I just dropped the price of
the permaculture playing cards
for a wee bit.

 

 

uses include:
- infecting brains with permaculture
- convincing folks that you are not crazy
- gift giving obligations
- stocking stuffer
- gambling distraction
- an hour or two of reading
- find the needle
- find the 26 hidden names

clickity-click-click

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making the move to off grid soon :)  RSS feed

 
Doug VanderSys
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Three weeks ago I sent this email to a relative that is knowledgeable about solar systems and he was going to give me input. Turns out he is not well and hasn't looked at his email in over a month.... best laid plans and all of that. In 2 weeks I will be moving to an off grid location to build a small home. Initially I'll be living in a very rustic hunting shack. Any input anyone can give me would be greatly appreciated. The moving process will be a week or 2 so the deadline isn't drop dead. For logistics I'm planning on having the panels shipped to my new location (about 350 miles from my current location).

Thanks in advance - Doug


Hi **** I want to make sure I don't purchase junk, incompatible, too expensive or just plain unwise equipment. My hope is to start small and expand without repurchasing everything piece of gear again. I'm on a tight budget.

Usage - w/ compact florescents or led light I'll go 150 watts
- small freezer 130 watts
- computer (infrequent use because no internet) 700 watts
- at some point I'll need to add a pump for water but at the moment its an unknown
- assorted personal items; phone charger, Ipod charger and battery charger - I already have a separate personal solar charger

Questions

1. Would I be unwise to go 12 volt?
2. I see battery banks using 2 volt batteries for 12v and 24v systems. Can I use 2 12v batteries for a 24v system.
3. Considering the above usage, how long could I use a 200 amp hour battery before I recharged (battery at 50%)

Shopping list

generator for charging and construction
http://www.amazon.com/Westinghouse-WH6500E-Portable-Generator-Starting/dp/B009PVNAYI/ref=wl_it_dp_o_pC_nS_nC?ie=UTF8&colid=1MO3QGHMB0HFR&coliid=I2EW7WSUTUQAIG

inverter/solar charger/battery charger - I called and talked w/ them. I can't afford the 3000 watt 24v but it looks like the wise decision
http://www.theinverterstore.com/low-frequency-inverter-chargers.html

batteries - I'm wandering in the dark here one or two of these depending on which voltage I decide
http://www.apexbattery.com/universal-power-group-ub-4d-agm-battery-car-batteries-bci-battery-group-numbers-group-4d-batteries.html

panels - 1 or 2 of these. I know the more I get the happier I'll be (the batteries too)
http://www.wholesalesolar.com/products.folder/module-folder/ET/ET-P672300WB.html

I know this is a lot of info and that there are an incredible number of variables.

I'm really looking for your overall view of if I'm on the right track.
 
Alder Burns
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When I first moved into my small cabin, years ago in GA, I did 12 volt for the first few years. I found lights....some were rechargeable camp lanterns I scrounged and then hard wired the 12 volt into where the batteries went, and had a car plug for the laptop. Places that cater to boaters and RV'ers will have a lot of stuff for 12volt systems but it will be pricey. We had a small Engel fridge/freezer too.
I found a town that I visited fairly frequently (Gainesville FL) that had a hazardous materials recycling facility. They had pallets and pallets of old batteries of all sorts that people had left, and they would let me go through them and take any I wanted. So I'd take my multitester and a little light bulb and look for any with signs of life. I kept my system up for years that way....sometimes I'd only get a few months out of a bat but it'd make do till the next trip. Eventually I got enough funds for a set of golf cart batteries....which I still have now some 8 years later. The other thing you can find at such a place are free inverters. They're called UPS units or uninterrupted power supply units which are used to keep computers etc. running in the event of a power outage. there's a fat 12 volt battery in there and you can take that out and wire it into a 12 volt system and plug AC stuff into it. Otherwise you can get pretty cheap car inverters at a place like WalMart. Neither will last very long though....
 
