# Gird Down Solar Energy



## 8301

Ok, Many of us are interested in ways to make electricity when the grid is down but rarely do we seriously test our systems. 

While I've used my solar system to run my deep freezer in the garage and during power outages before over the last 3 years I've not tried it at this house after no power for over 2 days (freezing rain got the trees to fall on the power lines). Going down to 9 degrees tonight.

The system, 490 watts of solar panels, TriStar 45 amp controller, 1000 watt pure sine wave inverter, 3 type 27 12v AutoZone deep cycle batteries Total cost about $1450 three years ago. I have a 3000 watt modified wave inverter capable of running the refrigerator but not hooked up; it would be hard on the small battery bank.

Heating by two woodstoves. Well and large old refrigerator hooked to a generator I run 4 hrs a day (1 1/2 gallons of gas per day)

Rechargeable battery lanterns that are recharged during the daylight hours from solar system combined with florescent lamps that run off of the solar batteries provide adequate light. 

DSL modem, computer, TV with satellite receiver, (115 watts) can easily run for 12 hours a day on the battery bank. Solar also kept phones and ipod charged.

This allows me to not draw the batteries below 50% extending battery life assuming decent but not super strong (some clouds) sunlight each day.

Yes, I prefer being tied to the grid and yes I wish my solar system was large enough to run the well but it sure is nice to go online while watching TV in the evenings without running the gas drinking generator.


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## Arklatex

Sounds like a great setup. How long will it run your deep freeze? I want to setup a system for mine. It is 5amp 115v 60hz. Would also like to do the well pump but I've heard that can be very expensive due to the cost of batteries and inverter. Haven't researched it much. I'm also looking at hand pumps for it since all I have now is a generator and a torpedo bucket.


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## paraquack

Can't you just open the garage door to keep your freezer cold? LOL


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## BagLady

That does sound like a nice set up. If I may ask, about how much have you invested so far?


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## 8301

Arklatex said:


> Sounds like a great setup. How long will it run your deep freeze? I want to setup a system for mine. It is 5amp 115v 60hz. Would also like to do the well pump but I've heard that can be very expensive due to the cost of batteries and inverter. Haven't researched it much. I'm also looking at hand pumps for it since all I have now is a generator and a torpedo bucket.


It runs my 7 cu/ft freezer all the time. since this freezer has a 1.69 amp draw at 120v (204 watts) and the freezer cycles so it's not always running. My solar system even with it's "getting older" batteries keeps it running.

The AutoZone type batteries (106 amp/hr reserve) age rapidly when used continuously. They are only good for 3-4 years when used in an active solar setup. High quality Golf Cart batteries will last a little longer and R/E batteries, especially the very expensive Surettes, will really last a long time but to save money I went with cheap batteries when I built this system back in 2011. I plan to get a better battery setup when these finally die. With a battery based R/E system the batteries are a major part of the investment. The three "cheap" batteries I'm currently using cost about $400, the solar panels with shipping cost about $500, the TriStar MPPT 45 amp charge controller about $300, the good 1000 watt pure sine wave inverter was about $170, A breaker, a 50 amp fuse, a Dr Watts power meter, and wire were the rest of the expense.

Running a deep well requires a serious 240v inverter, the type that comes with a built in battery charge controller when used with Solar. About $2500 for a 5500 watt peak and a 7000 watt 30 minute surge rating.  If instead you have a bored well that is shallower you probably can get away with some of the lower energy required solar pumps.


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## 8301

Gris power is back this morning. Nice to be able to run the hot water heater. 

I did just let the cold garage keep the freezer cold while I used the solar system to power stuff in the house.

BagLady, about $1450 for the materials and I built the stands from wood and wired it myself. It's not super hard to do but since I already play with electric turbines I knew to get a MPPT charge controller instead of one of those $40 20 amp solar controllers to maximize the energy produced.


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## Arklatex

I just checked out type 27 batteries. Seems they are mostly used for rvs and trolling motors. Nowadays they are running over $200 on average. The more expensive ones are gel cell, is that a big advantage as far as battery life?


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## Arklatex

I have to say that solar is probably not going to pay for itself in energy savings. But it pays for itself when you need it most so it's still a good investment imo.


