Please help, Very confused

VanDeusen · March 2010

ok, I will try to explain as best as I can. My question is at the bottom.

I have started a solar/wind 12v system to my OFF grid home. This is how I have it setup...

I have so far 2 120 watt solar panels and 2 400 watt wind generators. The 2 solar panels are running to ONE controller rated to handle 30amps so I am fine there. The panels are going thru the controller to the batteries.

My wind generators are running DIRECTLY to the battery bank as per its instructions.

I have a REGULAR 10amp battrery maitainer going to the batteries being supplied by the electric company. (the only thing that is 110 in the house that is running on the electric company)

NOW for the batteries, They are running in I believe SERIES as there are 10 (ten batteries) in ONE straight line and the first + pos is going to the 2nd batteries + pos which is going to the 3rd batteries + pos and so on all the way down the line to the 10th battery. The same is for the - Neg. side. I am running a 5000 10,000 surge inverter which has in the back 3 + pos and 3 - Neg's and each of the 3 are going to DIFFERENT batteries in the bank.

Now I can run the WHOLE house off this system BUT when I use the coffee pot for too long or the George Forman grill (not promoting him...LOL) it drains the batteries real fast.

The controller pretty much tells me that for most of the day (when the suns out) I am pumping 9 amps to the batteries and of course I have the battery maintainer/ charger on it that is pumping 10amps to the batteries. I also have the wind generator pumping something. I dont really know since I am still waiting for my inline amp meter to arrive in the mail. For the sake of argument lets just say that the wind provides 0.00 amps.

Can someone Please tell me what I am doing wrong? Seems like I drain too quick when I use appliances. I can have ALL 4 floors of lights on (energy saving florecent) and have the 50' Plasms the surround system and the reg. size fridge with pretty much NO problems but again if I put something like the foreman on it it will drop quickly.

I forgot to mention that the batteries are 12v deep cycle marine batteries with a min of 75 amp hour. I have a couple that are 105's and 115's. I know that I am short on panels and the next one is to be delivered Monday. My plan is to conncet that one to the controller as well as it says you can do 3-120's. I am ordering today a multi-stage battery charger that handles 3 battery banks. I am OPEN to all suggustions as to what I am doing wrong. I am pretty new at this but have some of the basic concepts.... Heck, after all I am 99% solar now. I also should mention that the way I understood it I needed 25 MORE 120's and 6 more batteries so I know already that I am short but am I THAT SHORT?

Thank EVERYONE in advance for helping me with this.

Rev. Marshall

Kamala · March 2010

Re: Please help, Very confused

Sounds like your batteries are in parallel, pos to pos & neg to neg.) Series would be pos to neg to pos to neg, etc. and with 10 12v batteries would create a 120VDC bank. So I'm certain that your batteries are not in series. That being said, 10 batteries is a lot to run in parallel. It is almost impossible to get charge/discharge balanced over each battery.

How old are the batteries? Mixing different types, capacities and ages also creates a host of problems.

Finally, appliances with resistive heating elements (coffee maker & grill) will drain batteries quickly. Very few off-gridders would even consider using PV acquired energy in this way.

Also, do a detailed analyisis of your power consumption. You need this information to size your system. Off hand, I would say that your PV is defintely undersize and your battery bank is, well, forgive me, pathetic.

Good Luck!

Craig

BB. · March 2010

Re: Please help, Very confused

Stop and understand your loads and your current system before you spend anymore money...

I think I am not understanding your setup--I am guessing that you have 12 volt batteries in parallel and 12 volt controllers, inverters, wind turbines.

Unless you are one of the few that is in a great wind area and have really nice running wind turbines--the amount of solar power you have available appears to way short of your expectations.

If you are deficit charging your batteries (using more power than you are putting back in every few days)--i.e., running the batteries below 75% capacity (or even way below)--in days/weeks/months you will quickly kill the battery bank.

So, from my limited point of view--do the following (in rough order of importance):

Determine the state of charge of your battery bank (hydrometer or resting battery voltage--no charge/discharge and accurate digital volt meter).
Get a good sized battery charger on the bank and start charging... Get above 75% state of charge quickly (day or so)--then finish the charge and check electrolyte levels... If low or wide range of SG (>0.030 units between cells), then equalize the battery bank (assuming this is a flooded cell bank).
Figure out the battery connections (series, parallel, Amp*Hour capacity, etc.).
Figure out how much power you are using (if AC, use a Kill-a-Watt meter). If DC/for long term, look at a Battery Monitor.
Now figure out the balance of system (amount of solar panel, how much power from wind, do you have a wind diversion controller--or do the wind turbines have internal charge controllers, etc.).