thomas rubino
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Hi Doug ; I.ve been living offgrid since 1983 , so i can give you some advice. In the long run a 24vt system is the better choice, more amps thru smaller wire.BUT everything costs that much more. Having said that I have been 12vt/110, for all these years so either will work. Fridge / freezer should be propane! electric freezers although much better these days are to much drain on your system. Yes you can use two 12vt batterys to make a 24vt system or four 6vt batterys. as far as inverters look at magnum energy brand, always go with puresine wave not modifided sinewave. solar panels should be as large and as many as you can afford. ebay has many choices. look at 90 watt and up. How long will it take to bank 100amp hours (lol) not long at all is the short answer. living offgrid is a mindset and not all people are cut out for it.Turn off any thing your not activly using. Buy items that use less power! use a laptop insted of a home pc. You must invest in a trimetric meter to moniter how much draw each thing you turn on is. what is the voltage of your batterys ? how many amphours . A good genset that you can start from your easy chair is needed,look at 7500 watt and up,don't try the 3500 it just isnt quite large enough. When your batterys start getting low, RUN it, let the inverter charger run the house and recharge your batts. Do laundry or use the microwave ONLY when the genset is running. Watch your batterys! CHECK THE WATER OFTEN !!!They are the heart of any system!!! I have ruined more L-16 batterys than i like to remember by not checking the water enough ! I now use an oil product that floats on top of the electrolite and keeps the water from boiling out while charging. I have a micro hydro system as well as solar and i must constantly moniter the state of my batterys. As far as a 200 amphour batterys I use 480 amphour L-16 batts with a hydro & solar and it doesnt take long to stack amphours against them, so if you have solar only then be prepaired to be suprised at how quickly you can run them down. Something else is a good charge controler, as easy as it is to run down a set of batterys it is also very easy to over charge them! Nothing smells quite like boiling electrolite. Well have I overwellmed you yet ? I could talk all night ... having said that ...DO YOU KNOW ABOUT rocket mass heaters Good Luck Tom
 
Bill McGee
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Thank you for the wholesalesolar.com site.
Bill
 
S Bengi
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Buy a used 17inch laptop for $220 that uses 40 watts vs 700watts, if you really must get a big lcd monitor get it but they only use an additional 40watts so still better
 
Marcos Buenijo
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Doug VanderSys wrote:

Usage - w/ compact florescents or LED light I'll go 150 watts
- small freezer 130 watts
- computer (infrequent use because no internet) 700 watts
- at some point I'll need to add a pump for water but at the moment its an unknown
- assorted personal items; phone charger, Ipod charger and battery charger - I already have a separate personal solar charger

Questions

1. Would I be unwise to go 12 volt?
2. I see battery banks using 2 volt batteries for 12v and 24v systems. Can I use 2 12v batteries for a 24v system.
3. Considering the above usage, how long could I use a 200 amp hour battery before I recharged (battery at 50%)



I can only offer opinions based on solid research:
1. 12 volt is ok based on what you've listed. However, if there is little room to upgrade.
2. Yes you can use two 12v batteries in series for 24 volt. If you want 12 volt, then I recommend a single large forklift battery for lowest long term costs.
3. First, get rid of a 700 watt computer... use a lap top. A chest freezer is generally going to use a KWh of electricity each day. I would devise the system to handle at least 3 KWh without excessive discharge. You need a bigger battery. A forklift battery would be nearly 500 pounds, $1200 new (includes delivery), and with 7 KWh storage capacity at 20 hour discharge. This battery will last many times longer than a typical 200 amp hour throw away. See giantbattery.com

POINTS:
- Panels are much lower in price, so get more panels.
- The battery is the heart of the system, and the single greatest long term cost over the long term. This decision is most important. Design the system to protect the battery against temperature extremes and excessive discharge. This generally means getting a larger battery than you expected, and extra panels.
- MPPT controllers are worth it
- Get a good pure sine inverter with the lowest rating that you need.
- There are ways to minimize electricity consumption and/or battery discharge from freezer (insulation and/or thermal mass)
 
S Bengi
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I really like the info on the battery vendor.

