Solar system up and running - pics included

[Walt Er]

This is the whole electrical setup.  Charge controller on the right.  The little gray device on the left is a 150W inverter from Radio Shack that we use to power the computer and the phone.  The white device on the left is a thermometer that connects to the inside of the battery box.  The battery box is on the other side of the wall, outside, with a vent through the wall to keep it relatively warm.

Notice the breaker in the lower left hand side of the breaker box.  T  The box wasn't designed for that - I just crammed it in.  Anyone see any problems with that?  It's the overcurrent and disconnect for the panels.  It needed to be high voltage because the panels put out 90V on a sunny day.

I took some liberties with the wiring.  The negative bus bar holes were too small for the 2AWG wire, so I split the wire in half and ran it into two holes.  Any one see any problems with that relating to safety?

?  

Here's another liberty taken.  Notice the two wires running out the bottom of one breaker. Anyone know if that's a safety issue?

 

Here's the battery box.  The tubes are for ventilation but they don't work.       .  It doesn't vent properly.  Actually it seems to vent in reverse, drawing air into the cabin.  I'm going to connect the ends of all those ventilation pipes to a small fan and suck the air out of the box to the outside.

The panels.  Three 180W Evergreens in series.  They put out 90V on a sunny day and the MPPT charge controller uses it to feed the 12V battery.  Today it's cloudy and they're putting out about 70V.  

The mounting system was built using unistrut from the hardware store.  It's tethered to those heavy timbers with three steel cables.  Hasn't been tested in heavy wind yet but I'm hopeful it will hold up.

The system is powering a DC freezer, computer, phone, and lights.  

This  board was super helpful in the beginning when I didn't know anything.  Thanks to everyone who helped me along the way.  If you think any of my creative wiring is dangerous please let me know.  Any other comments will be appreciated too.  Thanks again!

Walt Er

100% solar powered, off grid.  

[dnix71]

Having more than one wire off the bottom (output) of a breaker is okay. Why did you choose ac circuit breakers intead of fuses for the dc bus?

If you have 70 to 90 volts dc you should have a cover on the panel for safety.

[zeusmorg]

  Question: is that breaker you have for the panels DC rated? If not, then it is a problem. Some breakers are rated for DC and AC.

 To answer your other question NO IT IS NOT SAFE to run two circuits on 1 breaker.

Breakers are designed for a certain size wiring and circuit load. This would not hold up to a valid inspection.

 Another hint: i notice you are using a black wire for ground Mark it with white tape or wite paint at both ends to left the electrician behind you know it's a ground (neutral). Ground wires are white,(neutral) green (ground only) or bare, Power can be black, red (or in certain multiple runs(various other colors). Splitting the wire to run into two legs is fine, as long as they are properly attached.

 I also notice you are using no grommets on your box the wires are just through the holes. this could lead to the wires being cut and grounding to the box. Fire hazard.

 I'm also assuming the box cover is off just to show us the insides..

 An a/c wire "vibrates" due to the 60 cycle current and can eventually cause the insulation to be cut.(along with someone inadvertently hitting them).

 These issues do need to be corrected. Neatness counts, and codes were put in place to

keep people safe.

 Maybe a vent near the bottom would provide airflow in your battery box to keep positive airflow?

 It is better to do things right the first time instead of doing them over and over again.

 I hope my post doesn't sound to negative, I'm glad you have the system up and running.

[Walt Er]

Thanks -

These breakers are DC rated.  The small ones are Square D QO breakers (AC and DC rated), and the big one for the panels is DC.  I wanted disconnects as well as overcurrent protection, so this seemed to be the way to go.  The cover is just off for the picture.  

[Walt Er]

Thanks -

The two wires coming off the same breaker are both 10AWG, and the combined loads don't exceed the breaker current.  I figured that the worst case scenario would be a tripped breaker, which hasn't happened.  I've got 2AWG coming out of the adjacent breaker, so I figured that two 10AWG wires would be ok from a wire size standpoint.  Is it possible that under these conditions it's ok?  If not I'll just get another breaker.  I've got one more slot available.  

I thought about the grommets, but the way the wires are situated there is no contact with the box (or only very light, not enough to cut the wire).  All the current going through the box is DC.  The only AC is coming out of that little 150W inverter.  