Read the Battery FAQ's:

Deep Cycle Battery FAQ
www.batteryfaq.org

In the end--I think you have way more loads than you have solar/wind power to actually keep the battery bank charged... All you have probably done is discharge the stored energy in the battery bank--and it will damage the batteries if it is continued to operate in this manner.

The rest of the components are not (usually) affected by how you use the system--so we really need to concentrate on the battery bank and get that healthy again (if possible).

-Bill

VanDeusen · March 2010

Re: Please help, Very confused

Kamala wrote: »

Sounds like your batteries are in parallel, pos to pos & neg to neg.) Series would be pos to neg to pos to neg, etc. and with 10 12v batteries would create a 120VDC bank. So I'm certain that your batteries are not in series. That being said, 10 batteries is a lot to run in parallel. It is almost impossible to get charge/discharge balanced over each battery.

How old are the batteries? Mixing different types, capacities and ages also creates a host of problems.

Finally, appliances with resistive heating elements (coffee maker & grill) will drain batteries quickly. Very few off-gridders would even consider using PV acquired energy in this way.

Also, do a detailed analyisis of your power consumption. You need this information to size your system. Off hand, I would say that your PV is defintely undersize and your battery bank is, well, forgive me, pathetic.

Good Luck!

Craig

Thank you for answering Craig,

First pathetic? (LOL) What do you mean? should they be setup differently? not trying to sound funny of course but is there soething wrong with the batteries?

I should also mention that the entire sytem is a 12v system. All components are 12v. The batteries are all within ONE month old. They are running in parallel and my total house is 18000 watts and I use according to the local electric company if I understood them correctly 800kw per month.

What do you mean a detailed analysis? What I just did above?

Again thank you in advance
Rev. Marshall

VanDeusen · March 2010

Re: Please help, Very confused

Thak you Bill,

I beleive you are 100% correct, Yes I already know that I am short as stated earlier and Yes I believe that the problem is in the battery bank. I believe that walmart sells crap batteries and I really dont know how to get the CORRECT batteries, From day one I felt like there is a different kind of battery that I am needing and lacking but the locals here (live in the country) act like I am nuts when I ask for bigger batteries.

If the problem is in the battery bank OR the way that they are setup then can you please give me a recommendation as to what they should look like?

Again the batteries are all within one month old and are all flooded batteries NOT Gell.

mike95490 · March 2010

Re: Please help, Very confused

If you have an electric company (providing a 10A charger) Why bother with batteries?

VanDeusen · March 2010

Re: Please help, Very confused

mike90045 wrote: »

If you have an electric company (providing a 10A charger) Why bother with batteries?

??? I pay for electric service and took 99% off the electric company's breaker box and put it on my solar breaker box. What do you mean? I am only using the charger to HELP out the system since its short. In either case my electric bill went from 700 per month to 35.00 per month. Guess why? But this quiestion doesnt help me much but thanx for responding.

mike95490 · March 2010

Re: Please help, Very confused

Generally, it's less expensive to "buy" electricity, then it is to buy batteries, panels, rent a crane to repair the wind generator.
If the battery system is not designed right, and treated kindly, it will fail, and you get to buy all new batteries again. And new proper inverters, and chargers.

To help, we need to know what your loads are. Gas stove or electric stove. Air conditioning, or just heat. Computers, TV's, cable boxes. Water heaters for stock tanks. Then we can start to guess how much power you need to keep it running, and caculate how many batteries. Then caculate how much PV.
Where do you live, so we can see how much sun you get, and if wind is even feasable (most places where wind is useful - it's too windy to live comfortably)

Mike

VanDeusen · March 2010

Re: Please help, Very confused

mike90045 wrote: »

Generally, it's less expensive to "buy" electricity, then it is to buy batteries, panels, rent a crane to repair the wind generator.
If the battery system is not designed right, and treated kindly, it will fail, and you get to buy all new batteries again. And new proper inverters, and chargers.

To help, we need to know what your loads are. Gas stove or electric stove. Air conditioning, or just heat. Computers, TV's, cable boxes. Water heaters for stock tanks. Then we can start to guess how much power you need to keep it running, and caculate how many batteries. Then caculate how much PV.
Where do you live, so we can see how much sun you get, and if wind is even feasable (most places where wind is useful - it's too windy to live comfortably)

Mike

I live in southern IL. The very southern tip Cairo IL. My wind generators DO spin often. Sometimes not very fast but they do spin. I do not use the stove, air or heat. The ONLY thing the solar system will be for is lights, 1-50' plasma tv, 1- lg surround sound system, the fridge, ceiling fans, computer with 19' ldc monitor and of course small kitchen appliances. Again, if EVERYTHING at ONE time was turned on I would be using 18000 watts (according to my kill-a-watt) That would NEVER happen by the way because even though its a 4 story its just the wife and I. All the hallway lights are also on motion sensors so they turn off after 30 seconds of passing thru that section of hallway as it follows you throughout the house.