$1200=7kwhr battery
$1200=5kwhr solar panel (4hrs sunlight * 250w solar panel * 6)
$1200=MPPT charger+inverter

So $3600 would give you a very good solar system.
 
Chris Olson
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Doug VanderSys wrote:
generator for charging and construction
http://www.amazon.com/Westinghouse-WH6500E-Portable-Generator-Starting/dp/B009PVNAYI/ref=wl_it_dp_o_pC_nS_nC?ie=UTF8&colid=1MO3QGHMB0HFR&coliid=I2EW7WSUTUQAIG

inverter/solar charger/battery charger - I called and talked w/ them. I can't afford the 3000 watt 24v but it looks like the wise decision
http://www.theinverterstore.com/low-frequency-inverter-chargers.html

batteries - I'm wandering in the dark here one or two of these depending on which voltage I decide
http://www.apexbattery.com/universal-power-group-ub-4d-agm-battery-car-batteries-bci-battery-group-numbers-group-4d-batteries.html


My gosh, where do I start?

What are you running with the generator? You're going to charge two batteries with a 6500 watt generator? You're going to need to buy your own oil refinery to put fuel in it.

Don't buy an AIMS inverter. They're made in Taiwan and they're junk out of the box. For off-grid where there are no options of just throwing the switch and at the end of the month you pay the bill, there's only three brands that you can rely on to work every time - Schneider Electric (Xantrex), Outback Power, or Magnum Energy. Unfortunately, entry price for the cheapest one (Outback) is around $1,800. Buy a Schneider Conext/Xantrex XW-series system and you'll spend $6 Grand plus.

Batteries - stick with flooded lead-acid. There's a reason serious off-grid folks don't use anything else. And basically there's only a couple manufacturers that build real deep cycle batteries for off-grid - Trojan and Rolls-Surrette. Neither one is cheap. You can buy a forklift battery if you have a way to move it around (anywhere from 1,000 lbs to a ton, depending on the size you get).

You mentioned that you don't want to be buying stuff twice. Well, unfortunately there was nothing in your list except for the solar panels that are suitable for off-grid.
--
Chris
 
Marcos Buenijo
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Doug VanderSys wrote:Batteries - stick with flooded lead-acid. There's a reason serious off-grid folks don't use anything else. And basically there's only a couple manufacturers that build real deep cycle batteries for off-grid - Trojan and Rolls-Surrette. Neither one is cheap. You can buy a forklift battery if you have a way to move it around (anywhere from 1,000 lbs to a ton, depending on the size you get).


12 and 24 volt forklift batteries are available that are 500 pounds. It's also possible to have removable cells. The reason I prefer this option is because these tend to last longer than alternatives, and they tend to cost about the same or less than alternatives. Also, the fact that they are large will help to lessen their discharge all else equal while helping to moderate temperature changes, both of which will extend life (particularly the former).
 
Chris Olson
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Marcos Buenijo wrote:
12 and 24 volt forklift batteries are available that are 500 pounds. It's also possible to have removable cells. The reason I prefer this option is because these tend to last longer than alternatives


Well, again forklift batteries are a good option if you design the utility room for one and can move it around. And forklift batteries are flooded lead-acid type. That allows you to check the SG on the cells to make sure the battery is being charged properly. A sealed (VRLA) or AGM battery is just that - sealed. Equalize one, or have an issue with a charge controller, and boil the water out of it, and guess what you got? Junk.