Thanks a lot for your comments.  Not too negative at all.  I appreciate the insight.  -Walt

[thirteen]

could you at least put two wraps of electricial tape around the wire where it goes thru the box walls the gromlets are just for protection from possible movement and or rubbing of wires agianest the sharp edges of a knockout. If you work on the system you might cause problems. Prevents accidents. I would use some plastic wire ties to hold my wires together and a clamp to secure them in place. You might drop a broom aginest the wires or add things. ?? I don't know the venting inside but I might suggest that you put a clear plastic window for the batteries so they cna be seen from the inside. This will also transfer heat to the batteries. also put a loop on the top instead of a vent directly upward. It will keep from little things getting into them and put a small screen over the ends and draw from under under or beside the batteries. In my area the panels would have to be off the ground because of the snow. You might put them up higher to keep them from getting damaged by dogs or lawnmowers or a cold beer dropped bu accident. Looks like your on the right tract and are using it. Better than $$$$$ power bill. Just some ideas use or laugh at or throw away.

[spinningmagnets]

I am no electrician, but I have experience fixing old cars, and many a mystery intermittent short was traced to a wire passing through a hole in the firewall with a degraded grommet, or never had a grommet.

Vibration over time does wear through the wire insulation, leading to it occasionally touching bare wire to metal body. As a temp fix, I have often slipped a two-inch section of rubber fuel line (slit down the side like a hot dog bun) over the wire location of concern, and held it on with a hose clamp and silicone.

Just a thought...(great pics, BTW!)

[Basil]

I'm going to connect the ends of all those ventilation pipes to a small fan and suck the air out of the box to the outside.

May be a fire hazard that way.

May want to put the fan blowing into the box. That way the gas from the batteries will not go throuh the fan.

[MattM]

Those little hoses coming out won't ventilate because they are restricted space.  A gap in the wood has much less resistance than a hose.  You are better off to cut a hole for a louver.

[12AX7]

Hello!

I'd like to comment on the "terms" used.

Here in the USA,  earth ground and neutral are confused to often.

The Neutral wire is WHITE and is not to be confused with Ground.

Ground is GREEN, Green with a white or yellow stripe (runner), or bare.

The hot is BLACK

if the circuit is 240 Both hots are BLACK

If the supply power is 3 phase the colors get a bit "fuzzy"   the three hots might be

RED, WHITE and BLACK.

In a normal house system the WHITE Neutral is Tied (connected) to the Earth/Ground at the main breaker/fuse panel. And normally this is the ONLY place the Ground and Neutral are tied/connected together.

In a "three way switch" system there may be a White wire that can/is also Hot and is normally marked with one or two bands of Black electrical tape at each of it's ends.

Yes, anywhere in the house there is Power/voltage between the Hot and Ground, but all the loads should be connected between Hot and Neutral.

ax7

ps..   splitting the heavy gauge wire to fit under the smaller screws wont meet "code".

and could be "unsafe" if one of the two connections would fail (loosen). If the screw terminals are too small chances are that the "buss" is undersized.

Mind you, I'm not an Licensed electrician and probably have wired it the same as you.

[mo pharms]

Thank you 12AX7 so much for the wire color corrections,

in addition I agree that wire penetrations through the

box have to be corrected. I would use ordinary metal romex

connectors (about $0.39 each), however it involves 'undoing'

wiring to slide wires through.

Venting the battery box - I don't see how gases get in the

house unless there's a hole. The box could be (should be)

sealed from the house, put a large vent on side low and a

large vent on other side high, and hinge the lid for access.

This will also help keep the heat/cool in the house

(if air comes in one place it must be going out somewhere else)

Take pride in your hard work, clean it up a little bit,

and.....I wish I was as far a long as you.

(GET THAT PV ANCHORED)

[StorminN]

Walt,

For the unistrut panel rack, you might think about adding some diagonal braces to the back... the triangles that the unistrut forms on either end are strong and will resist forces from the front and back, but from what I see, the side-to-side stiffness of that rack is dependent upon the Evergreens, and you don't want to ever stress those module frames... a couple of more pieces of unistrut are a lot cheaper than replacing a panel if it gets cracked / looses its weather seal, etc. because it got twisted in some winds. Make sure the unistrut frame is completely rigid on its own, before you mount the modules to it.

