Fuzing and Grounding

[Lightnin1960]

I got a quick question on Fuzing.

Seeing how Lighting could get to the panels by the pos. or neg. should I put a fuze on each of them. Each of my panels put out 3.6 amps. so should I use a 5 amp fuze in it?

Does this sound like a good way of wiring the system? I've thought of putting in a bus block where you would have 5 or 10 panels going to it inside of a water proof box and then have the one wire going to the charger controller.

As far as the ground goes what I've thought of doing is along with running the neg side to the controller and have it running from the bus along the top of the house and down the side connected to a 4-6 foot grounding rod. Also what size wire should I use for the ground.

Thank you
Jack

[12vman]

Most times the common (negative connection) of a charge controller is the same on the input and the output. (Battery side and panel side) The common connection is complete from the battery to the panel(s) as one solid circuit. This means that if you were to connect the common wire (negative) to a ground rod at any point, it would be connected to the complete system.

I would suggest making this connection before the charge controller to shunt a lightning surge before it enters the house. Maybe at your combiner box for the panels or just outside of the house before the ground wire enters the inside.

A lightning surge will tend to travel to the point of least resistance, which would be to your common (negative) if you have a ground rod connected to it. Some of the surge may travel down the positive wire but it would be suppressed mostly at the charge controller. Most charge controllers have high voltage supressors built in to them which would divert the surge to the common (ground) connection internally before it gets to the battery.

No fuse can open fast enough to stop a lightning surge so direct grounding of your negative wire is important. The surge suppressors in the charge controller will do their job by shorting the positive connection to the common. They will be destroyed but they will do their job. In this event, now we have a short to ground at the charge controller. If there isn't a fuse between the battery and the charge controller, there could be a fire!

You should place a fuse between the battery and the charge controller. Sizing this fuse will depend on how many amps the panel(s) will provide to the battery from the charge controller. This fuse has nothing to do with the loads added to the battery that you may be using in your home, just the amount of amps your panel(s) can deliver to the battery.

[Lightnin1960]

Thank you some of this is close to being over my head a bit but I think I really understand the most of it.

protecting from Lightning is done through the controller and fuze the batteries in case of short.

I want to end up putting a breaker box on the side of my house in the beginning to wire in all the 120 circuits and just have the 220 run from the electric company for now. and try to get something that will automatic change from the batteries to the grid when the voltage is down in the batteries.

[patience]

I have a fear, maybe irrational, maybe not, of connecting anything to the grid with their known propensity to attract lightning strikes. Consequently, I'm wiring the entire house AGAIN, separately, for the alternative system. There will be no connection whatever to the grid in any way.

There will be 2 outlets by the refrigerator--the existing outlet from the grid, and my outlet fromthe solar system. It will be either one or the other. Home lighting is the same. I'll leave in the original wiring, but I have added 12 volt circuits for entirely separate 12 volt CFL lighting.

Call me paranoid. I don't mind. I got to thinking this way after a talk with our Duke Energy lineman, who asked how I was going to hook it up to the grid system--did I have a transfer switch? I said no, no connection at all, anywhere. He said, fine, otherwise duke had some regulations to follow. He was the one who co-signed the lightning safety idea of no connection.

Point well taken where 12VMAN said that a fuse won't stop a lightning strike. That was echoed by a communications engineer friend of mine, who said, "When lighning has just ionized a mile or so of air to get to your stuff, you don't think it is going to slow down for a half inch gap in a fuze, do you?"

I guess all you can do is send it somewhere safer, huh, 12VMAN?

[12vman]

Yep.. Send 'er to the earth! That's where it wants to go anyway. Sorry about anything in between the two..

In most cases, if a lightning strike is direct to your system, it's not going to matter how much grounding you have. Things will fry! Probably everything connected to the system!

Most of the time it's close strikes that cause problems. They'll cause an electrical surge to anything conductive in the area. Wires from panels and internal house wiring included. This surge is looking for a path to earth and will take the path of least resistance (shortest path) and it will find it, regardless of what it needs to travel through to get there.

If the negative wire is connected to a ground rod, at least half of the total induced voltage spike collected by the wiring will be directly diverted to the earth. The surge collected by the positive wiring will be absorbed to the ground of the system through the charge controller and the small amount of resistance of the panels themselves. The surge induced on the positive wiring inside the house will be shunted by the battery.

If you operate an inverter, the A.C. wiring in your house can induce a voltage surge also. The path to earth ground would be through the inverter. The best ground it sees is the common to the battery. To avoid the issue, add a surge suppressor between the inverter and the house wiring and connect this to the same ground rod that's connected to the solar power system.

