complete mixed system

Hello Everyone, I am sort of new to all this and need some assistance/advice/direction please. I have a mixture of odd and end panels all 12v some have no labels but none are newer that 12 years, I propose to combine all together and charge batteries/battery and run one circuit in my home, my bedroom. I am pretty much disabled and a senior, I spend a lot of time in here watching TV (on 24-7) and some other items as well, air freshener, some CFL and or LED light(s), 5K window A/C year round, and a dorm refrig, computer charger, clock radio, and a ceiling or tower fan at times. I would like to run this circuit for as long as the DC source holds up and automatically switch to backup AC when batts are down, until recharge then auto switch back to DC, repeat, repeat. I know this is not much, but if I can stay off the grid for 3 hours in 24 to me thats better than nothing, I already have the panels, and inverter, and a 100 amp(uncertain) transfer switch, just need diodes, and batt(s) Now for the questions, How do I size the diodes for each panel not knowing some of the specs? If I have a broken glass panel that produces less than the others then the complete system will be at what the lowest value is in the array, correct? Would it be better to leave the weaker panel out ? I have a 2000 watt inverter, if I omit the window A/C and the circuit is well below the 2000 watt level do I need to have a smaller inverter? I read somewhere that one must not oversize the inverter to the load or battery, is this correct? Being on a fixed income I can't afford a new batt(s) would the marine batts at Walmart be my best bet? Do I need a charge controller between the batts and panels? Sorry for all the Q's but I would like to get these panels out of the shed and put them to use, Or would I be better just to sell these panels and start over ? Some are twenty plus years old and used, then others were purchased in between those and 10 -12 years ago new. Thanks for all the help.
Wilber256
Wilber256
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Battery based solar power systems will not save you any money, in fact they will cost you much more per kilowatthour than what you are paying the power company.
If you have favorable net metering laws in your location, a grid-tied system can be cost effective with a payback of just a few years. In a grid-tied system, the grid is your battery... when you have extra power you sell it to the power company.
Those marine "deep cycle" batteries at Walmart are not true deep cycle batteries... they will last about a year in real deep cycle service.
--vtMaps
But first reduce the load for there are needs versus wants. Wants are much more expensive to power ... but, if you live in a very hot area, aircon is not a want, it becomes a need.
If you have the parts, what I have done was to mount enough panels, yes you need a charge controller between panels and batteries, to power my load daytime with the absolute minimum batteries. Batteries are there for 2 reasons: 1) as backup in case of power failures and 2 ) to power the inverter via the solar panels.
The trick comes in by discharging the batteries as little as possible. In my case, the Depth Of Discharge is set to 5% (95% remaining) of battery capacity at which time the system switches back to utilities automatically. I do this with a Victron BMV700 battery monitors relay, switching larger 220v relays. Yes, I do need a UPS to handle the break between utilities and solar power changeover, but it can be handled without one if you can set say a 8ms changeover break between utilities and inverter power. You cannot swap instantaneously between inverter power to utilities and back. Equipment will eventually fail.
So, the less batteries AH you use, the longer they will last plus less charging is required in the mornings meaning faster switch over to using solar power daytime. I run off solar from +-8h30 till 18h30 with 5% of the batteries used early evening, in summer.
In this case it may be an option to get cheaper batteries, for they may last 3-5 years if not discharged below 20% DOD, less is better.
And it is especially good if the batteries have the ability that you can check their water levels, not the maintenance free ones, for then you can check the water levels over time.
--vtMaps
How many and what size panels do you have? Yes size as in 2 feet by 4 feet works also. If you don't know what voltage give us a count of the number of cells on the panel. Something like 2x4 feet with 36 cells. They cell count will give us a general idea of voltage.
I would suggest leaving out cracked panels and 32 cell panels (if you have any).
If your idea is to save money. The first plan would be to use what you've got. Money is almost always better spent reducing your load than buying solar, particularly off grid (not feeding electric back into the grid) but perhaps if you have enough, panels to make it worthwhile, some minimal additions would be okay.
If you are home all day, you might want just a minimal battery, primarily for starting loads. and run as near as possible to what the array can generate.