SO, I would probably be watching the tv and surround sound while the wife would be cooking dinner. I would be using energy saving lights in the lamps in the entertainment room at that time as well. As she cooks she would be using (not installed yet of course) 4 110v burners and a convention oven (looks like a microwave) The fridge of course is always on. (when compressor kicks in of course) We wash ONE load of laundry a week and hang the cloths out to dry. (we do have a dryer that I would later be making a 220v system for it. first got to get this one right)

Very little gets used as only during cooking is the wife and I really in 2 seperate rooms. I work at home so during the day the lg surround sound system is on and the computer is on. When the wife gets home at 3:30pm she cleans until dinner time. I DONT turn on the 50' plasma before 6:30pm (wheel watcher..LOL) and we turn it off at 9pm where we retire upstairs to the 37'lcd tv and ONE bedroom celing light (energy saver)

Hope I didnt go on and on..LOL but that is the routine. We pretty much dont use the whole house. Remember the elec. company said our average per month was 800

RCinFLA · March 2010

Re: Please help, Very confused

From what you have included.

Grill - 1200-1600 watts when running.

Refrig - depending on size and age, between 1.5kWH/day to 3 kWH/day.

Lighting and other ? Four floors of lights, doesn't sound like a small cabin.

Assume the "50' Plasms the surround system" is a 50" plasma TV and surround sound system. - 250 to 400 watts.

I am surprised you are getting as far as you are. Your refrig is probably dominating but depends on how much TV and grilling you are doing. The 10 amp charger is likely where most of power is coming from but I have no idea how much you are yielding from wind generators.

The panels will produce 6.7 amps each at full facing sun. Sounds like you are using PWM charge controller so panel power rating is based on MPPT or 18v @ 6.7 amps so for a PWM controller you get the 6.7 amps maximum at what ever your battery voltage is (not 120 watts). For two panels, in winter, depending on where you live, you will get 3 - 5 hours of equivalent full sun on a good sunny day. That is between 500 watt-hours to 830 watt-hours on a sunny winter day. About enough to run the grill for 20-30 minutes a day. Your 10 amp charger will beat that production in less then seven hours.

Buy a 'Kill-A-Watt' plug in power meter (less then $30) and make some measurements on your appliance consumption.

For marine batteries you should only be using about 50% of A-H's or they will not survive very long lifetime wise. That's about 4800 watt-hours for your ten batteries.

The inverter is about 80-90% efficient depending on loading. 4800w-H*0.87 = 4200 watt-hrs of power from batteries.

It's sounds like your power appetite is out of the league of a 12v system. A 5kW, 12v inverter is a bit of a joke. The 12v current for a 5 kW load would be about 500 amps from batteries, forget about the 10 kW surge rating. Realistically, a 12v system should be less then 1500 watts, 24v system less then 3kW, over 3kW use 48vdc system.

RCinFLA · March 2010

Re: Please help, Very confused

VanDeusen wrote: »

??? I pay for electric service and took 99% off the electric company's breaker box and put it on my solar breaker box. What do you mean? I am only using the charger to HELP out the system since its short. In either case my electric bill went from 700 per month to 35.00 per month. Guess why? But this quiestion doesnt help me much but thanx for responding.

You can accomplish the same thing by changing the main panel breaker to a 15 amp breaker. (forced consumption reduction) Your panels and wind generator are probably just about making up the inefficiency of running power through the 10 amp charger to the batteries and back through the inverter. (about 30% net power loss)

Sounds like you have been taken in by the scam ads. "buy a couple of PV panels and eliminate your electric bill"

You will never get a cost reduction with a lead acid battery based system. A $700 a month grid electric addiction is a hard habit to break overnight. A divorce is even more expensive.

If you want to reduce your electric bill, first do conservation items, then consider a grid-tied PV system.

Tazman · March 2010

Re: Please help, Very confused

First: your batteries are in PARALLEL +>>>>+ and ->>>>-
2nd: what do you mean by a REGULAR battery maintainer? Sound like this is what is actually keeping your batteries topped up.
3rd: 2 @ 120w and 2 @ 400w may keep a motorhome going when you are in Arizona or a place where the sun shines and the wind blows a lot.
4th: Appliances draw a lot of current when starting up. Try your system with just your lights. Then add devices one at a time.

Kamala · March 2010

Re: Please help, Very confused

VanDeusen wrote: »

Thank you for answering Craig,

First pathetic? (LOL) What do you mean?

I may have been a little harsh. Glad you have a sense of humor.

Did you build this system or did you inherit it? How long has it been in service? Do you check the water in the battery cells and measure their specific gravity?

The major problem with your battery bank is the number of batteries in it. This page at smartgauge might help to explain some of the problems created by putting so many batteries in parallel.