[Lightnin1960]

Yes I do have an inverter a new 1500 watt and an older 8500 watt inverter I figure it should run the entire house if I can keep the batteries charged up... waht type of surge protector should I get for it to take it to the house.

Thanks for all the info
Jack

[keydl]

One of the cute things about lightning is that it will leave a lightning protection wiring if the bend is to sharp, there are rules on the radius of the bend. A second is that a .025 gap will usually hold about 25KV and the equipment will often shed 10KV. Add these 2 together ground the negative with large radius bends and make a spacer to hold .010 clearance on the positive lead. Pay close attention to galvanic corrosion in grounding the mount.

[Lightnin1960]

Let me make sure I got this right. I put all neg to grounding rod Batteries, inverter, solar panels, charge controller. is that right??

Will I need a certain kind of breaker box if I only got 110 volts in it.

I would like to figure out how I can get 220 volts in it but I'll worry about that later I reckon.

Thanks
oh btw... I got my first panel put together and took it out in the sun and tested it, it's suppose to have 18 volts and it is putting out 19.7 volts so it's working good.

One other question my Battery bank is in a small shed I've got the Solar Panels will be on top my house because it gets more sun. I guess it's about 20 feet from the house. I've thought of running the wire from the top of the house and put up a pole next to the shed and run the wire to the pole high enough so I can drive under it with room to spare. Is that a good idea or because of Lightning would it be better to run down the house and underground to the shed.

Thanks again
Jack

[12vman]

Connect your negative lead from the panel(s) to a ground rod before the charge controller. This will ground everything. (Panels, Charge Controller, Battery, and everything connected to the negative lead).

If you ain't worried about codes, you can use a standard 220 box. Just jump the two outside hot lugs together with a short piece of wire and connect the live wire from your inverter to either one and connect the common to the center. Now both sides of the breaker box will be 110 volts. If you decide to convert to 220, all you have to do is remove the jumper between the two outside lugs and Vala!

Why do you want 220? You're gonna have enough problems trying to operate things on 110!

[Lightnin1960]

well I want to operate my stuff like water heater, compressor, AC/Heater, and Dryer, you know all the 220 stuff that are in the house...

Thanks on the breaker box hook up. lots of help!!!

[keydl]

Your power calculations have to be off by a factor of 100 or you are a lottery winner.

The cost to run a water heater is about $17000 dollars.

[Lightnin1960]

Keydl sorry but I really don't understand what you mean unless you got this message in the wrong thread

[patience]

He means that the amount of power needed to run a water heater is astronomical. The cost to do that with solar panels would be more than some houses cost. In general, if it is a heating application, you probably can't afford to do it with alternative electricity, be it solar, wind genrator, or whatever. It simply costs far too much.

Alternative electricity costs more than the grid, by a LOT, when capital investment is considered.

Most off grid homes that I've heard about use LP gas for heating water, often with an on-demand type water heater to save gas. My daughter and SIL do that. You need to approach each usage point as a separate problem, and seek out the most sensible way to meet THAT individual need. When using grid electric, it is cheap enough that you can use the broad-brush approach and just wire everything to it. NOT so with alternatives.

Typically, off-grid homes may use LP for heating water, maybe wood for home heating, and maybe LP for cooking. The fridge may be 12 volt DC, or 110 volts from an inverter (costly, so get an efficient fridge), or LP. Alternative electricity is most often used for lighting (since it is relatively low power requirement), and communications, like phone, internet/computer, and TV (digital flat screen), radios, and such things. Maybe some small fans.

This requires that we re-think every single power use, and decide just how bad we need that? For instance, AC can be a deal-killer. You might get by with a small window unit, but forget central air, unless you want to spend mega bucks on a solar system. This whole line of thinking is a big wake up call for most people considering alternatives. It requires changing almost everything about your lifestyle.

In my case, I have a total of 1,400 watts of panels, which, at 4.2 hours of sun/day average here in Indiana will get me a max of 5.88 KWHRS per day X 30 days per month = 176 KWHRS/month. My last electric bill for our all electric home showed over 2,000 KWHRS usage for the month. The system that will provide 176 KWHRS cost me about $12,000 for the parts only, assuming that I do all the design and install. Obviously, my usage has to go DOWN, dramatically! And we have a modest home, 3 bedroom, only window AC. All we plan to run off the solar system is a freezer, a fridge, some lights, and the phone and a laptop.

Look at your electric bill, and figure out what you can do without.