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## 8301

Arklatex said:


> I just checked out type 27 batteries. Seems they are mostly used for rvs and trolling motors. Nowadays they are running over $200 on average. The more expensive ones are gel cell, is that a big advantage as far as battery life?


Yep, they make dandy trolling motor batteries, Gel batteries and regular "add water to them" batteries have about the same life span assuming you check the water level in the regular batteries every few months. Gels cost more for the same quality and output but if you're into lower maintance can be a good choice.

Personally I'm lazy and only check the water in my batteries about three times a year. Usually they need a little water, once a few years ago they really needed it so I probably did a little damage to them but they are still working. Rapid charging in high solar conditions is what "boils" the water out so I tend to check them more in the summer.

With the additional cost of the batteries that need to be replaced every 3-10 years for most of us a solar system probably won't pay for itself. A grid tie system without batteries will pay for itself but it may take 10+ years.


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## BagLady

FoolAmI said:


> Gris power is back this morning. Nice to be able to run the hot water heater.
> 
> I did just let the cold garage keep the freezer cold while I used the solar system to power stuff in the house.
> 
> BagLady, about $1450 for the materials and I built the stands from wood and wired it myself. It's not super hard to do but since I already play with electric turbines I knew to get a MPPT charge controller instead of one of those $40 20 amp solar controllers to maximize the energy produced.


That's not bad at all! Even using the expensive batteries would be affordable. I'd always heard quotes to $25,000.


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## HuntingHawk

BagLady, I ended up with just shy of $1,700 into my 520watt system. Three 125AH 12V batteries. But my inverter is twice the size of FoolAmI. Prices have come down on panels since I had bought mine. I collected old bed frames from the dump & used that angle iron to weld up my frames. I used all 8 gauge stranded wire for my system.


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## Arklatex

HuntingHawk said:


> BagLady, I ended up with just shy of $1,700 into my 520watt system. Three 125AH 12V batteries. But my inverter is twice the size of FoolAmI. Prices have come down on panels since I had bought mine. I collected old bed frames from the dump & used that angle iron to weld up my frames. I used all 8 gauge stranded wire for my system.


Are those the type 27 batteries? Or a different type.


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## HuntingHawk

I had to go look. Mine are marked 29DC. And yes, they are from Walmart.


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## Slippy

Excellent thread to all! This is the kind of information that makes being a member of Prepper Forum worthwhile. Solar is one thing that we are constantly researching and hope one day to have our system in place.

Thanks


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## HuntingHawk

You buy solar panels from a local s&b & you'll pay out the butt & sales tax. Mail order you have to pay oversize shipping. Depending on physical size of the panels this might be $15-25 per panel. And panels are normally shipped two to a box. So buying on sale helps with pricing. Another option is buying by the pallet which is normally 10 panels per pallet. Pallets can be drop shipped.

Controller, inverter, etc can be shopped for best price on amazon, ebay, etc.


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## HuntingHawk

Three 125AH panels in parallel equals a total of 375AH & rule of thumb of not draining batteries below 50% would be 187AH available for use from full charge.


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## HuntingHawk

The big advantage of a solar system running a chest freezer is making ice. Loss of commercial power & I can use frozen ice jugs to keep stuff in frig or coolers cold & keep rotating jugs.


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## HuntingHawk

Just something to consider:

Gas generator, battery charger, battery bank, & inverter. During the day you can use the generator to run the frig & such at the same time charging the batteries. Then at night with generator off run stuff like lights off the batteries & inverter.

Batteries & inverter will give you part of a solar system.


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## 8301

BagLady said:


> That's not bad at all! Even using the expensive batteries would be affordable. I'd always heard quotes to $25,000.


 A system that can completely replace all of you electric needs including an electric stove and hot water heater with a battery bank good for a few days can easily top $25,000. Unless you're made of money you've got to be realistic about how much you're willing to pay for when the grid goes down. Back then it started out at about $1000 for me with 200 watts of panels and 2 batteries. A year later I spent much of my prepping budget on another 290 watts worth of panels and an additional battery. Since I spent the money on a good charge controller at the start I was able to expand my system although to go any larger I'll need to go to a 24v or 48v battery bank to reduce the amperage going through the charge controller. The higher battery bank voltage will require a different and very expensive inverter so I didn't expand it the last 2 years. Maybe this summer.