But since you have a 12V inverter (I don't see that you are running any 12V devices directly) and 12V batteries, there really is no other way to hook them together.

If you want to retain a 12V 750AH (10*75) bank, you could:

Get new batteries. Say eight 6V 220AH "golf cart" batteries in a series parallel configuration. Then you would have 4 strings of 2 batts in series for 12V @ 220AH per string. Then the 4 strings in parallel (paying attention to the connection diagrams at smartgauge) for a 12V bank at 880AH. Or get six 2V single cell batts of ~ 750AH in series.

Or get a different inverter as RC suggests. For a 48V inverter you could take 8 of your existing batts, make two strings of four batts in series for 48V at 75AH per string and then put the two strings in parallel for a battery bank of 48V @ 150AH. Sure 150AH is less than 750AH, but what you really care about is the WH. 12V*750AH=9000WH compared to 48V*150AH=7200WH.

Problem is though, your batteries may already be suffering. Depends on how long you've using them this way. Your charger, even though always on is charging at less than 2% AH capacity. 3 to 5% is the recommended minimum. And there is almost no way that each battery is getting a charge equal to any other battery.

Sadly, it appears to me that the 2 panels are the only items that you have that can be used in a properly designed system for, what I have to guess are, your goals.

audredger · March 2010

Re: Please help, Very confused

SOMETHING IS WRONG HERE!

"inverter which has in the back 3 + pos and 3 - Neg's and each of the 3 are going to DIFFERENT batteries in the bank."

There should only be ONE Positive and ONE Negative going to the battery bank. If (IF) your bank is parallel +to+to+ & -to-to- the positive should connect to one end of the bank and the negative should connect to the other end. End not side. Then and only then will you be drawing off all the batteries!

loosed the grill... resistance loads are a No No.

mike95490 · March 2010

Re: Please help, Very confused

VanDeusen wrote: »

the fridge,
4 110v burners and a
convention oven (looks like a microwave)
(we do have a dryer that I would later be making a 220v system for it.

This is way beyond the capacity of most RE off grid systems. 2 panels and 2 non-functional wind gens (unless they are spinning like a jet turbine, they are not making any power) will not take this very far.
TV, computer, some CFL's don't burn that much unless they are on 24/7 The big heating appliances, are real battery killers.

VanDeusen · March 2010

Re: Please help, Very confused

we are barely using anything. Yes its 4 floors but as stated earlier pretty much 3 rooms get used. Kitchen, Entertainment room and of course the bedroom. We eat dinner evern nite in the dining room but again all the lights are energy savers. The grill was used ONE time and when it killed everything I turned it off.

What would you recommend doing different. My goal is to have 35-120 watt solar panels, 16 100ah batteries and of course the 2 wind generators which btw are mounted on the roof. (extending 20ft above)

the 5000 watt inverter is a modified sine inverter. Here where we live be pay about DOUBLE what the national average is for electric and I dispise them so bad I would live like the amish before I give them crooks another dime. If it takes every dime I have not to pay them a dime then it would be well spent.

I really need to figure this out and all help would be great. Remember if I didnt turn on anything but the fridge and loights I would be fine. Its the PLUG-IN type stuff that is hurting me.

VanDeusen · March 2010

Re: Please help, Very confused

the electric company here does NOT allow for grid tie. Its either off or them. I know that I am short and working on it. I am asking questions because I dont want to spend anymore money on batteries until I figure out which is the right ones to get in the first place.

The 2 solar panels I have show they are pushing around 10 amps in mid-day, the wind generators I will not even factor in as I cant confirm what they are providing. I did NOT enherit this system I started it a month ago and everything is NEW.

VanDeusen · March 2010

Re: Please help, Very confused

audredger wrote: »

SOMETHING IS WRONG HERE!

"inverter which has in the back 3 + pos and 3 - Neg's and each of the 3 are going to DIFFERENT batteries in the bank."

There should only be ONE Positive and ONE Negative going to the battery bank. If (IF) your bank is parallel +to+to+ & -to-to- the positive should connect to one end of the bank and the negative should connect to the other end. End not side. Then and only then will you be drawing off all the batteries!

loosed the grill... resistance loads are a No No.

on the back of the inverter there is again 3 pos and 3 neg. Instead of running all 3 pos's to ONE battery I divided it amnong the first 3 and the same thing for the neg's. in addition to running them in paryallel I also crossed every other one over so im pretty sure the batteries are being drained pretty close to the same time.

again the issue is plug-in type appliances. I read resistence (like coffee) is bad and that is good to know. I can run the whole house as long as I dont use plug-ins. I only watch the big tv for 3 hours a day and we are changing that to a LCD is its less watts. I already have a kill-a-watt and checked everything which is how I came up with 18k,. I should also mention that the 700 elec. bill is before MY time. That is the average to this house PRIOR to me moving in. With the system I currently have last months bill was 35.00 and the electric comapny reacted to that as well. (they didnt like it being so small that they came to check my meter) If you lived in this town you would understand. For Example My SINGLE mother's utility bill last month was 600.00 for a 900sqft house. These people have been reported as our rates are DOUBLE the national average.