What type of inverter do you have? Most inexpensive inverters are modified sine wave and could create problems by shortening the life of motors and some electronics.
A TV on 24/7 can be quite a load!, what type of TV do you have? Some big screen TV's of early design can use 200 and up watts, Some new designed LED back lit designs use closer to 30 watts. I have and energy star 24" TV from @10 years that uses about 55 watts, I replaced that about 5 years ago with an energy star 39" that uses about 55 watts, today some 55" TV's use less than 40 watts!
Where do you live, that an air conditioner is run year round! I would be sure to look into how well insulated the house or room is! If it's a single room inside a larger house, be sure your door and window seals are good!
You might dump the air freshener and put in some plants, some plants are good air fresheners as will as filters and providers of oxygen....
I switched from a 2nd shift job to a 9-5 job a few years ago, being at home works pretty well for a lot of what solar does. So let us know what you've got and we'll see if we can come up with some targeted solutions!
Also read and watch some videos about basic solar setups, lots of bad info out there, but a lot of good too. You will need a charge controller to correctly charge your batteries. Solar panels tend to be fine with age, I put back in service a 35 year old panel last year to run a water pump in a hydroponic garden and she wants my other 2 for this year!
WalMart Marine batteries are a waste of money. a golf cart battery is likely the way to go, but lets see what you are starting with!
Thanks All
They are a wee bit expensive but sometimes you can get a 2nd hand BMV600, for next to nothing. The SOC and relay contained in them, is what I was always after.
VTMAPS, interesting. I did not know of potential lead dioxide clumping.
At least there are some suggestions here now that Wilber can start working from. If I was close, I would have donated a few unused parts to him, for as with most solar experimenters, we always have parts we never use.
Any case, leisure batteries are more suitable for UPS'es, they are left in fully charged state most of the time until power is needed once in a while, therefor my suggestion. So Wilber going to 20% should be perfect I recon, for as Photowit said: "If you are home all day, you might want just a minimal battery, primarily for starting loads. and run as near as possible to what the array can generate."
Ps. I think I am going to start using my T105RE's on Friday and Sat evenings up to 50% DOD, for Sat and Sun mornings most computers are off, wasted power.
You need a charge controller between the panels and the batteries.
A battery monitor is often compared to the gas gauge in your car, but that is not a good analogy. The gas gauge in your car actually measures the level of gas in your tank. A battery monitor doesn't measure the level of anything. It is more like the odometer in your car. The odometer counts miles and the battery monitor counts ampHours.
Suppose you have a car that gets about 25 mpg and has a 15 gallon gas tank. Suppose also that your gas gauge does not work. What do you do? You use your odometer. For example: After a fill up you drive 150 miles and you expect that you have used 6 gallons and have 9 gallons remaining in your tank.
If you fill up the tank again you can, as above, use your odometer to estimate your gallons remaining.
But what if you do not completely fill your tank. For example, starting from a full tank you drive 150 miles and then you add 3 gallons to your tank and then drive 100 miles and then add 4 gallons to your tank and drive 150 miles and then add 5 gallons to your tank and drive 100 miles. At this point you estimate that you have 7 gallons remaining in your tank, but that estimate is not too accurate because your mileage is not exactly 25 mpg. The only time you know exactly how much gas is in your tank is when you have just filled it up (or when you run out of gas).
So it is with your battery monitor. The only time it is exactly accurate is when you fully charge your batteries and reset the battery monitor to read 100% full. It can be very accurate counting the amphours in and out of the battery, but it can only estimate the state of charge based on what you tell it of the battery capacity and of the battery efficiency. And remember, capacity and efficiency depend on temperature and vary over the life of the battery.
When a battery is cold or old, it has reduced capacity... if you draw 50 ah from a 200 ah battery, the battery monitor will say "75% SOC". But if your battery has an actual capacity of 100 ah and the battery monitor doesn't know that, it will still say "75% SOC" when your actual SOC is 50%.
By the way, you need to tell the battery monitor the efficiency of your battery... otherwise it can read 100% (by counting amps into the battery) before the battery is fully charged.