On proper sizing of equipment:
The generator should be sized to the inverter and battery bank. Generators run at best efficiency at 80% load or better. Few generators built will run at that continuous output without overheating or damaging them. Most are designed for no more than 50% load continuous. You want to start a junk generator collection? Buy cheap ones for off-grid use. Generators have a prime and standby rating (good ones). Cheap ones just have a "running watts" and "surge" rating. The generator should be sized so it runs at 80% load using the maximum capacity of the inverter's charger, or at C/10 of the battery capacity, whichever is smaller. And don't forget to take into account the Power Factor of the inverter's charger when sizing an off-grid generator.

Inverters are a whole 'nother issue. Good ones are expensive. But the good off-grid inverters have features like Generator Support. Rather than try to explain what that is, this is a video I made back when we had our old SW Plus system that shows how it works and what it does. Basically it allows you to power very large loads without having to run stacked inverters (and purchase the additional battery capacity for stacked inverters), and at the same time not have to buy a big generator that's only going to run at 30% load during battery charging.



For our own system we have two generators. Our Honda generator is used for peak load support and the inverter automatically starts it when the load amps exceed the threshold where Generator Support is required to power the load. Our diesel generator is used for prime power. No matter how much money you spend on solar, wind or hydro power, the times come when you get almost zero power from RE sources and have to revert to the generator. Batteries are the most expensive part of an off-grid system and they wear out. They have a limited number of cycles before they're junk. Rather than dig into the batteries and then have to recharge them with the generator and inverter charger (very inefficient) we start the prime genset and run it, powering loads directly with it and let the batteries "float".

Our generators reside in a insulated and sound attenuated powerhouse that's about 200 feet from the utility room



Why do we have two generators? The Honda is gasoline fueled and we live in an area where it gets to 30-40 below zero in the winter time. We don't keep the powerhouse heated but it can get down to zero F in there and the Honda starts at those temps. The gasoline fueled genset is better suited to peak load duty than the diesel. When the inverter calls for Gen Support it starts the generator, warms it up for about 30 seconds, then applies full load to it. Diesels aren't suited for that duty.

The diesel generator is efficient and that's why we use it for prime power. The Honda produces 5.4 kWh/gallon of fuel. With regular gas at $3.74/gallon here currently, the cost is 69 cents/kWh for the Honda. The diesel produces 8.5 kWh/gallon of fuel. #2 off-road diesel fuel is currently $3.34/gallon here. So the cost for the diesel is 39 cents/kWh.

When it comes to selecting a generator, stay away from the cheap Chinese stuff. It might last most people 10 years for the stuff they use it for, but it won't last even one year on off-grid duty. Generac Guardian/CorePower series - forget it. Generac will void the warranty on a Guardian or CorePower generator if you use it for off-grid power. Honda generators are suitable for off-grid duty because they're powered by the legendary GX or iGX engine. But they also have generator heads with prime (continuous) and standby (max) rating. Entry price for a Honda is around $2,000. Diesels (good ones) aren't cheap. You can buy the cheap no-name diesels for $1,500 with the Chinese 186F Yanmar clone engine and you won't get a year out of it. Entry price for a quality 3 kW diesel genset that will stand up to off-grid duty is going to be about $3,500.

You might be detecting a theme here - cheap stuff does NOT cut the mustard for off-grid.

Marcos Buenijo wrote:
12 and 24 volt forklift batteries are available that are 500 pounds.
[........]
Also, the fact that they are large will help to lessen their discharge all else equal while helping to moderate temperature changes, both of which will extend life (particularly the former).


Our Surrettes weigh 285 lbs each - and we got 24 of 'em (our system is 48V). They have a 10 year warranty. But Rolls-Surrette is a premium battery:
http://rollsbattery.com/public/specsheets/2YS31P.pdf

You also make a good point about controlling temperature for the battery. Some people put them underground in a bunker. But I've never liked that idea. Underground bunkers can get flooded with water (especially during spring snow melt) and I'm not about to lug 3 1/2 tons worth of lead down into an underground bunker. Our utility (power) room is built on the side of the house and it is unheated in the winter time. The batteries, however, are in an insulated case made of wood and we have a duct that comes from the basement that blows into the battery case with a small duct fan. The air in the basement is cool in the summer, which keeps the batteries below 80° F, and warm in the winter (our central forced-air wood furnace is in the basement), which keeps them above 50° F in the winter.