VanDeusen · March 2010

Re: Please help, Very confused

also if I wanted to run the batteries in series to get 48v then would the 12v inverter need to be replaced? (this is to response to a earlier post)

dsp3930 · March 2010

Re: Please help, Very confused

Your current assets:
(2) 120w solar panels (about 40-50kwh per month between both)
(2) 400w wind turbines (about 15-30kwh per month each)
(10) 12v Marine Deep Cycle Batteries (Long parallel string in an odd configuration)
12v 5kw/10kw Inverter
12v 10a Battery Maintainer/Charger

The most you are getting out of your current system is perhaps 80 kwh per month from renewable energy. The rest must be coming from your 12v 10a charger and the grid. (unless there is something else I am missing)

Your usage:
Get out your power bill and report back the kwh that it says you used for the past three months. Report back with the total bill in $ and the kwh used for each of those three months. (From that we can at least have a rough idea of your actual usage.)

VanDeusen · March 2010

Re: Please help, Very confused

ok for those that want to know the battery size in all of this, here it is.

I have the following (as described on the batteries)

5- 75 @ 100 (reserve)

1- 925 cca @ 160 which also says 850 under load.

1- 115 @ 160

1- 105 @ 182

2- 115 @ 160

that makes up the 10 batteries I am currently using which are LESS then one month old with the last 2 being 1 week old.

VanDeusen · March 2010

Re: Please help, Very confused

dsp3930 wrote: »

Your current assets:
(2) 120w solar panels (about 40-50kwh per month between both)
(2) 400w wind turbines (about 15-30kwh per month each)
(10) 12v Marine Deep Cycle Batteries (Long parallel string in an odd configuration)
12v 5kw/10kw Inverter
12v 10a Battery Maintainer/Charger

The most you are getting out of your current system is perhaps 80 kwh per month from renewable energy. The rest must be coming from your 12v 10a charger and the grid. (unless there is something else I am missing)

Your usage:
Get out your power bill and report back the kwh that it says you used for the past three months. Report back with the total bill in $ and the kwh used for each of those three months. (From that we can at least have a rough idea of your actual usage.)

There is NO grid. This is off grid. the batteries are in paryallel and everything else you typed is correct.

VanDeusen · March 2010

Re: Please help, Very confused

Am I describing the system accuratly? I seem to lose alot of people in this forum?? Remember I am 2 mo. new in this so I am learning and if it cost me a lil in $$ for mistakes that is fine as long as I dont give it to the elec. co.

Remember the 3rd 120 watt solar panel will be here Monday so there will be 3 so far in this equation.

VanDeusen · March 2010

Re: Please help, Very confused

here is the description of the 120 watt solar panels that I am using and will continue to buy unless im told there wrong.

ITEM TITLE : 120 WATT 12 VOLT SOLAR PANEL

MODEL NUMBER: ASM120P-N

UL CERTIFIED: E309468

IEC: C1-ASN07001

TUV: 0000022551

Nominal Voltage: 12 Volts

Maximum Power at STC: 120 Watts

Optimum operating voltage: 17.3 Volts

Optimum operating current: 6.93 Amp

Open circuit voltage: 21.60 Volts

Short circuit current: 7.62 Amp

Cell: Multicrystalline Silicon Solar Cells 156mmx156mm

No. of Cells and Connections: 36(4x9)

Weight (Panel Only): 36 lbs

Dimension of module: 58.35 x 26.61 x 1.97 (in)

Solar Panel Grade: A

Operating temperature: - 40 to +85 C

Maximum system voltage: 1000 V DC

Type of output terminal: Junction box

Cable Length: 3 ft.

Connection: MC4 style connectors

BB. · March 2010

Re: Please help, Very confused

I would suggest that you read up on the batteries first:

Deep Cycle Battery FAQ
www.batteryfaq.org

Assuming you have the power/heat/etc. that you need (no danger of food going bad, freezing to death, etc.) because you have alternative power sources (fuel, genset, grid power) because of:

I have a REGULAR 10amp battrery maitainer going to the batteries being supplied by the electric company. (the only thing that is 110 in the house that is running on the electric company)

It is fine that you want to go off grid--but right now, it sounds like your batteries are miss-matched (miss-match batteries do not share charging/discharging current--some will carry most off the load, and the others will not).

Also, Marine/RV batteries are not really designed for deep cycle duty--they are a hybrid of starting battery (short bursts of high current to crank an engine) and to support a bit of deeper cycling (a normal starting battery will can only be discharged by 15-25% before the plates get damaged).