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## 8301

HuntingHawk said:


> Just something to consider:
> 
> Gas generator, battery charger, battery bank, & inverter. During the day you can use the generator to run the frig & such at the same time charging the batteries. Then at night with generator off run stuff like lights off the batteries & inverter.
> 
> Batteries & inverter will give you part of a solar system.


I agree that that's a good way to go except for how slowly most battery charges work. A 500 watt solar system is putting out 35+ amps at 12v for 5+ hrs a day and about 10-20 amps a few more hours a day which can easily charge three type 27 or 29 batteries. Most battery charges that we would own can't put out over 12 amps for more than a few minutes so figure 12 amp output from a plug in charger so the generator would need to run about 15-20 hours a day to power the battery charger putting out 12 amps to recharge the three fairly large batteries. I'd instead suggest having just one type 29 (125 amp/hr) battery (so it charges faster) and realize that you don't have a ton of TV and internet time with it but still a few hours. You can also power lots of other stuff while the generator is running.

I keep a 12 amp charger that can run off the generator to help charge the batteries if it rains all day but I've never had to use it. They've always held enough charge to run the freezer chest until the sun comes out.


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## 8301

Type 24, 27,29 ect are just the battery case sizes but a type 27 is usually about a 105 amp/hr battery and a size 29 battery case usually holds about 125 amp/hrs worth of battery at 12v.


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## HuntingHawk

A friend has over 11K in solar panels. Even with that, in the summer he has to turn the AC off at sundown because it would drain the batteries too quick. And he has a gas stove & hot water heater. But two large chest freezers as he's a deer & wild hog hunter.


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## HuntingHawk

My solar system is basically 30amp at 120VAC. When I expand, it will be a completely separate system, probably 20amp due to available roof space for panels. You don't mix old & new batteries. So if a battery dies you replace all at the same time. In my case, that is three batteries which is about $300. So with two systems & the batteries of the systems 3 or 4 years apart. no big expense at one time.


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## alterego

I have become a solar pervert looking at every thing.

Most batteries flood lead acid of gel sealed even the really good ones from rolles have 1000 cycles when drained 70 percent and less than 500 when drained 50 percent. If you use battery 1000 cycles divided by 365 days is an incredibly expensive means of power.


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## 8301

alterego said:


> I have become a solar pervert looking at every thing.
> 
> Most batteries flood lead acid of gel sealed even the really good ones from rolles have 1000 cycles when drained 70 percent and less than 500 when drained 50 percent. If you use battery 1000 cycles divided by 365 days is an incredibly expensive means of power.


Expensive,,,, I agree but if you keep an eye on your battery bank and keep it over 50% those same batteries will last for 10+ years.


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## 8301

A quick thought for those of you who think an EMP event will be what brings us down. Depending on where you live solar may not be a good choice. Most charge controllers and pretty much all inverters have solid state electronics which probably will not survive a strong EPM pulse.

We all think about EMP from the book One Second After where 2 EMP bombs bring down most of N. America but scientist have since chimed in and shown us that while an EMP device close by will damage fragile microchip devices such as that electronic lock on your safe or that radio you love so much. The EPM effect is reduced by distance so unless you live within 100 miles of a major potential target you're probably safe.

I suspect that if the terrorist do manage to get a hydrogen bomb (and they very well may have managed to get one from the decaying Soviet Union) and they also get a missile that can deliver it (harder to get) I doubt they will manage to shoot more than one or two. Those of you out in Montana are probably very safe from an EMP attack. People close to Washington DC are at a much higher risk.

And assuming the terrorists have managed to get a hydrogen bomb they would probably prefer to put it on a boat and ship it to NY or LA harbor instead of going through the almost impossible process of getting an ICBM which would more than triple the chances we would find out about their plans in time to stop them.


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## alterego

FoolAmI said:


> Expensive,,,, I agree but if you keep an eye on your battery bank and keep it over 50% those same batteries will last for 10+ years.