For the breaker panel, I wouldn't put two conductors into one breaker, but that's just me. Those QO breakers are maybe $12, that's worth it. For the split #2 going to the ground bus, it's probably functionally fine the way you have it, but FYI, you can buy a Square-D add-on terminal block that sits on top of the bus... it replaces a screw on that bus and will take #2 wire... it looks just like the blocks that your other #2? wires are going into.

Use grommets or clamps where the wires go through the knockouts... even the plastic grommets, which are maybe $0.89 for a bag of ten are better than nothing. The wiring should be secured (stapled) to the plywood just a few inches after it comes out of the breaker box... I think NEC code says four or six inches, to give you an idea.

For the big breaker... DC can arc pretty well, and you don't ever want it arcing to the side of that QO box. I can't tell what type that breaker is from the pics, but Midnight Solar sells a "Baby Box" that's perfect for mounting one or two DIN rail mounted DC breakers in, I think it's $35 or so. If it's a Square-D breaker, you can get a small Square-D disconnect box for under $20... they're sold for hooking up outdoor hot tubs or RV's.

Hope this helps,

-N.

[tecker]

Looks like your well on your way .Those are some nice panels . I wish I could buy a couple but I'm on a mission to make some so I'm invested this year .I like the breakers also . It's a good idea to  test em to make sure they trip close to the right amperage

One thing I've determined from the panels I've gone through so far is that no one panel can physically pass more than twice it's power rating . As the panel gets to say 4 amps over the It's rated short circuit (Isc) amperage heat  measured on the backside of the panel rises fast . It's not as noticeable on silicon single and multi crystal as it is on amorphous panels .But all in all the power is just not available at the load.

So the panel on the home run side of the series string is going to heat up out of range and block power as that happens  . Those panels have a max fuse rating of  15 amps .  It's important to realize what your dealing with .Even though they are tested at 1000W/m2 and considered as 800W/m2 they're semiconductors and it's kinda like asking a 180 watt transistor to handle 540 watts .  Most panels see a

noticeable  power drop per panel over 150 degrees anyhow . The home run panel is taking a beating at high noon .

The mppt is reacting to the battery state of charge and holding the charge current down

so this may not be a factor until you've added a lot of batteries to your system . These are panels are good to go for a 24 volt system .

[SparWeb]

Hi Walter,

Thanks for posting pictures.

I appreciate your honesty.  I have made many of the mistakes/shortcuts you have, and haven't burned anything down (yet).  I keep improving it, and take the warnings to heart.  Posting the photos helps zero in on the important things to fix.

I'm surprised nobody harped on your split ground wire.  It's not a direct hazard, but it's a red flag.  Where does it go, btw?  When you find yourself doing that, you can ask yourself a) is this ground bar too small? or b) is this ground wire too big?  The NEC code is picky about the relative sizes of current-carrying conductors and the ground conductors.  The ultimate goal is to protect your from equipment faults, shorted wires, lightning strikes, AND improve reliability, AND reduce electromagnetic noise.  With so many different purposes and rules, grounding still confuses me, too.

Wouldn't those timbers have served better as the panel mounting structure, instead of just ballast weight?  If the timbers were cut and joined as a pair of A-frames, you would have a sturdy and heavy mount.  Or something like the little animal shelter I see in the background, in fact.  The unistrut would still come in handy to attach the panel frames, adjust angles acording to the season, etc...

[Ungrounded Lightning Rod]

Having more than one wire off the bottom (output) of a breaker is okay.

IF they're exactly TWO of exactly the same gauge solid wire.  Three or more is a no-no for solid.

(I'm not sure about stranded.  You might be able to stuff multiple lines, OF THE SAME GAUGE so the strands are the same size, into the connector until you hit a cross-section that corresponds to the maximum capacity of the connector.  But I wouldn't do it.  I've seen too many cases where one of a set of multiple wires in a connector came loose and pulled out, leaving the rest of the wires loose and the connection resistive.)

Check your local codes and the breaker's spec sheet for the definitive answer.

[Ungrounded Lightning Rod]

Also:  EACH of the wires must be capable of carrying ALL of the current of the breaker's rating.

Unlike the situation inside a motor or transformer and its junction box, paralleling two wires to get a higher current rating is out for interconnect wiring:  A failure in one puts all the current in the other one, resulting in a fire hazard against which the breaker won't protect.