The rest of the parts will not go bad while we look at your system and try to help you figure out where you want to go next--But the batteries will (if cycled to dead, stay days/weeks/months below 75% state of charge, etc.).

Frankly, for an off grid system, you have so many miss-matched items (battery bank, huge inverter, tiny amount of solar power, unknown amount of wind power energy, etc.)--I am not sure how much can be salvaged to get you to where you want to be--Off Grid.

Another good place to start would be Home Power Magazine.

To be successful (for a reasonable price)--you to really change your lifestyle to conserve electric energy as much as possible... For the most part, off grid power will cost you in the neighborhood of $1-$2+ per kWhr... Or about 10x what your electric utility charges for power.

We want you to be successful in whatever you end up choosing--but we are also a very practical group and cheap. We don't want to see you damage the batteries you have, and don't want you to spend lots of money needlessly (but remember, solar RE power is expensive--there are things you can do to reduce costs--used forklift batteries, surplus solar panels, etc.).

But it can also be a bit dangerous too. Large battery banks that are full of acid and hydrogen gas. Batteries that can output more current in a dead short than if you did a dead short at your electric meter. People have had fires from failed (off-brand) solar panels, electrical shorts, etc.

After you have your batteries stabilized and enough power from the grid to keep your family safe--then we can talk about your loads, how much you want to spend, and what your goals will be.

Even a good sized off-grid solar system will need alternative sources of power (genset, backup grid power, etc.) during winter months--Normally, people only design the battery bank large enough to support approximately 3 days of no sun--after that, a generator and/or conservation is used to keep the family happy and prevent damage to the battery bank.

-Bill

VanDeusen · March 2010

Re: Please help, Very confused

BB. wrote: »

We want you to be successful in whatever you end up choosing--but we are also a very practical group and cheap. We don't want to see you damage the batteries you have, and don't want you to spend lots of money needlessly (but remember, solar RE power is expensive--there are things you can do to reduce costs--used forklift batteries, surplus solar panels, etc.).

But it can also be a bit dangerous too. Large battery banks that are full of acid and hydrogen gas. Batteries that can output more current in a dead short than if you did a dead short at your electric meter. People have had fires from failed (off-brand) solar panels, electrical shorts, etc.

After you have your batteries stabilized and enough power from the grid to keep your family safe--then we can talk about your loads, how much you want to spend, and what your goals will be.

Even a good sized off-grid solar system will need alternative sources of power (genset, backup grid power, etc.) during winter months--Normally, people only design the battery bank large enough to support approximately 3 days of no sun--after that, a generator and/or conservation is used to keep the family happy and prevent damage to the battery bank.

-Bill

Thank you Bill. the 5000 watt inverter is a modified sine and I thought that I needed a 5000 for the size of the house even though there is just 2 of us here.

Since the batteries to you are wrong, and we have to it seems start there, what would you recommend for batteries and how many?

Thanx

audredger · March 2010

Re: Please help, Very confused

VanDeusen, "We" are trying to be helpfully, not critical. Be patient and don't get offended. "We" will get you there...
With three + & three- cables being attached to different batteries you will not / can not be drawing off all the batteries evenly. With the mismatch group you listed, it would be difficult to do so under the best of circumstances.

I / "we" are concerned that you do not have enough charging for the batteries that you do have... The two solar panels are fine to me, just not enough of them! Do you have a charge controller?
"2) 400w wind turbines (about 15-30kwh per month each)" is the 15-30Kwh per month a calculate amount or measured amount? You say the wind turbines are hooked directly to the batteries? Are the turbines self regulating? Note: most wind turbines do not produce what they claim! If yours do, great, "we" / I would like to hear about your success.

Any circuit breakers or fuses in this system?

As to battery brands, I like Surrette and Trojan... I also like BIG 2v cells. That having been said, I do not recommend you going out and buying as many as you can afford! Without proper wiring and charging, you will kill them in no time. I know you don't want to give it to the stinking power company but, you don't want to just trow it away either!

If you can, post a picture or diagram of how your current batteries are wired. That may be the best place to start.

audredger · March 2010

Re: Please help, Very confused

I just went back through your posts, " As she cooks she would be using (not installed yet of course) 4 110v burners and a convention oven (looks like a microwave) (we do have a dryer that I would later be making a 220v system for it. first got to get this one right)

The 110v burners are battery killers; The convection oven is also a battery killer and the 220v drier will be a battery killer!

The "rule" in off-grid is: if you want to heat something then you have to burn something! You can burn; natural gas, propane, wood, gasoline or diesel. Otherwise you will be burning batteries! Get your wife a Peerless gas range, a gas dryer, and a tank less gas water heater.

How is the house heated?