Heat shortens the life of your batteries. For every cycle, for every 10°C over 25°C, you lose one cycle from the battery's life. Cold batteries lose capacity. At freezing temp they only have 50% of the capacity (amp-hours) that they have at 77°F.
--
Chris
 
Chris Olson
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Doug VanderSys wrote:
inverter/solar charger/battery charger - I called and talked w/ them. I can't afford the 3000 watt 24v but it looks like the wise decision
http://www.theinverterstore.com/low-frequency-inverter-chargers.html


I shudder when I think of somebody buying one of these inverters for off-grid. They are cheaply built and poorly designed. I mean, look at the idle power consumption of the 24V one - 3 amps. At no load the thing pulls almost 75 watts @ nominal bank voltage. You can't afford that for off-grid.

When you select an inverter you first need to decide whether you need 120V output only or 120/240V split phase. If you plan on adding a well pump eventually, then go with 120/240V up front. The most efficient deep well submersible pumps are 240V. DC well pumps are a non-starter because of the size of the wiring required to run them. 120V well pumps have th same problem - low volume and pressure output for the amount of amps they draw.

Assuming 24V system:
If you need a 120V inverter I would recommend the Outback VFX3524. It has long been the Gold Standard for off-grid 120V inverters.

If you need 120/240 split phase I would recommend the Schneider Electric XW4024. It is a beast and it takes two men to lift one onto the wall bracket (well over 100 lbs). The XW-series (thru its predecessor, the SW/SW Plus) has been the premium off-grid inverter for over 20 years.

Magnum Energy also builds both 120V and 120/240 split phase inverters. Magnums have notoriously poor voltage regulation so varying loads (like a washing machine running) are going to cause the lights in your house to flicker like a disco. But they are a cheaper alternative to the expensive Schneider XW's if you need split-phase power. If you need 120V I would recommend the Outback over the Magnum.

Another possibility is Schneider Electric's new Conext SW. It is a 24V, 4.0 kVA 120/240V split phase output unit that Schneider has just released. I saw one at the local dealer being prepped for an install and the thing is built like a tank. It is a smaller and more economical version of the venerable XW for smaller off-grid systems that need 240V power. It uses all the same Xanbus equipment as its big brother - the System Control Panel (SCP), Automatic Generator Start (AGS), etc.. They are priced around $1,200-1,500. This a video from the 2012 Solar Show when Schneider was showcasing this new product:


Of all the above inverters, only the Schneider Conext XW and SW have the Generator Support feature in them. Magnum Energy was supposed to be releasing a new inverter very soon that has Generator Support, but I haven't seen it yet. Outback was supposed to add Generator Support in the FX for years, but they never did it. Bob Gudgel, who used to do the software/firmware programming for Outback equipment put the options in the Mate menu, but the functionality never got added to the hardware.
--
Chris
 
Marcos Buenijo
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Chris, excellent advise and discussion - especially on generators. There really is a lot of junk being sold to uninformed consumers. I also would like to reemphasize your point that the efficiency of a generator can vary dramatically based on many factors, and the one you listed (load) is perhaps the single most important. I also concur that Honda makes the best small gas engines. Doug is getting some great information. Also, I love the emphasis on the battery system. The system should be devised to protect the battery at all times because the battery is the single greatest expense (especially over the long term). Use flooded lead-acid, get a good brand, protect from excessive discharge/temperature extremes/excessive charge (water loss!).

Chris, yours is the largest battery system I've yet seen for powering a home. By my estimates that battery system cost nearly $20,000, and it has a capacity of about 116 KWh at the 20 hour rate. Are you powering a small community, or just a single home? How many KWh of electricity does the system provide each day on average? What's the rating of the solar array you have to feed that beast?
 
