My 12v Solar Panel Plan.. I would like feedback..

ywhic

Heres what I came up with after 2 months of crunching numbers..

For starters on my OFF GRID Cabin in TX..

MorningStar Pro 30 Charge Controller (30 amp) $129 (1ma draw)
Xantrex Pro SW1000 Sine Inverter $246 (0.6 amp draw when not in use)
NAPA 8144 6v Deep Cycle Batteries 186ah each (to be parralled) x 2 @ $136 each.. $272
MC4 wire 10 ga std.. run is going to be about 15' in length.. (I may parallel the 1st two.. with the adaptors)

6ga wire from charge controller to battery bank (terminal limit on the MS Charge Controller) no more than 3-4 feet

then 4 gauge wire from battery to inverter no more than 2 feet. I plan on getting the + terminal from the battery to the inverter in about 1 - 1 1/2 foot (gotta have that breaker)

ICB 150 amp breaker from battery to inverter (per the Xantrex directions).. ICB 40 amp breaker from the solar panels to the controller.. ICB 60 amp breaker from the charge controller to the battery..

Starting with 2 panels in 100-140 watt range.. (this will come down to WHEN I do the install and availabilty)

Either:

2 of the Solar Blvd Solar Cynergy 100 watt panels 17.2 v and 5.81 amp (max) @ $139 each (and ughh shipping)

or

2 of the Grape Solar 100 watt panels 18.5 v and 5.4 amp (max) @ $199 each (local dealer)

if the 120 or 140 v panels are in stock at that time I will jump on them..

I plan on running 2 fans, 2-3 7 watt CEL/CFL bulbs and my laptop..

I also got the suns angle for spring/summer/winter which is 60 deg /84 deg /36 deg for my hemisphere location.

My water pump is going to be a Shurflo 12v unit (2088 model) that says max of 7 amps.. (which would be used intermittant at most during the night for 10 minute shower and such).. this will be direct wire off the 12v battery system.

Going to grab a 2-3000 Watt Generator for back up plans in case I need to run anything larger.. (like an A/C intermittant during the day)..

So does this sound like a viable start plan??

Cariboocoot

Re: My 12v Solar Panel Plan.. I would like feedback..

NAPA 8144 6v Deep Cycle Batteries 186ah each (to be parralled) x 2 @ $136 each.. $272

Whoops. You mean in series, not parallel. You need two 6 Volt batteries in series to get 186 Amp hours @ 12 Volts.

With that much battery, a 30 Amp charge controller is oversized (unless you plan future expansion). It only needs 20 Amp (like SunSaver20) to handle the 18 Amps required for charging. Which would be (18 * 12 = 216 / 0.77) 280 Watt array.

Your two panel proposals have about 10 Amps peak current each, which is just barely 5% for that battery bank. If you go with the smaller controller and save $40 will that help buy more panel? You're just a little shy there I'd say.

Those batteries would supply about 950 Watt hours AC at the most. 475 @ 25% DOD, which is going to require more than 200 Watts of panel to replace.

You're nearly there, though.

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

Cariboocoot wrote: »

Whoops. You mean in series, not parallel. You need two 6 Volt batteries in series to get 186 Amp hours @ 12 Volts.

With that much battery, a 30 Amp charge controller is oversized (unless you plan future expansion). It only needs 20 Amp (like SunSaver20) to handle the 18 Amps required for charging. Which would be (18 * 12 = 216 / 0.77) 280 Watt array.

Your two panel proposals have about 10 Amps peak current each, which is just barely 5% for that battery bank. If you go with the smaller controller and save $40 will that help buy more panel? You're just a little shy there I'd say.

Those batteries would supply about 950 Watt hours AC at the most. 475 @ 25% DOD, which is going to require more than 200 Watts of panel to replace.

You're nearly there, though.

Yes..

I meant series on the battery.. yes, I plan on adding probably 1 more panel from the get go.. (pending on funds).. and max of 4 panels for this setup IF using the 100 watt panels at 5.4 Amp (max per the spec sheet) each (using the Grape ones).. Thats why i decided on the 30 amp charge controller (little bit of room to grow)..

I'll be adding 2 more of the same 6v batteries in series then combine the 2 pairs into a single large 12v bank down the line..

Do you think 1 more panel (from the gate) and leaving the battery bank at just 2 of the 6v 185 ah batteries would be sufficient for what I listed as usage...??? (couple of 20" box fans and some low wattage bulbs)

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

I did (in my searching last month) find some 140 watt 12v panels for $299 each.. (free shipping)

There rated at 18.4 v and 7.65 amps each...