[Lightnin1960]

wow that sure POPPED my balloon but I have to start somewhere.... I know for starters all I want to run is a fridge and freezer thought I could get away with 5 or 10 panels but 10 would only be 648 watts I guess I'd need about 20 to get close to anything I wanted to do. I know I've got some more figuring to do... I can build a panel for about $100 per panel that gets 64.8 watts 18 volts I've got a battery bank of 12 6 volt batteries. but I have 26 batteries 14 not hooked up to nothing yet. 2 inverters 8500 watt, and 1500 watt

[12vman]

To start, I'd build a few panels, get a charge controller, and get some charge into those batteries before they go bad! Letting them set around with no charge at all is the worst thing you can do!

I'd connect all of them in series/parallel to get 12 volts and get a charge going on them pronto! As you get your panels built, just put them online with the rest of them that you already have connected until you reach the maximum current level of your charge controller.

I have 512 watts here and I couldn't support a standard fridge very well but I run my whole house! ;)

[Lightnin1960]

yeah I got them used and hooked them up to a battery charger 2 at a time with a desulfator I had 30 but 4 of them I couldn't bring back to life... but the 26 are very good. but yes I do know what you mean though. I've got 2 controllers a 10 amp and a 200 watt so neither is very big.

What size wire should I run say 50 feet and figure 10 panels 648 watt 36 Amps. or should I go ahead and run the wire for 20 panels.

my fridge uses 4.88 amps and 588 watt..... one thing that's weird is the longer it's running the less it using. after about 5 mins running it's 2.68 amps and 277 watts

[patience]

Here's a brief table on wire gauge and power capacity:
http://www.the12volt.com/info/recwirsz.asp

Wire gauge must be determined by the max watts it will carry. (Watts = volts X amps) But to figure out the size of your system, think in terms of watt-hours, because solar panels only produce when the sun is on them. It's like filling a bucket (your batteries), where the pressure = volts, the flow = amps and the total is gallons, or watts. You can only put in the batteries what is produced on a given day.

Accordingly, you need to find out watt-hour usage over a 24 hour period for each load, such as the fridge, or a light. Add up the watt-hours for the day's usage, and you can figure out how big your system needs to be. Harbor Freight sells the "Kil-A-Watt" meter that enables you to find the watt-hours used for a given appliance by simply plugging it into the meter, then plug the meter into the wall. Come back in 24 hours to read it. It even has a clock, so you don't have to be exactly on time to read it. By pushing buttons on it, you can learn how many hours it has been on and all about watts, watt-hours, amps and volts. Do your figuring and you'll know what an intermittent ( and variable) load like a fridge uses over time, since it only runs PART of the time.

My 15 cu.ft. fridge/freezer uses 840 watt-hours per 24 hour summer day, a bit less in winter, since the house is cooler then. So, to run that, day in and day out, I have to produce that much. Reference books tell me that I can expect an average of 4.2 hours of effective sunshine/day where I live in southern Indiana. 840 watt-hours divided by 4.2 hours/day = 200 watts of panels MINIMUM to get it done, assuming I never have a run of cloudy days, and if everything were 100% efficient. Sensibly, I need probably 300 watts of panels, or more, to realy do it, especially in the winter, without having to run a backup generator to make up the difference.

I'm building a backup generator anyway, with a 6.5 HP gasoline engine and a 100 amp Delco alternator. Here's a link for building a 12 volt genertor from a lawn mower:
http://www.theepicenter.com/tow082099.html

Hope this helps some.

[patience]

Very quickly we run into the need for everything to be efficient, both producing and using the power we make. A new, efficient fridge uses far less power than an old one. My 20 year old fridge used 2400 watt-hours a day! No way could I afford to run that. the new one is the same size and uses 800 to 840 watt-hours per day. Much better.

12VMan has posted a lot about very efficient lighting compnents and other things. There are a lot of efficient 12 volt items out there now, that run on very little power, and also do NOT require using an inverter to change it to 110 volts. Inverters are an important part of the picture, but they do have efficiency losses. Inverter losses can run from 5% to 30%, depending on many things--what quality inverter, and whether you are using it to full capacity--they work better at about 2/3 capacity, usually. Running on 12 volts directly will eliminate the inverter loss, but costs more for the fatter wires needed for higher amps at 12 volts. There is the trade-off. It was enough cheaper for me to buy a 110 volt fridge than a 12 volt one (very pricey) that I can buy the extra panels/batteries/inverter to run it.

My thinking has been to first decide what functions I absolutely won't do without (fridge, freezer, lights, and communications), then get the most efficient units I can manage for each of those. Add up the loads over a day, and figure out what I need to power that total load.