Chris Olson
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Marcos Buenijo wrote:
Chris, yours is the largest battery system I've yet seen for powering a home. By my estimates that battery system cost nearly $20,000, and it has a capacity of about 116 KWh at the 20 hour rate. Are you powering a small community, or just a single home? How many KWh of electricity does the system provide each day on average? What's the rating of the solar array you have to feed that beast?


It is just our home and my machine shop for my wife and I. We have lived off-grid here for many, many years and built our system over time. It would cost in excess of $75,000 to just buy the equipment we have - like you said our batteries alone are close to $20,000. The batteries are 58 kWh capacity (50% DoD).

Our average daily consumption is 40-60 kWh/day in the summer and 30-40 kWh/day in winter. We have a totally electric home - my wife will not allow a propane tank on the property. So we have electric range (high efficiency unit with induction cooktop and convection oven), electric water heating, central A/C, etc.. We enjoy having the central A/C for July and August when it gets very hot and humid here.

Our power system is a solar/wind/fossil fuel hybrid. The solar (6.0kW installed capacity) produces average 29 kWh/day in the summer. In the winter the solar produces average 9 kWh/day. The wind (7.5 kW installed capacity) produces average 7 kWh/day in summer. In the winter the wind produces 30+ kWh/day, and I put it that way because if we had the loads for it there's many days in the winter when we could get 100 kWh but simply don't have the loads to use that much power. Wind power works MUCH better in winter than it does in summer - it's basically an expensive monument in the summer because $1,500 worth of solar power will produce more than $30,000 worth of wind power. But it's the other way around in winter.

The balance of our loads at all times is provided by generators - we have one generator for when the inverter overloads (peak load support). We have another one for heavy continuous loads like our A/C system (prime power). The generators are an integral part of our off-grid system. This is a photo of our utility, or power room:



Many people believe in some pie-in-the-sky idea about "sustainable living" and whatnot - my wife and I don't buy into that. All living is sustainable or you wouldn't be here. And no matter how "sustainable" you think your lifestyle is - the fact is that this planet cannot continue to support the present level of human population on it. The sun's energy from millions of years ago was stored in plants that today are crude oil. This as renewable of a process as using solar panels to generate electricity is. It's just not renewable in your lifetime is all. We still live in a closed eco-system on this planet. If humans over-populate it and ruin it, Mother Nature will reign supreme and billions of people will die and Mother Nature will clean up the mess.

So we designed our system as a solar/wind/fossil fuel hybrid that minimizes the use of fossil fuels, but still allows us to have a practical and comfortable off-grid lifestyle. Setting up a system like ours is way more expensive than just buying grid power. But it is what we chose to do.
--
Chris
 
Marcos Buenijo
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Chris, I have some questions about how your system operates. I watched your video describing generator support. I understand that the inverter matches the phase of the generator while operating (not unlike a grid tie inverter would do). So, they would work in tandem, right? My concern is that the generator might come on when the inverter load is exceeded, yet only supply the balance of power required (for example, if 40 amps is the setpoint for the generator, and 45 amps is the load, then would the generator supply only 5 amps?). It seems the ideal configuration would be for the generator to always operate within a narrow range where efficiency is optimal and with the inverter supplying the balance of power when necessary, and not vice versa. Can your system do this?
 
Chris Olson
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Marcos Buenijo wrote:My concern is that the generator might come on when the inverter load is exceeded, yet only supply the balance of power required (for example, if 40 amps is the setpoint for the generator, and 45 amps is the load, then would the generator supply only 5 amps?).


No Marcos, it is the other way around. Our previous SW Plus system operates identically to our XW system. There is many settings in the inverter for AC inputs (we have generators on both of the AC inputs of our XW) such as amp limit for the generator, acceptable voltage and frequency limits (for the inverter to qualify or disqualify the genset), etc..