Would 2 of them (140 watt panels) vs. 3 of the 100 watt panels be better for a start??

You get 16.2 amps from the 3 100 watt panels or 15.3 amps with 2 of the 140 watt panels.. both setups fall into about 8-9% recharge for the 185ah battery bank.. (if I did the math correctly).. which is closer to the magical 10% that Trojan says to have..

Both ways its work out to be a $600 expense...

Whats you thought on that??

Cariboocoot

Re: My 12v Solar Panel Plan.. I would like feedback..

One more of either panel puts you at 300 Watts, which will make that much battery very happy.

Will it be enough to suit your needs? It's all a matter of how long you leave how much on. During the day you will probably have power to spare (batteries full; panels capable of supplying more Watt hours). But at night with lights and fan you'll be draining from batteries only.

You can use the ProStar's LVD on the load terminals to trigger a relay to shut off "optional" loads and warn you you are running out of power (although the Voltage point is fixed and is at the "terror" level by my standards). Do not run the inverter from the LOAD terminals.

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

Cariboocoot wrote: »

Do not run the inverter from the LOAD terminals.

Thats what MS told me when I called them last month.. I asked them whats the point of having the METER on the front if its only for the load terminals... LoL..

I opting to save the $45 and not have the load meter at this time on the MS Pro 30 model I'll be ordering up soon..

Then the Xantrex Pro SW1000 Inverter will be next.. then the wiring,breaker, connector mess.. then the panels last..

So 300 watts of panel (or so) should be my initial goal for the 185ah battery setup.. good to know..

Like I said just fans and laptop during the day.. I have 2 skylights (opposite sides) on the building for the daytime.. (see pic)



Does my wire Gauge and Breaker size I chose sound ok/correct for the loads?? (I know to keep all the leads short as I can)..

Cariboocoot

Re: My 12v Solar Panel Plan.. I would like feedback..

Wiring and fuses: the ultimate bugabear.

If you run three of those panels each will need a fuse on it to prevent two of them ganging up on the third if something goes wrong. 7.5 Amp auto fuses should work (someone will no doubt correct me on this).

It is not essential to have a fuse/breaker on the combined panels, but if you do it should be the same size as the output (because the current on a PWM controller is essentially the same going in as coming out).

10 AWG will be a bit small for three of those panels (15 Amps current) running 15'. Think you can get the distance down to 10'?

6 AWG will definitely work on the controller output. This will need 20 Amp fuse or breaker on it. If you up the panels and "max" the controller the wire is still good, but you will need to increase the circuit protection rating to 40 Amps.

A 1000 Watt inverter on 12 Volt will normally draw less than 100 Amps. Check the Xantrex recommendation on this. 4 AWG is slightly "iffy" here as it will be borderline at maximum current. I would use only a 100 Amp breaker on it and try not to max out the inverter's capacity.

Someone is bound to point out that the NEC rules call for fuses/breakers to be sized 1.25 times the expected maximum current and then rounded up to the nearest available size. But that's more of a maximum than an absolute; as long as the fuse goes first the wire stays safe. What's most important is to make sure the wire can handle the current and the fuse is "lighter" than the wire.

Photowhit

Re: My 12v Solar Panel Plan.. I would like feedback..

A few things,

Try, or at least check out the O2cool 10" fans, they put out a lot of air, run about $25 Some WalMart's carry them, and I think you can get free shipping to store and buy one on line, if your not happy I believe they take returns at the store (check all this as things change)

I have one running in the window now, I'm up to 5(maybe 6) of these now the new ones have a better wall wart that doen't heat up, I'm actually using an old one now, It's running on a 700 ma 12 volt wall wart or about 10 watts. I have it on low, but there is little difference in current draw, just a tad quieter. Large box fans can run many watts, I checked 20" box fan Lasko's at WallyWorld and someone says they draw 125 watts!!! My AC is less than 500 watts. I wouldn't try to run that on a small system, I have run 2 of the O2Cool's over night every night through the summer (in Missouri, in the shade) While I'm not a 'fan' of 12 volt equipment, this would run off 12 volt as well saving the inverter and wall wart ineffiecencies.

Something you may have heard little of, is load shifting, run your pump during the day and store your water at shower height, saves running the battery down.