I really wish you were correct. However the information on the manufacturer Web site stops charting at 2500 cycles or days.

believe me the manufacturer are not going to publish data that looks worse than reality.

Surrette Batteries 6-Cs-21Ps 6V, 683Ah (20Hr) Flood L-Acid
Basically no one can aim for ten percent battery discharge because of the cost. 30 percent discharge is about the best you can do. 30 percent puts you at 1800 cycles. 1800 cycles is 4 years and 9 months.0 SD


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## 8301

Surrette has a 10 year prorated warranty on many of their batteries including the ones on the cycle chart listed below. Personally I rarely go below 30% depth of discharge and most days less than 20% discharge. As I mentioned in an earlier post longer lasting batteries tend to cost more, sometimes a lot more, this is why I currently run a very inexpensive brand of battery and I'd be surprised if they make it through another summer which will be their 4th year at which time I intend to put a better set of batteries in.

And for the really expensive batteries the Edison Iron RE batteries can handle 16,000 cycles at 90% discharge. Iron Edison USA Series Nickel Iron (NiFe) Battery

final thought,,, As someone who has been installing Hydro generators as part of my job occasionally for the last 10 years and sometimes hooking them to preexisting RE systems do you really want to debate this??? I agree that battery backups for an RE system are very expensive but something I loved having when the power went out this week.

I'm sure you are much more knowledgeable than me at what you do for a living. However this is related to what I do for a living, especially back when I was designing and building small (less than 1200 watt) custom Kaplan and Turgo turbines.

Warranty Information from Rolls website

Number of Cycles 
% Discharge Series 4000 Series 5000 
20% 2000 5000 
30% 1707 4200 
40% 1493 3700 
50% 1280 3200 
60% 1120 2800 
70% 960 2400 
80% 800 2100 
90% 700 1800 
100% 590 1500


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## HuntingHawk

Setting up a useable solar system isn't cheap. And if you are mostly concerned about payback time forget it. I initially did four 80watt panels & it wasn't quite enough to operate anything except some lights. But after adding two 90watt panels I had enough I could operate a small chest freezer 24/7. So I think right at 500watts is minimum to do something with. I have disconnected from the chest freezer & run a 10,000BTU air conditioner for an hour with the system. Would probably take 1K to run that AC during daylight hours. Temperature setting on the AC would make a difference also.

Commercial power is lost & you don't have to make trips trying to find fuel for your generator is when solar really pays for itself.


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## alterego

FoolAmI said:


> Surrette has a 10 year prorated warranty on many of their batteries including the ones on the cycle chart listed below. Personally I rarely go below 30% depth of discharge and most days less than 20% discharge. As I mentioned in an earlier post longer lasting batteries tend to cost more, sometimes a lot more, this is why I currently run a very inexpensive brand of battery and I'd be surprised if they make it through another summer which will be their 4th year at which time I intend to put a better set of batteries in.
> 
> And for the really expensive batteries the Edison Iron RE batteries can handle 16,000 cycles at 90% discharge. Iron Edison USA Series Nickel Iron (NiFe) Battery
> 
> final thought,,, As someone who has been installing Hydro generators as part of my job occasionally for the last 10 years and sometimes hooking them to preexisting RE systems do you really want to debate this??? I agree that battery backups for an RE system are very expensive but something I loved having when the power went out this week.
> 
> I'm sure you are much more knowledgeable than me at what you do for a living. However this is related to what I do for a living, especially back when I was designing and building small (less than 1200 watt) custom Kaplan and Turgo turbines.
> 
> Warranty Information from Rolls website
> 
> Number of Cycles
> % Discharge Series 4000 Series 5000
> 20% 2000 5000
> 30% 1707 4200
> 40% 1493 3700
> 50% 1280 3200
> 60% 1120 2800
> 70% 960 2400
> 80% 800 2100
> 90% 700 1800
> 100% 590 1500


Thank you for the information. I just read the battery Web site mentioned above. 5800 for a 100 ah battery. 11200 for a single 300 ah battery. We have been averaging 640 kw of usage per month by rounding up as every one indicated we need a minimum 840 ah battery. This would be we well over 30 thousand from your post.

