it a 24 volt (so actually around 37) or a 48 volt. If they are 48v: running three panels together will be too high as they'll run at 60v each during cold weather. So 180v. The controllers in this category handle 150v. So you're a little high. Check with Morningstar though to be sure. You might be okay. I forget the leeway they allow for.
If your panels (and I think the ones you were looking at) are 24v panels, but actually 35v or so. Then 3 times 40v = 120v and you're fine stringing those panels together with that controller.
The morningstar has built in lightening protection. and internet monitoring. a nice feature.
If you look around I wrote out a simple wire scheme. Basically it's wire from panels to the combiner. From the combiner go to the charge controller. From the charge controller go to the DC switch. From the switch go to the batteries.
On the inverter side. From the batteries go to the fuse on the red/hot line. Then both lines continue to the inverter. From the inverter go to the panel box. From the panel go to your plugs etc.
You can use the same bus bars from the batteries to the inverter and charge controller.
There's a site sometimes referred to as naws. they have some real pros there and a good starter section.
I mean if I can figure it out. Make my own wires. etc. And run the system for three years (going on 4). Anybody can. I have a few pics on my "build" post. Don't know if they'll help.
PS-For the DC switch I used an old DC motor switch. Don't know if you have a recycle/used industrial equipment place nearby but it might be worth looking into. My switch cost 20 bucks.
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MtnDon
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# Posted: 14 May 2014 02:09pm - Edited by: MtnDon
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Quoting: creeky If your panels (and I think the ones you were looking at) are 24v panels, but actually 35v or so. Then 3 times 40v = 120v and you're fine stringing those panels together with that controller.
Not when you factor in the cold weather spike (Best to use a multiplier of 1.25 for safety sake) plus the NEC required 25% safety margin on top of that. That is 1.25 x 1.25 for a total of a multiplier of 1.56) I mentioned that above and it is important; more important where the winters get cold. 120 Voc x 1.25 x 1.25 = 187.5 volts. If you know the lowest likely temperature that can be fine tuned using calculators available online from the major MPPT manufacturers. Mild climates don't have as much of a concern as do those where the temperatures may drop to -20 or lower.
Excellent article on that: http://www.midnitesolar.com/pdfs/whyHyperVOC.pdf some specifics about Midnite Solar products, but very useful to know when looking at MPPT charge controllers and running panels in series.
Another Reference: http://www.homepower.com/articles/solar-electricity/equipment-products/2012-charge-co ntroller-buyers-guide
quote: "Be careful when sizing series strings of PV modules that feed an MPPT controller. The "maximum open-circuit voltage" listed in the comparison table is just that—if you exceed this voltage, the controller can be permanently damaged. Remember that PV modules produce higher voltages in cold weather, so an array of three 45 V modules in series for 135 V might be just fine during the summer for an MPPT controller with a 150 V maximum rating—but could damage the controller when it is cold and sunny."
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MtnDon
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# Posted: 14 May 2014 02:42pm
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And an article by John Wiles, whom I consider to be the leading expert in the field of PV system design.
http://www.nmsu.edu/~tdi/pdf-resources/cc101.pdf
That's a 10 year old article but everything is still valid except for maybe references made to some of the NEC code sections. The basic cold weather, hot weather, high altitude performance information is science and that has not changed.
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creeky
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# Posted: 14 May 2014 03:09pm
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My panels are 57 open voltage. The highest voltage I've seen is 64. That's at -30.
Tho that hyperVOC article is interesting.
Still, it's all so much air unless we know the actual max voltage of the panels.
Groingo, you may be better off with two panels in series. And then use the cash from the third to buy combiner boxes etc.
When you get more cash or see a need for more power. Just add two more panels in parallel. that way you keep the voltage but double the amps.
Or go three panels in series for the summer and unplug one of the panels during cold weather to protect your charge controller.
Any body have thoughts on two panels in parallel hooked in series to the third panel?
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groingo
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# Posted: 14 May 2014 04:38pm - Edited by: groingo
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My situation is I live in a low sun exposure area so I would have to overbuild to compensate and or reduce energy consumption.
I looked at the 750 watts because it would be much more than I would need in the worst of times, 500 would have gotten the job done but not allowed much room for error.
Of course, everyone has run the gauntlet of getting "correct information" and the hidden complexities can be not only annoying but very expensive.
So for now I am back to square one and re-evaluating the whole thing and particularly cooling off.
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MtnDon
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# Posted: 14 May 2014 05:03pm - Edited by: MtnDon
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The Voc of our three panels is 108.3 volts. The CC has recorded 141 volts several times. Winter, not sure what the temperature was. That voltage is less than the theoretical math rule max, and it does calculate out as being a safe installation when the Outback or Midnite system sizer calcs are used with the average lowest temperatures for our area. We don't drop as low as many places further north do.
It's interesting that our altitude gives us an amperage boost that can be seen frequently on the recorded data.
Quoting: creeky Or go three panels in series for the summer and unplug one of the panels during cold weather to protect your charge controller. Any body have thoughts on two panels in parallel hooked in series to the third panel?
There is a device that tracks the temperature and when it falls below the preset the panel at the end of the series chain is dropped from the array. It reconnects when the temperature hits the preset high. I forget its name right now. It's a couple hundred bucks IIRC.