I also remind people about now that for a long time it was rare to fuse solar panels, and you could just use a distribution block to bring them all together. Even some 3 panel setup don't require fuses though I can't recall the standard. As Coot (?) said you might use an auto fuse setup, some auto stereo fused distribution blocks.Use AGU fuses which are the same size as my combiner box.



I've had a similar setup, perhaps a tad more solar, but not much 4 - 55 watt panels 3 quite old and had batteries last 3-4 years. Ran the 2 O2cool fans and laptop, and 1-2 13 watt CF lamps, a Small tv from time to time, Video tape player from time to time, an mp3 player nightly <5 watts.

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

Thanks.. I bookmarked the OC2 fans at WM.. they do the site to store for free..

I redid my breaker setup (on paper)

30 amp breaker for inbound panels to controller with max of 13' leads from the panel.. (ok per the 10 AWG sheet online)..

I really don't want separate leads for each panel.. I was going to parallel no more than 2 per 1 wire pair coming down..

If I go with 2 more panels I will just duplicate the setup coming down and setup another 30 amp breaker to ride on that set..
(I'll premount another 30 amp breaker ($10) on the board for the proposed upgrade).. I may get one of those small distubution block to tie things up neater near the controller.. thanks.

All the panels I see for my budget have the MC4 connectors and this makes my choice of prewired wire set at 10 awg..

40 amp breaker for controller to the battery bank on the 6ga wire.
100 amp breaker (with screw terminals) from the battery to inverter.. I found some short 2 awg wire with ends at autozone..

Photowhit

Re: My 12v Solar Panel Plan.. I would like feedback..

Typically since you need the MC4 connectors at only one end you buy a wire 2x as long as you need and cut in half, 'By Code' I don't think that you can parallel one set and then add panels, I think you would want to fuse each panel for 3+, the idea being that if you have a short in one panel, the other 2 will over power a single unit. And here I often wonder, and what, catch the glass on fire, the aluminum, maybe the tedar will burn. Maybe the fine copper leads will melt, Ooops then no fire.

There is a possiblity, we've seen photos of homemade plastic/poly fronted panels that have burned to a crisp. Don't think I've ever seen glass panels that burned.

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

Photowhit wrote: »

Typically since you need the MC4 connectors at only one end you buy a wire 2x as long as you need and cut in half, 'By Code' I don't think that you can parallel one set and then add panels,

I was going to circuit breaker the 1st parallel set.. and yes a 30' cable 'cut in half' was the plan..

If I add a 2nd 'set' of 2 panels I would repeat and add another breaker for that individual set..

I decided the junction block idea is good for both the + and the - wiring. Like using the mini-box some places sell.. but alot cheaper.

Heres a doodle I did up.. 30 amp breakers on each pair of panels.. (though I can use 20 amp breakers and would be better served).

Cariboocoot

Re: My 12v Solar Panel Plan.. I would like feedback..

It doesn't matter where the connections are made: if more than two panels are connected in parallel all have to have circuit protection.

I think the OP is considering one array of three on one set of down leads and then adding a duplicate array later. In that case, each group of panels would have one fuse each and each down lead would have its own breaker.

If the arrays were just two panels each, when the second set is added each panel would still have to be fused individually; the circuit protection on the down leads would not protect against three of the panels causing a fire in the fourth should it become shorted.

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

Cariboocoot wrote: »

I think the OP is considering one array of three on one set of down leads and then adding a duplicate array later. In that case, each group of panels would have one fuse each and each down lead would have its own breaker.

One array of 2 panels on one set of down leads.. then duplicate later.. each down lead with a breaker..

niel

Re: My 12v Solar Panel Plan.. I would like feedback..

albert,
this just won't work as you have to have all pvs fused or breakered. picture from your drawing a short occuring in the first pv. immediately you could see the power from the 2nd pv going straight into the 1st one, which by itself would not harm anything. now the 3rd and 4th pvs are not going to trip the breaker going into the 1st and 2nd pvs so it will add to the power already being shorted too so this is ganging up on the 1st pv 3 to 1.

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

niel wrote: »

albert,
this just won't work as you have to have all pvs fused or breakered. picture from your drawing a short occuring in the first pv. immediately you could see the power from the 2nd pv going straight into the 1st one, which by itself would not harm anything. now the 3rd and 4th pvs are not going to trip the breaker going into the 1st and 2nd pvs so it will add to the power already being shorted too so this is ganging up on the 1st pv 3 to 1.

So I need a breaker/fuse on every line and 4 separate lines coming down to a fused junction block..??

Heres the pic showing 2 panels into a junction box with 15 amp breaker on each panel line, then off to a 30 amp breaker to the controller..