Please do not get so defensive. I do not see in your work history that you are a battery design engineer.

I will debate any thing if armed with manufacturer provided data.

I am truly interested in putting a solar system in at our house that would make it usable. I am not interested in a few thousand play toy.

I am willing to spend up to 25 thousand to have an operating system. However to be able to fully operate our home it looks more like 30 thousand and the batteries will need to be replaced every five years. For a cost of 8000 alone. By your post above it would be more than 30000 for an operating battery to last 20 years. So now I am at 55 to 60 thousand.

At that cost it becomes ****ing stupid to consider solar.

I really want to do something.

I apologize you have such a complex that you believe you know everything.


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## 8301

repost below


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## 8301

alterego said:


> Thank you for the information. I just read the battery Web site mentioned above. 5800 for a 100 ah battery. 11200 for a single 300 ah battery. We have been averaging 640 kw of usage per month by rounding up as every one indicated we need a minimum 840 ah battery. This would be we well over 30 thousand from your post.
> 
> Please do not get so defensive. I do not see in your work history that you are a battery design engineer.
> 
> I will debate any thing if armed with manufacturer provided data.
> 
> I am truly interested in putting a solar system in at our house that would make it usable. I am not interested in a few thousand play toy.
> 
> I am willing to spend up to 25 thousand to have an operating system. However to be able to fully operate our home it looks more like 30 thousand and the batteries will need to be replaced every five years. For a cost of 8000 alone. By your post above it would be more than 30000 for an operating battery to last 20 years. So now I am at 55 to 60 thousand.
> 
> At that cost it becomes ****ing stupid to consider solar.
> 
> I really want to do something.
> 
> I apologize you have such a complex that you believe you know everything.


As I've said in previous postings while in many cases battery less grid tie solar insulation will often pay for itself the expense of a battery bank capable of running a modern home for 3 rainy days is prohibitive. This is compounded by the face that inverters that can also handle battery charging tend to be less efficient.

There are two compromises available; both use a grid tie setup. One is to simply limit the battery bank to a small affordable size with the realization that you will really be limited when the grid goes down.

The second choice is an inverter made in Germany (can't remember the company name) that works as a batteryless grid tie inverter. when the grid is down during daylight only the inverter supplies 1500w AC to a box you can hook to. The inverter is around $4000 and capable of putting out close to 7000w with high efficiency when tied to the grid.

There are many people on this forum who have solar systems and know the basics, an important survival knowledge in my book but when it comes to RE energy on this forum I may be about as close to an expert as you are going to find. I've played with solar and RE systems (including wind and hydro) for over 30 years but never was interested in the 2 years of schooling to get my NEC license.

Perhaps you'd like to discuss panel matching to maximize controller output? Or perhaps rewiring a PM gearmotor to make it a low input rpm PMA?


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## HuntingHawk

$4,000 would be enough to make a 1KW solar system with plenty of battery bank using four 6V batteries.


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## 8301

HuntingHawk said:


> $4,000 would be enough to make a 1KW solar system with plenty of battery bank using four 6V batteries.


I like to figure pricing by $ per watt. With a modest battery bank (about 200 amp/hr at 48v) I'm comfortable with about $3 to a watt with my current controller or $4.50 a watt if I go with a 240v controller/inverter. I agree with your earlier post about 500 watts barely being enough to do much with when the grid is down so I've been considering expanding my system this summer. I'd love to be grid tied to maximize my ROI and get the tax break but I'm having trouble finding a certified electrician willing to deal with a RE system in my area and the local utility would want to know a certified electrician did the work and signed off on the panel grounding before they swapped the power meter.

The electricians I've talked to are willing to install the entire system (for a ton of money) but not interested in doing just the final hookups and certification.

My site has very little shading so I should be able to avoid the expense of micro-inverters.


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## 8301

HuntingHawk said:


> Setting up a useable solar system isn't cheap. And if you are mostly concerned about payback time forget it. I initially did four 80watt panels & it wasn't quite enough to operate anything except some lights. But after adding two 90watt panels I had enough I could operate a small chest freezer 24/7. So I think right at 500watts is minimum to do something with. I have disconnected from the chest freezer & run a 10,000BTU air conditioner for an hour with the system. Would probably take 1K to run that AC during daylight hours. Temperature setting on the AC would make a difference also.
> 
> Commercial power is lost & you don't have to make trips trying to find fuel for your generator is when solar really pays for itself.