Say the generator is rated at 30 amps @ 80% load. You set the Load Start Amps in the inverter to a level that your batteries and inverter are comfortable with for a given time - say 5 minutes - and lets say 40 amps. The delay time prevents nuisance starting of the genset for a temporary heavy load that exceeds the Load Start setting. These big Xantrex inverters can run well over their rated continuous output for quite awhile - for example, our XW6048 will run at 7,200 watts output for 30 minutes with no problems.

So now let's say we get an inverter overload at 50 amps (25 amps @ 240V but Load Start setting in the XW is based on the sum of current between L1 and L2). The inverter will carry this for five minutes, and if the load is still over the setting it will start the generator and sync with it while the genset is warming up. Then the inverter loads the generator to the capacity that you have entered for it in the Gen Support Amps setting. If that is 30 amps, the inverter will load the genset to 30 amps and supply the remainder (20 amps) from battery power.

The Gen Support Amps setting can be adjusted to whatever you want to match the size of the generator and how heavily you want to load it during Gen Support.

And getting back to the OP's proposed setup - the above example is stuff that serious off-grid inverters have for features that cheap units like the AIMS one pointed out do not have. Too many folks make off-grid living a chore because they put together a system that requires constant attention and maintenance to even use it on a daily basis. You should not have to baby sit an off-grid power system - designed properly, off-grid power is more reliable and just as convenient as grid power. But you can't do that with cheap stuff. And if you can't afford the equipment you should have for an off-grid system, you are better off to remain on grid power because you will have nothing but headaches and problems with it. And that's why so many off-grid attempts are dismal failures.
--
Chris
 
Marcos Buenijo
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Chris Olson wrote:No Marcos, it is the other way around. Our previous SW Plus system operates identically to our XW system. There is many settings in the inverter for AC inputs (we have generators on both of the AC inputs of our XW) such as amp limit for the generator, acceptable voltage and frequency limits (for the inverter to qualify or disqualify the genset), etc..

Say the generator is rated at 30 amps @ 80% load. You set the Load Start Amps in the inverter to a level that your batteries and inverter are comfortable with for a given time - say 5 minutes - and lets say 40 amps. The delay time prevents nuisance starting of the genset for a temporary heavy load that exceeds the Load Start setting. These big Xantrex inverters can run well over their rated continuous output for quite awhile - for example, our XW6048 will run at 7,200 watts output for 30 minutes with no problems.

So now let's say we get an inverter overload at 50 amps (25 amps @ 240V but Load Start setting in the XW is based on the sum of current between L1 and L2). The inverter will carry this for five minutes, and if the load is still over the setting it will start the generator and sync with it while the genset is warming up. Then the inverter loads the generator to the capacity that you have entered for it in the Gen Support Amps setting. If that is 30 amps, the inverter will load the genset to 30 amps and supply the remainder (20 amps) from battery power.

The Gen Support Amps setting can be adjusted to whatever you want to match the size of the generator and how heavily you want to load it during Gen Support.


OK, that's just freakin' awesome. I had no idea inverter systems were so sophisticated. I thank you for the information. Now I have research to do, .
 
Chris Olson
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Marcos Buenijo wrote:
OK, that's just freakin' awesome. I had no idea inverter systems were so sophisticated. I thank you for the information. Now I have research to do, .


Marcos - off-grid inverters have had this level of sophistication for better than 20 years. Trace Engineering originally invented the legendary SW-series inverter. Trace was eventually sold to Xantrex in Canada. Xantrex improved the SW with the SW Plus-series. These older inverters were all 120V output and for 120/240V split phase they were either series stacked or the Trace T240 autotransformer was used on them.

In 2006 Xantrex released the XW-series. The XW is native 120/240V split phase output (for North American market). It set the new standard in off-grid inverters, and has remained king of the hill for the last 7 years. Xantrex was bought by Schneider Electric (maker of SquareD electrical equipment) in 2009. Schneider Electric is based in France and they are the largest manufacturer of electrical components and control systems on earth, and they now have a huge solar/renewable energy division.