A modified sinewave inverter is not good for motors, the refer will use less wattage and last longer on a full sinewave inverter.

Note: I am off-grid. Last power pole is 1/2 mile away. 220v is not need unless, for a well pump... When I need 220v (welder) I burn something... diesel.

Kamala · March 2010

Re: Please help, Very confused

VanDeusen wrote: »

also if I wanted to run the batteries in series to get 48v then would the 12v inverter need to be replaced? (this is to response to a earlier post)

That is correct. See below.

RCinFLA wrote: »

... A 5kW, 12v inverter is a bit of a joke. The 12v current for a 5 kW load would be about 500 amps from batteries,

This is why you have 3 positive and 3 negative connections to your inverter. Not the best design.

RCinFLA wrote: »

forget about the 10 kW surge rating. Realistically, a 12v system should be less then 1500 watts, 24v system less then 3kW, over 3kW use 48vdc system.

BB. · March 2010

Re: Please help, Very confused

Ideally, start with your load requirements...

A good place to aim at for an off-grid installation is 100 kWhrs a month or less... More than that--a big and expensive system. Smaller than that, and you have a reasonably sized and cost system.

100 kWhrs per month / 30 days per month = 3.3 kWhrs per day = 3,300 WH per day

The sizing of the bank not only is based on how much energy you use in a day, it is also what peak energy you will need...:

3,300 Watt*Hours per day / 24 hours per day = 137 watt average load

But--realistically, you will have appliances and such that will require starting and sustaining loads (refrigerator, TV, microwave, etc.).

For the most part, I like to recommend a maximum of 1,200 watts on a 12 volt battery bank--otherwise the wiring/fusing/etc. become unmanageable. To give you an idea--a 1,200 watt inverter would power your fridge (nice energy star version) and a few CFL lights. And the fridge itself would be responsible for ~1-1.5 kWHrs per day of your 3.3 kWH aim point. For a 1,200 watt inverter on a 12 volt battery bank, you would need to size the wiring to handle:

1,200 watts * 1/10.5 volt cutoff * 1/0.85 inverter eff * 1.25 NEC fuse/wiring safety margin = 168 amp wire+fuse minimum

A 5 kW inverter at 12 volts is looking at 700 amps of current at maximum load.

Normally, for a full home off-grid system you would be looking at a 48 volt battery bank--or at least 24 volts.

To give you an idea of what sort of battery bank we would be looking at for a 100kWhr per month off-grid home... Assume you are using AC power (0.85 efficient inverter) and a 48 volt battery bank. Assume 3 days of no sun and 50% maximum battery discharge (for long life):

3,300 watt*hours * 1/48 volt bank * 1/0.85 invtr eff * 3 days * 1/0.50 max discharge = 485 Amp*Hour battery bank @ 48 volts

That is the equivalent of 485AH*4=1,940 AH rated 12 volt battery bank...

My two cents of recommendation--I would get a 48 volt bank (2 volt, 4, 6, 12, etc.) where each cell/battery was at least 485 AH...

So, for example using good quality (not the best, not bad) Trojan batteries--we see that our options would be:

[FONT=Fixedsys]Part Number/Volts/AH @ 20 HR Rate/Length/Width/Height/Weight(lb)
T105-RE     6     225     10.375"     7.125"     11.75"     67
L16RE-A     6     325     11.575"     7.125"     17.7"     115
L16RE-B     6     375     11.575"     7.125"     17.7"     118
L16RE-2V    2    1110     11.575"     7.125"     17.7"     119[/FONT]

At the 20 Hour Rate (good number for an average off-grid solar system)--There is the T105 (6 volts, 225 AH) or the L16RE-2V (2 volt cell, 1,110 AH)...

For the T105, a string with 8x 6 volt batteries will give you 48 volt. And 2 strings in parallel will give you 2x225AH=450AH of storage (bit on the small size--but would work).

8*2=16 T105 batteries
4 for $560.00
16 batteries * 1/4 * $560 per set = $2,240 (plus shipping, taxes, etc.)
there will be 48 cells to water...

On the other side, the very large L16RE-2V 2 volt cell:

24 cells in series => 1,110 AH per string (>>485 AH suggested)
12 for $3,695.00
24 cells * 1/12 set * $3,695.00 = $7,390 (2.5x larger battery bank)
in this string, there will be 24 cells to watch/monitor

Note that the T105's weigh around 67 lbs each... the L16RE-2V cells weigh 119 lbs each (probably about the maximum weight that you would want to move around by yourself or with a friend).

The above is just to give you an idea in sizing the battery bank... Not a suggestion that you go buy a set today (we have more work to do--including figuring out your real loads).