--vtMaps
You americans are softys, got used to your central heating. The average indoor temperature in NZ is something like 14-16 degrees celciius (60F). If you want to save some money, then reducing the thermostat to 60, and putting on a layer or two is going to cost you the grand total of...exactly nothing.
Quite tricky to cut heating costs in the wintery north though. NZ power bills (depsite really high grid charges) are a good deal less than yours. How many kWh do you use each day? NZ average is 20kWh/d, the US is 32kWh/d, which is the second highest in the world. See http://shrinkthatfootprint.com/average-household-electricity-consumption
Solar can however be a neat project, something to keep the hands and mind busy. So if you can locate a real good deal on a battery, then you might be able to get a system going with some surgical additions, and careful planning.
As far as new batterys go GC2s are as cheap as they get. But you may not have a place to store them, and you just might be able to, with some research locate some ex telco AGMs, that while not an ideal battery, can be made to work, and can be picked up dirt cheap. Theres a few here who have done it, The key for you is keeping the cost down.
http://zoneblue.org/cms/page.php?view=off-grid-solar
Don't go out and buy anything, until you/we figure out what you have!
I think you might impose an 'unemployment policy', strange as it seems. After 10 years at a job that largely went south, first cut back, then disappeared. I found my self on unemployment 3-4 years ago. I had no bills and was comfortable collecting unemployment, but they have this nasty requirement that you must record 3 contacts that you made for employment each week. I really was sorta milking the system, but during those required contacts I was first offered a part time job, that I could reasonably refuse (35 miles from home) then a full time job, which I accepted. If they are there and able-bodied requiring them to look for work and/or do a few hours of work around the house each week is more than fair. It will make them better people!
Kinda major off topic, but tough love man, a 22 year old needs to be paying full market board. Thatll make him find a job right smart. Give him a window to sort it. Nagging as you found tends to be ineffective.
http://zoneblue.org/cms/page.php?view=off-grid-solar
1. MFG. ?
Model?
Volts: 22.3
Watts:?
Amps:?
18.5"x12.5"
Made in China (MIC)
Thin film panel?
Condition: New, but old
Notes: Has batt clamps they plug into a built on receptacle. may have used in past to keep charge on auto, mostly stored in shed.
2. MFG.?
Model: MODSP30
Serial: SP1000309342
Volts: 21.9
Watts: 30
Amps:?
31.75"x13.50"
Made in: Overseas
Thin film?
Condition: New, but old
3. Phoenix or maybe Intersolar LTD?
Model: B107W ?
Volts: 22.5
Watts:12
Amps:?
12.25"x36.25"
Made in:
Condition: New, 15-20 years old?
Notes:
: B107W ?
Volts: 22.5
Watts:12
Amps:?
12.25"x36.25"
Made in: United Kingdom
Thin film Silicon
Condition: New, 15-20 years old?
Notes: Had to remove connector to get any reading
4. MFG: Uni-Solar
Model: US-64
Serial: US-64 114870
Volts: 23.1
Watts: 64
Amps: Max=3.8 Short=4.8
29"x53.5"
Made in MI.USA/Mexico
Cells: 2 rows of 11
Condition: Used, 13 years old, minor damage
Notes: Made of plastic/fiberglass? Frame less, Has J box, came from highway dept road sign. WWW.uni-solar.com
5. MFG: Arco Solar
Carrizo Solar Corp
Model: M51
Serial: 119622
Volts: 20.4
Watts:?
Amps:?
12"x48"
Made in CA. USA.
Cells: 2 rows of 12, 1 row of 11 (center)
Condition: Used, 30 + years old
Notes: Has Diode connected to + in J box.
6. MFG: Arco Solar
Carrizo Solar Corp.
Model: M51
Serial: 120223
Volts: 19.9
Watts:?
Amps:?
12"x48"
Made in CA USA.
Cells: 2 rows of 12, 1 row of 11 (center)
Condition: Used 30 + years old, SHATTERED GLASS
Notes: SHATTERED GLASS, Has diode connected to positive (+) in J box
7. MFG: Arco Solar
Carrizo Solar Corp.
Model: M51
Serial: 119606
Volts: 19.7
Watts:?
Amps:?
12"x48"
Made in CA. USA.