I ran a 5000 btu window AC for 2 summers off of my smaller solar system. I generally limited it to about 6 hrs a day. The 490 watts of panels could almost hold it when the sun was strong and the small battery bank could take it another 2 hours so I'd start it when I swung by the house to put the dogs out about 3pm and run it until a bit after sundown. I could have run it about an hour longer each day and some days I did but I didn't want to stress the batteries.

I sometimes used a meter inline and the 5000 btu AC unit pulled between 495 and 510 watts so you're dead on with the 1kw for the 10,000 btu AC.


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## alterego

I believe I will be looking to run ac from a timer. From 11 am to 4 pm this should allow a few hours in the am uninterrupted to recharge batteries. I believe you could run our deep freeze from a timer as well. Run during solar generation and then shut it off in sun down. 

All this to limit drag on the battery bank.


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## 8301

I'd suggest just leaving the chest freezer on. A timer on the AC is a good idea assuming you unplug it so it doesn't come on rainy days. With Mono-Crystal panels that charge some in low light you will still get some charge on very cloudy days but probably not enough to protect the batteries from a AC's draw but.... Remember that most inverters shut off automatically when the input voltage gets too low helping to protect your batteries usually around 11.5v when your batteries have about 10% charge left. Since this 11.5v shutoff is while the batteries are under a load in reality a few minutes after the load is off the batteries their resting voltage will bounce back a bit, maybe to around 11.8v so while resting your batteries are still showing about 30% charge.

see

http://modernsurvivalblog.com/wp-content/uploads/2013/06/battery-state-of-charge.jpg


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## HuntingHawk

Heck, full moon I get a trickle charge about all night.

With the AC, not matter what size AC or the space, there is a difference in accumulated power use between a 72, 80, & 85F setting.


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## 8301

HuntingHawk said:


> Heck, full moon I get a trickle charge about all night.
> 
> With the AC, not matter what size AC or the space, there is a difference in accumulated power use between a 72, 80, & 85F setting.


The Kill A Watt power meter I use showed a very consistent amount of power being used as long as the compressor was on and sometimes it could be on for several hours at a time. After the crank up power surge you'd see about 495 watts and after a few hours it would rise to a consistent 510 watts sometimes dropping a few watts much later, probably as the battery voltage began to dip. Since I only had a 5000 btu unit and that room was in full sunshine with poor insulation the AC unit rarely got the room cool enough to cycle the unit on 90+ degree days.

When the compressor did cut off you'd see the power consumed drop to about 40 watts from the fan on low setting (where I always kept it) if I remember correctly.

With higher temperature setting on the thermostat in a better insulated room the unit will cycle much more than mine did on hot days using less energy with the compressor off.


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## 8301

With my new home I don't intend to use a window AC since I have both central air and a whole house attic fan, something you don't see much anymore and I'm surprised this house was built with one. I'll probably hook the solar system to the attic fan this summer since it pulls relatively cooler air all through the house actually creating a good breeze through all of the house..


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## sulfur

alterego said:


> Thank you for the information. I just read the battery Web site mentioned above. 5800 for a 100 ah battery. 11200 for a single 300 ah battery. We have been averaging 640 kw of usage per month by rounding up as every one indicated we need a minimum 840 ah battery. This would be we well over 30 thousand from your post.
> 
> Please do not get so defensive. I do not see in your work history that you are a battery design engineer.
> 
> I will debate any thing if armed with manufacturer provided data.
> 
> I am truly interested in putting a solar system in at our house that would make it usable. I am not interested in a few thousand play toy.
> 
> I am willing to spend up to 25 thousand to have an operating system. However to be able to fully operate our home it looks more like 30 thousand and the batteries will need to be replaced every five years. For a cost of 8000 alone. By your post above it would be more than 30000 for an operating battery to last 20 years. So now I am at 55 to 60 thousand.
> 
> At that cost it becomes ****ing stupid to consider solar.
> 
> I really want to do something.
> 
> I apologize you have such a complex that you believe you know everything.