[Ungrounded Lightning Rod]

if the circuit is 240 Both hots are BLACK

Or one is black and the other red.

Red may also be used for hot, and typically is in a multiconductor cable.  A typical cable (3+G) has a white (neutral), black (hot), red (hot), and bare (ground).  (When one is hot all the time and another switched the usual practice is for the red to be the switched wire.  But there's no requirement for that.)

(When I rewired my place for 200A I made sure that all the 240 circuits used red on the same side of the 240 line, and all my "run on the generator in an outage" circuits were on a particular side.  This included the double boxes with the 240 feeds and two 120 outlets that I put in every room.  That way I could hot up one side of the line during an outage with my dinky 220 emergency generator and have everything important running.)

As I recall the code, above a certain wire gauge using all black, even for neutral, is OK.  (And thus you can't find non-black insulated wire at the hardware store in those gauges.  B-)  )  Usually the drop and the wiring between a main and a sub panel are above the size in question and the individual circuits are below it.

[Ungrounded Lightning Rod]

I'd use the strain reliefs required for house wiring code compliance.

They do a dandy job of protecting the wires long term and thus preventing shorts and fires - and the insurance companies' laboratory (UL) has tested the heck out of them on that issue.

[Ungrounded Lightning Rod]

Your battery box should not be connected to inside air.

As you've found out, because it's low and the house acts as a chimbney, the airflow is from outside to inside.  This both defeats your intended purpose of keeping them warm and draws a mist of corrosive and toxic acid and explosive gases into your home.

But you don't need to warm your batteries.  Just insulate the box and keep the (purely outdoor) venting limited, at least during cold weather.  The losses in the batteries, both during charge and discharge, along with their thermal mass for those short periods where generation and load are balanced, are adequate to keep them warm if you don't over-vent them.

Meanwhile the acid in an even partly-charged battery acts as an antifreeze to protect against freezing to very low temperatures.  Low battery temperature is mainly an issue of efficiency, not damage risk.

[DigitalMind]

Thanks for sharing and for the great write-up full of information.  Do you mind if I write a blog post about your install that will be put on techieNATION.com ?

[Chuck]

Hi Walt,

It looks like a good start. I'll just second a few comments others have made.

First, clean the box up. Get the grommets in there and route the wires neatly. There is nothing better than looking at your work with the pride of a job well and neatly done. It took me a while, with the help of an electrician friend, to figure out what craftsmanship in wiring was, but you know it when you see it.

Second, Use some earth anchors and cable to hold down those panels. I had a similar setup. The wind flipped it and I was lucky to only loose one panel. It can never happen until it does.

Chuck

[Walt Er]

Man this board is helpful.  Here is a summary of the issues raised and my responses.  

Grommets.  There seems to be consensus that the wires need to be protected from the sharp edges of the knock-out.  Various proposed solutions included grommets, electrical tape, rubber fuel line hose, strain reliefs, and metal romex connectors.  For now I've wrapped all the wires and/or knock out edges with many layers of electrical tape - I just couldn't bear one more trip to the hardware store.  I'm moving the system in a year and will plan ahead for proper protection as well as "craftsmanship in wiring".  I do know what you mean.  

Split 2 AWG into to neutral bus bar holes.  Seems like this is ok as long as both ends stay secure, but I like the add-on terminal block option.  I'm going to get one of those.  

Two wires coming out of one breaker.  Since I have room for another breaker, I'll just add one.  

Wire color.  There won't be anyone having to deal with this after me because it's a temporary (1 year) setup, but when I move it to its more permanent home I will make sure that all my hots are red or black, my neutrals are white (or white striped/taped) and my grounds are bare or green.  

Big breaker screwed into box.  The QO box itself is grounded, but I'll look into that "baby box" as a mounting option.  