I believe two in series with a single third in parallel is not workable. The voltages are so different... I have no real idea what will happen for certain, but considering the rule of thumb when panels are to be placed in parallel with another(s) is that they should have their voltages within 10%, something will be "off".
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MtnDon
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# Posted: 14 May 2014 05:16pm
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Determining the wattage needed to make a usable system is only half the battle. Finding a panel combination that works with a CC is another battle and complicated in both my situation and groingo's by the distance from panels to the balance of the system. If the distance was typically short it would be a simpler matter; use parallel connections.
Can you find any smaller wattage panels and connect 4 in a series - parallel array?
Midnite makes some CC with 200 and 250 volt maximums.
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creeky
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# Posted: 15 May 2014 08:50am
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To my mind none of this is a "battle and complicated."
To anyone thinking about an offgrid solar system. It's easy. It's not magically easy, there are a few steps involved. Same as buying a car, or researching a new fridge. But solar has been around for quite awhile and there are plenty of resources available.
Mtn Don and I are probably in agreement, just take your time and draw a schematic of your system. They really are very basic.
Groingo. I missed your setup details. Where did you post them? How far from the batteries are you putting your panels? I kept my batteries close to my panels and then put the inverted power (AC) lines to the studio and washroom. I used 10 and 12 gauge underground rated wire. Cost 100 bucks. I ran my lines over 200 feet. But I have a backhoe for trenching.
For my second set of panels (500 currently ;) installed) I'm going to 96 volts DC and running 10 g wire 50 feet to the combiner box and 2nd controller. I didn't get as good a deal on the wire. I think it was 60 bucks.
Mtn Don. I have a 150v breaker at the combiner box. Will that trip if my voltage goes over 150v or do I need to turn off two panels when it gets cold (I have each pair of panels in parallel and then the combined panels in series)?
Also. For the morningstar. Those CCs will "reliably" limit charging power from your panels. They have a great article at their website on the benefits of using too many panels.
And the advantages are many as I've stated many times. Esp. in the low light times of year. But I am using my system year round.
Just a note: my dishwasher has washed three loads of dishes this week and I did two loads of laundry yesterday. All for free. Batteries were charged and the power for the devices came direct from the sun. One load of dishes uses 700 watts and the laundry uses 100 watts per load.
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MtnDon
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# Posted: 15 May 2014 02:18pm - Edited by: MtnDon
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Quoting: creeky Mtn Don and I are probably in agreement, just take your time and draw a schematic of your system. They really are very basic.
I draw everything I make or plan. It helps me to not forget things. If the battery bank size is already known, including the voltage, next is how many watts of PV panels are needed. I am assuming you are reusing a previous inverter?
After the desired watts are known then looking for panels and a CC to go with them. As I said before the 100 foot distance can be a bit of a handicap in trying to find panels that will work in series w/o over volting on a cold winter morning.
After the major components the breakers, lightning protection, etc.
Quoting: creeky Mtn Don. I have a 150v breaker at the combiner box. Will that trip if my voltage goes over 150v
If the voltage goes higher than the rating for the breaker the breaker may not be able to protect the circuit properly. If it does trip the excess voltage may cause more arcing inside the breaker than it was designed to handle.
When selecting DC breakers the possible surge voltage from cold weather must be taken into account as well. So that same calculation that should be done for checking on a CC should be followed for the DC breakers as well. Voc x 1.25 x 1.25 according to the NEC.
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MtnDon
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# Posted: 15 May 2014 02:19pm
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Quoting: creeky I didn't get as good a deal on the wire.
...wire pricing follows the commodity markets.
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creeky
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# Posted: 16 May 2014 08:50am
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In my case I found the first batch of wire on kijiji. Odd bits from an electrician cleaning up after a big job. The second batch came from the electrical supply. So paid retail. 
All part of the fun. The kijiji score saved another 100 bucks.
Hey Groingo... how goes your plan?
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groingo
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# Posted: 16 May 2014 01:22pm - Edited by: groingo
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If I do choose to go solar it won't be with Sharp panels, just got an email back from them that they shut down production in the US in March and no longer sell, supply or support their solar panels....that sucks.
As for plan B, I am still looking and studying alternatives but solar has been put on the back burner for now and further energy reduction from 0.50 Kwh a day to half that is the target.
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creeky
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# Posted: 16 May 2014 02:25pm
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Keep an eye on craigslist etc I think Yakuza in your area?
Bargains are there to be had. I watched kijiji, the canadian version of craigslist and got my panels for about 1/3 off. even less when you compare to retail. i saved a tonne on wiring. from free to very cheap.
like you it was the bus bars and the combiner box and the $100 dollar fuse that surprised me. Prices have come way down since I bought my system tho.
In the summer .5 kw a day is a 250 watt panel (will actually generate more like 2 kw on a clear sunny day), an el cheapo mppt controller and an inverter (most cheap inverters have built in fuses). You already have the batteries.
Your disconnects can be a manual "unplug". Fire extinguisher at hand. (kidding)
Remember that, offgrid, you can bypass some of the "NEC" well meaning hot air for a system that works and is completely safe. Sometimes the number of angels that can dance on the head of a pin is just that. Flights of fantasy.
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