Why then do companies ALLOW and show (and sell) panels to be paralled??



It doesn't make sense.. each 15 amp wire coming down will have its own breaker.. would you suggest maybe a 20 amp FUSE on each leg coming down.. and wouldn't the SEPARATE fuse/breaker on the 2nd array protect from the 1st??

Why do soo many on here say 2 panels on 1 leg coming down is OK, and why do they sell the Y MC4 connectors and the Y MC4 cabling???

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

I guess this would work and just put in individual fuses.. it handles 4 inputs.

Attachment not found.

Would it be better and smarter just to put the fused junction box near (less than 5') the panels (under cover) and come down with just one set of +/- legs of HEAVY wire??



What guage wire should that 1 leg coming down to the controller be?? I'm thinking 6 awg to go 15 foot..

Does this make more logical and safer sense??

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

ywhic wrote: »

I guess this would work and just put in individual fuses.. it handles 4 inputs.

Attachment not found.

NOTE** The fused junction block (above) handles 8 awg out (down to 12ga) and upto 4 AWG in (down to 10).. (whichs means I can run the 6 awg down to the controller)..

Photowhit

Re: My 12v Solar Panel Plan.. I would like feedback..

Please note, while that fused distribution block is covered it is not weather tight. and indeed it is normal/advisable to connect the panels near the array and have a single set of wires going to the CC.

vtmaps

Re: My 12v Solar Panel Plan.. I would like feedback..

ywhic wrote: »

Why do soo many on here say 2 panels on 1 leg coming down is OK, and why do they sell the Y MC4 connectors and the Y MC4 cabling???

It's OK to parallel panels without fuses... as long as there are only two panels (or two series strings of panels).

You probably know that MPPT controllers are more expensive than PWM controllers. But MPPT controllers can save you money in many ways. One way is to eliminate the need for combiner boxes and fuses. Depending on the max voltage of your MPPT controller you could wire four or more panels in series and need no combiner. Some of the less expensive MPPT controllers have a Vmax of only 60 volts, but even with these you could wire up four panels in two strings of two panels and need no fuses.

As Photowhit pointed out it is usual to have your combiner and fuses/breakers very near the panels. Thus the wiring from the panels is fairly short. Once combined you run a single, heavier gauge line down to your controller. The combiner box (with fuses or breakers) needs to be weatherproof or you will have troubles. I suggest that you look at the midnite line of combiners (good prices at NAWS).

Try crunching the numbers... what you save by not buying a weatherproof combiner box may be enough to upgrade your controller to a Rogue or morningstar MPPT (in which case you will not need the combiner).

This whole issue (of fuses) would not be so important if the panels were mounted far away from anything (like your cabin) that could burn. Of course, if the panels were that far away you would be using an MPPT controller for another reason... to save on the wiring costs between the panels and the controller. (another way that MPPT can save money).

One more consideration... The best deals on panels are on those panels with the higher voltages. Of course, to use them you will need an MPPT controller. (still another way that MPPT can save money).

My advice now is to do some more number crunching.

--vtMaps

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

vtmaps..

I understand they need to be dry.. but instead of paying $142.xx for the prewired 4 panel Combiner which I'd want because I'm an idiot..

I'd rather buy a single gang NEMA 3R box maybe for $29.. and put my $20 junction/fuse block into it.. or something off the shelf from my local home depot..

I will be starting with 2 panels.. and then do 2 more down the line..

The 3R box with fused junction block will be my best option as then I don't need to play with the wires COMING DOWN to the controller and everything can be done at the box.. I still will be putting a CB on the inside just before the charge controller so I can shut it down for maintenance if needed..

For maintenance on the panels to add more to the junction/fuse block I guess I just pop the fuses out carefully at night??

Or should I get 4 separate 15 amp inline breakers for each panel.. and then get a non-fused juntion panel.. and pack that all inside the 3R NEMA box... <<<may be the smarter option..

solarvic

Re: My 12v Solar Panel Plan.. I would like feedback..

http://www.solar-electric.com/baby-box.html Sometimes cheapness cost you more in the end. Buy a couple of busbars and whatever breakers you want. This rquipment is made for DC. :Dsolarvic:D

niel

Re: My 12v Solar Panel Plan.. I would like feedback..

you should note that only one polarity of the pvs needs to be fused and most opt for the pv+. if you don't opt for solarvic's excellent suggestion then know that you could disconnect all of the pvs after they've been combined and sending it through a switch like this one,
http://www.solar-electric.com/miblseabases.html

vtmaps

Re: My 12v Solar Panel Plan.. I would like feedback..

ywhic wrote: »

Or should I get 4 separate 15 amp inline breakers for each panel.