Battery box.   The purpose of the battery box is to keep the batteries warm from the heat of the house but to store them outside of the house for space and safety reasons.  I understand that there is little risk of them freezing, but I would like to minimize their capacity loss due to the cold.  The floor, walls, and cover of the box are all heavily insulated and there is a vent between the back of the box and the house.  I replaced one of those little 1" vent tubes with a bigger 4-6" tube, but the gas is still being drawn into the house.  I picked up a 3 Watt DC brushless fan with the intention of sealing the hole between the house, poking that fan through, and running it all the time, but the thing was so loud in this tiny cabin that I'm not going to go that route.  Now I am considering placing the fan outside over the 4-6" hole in the box lid and suck the warm air from the house, as well as the battery gases, through the fan to the outside.  My understanding is that since this is a brushless fan, I should be OK.  Anybody ever blow up trying this?  Another thought I had was to put some sort of heat source, like a small light bulb, in the battery box to keep the temperature warm enough so that the air flows in the right direction.  I will keep experimenting with this until I get it right then let everyone know what worked.  Any ideas are appreciated.  

Panel frame.  I'm going to take the suggestion of putting diagonal cross braces across the frame for lateral strength, and also cable tie the frame down to some ground anchors.  Thanks for the warnings from personal experience on this one.  

Summarizing this has been as much for my benefit as anything, so sorry if this post was a little boring. If I missed anything feel free to remind me.

To the person who wants to blog post this installation - go for it - and feel free to include this summary of suggestions and responses.  

Thanks to everybody.  This board is great.  

-Walt

[ghurd]

Yea... Stuff that works is boring.  

Only bother everyone with stuff that does NOT work?  I fell asleep twice.  ;-)

The item I use for a grommet is a "water-proof strain relief".  It is not really waterproof, but it is nice enough.  The wire goes through a rubber gasket

They come in 1/2" for #12 and #10 romex at Lowe's and Home Depot for about $1.50 each.  

That stupid plastic bag does not include the 15 cent nut, so get them while you are there.

For the larger single-conductor wires, I use standard romex fittings.  Usually I wrap several layers of tape over the wire.  Better fittings are available at the store.

The light bulb in the battery box idea to keep the air flowing in the proper direction sounds a bit "off".  Meaning I think it won't work like you expect it will work.

RCpilot had some good ideas.  The battery gasses when it is charging past a certain voltage.  Run the fan if the battery is gassing.

The relationship to me is not an ad, just I thought it was a good idea.

http://www.fieldlines.com/story/2007/10/7/51422/5894

http://www.fieldlines.com/story/2007/10/15/35939/022

Personally, if my batteries were out side, I would insulate the heck out of the battery box (twice), except for the side sharing the house.

That's a lot of PV.  The angle is off, so they are losing a LOT of power.  More power than the MPPT is making.

And I would anchor the front, middle, and back 7 ways from Sunday.

Looks great to me.

G-

[SteveCH]

Congratulations on getting this DIY thing working. Even with the suggestions above for alterations, it is more professional than my first incarnation was. Good work.

I will add another push to add the diagonals to the panel rack SOON. If it's at all windy where you are, this is important. My first rack was near-victim of winds, which are quite strong and persistent here at times in the winter. The first spring I got up on the roof to check some stuff, I discovered by total accident that my horizontal rack members were cracked about midpoint and about ready to fail. I had to disassemble, weld some angle in there, then added the diagonals [my rack was steel angle]. Since then, 25 yr. ago, I've added maybe six or seven more racks and all of them have diagonals and none have had a wind-derived problem.

Enjoy your from-now-on free juice.

[medicmike]

Your system will never work.  You might as well pack it up and ship it to me.. Just kidding, great work.  I have no idea on the electrical issues however on the battery box you might try a 12 volt CPU fan.  You can pick one up for $5 and you could get a $12 12 volt panel to run it.

[independent]

The only thing I've got to add is something I came across when I fully rewiring a house to modern spec (fully signed off and legal with proper documentation). I don't live in the States so codes are different here obviously.

But the thing I want to point out, that was pointed out to me, and I've seen others' do badly is properly fixing wire into screw down connectors (like bus bars) especially in permanent installations. There is a proper technique for forming the wire, depending on it's size, big or small, multistrand or single strand. And there is almost an art to how much torque to put on the wire.

For example, a single strand cable (not used in RE here except in AC lighting circuits) can only be tightened down so much and then it will snap. It needs to be folded in half and fully inserted into the receptacle without any bare cable showing.

The biggest thing, from what I've seen and been told and seen.. and done, is that people do not screw down these points tight enough. This can obviously lead to arcing and fire.

Without wanting to sound like a spoilsport, a half an hour with Sparkie (electrician) mate and getting him to show you the proper way to do this is a worthwhile investment in beer in gratuity.