Since solar systems can be troublesome to increase in size (mismatched panels and mismatched batteries don't get along), I chose to build TWO smaller, stand-alone systems, giving me a partial backup if I have trouble. If I find that I still don't have enough power, I will build another small system that will get used for a certain part of the load. That eliminates the many problems with adding to an existing system, since system components need to be matched for size, that is, batteries need a certain minimum amount of charging, charge controllers have amperage limits, wire sizes have to be big enough, etc..

[Lightnin1960]

my fridge is 18 years old and if I'm reading this right it's still got about 2 hours to go to get to 24 hours but I think it's telling me that it's 5.13 kwh in 21:50 ;hours so it looks like I'm using about 5500 watts a day from this thing.
I think I'm going to need a new one.... that's probably burning more then anything else in my house including my shop equipment. I've got a appliance warranty plan so maybe I can get them to pay some on a new one.

where do you get one of the Ref. books about the sun. I'm farther south so I should get a little more... I'm in NC. My main roof faces south so I reckon that good...

thank you, ya'll are helping alot to plan my system and my next move.

[patience]

This is the best one I have found. It answered pretty well all of my questions. The authors aren't selling anything; it's a nn-profit, IIRC. Covers everything from your home site to wire gauges, solar data, you name it. How to correctly wire a battery bank, and why, etc..

http://www.google.com/products/catalog?hl=en&q=photovoltaics+design+and+installation+manual&wrapid=tlif12821759967652&um=1&ie=UTF-8&cid=13783690254334939889&ei=GHRsTJ_YD8aAlAeAk7SUAQ&sa=X&oi=product_catalog_result&ct=result&resnum=1&ved=0CCcQ8wIwAA#


That sounds like far too much for a fridge to draw. I hope you just read something wrong. It would have to be a self-defrost, icemaker, super-size model with hot and cold running handmaidens to draw THAT much, surely. :fie:

Yeah, NC is good. South-facing is even better! (My house faces west--UUGGGHH!) Latitude is what matters. Our latitude is 38 degrees, 35 minutes north. Asheville is 35.6 degrees north, which is better by almost 3 degrees.

The next item to look at is whether you make your panels TRACK the sun, to collect the very last smidgeon of sunlight per day. I chose to not do that, because it can get complicated and expensive. Simple = cheap and reliable. For stationary panels, the best compromise position is usually said to be set for the winter sun angle, since that's when you need it most (shortest days) and in summer, the sun is so bright that the angle being a bit too vertical doesn't matter that much--you have more sun than you need anyway. That is the logic, anyhow.

RE: Popping your bubble. Sorry about that , but it is really an advantage to have it figured out before you have to depend on alternative energy. It's the poor folks who don't understand that will be in real trouble. You're started and working on it, so you are way ahead of most people. Getting into alternative energy and learning how hard it is to get what energy we want some other way really makes the point about how dependent we are now on the grid and on petroleum. There just isn't any better, cheap alternative out there. But there ARE other ways to get done what we need done.

Daughter and SIL have 32 acres of mostly very steep forest, with about 7 or 8 acres that could be tilled. They learned that you have to exploit whatever you have available. So, they wil use wood heat, grow some food, solar PV, with a windmill to help, since they are in a rare spot here that gets some wind. They plan on sharing a horse with the neighbor to work the garden and drag in firewood. Look over your situation and see what might be available to you. A caution on water power--it takes a fairly fast, constant river to make any significant power.

[Lightnin1960]

I think it is bad I told them when they came out here last it seems like it never shuts off. this is the reading I got off the meter. 2.56 Amps, 261 watts, 6.11 kwh that's after 24 hours now I know why my electricity is so high.

[patience]

Yeah, that's bad all right. If you go for a new one, be sure to check out the annual energy usage on the yellow sticker. We bought a Frigidaire Galaxy, 15 cu. ft. with a top freezer, that I was talking about above, at 840 watt hours/24 hours.

[Lightnin1960]

They said they really couldn't find anything wrong with it. I told them it's burning way to much electricity. they said that it may be a ground wire off. But I'm going to get a new one though.. going to find out just how good my warranty thing is.

The one thing I want to run more then anything is the fridge and freezer I figure I can work around almost anything but storing food.... The other main problem I'm going to have is water.... Which if things get bad I'll go to my son's we're trying to get his place set to run his well. he's looking in on that there.

[Lightnin1960]

Went up and looked at the new side by sides fridges they say they only use 509 kwh and that's for a 25 cu ft one... so I could save a bundle and they should only take 2 solar panels to run them