If you go that route, be sure to get DC rated breakers. Be aware that some DC breakers are polarized, and some DC breakers must be in a particular orientation, i.e. they do not work if upside down or on their sides.

ywhic wrote: »

I understand they need to be dry.. but instead of paying $142.xx for the prewired 4 panel Combiner which I'd want because I'm an idiot.

Nobody here would think you're an idiot for buying safe, UL rated, quality equipment. Much of the advice you get here is from folks who learned by experience that buying safe, UL rated, quality equipment is smart and pays off in the long run. If you ever have an electrical fire or liability due to an electrical accident, your insurance company will be able to deny your claim based on your installation not being up to code.

Very recent example of saving money by ignoring code:
http://forum.solar-electric.com/showthread.php?15474

--vtMaps

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

So if I go with the baby box its has room for 4 breakers the downside its not 3R rated..

Now I found a 6 finger breaker bus bar.. http://www.solar-electric.com/mnpv6-bb.html If I only need 4 of the fingers do I just cut off the 2 fingers and the 1 extra main lug?? or just leave it alone??

Would I be better served by buying the ready to go MNPV3 Combiner for $64 which is 3R rated and then just change the 6 bussbar (above) to a 4 holder (6 cut to 4 position).. and put 4 breakers in (2 for now and 2 for later)?? (It has a 6 position negative and 6 position ground bar with it..)

It appears as the DIN flange has room for 4-5 breakers.. I'd only need 4 positions for this setup..

Attachment not found.

What would be the correct amperage BREAKER to use on panels that are rated at 7.84 amps each??

I appreciate the help..

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

Anyone??

What would be the correct amperage BREAKER to use on panels that are rated at 7.84 amps each??


Would I still want 15 amp breakers or less??

niel

Re: My 12v Solar Panel Plan.. I would like feedback..

keep calm as we don't always sit in wait for someone to ask a question. we do still have lives, sort of.

use a 15a breaker for it's 1.25 x 1.25 x isc and round up to nearest commercial value available. i suspect the isc won't be far enough above the imp to put it to 20a, but you can do your own math or read the specs on your pv as they often state the fuse value needed.

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

Thanks for the answer...

Should I stick with the MorningStar Pro 30 Amp controller or go with the Xantrex C40 Amp charge controller??

It appears as though the MS30 is simpler and no adjustment pots' but the Xantrex C40 seems more industrial and can handle another 2 panels (or so down the line)..

Which would you get??

niel

Re: My 12v Solar Panel Plan.. I would like feedback..

your call as its 30a vs 40a and price increases for more current. no matter what you get be sure to have the bts (battery temperature sensor).

SolaRevolution

Re: My 12v Solar Panel Plan.. I would like feedback..

The grape PV modules have a 10 amp max fuse rating.
I could not find a listing for the cynergys.

On another note,
You may want to consider a battery charger to use when you run your small generator.
Something like the Iota DLS-15 or DLS-30 depending on how big you intend to "grow" your battey.
http://www.solar-electric.com/bach1.html

You may not need it, based on how and when you use you power. Keep in mind, though that "crap occurs" and you may wish you had another means of recharging those batteries.

Alex

niel

Re: My 12v Solar Panel Plan.. I would like feedback..

solarcynergy specs-- http://www.solarcynergy.com/images/PV-SC060J12_PV-SC080J12_PV-SC100J12.pdf

6.46a x 1.56 = 10.09a. normally that should be rounded up, but you can't get too much closer to on the money so i'd use a 10a fuse.

ywhic

Re: My 12v Solar Panel Plan.. I would like feedback..

So I can run 10 amp breakers for the 100 watt Grape.. and the same for the 100 Solar Cynergy..

I just read the Grape 100 watt spec sheet. 5.42amp max current out and 6.29 amp short circuit.. = 9.81 amp..

If I push up to 145 watt Solar Cynergy panel at 8.43 amp max current and 9.32 amp short circuit.. = 14.53 amp.. (aka 15 amp).

The Kyocera 145SX is 7.91 max current and 8.68 amp short circuit.. = 13.54 amp (aka 15 amp also)..

So 1.56 x IMP (short circuit) = breaker/fuse size (rounded up)... Thanks niel.. I made a note..