[Big mistake below--I was working with a 48 volt battery bank but fell into describing it as 12 volt battery bank when trying to equate to your current setup--I thought the numbers looked "too nice". I will retype here and do a followup post--sorry. BB. ]

Now, to charge such a battery bank--another rule of thumb is ~5% to 13% of rated bank capacity... So low power on small bank vs high end recommendation on large bank worth of solar panels:

450 AH * 0.05 charge * 14.4 volts charging * 1/0.77 panel/controller derating = 420 watts of solar panels minimum

1,110 AH 0.13 charge * 14.4 volts charging * 1/0.77 panel/controller derating = 2,700 watts of solar panels maximum needed

Take the above and change to a 48 volt battery bank--i.e., everything will be multiplied by 4x for the higher voltage bank:

Now, to charge such a battery bank--another rule of thumb is ~5% to 13% of rated bank capacity... So low power on small bank vs high end recommendation on large bank worth of solar panels:

450 AH * 0.05 charge * 57.6 volts charging * 1/0.77 panel/controller derating = 1,680 watts of solar panels minimum
1,110 AH 0.13 charge * 57.6 volts charging * 1/0.77 panel/controller derating = 9.964 watts of solar panels maximum needed

So--just based on battery bank sizing, there is a wide range of possible answers for your solar power.

Now, we can predict (roughly) how much solar power your various panel options will provide using the PV Watts website. Assuming you are somewhere around Indianapolis Indiana; assume an end to end efficiency of 0.52 (assuming flooded cell battery bank, AC inverter)--gives you an At the Wall Plug estimate of power available.

Starting with 1kW (1,000 watt) minimum array (smallest supported by program) we get:

"Station Identification"
"City:","Indianapolis"
"State:","Indiana"
"Lat (deg N):", 39.73
"Long (deg W):", 86.28
"Elev (m): ", 246
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 39.7"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 7.3 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.18, 52, 3.80
2, 4.14, 61, 4.45
3, 4.44, 69, 5.04
4, 5.15, 75, 5.48
5, 5.73, 84, 6.13
6, 5.84, 79, 5.77
7, 5.92, 82, 5.99
8, 5.67, 80, 5.84
9, 5.20, 72, 5.26
10, 4.70, 71, 5.18
11, 3.07, 45, 3.29
12, 2.37, 37, 2.70
"Year", 4.62, 806, 58.84

We get around 37 kWhrs to 84 kWhrs per month or roughly 1.2 to 2.8 kWhrs per day--depending on season and weather patterns at the time.

If you go with 2.7 kW of solar panels:

"Station Identification"
"City:","Indianapolis"
"State:","Indiana"
"Lat (deg N):", 39.73
"Long (deg W):", 86.28
"Elev (m): ", 246
"PV System Specifications"
"DC Rating:"," 2.7 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 1.4 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 39.7"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 7.3 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.18, 140, 10.22
2, 4.14, 165, 12.04
3, 4.44, 186, 13.58
4, 5.15, 202, 14.75
5, 5.73, 226, 16.50
6, 5.84, 213, 15.55
7, 5.92, 221, 16.13
8, 5.67, 216, 15.77
9, 5.20, 194, 14.16
10, 4.70, 190, 13.87
11, 3.07, 123, 8.98
12, 2.37, 101, 7.37
"Year", 4.62, 2177, 158.92

With that size of array, we even meet the 100 kWhr target for winter (101 kWhrs per month of useful power at the AC wall outlet).

Remember the above numbers are all approximate. Local climate and weather conditions will always drive how you use power and alternative sources for backup power (grid, genset, conservation, etc.).

Rev. Marshall, please don't take what I say as any sort of useful answer for you to reconfigure your system... I have no idea of your power usage, where you life, your system requirements, etc...

My/our aim here is to give you the tools to understand and begin to design your system based on your needs and abilities.

If anything I suggest does not make sense to you--please ask. I may have misunderstood something you typed and/or I may flat out be wrong in my opinions/suggestions... But at least it will be a good starting point.

-Bill

VanDeusen · March 2010

Re: Please help, Very confused

there is totally NO offence. I appreciate ALL the info regardless as I need to learn the RIGHT way.

As far as the 3 POS and 3 NEG's going from the back of the inverter to 3 different b atteries that has now been changed. ALL the pos's are going to the FIRST battery and all 3 NEG'S are going to the LAST battery and the MAIN 100amp breaker in the breaker box has been changed to a 30 amp. Batteries now seem to be charging a lil faster then before.

Also let me try to better explain how the batteries are running in parallel. 5 battery deep so there is 2 rows.

with 10 batteries they are

battery 1 pos and neg's are going to batter number 2 which goes to #3 to #4 all the way to 10.

battery #1 pos is going over to battery #6 as well as the neg.

Battery #5 is doint this as well.

os in addition to the batteries going in parallel 1-10 1&5 and 6&10 are connected as well.

Thanx

Please help, Very confused

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