If you are willing to spend $25,000 and install it yourself, you may be happy with a system similar to mine. My solar system is grid tied most of the time, but it can also run off grid. I have 3 SMA Sunnyboy 7000's, each 7000 watt inverter has 28 panels, 56 240 watt panels and 28 250 watt panels, each inverter has 2 parallel strings of 14 series panels. I also have an SMA Sunny Island and golf cart batteries, that allows me to run the system off grid. I did not invest a lot in batteries yet, since I only use it grid tied, so I would have to conserve power at night if the grid went down, but I could have a lot of power available during the day with grid outage. This is a 20,000 watt solar system, I have a net metering meter that spins backward when I produce more than I use? This makes about $230 per month of electricity on average, much less in winter, much more in summer. The grid tied portion will pay for itself in about 7 years, another couple years for the off grid portion. Grid tied solar is far more efficient and I am not stressing my batteries at all. A system like this may be ok for someone that is willing to conserve power at night in a grid outage situation, also reduces battery replacement cost and frequency. My house is all electric, no gas, geothermal heat pump but I can also heat with wood. I bought the panels on E-Bay and Sunnyboys also on E-Bay, I think I got the Sunny Island at some solar website, batteries from Sams Club. If i was going to be off grid a lot, I would get a lot more batteries, I have 8 @ 6Volts each. You have to carefully plan how to tie in this large of a solar system due to not being able to exceed 120% of bus bar rated amps, most installations may involve installing a larger main panel, but there are some other options. I am posting this since I saw people saying solar can't pay for itself.


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## alterego

sulfur said:


> If you are willing to spend $25,000 and install it yourself, you may be happy with a system similar to mine. My solar system is grid tied most of the time, but it can also run off grid. I have 3 SMA Sunnyboy 7000's, each 7000 watt inverter has 28 panels, 56 240 watt panels and 28 250 watt panels, each inverter has 2 parallel strings of 14 series panels. I also have an SMA Sunny Island and golf cart batteries, that allows me to run the system off grid. I did not invest a lot in batteries yet, since I only use it grid tied, so I would have to conserve power at night if the grid went down, but I could have a lot of power available during the day with grid outage. This is a 20,000 watt solar system, I have a net metering meter that spins backward when I produce more than I use? This makes about $230 per month of electricity on average, much less in winter, much more in summer. The grid tied portion will pay for itself in about 7 years, another couple years for the off grid portion. Grid tied solar is far more efficient and I am not stressing my batteries at all. A system like this may be ok for someone that is willing to conserve power at night in a grid outage situation, also reduces battery replacement cost and frequency. My house is all electric, no gas, geothermal heat pump but I can also heat with wood. I bought the panels on E-Bay and Sunnyboys also on E-Bay, I think I got the Sunny Island at some solar website, batteries from Sams Club. If i was going to be off grid a lot, I would get a lot more batteries, I have 8 @ 6Volts each. You have to carefully plan how to tie in this large of a solar system due to not being able to exceed 120% of bus bar rated amps, most installations may involve installing a larger main panel, but there are some other options. I am posting this since I saw people saying solar can't pay for itself.


Based on the numbers I am getting from solar world. If I get about 9000 in federal funds back on my income tax return s over a two year term. It would pay off in about seven years. The battery s however to go off grid would take the cost up to 34 thousand for system cost and would get me 8 265 ah battery s gel type so they can be in my basement. This would substantial drag out pay back if at all because of battery replacement cost at five years.


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## sulfur

what inverters are they quoting you? A "hybrid" system is always using your batteries, my solar system does not use the batteries unless the grid goes down, I keep them on a float charger and equalize them once a month. Seems like they should last 10 years in that service, but time will tell. I only bought $700 in batteries, 208Ah @ 48VDC. How much power do you really need at night in grid down situation? If money was unlimited, I would have bought more batteries, but this works good for me. The Sunnyboys can power the house directly in the day time, but they are slow to adjust to power demand so the Sunny Island uses the batteries to provide quick demand changes when grid is down. Just means I would need to heat water and do most of my cooking, drying clothes, in day time if grid is down.


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