Cells: 2 rows of 12, 1 row of 11 (center)
Condition: Used 30 + years old
Notes: Has diode connected to + in J box.
More or less, get a cheap weather station or indoor humidity meter and monitor what goes on in the home. Over 60% relatively humidity for 3+ straight days, and you have the starting of a good mold/mildew farm.
There are other ways of controlling humidity (dehumidifier, heat recovery ventilator, etc.).
Don't trade one solution (lowering heating bills) with other expenses (running a dehumidifier) or worse, damaging your home and health (mold).
-Bill
Many of your panels are 12 watt (to maybe 20-40 watt maximum). By time you wire those panels up--You have a lot more money/time spent in mounting and wiring. Plus, the problem of maintenance (failed wiring connections from weather/time, etc.).
One 140 Watt panel (which is relatively small these days) is the equivalent of ~10 to 12 of the small 12 watt panels you are looking at using. 1/10th the wiring, 1/10 the mounting, 1/10 the possible wiring issues/costs.
Look around (Craig's List, etc.) and see if you can find some larger panels at $1 per watt or less. $1-$2 per watt + shipping is the rough price for panels these days.
And, depending on what panels you find (Vmp~18 volts vs Vmp~30 volts or other)--You may have to change charge controllers (PWM vs MPPT) and/or battery bank voltage for optimum system design.
But--Be careful here. We are putting the cart before the horse. You need to design a "balanced system" that will support your loads. If the system is too small--It simply will not give you the power you need. And if too large, it is a waste of money.
In the end, if you are trying to save money--Start with extreme conservation in your home. It is almost always cheaper to conserve power than to generate it. And for off grid power systems, it is not unusual for the all up costs of off grid power to cost you 5-10x the cost of utility power. Batteries that last 5-8 years, electronics (inverters, charge controllers) that need replacing every 10+ years, etc... It all adds up.
For pure off grid homes--It is possible to get down towards 3.3 kWH per day (100 kWH) per month and live a near normal electric life (use propane, wood, etc. for heating/cooking/hot water--And/or solar thermal for hot water/heating). That may be a $20 per month electric bill.
If you still want solar/battery backup to ride out power failures (weather, accidents take out power pole, etc.), solar+genset backup can still make sense--But this is usually a secondary reason. And if your outages are relatively rare--A backup genset can be a lower cost solution. And you still need to analyze your emergency loads. Again, balance the power source to your power needs.
-Bill
Wilber, I don't think there is enough there to suggest you continue building a system, if your goal is saving money.
If every thing that isn't cracked worked you might have;
1 amorphous pnel with likely a 10 watt output
2. amophous panel with a 20 watt output
I'm guessing these are actually amophous panels, voltage is too low to be thin film panels (generally)
3. amorphous panel with a 12 watt output
4. US-64 a good panel, but since they are not glass tend to cloud up and produce less over time.
5. Arco m51 about a 50 watt panel?
6. M51 shattered glass
7 M51 about a 50watt output.
I wouldn't use the shattered glass panel, I would be more worried about it it losing a connection than shorting out, but it is likely a headache waiting to happen.
The M51's are a bit of history You state 'carrizo' panels so they were likely made for a large power plant in Carrizo valley(?) that was never made after Arco sold out to Seimens(?) (Needs some serious fact checking here!)
So you have what might be 200watts of array if everything was working fine and newish. More likely they have reduced 1/2-1% per year and the plastic coated UniSolar panel at about half of capacity. So 120-150 watts of array possible, when in perfect conditions. Maybe 75% of that in normal conditions. say 100 watts, a nice round number to work with.
On an average day you will have 4 hours of sunlight (you can check charts of solar isolation to find closer to your area) so might generate 400watt hours of electric, or about 4 cents. Thaat's a bit less than $15 a year. Batteries, a reaccuring cost would run a minimum of $100 every 5 years. And we haven't talked about fusing or a charge controller or other expenses.
If you would like to play, understanding that you will likely spend more than it returns. I know where an inexpensive charge controller can be had that would handle the 3 good larger panels. and you might hook up a throw-away car battery and try to run a few things directly off 12 volt during the day. Maybe even a couple 12 volt fans like the 0'2Cool fans, which might run off a single panel directly....