Some of the engineers that worked at Trace left when Xantrex bought trace. Those engineers founded Outback Power Systems. Outback Power was eventually bought by the Alpha Group. Those same engineers that went from Trace to Outback have now founded MidNite Solar and the step-son of one of the engineers co-founded Magnum Energy.

So basically, all the high-quality off-grid equipment available today was designed by the same engineers. And anything else is pretty much a wannabe. So when you go shopping for off-grid power there is basically only three to choose from - Schneider Electric (Xantrex), Outback Power, or Magnum Energy. They are the only three brands that anybody who knows anything about off-grid power trusts to work every single time and not break. And they all have this same feature set, more or less. The Schneider Conext/Xantrex XW-series is pretty much the premium off-grid inverter. The Outback system was designed to be cheaper and is missing some of the features of the XW's. Magnum inverters are also a lower price point unit designed to take up less space. The Magnums are also less electrically efficient because they use high-temperature transformer windings and they were originally designed for mobile applications (very big in the RV business). Even among the Big Three there is a dramatic difference - for instance, JUST the transformer in a XW weighs more than a whole Magnum inverter.

Overseas, the German-made SMA Sunny Island inverters are also very good for off-grid power. But they are quite expensive here in the US.
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Chris
 
Marcos Buenijo
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Chris, you've done some great research. Thank you for the information. I was aware of a general consensus that Xantrex, Outback, and Magnum are the best inverters. However, I didn't know the reason. It makes good sense that the same pool of engineers designed them all. You sold me.

Please consider making a post dedicated to describe the details of your system. Believe me, a lot of people here will be fascinated with what you've done and you will help to educate us all. We can do research all day, but there's no substitute for experience. Personally, I love to see as much real world data as possible. I am particularly interested to know if you're limited in any respects with providing central air conditioning for your home along with a description of the conditions like average summer temps and thermostat settings, etc. The reason I ask is because I have plans to finally settle in east Texas where the heat and the humidity is brutal, and a/c is not merely a luxury.
 
Chris Olson
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Marcos Buenijo wrote:I am particularly interested to know if you're limited in any respects with providing central air conditioning for your home along with a description of the conditions like average summer temps and thermostat settings, etc. The reason I ask is because I have plans to finally settle in east Texas where the heat and the humidity is brutal, and a/c is not merely a luxury.


I could do that - I've made lots of videos of our system, including both the solar and wind power parts of it. And have lots of photos on my Picasa web albums of various aspects of our system.

Running A/C off-grid is basically only practical with prime diesel power. The investment in solar and batteries makes it prohibitive. You can run it part-time on solar or wind power. And you don't want to try to run it on battery/inverter and then have to recharge batteries with the generator and inverter/charger because that's very inefficient. So the only practical way I've found to run A/C is with a properly sized diesel prime power genset, or using a co-generation set driving a heat pump and generator.

A/C systems draw an incredible amount of power for an off-grid installation - even a small 2-ton A/C unit (24,000 BTU) will use 35 kWh in a day.
--
Chris
 
Kugel Ludens
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I'm doing some research and analysis for an off-grid solar home I'm planning to build starting next year. I came across some information about the NiFe battery as an alternative to flooded lead battery. Does anyone have any experience or thoughts about this type of battery? I've heard they're prohibitively expensive, but their lifecycle costs are better due to lower maintenance cost. Any thoughts would be appreciated.

Kugel
 
Chris Olson
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Nickel-Iron batteries are going to be about $1,200 per kWh and will last about 50 years. Flooded lead-acid is typically $170 per kWh for premium batteries that will last about 10 years.

So it all depends on how much money you got.
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Chris
 
Marcos Buenijo
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Kugel Ludens wrote:I'm doing some research and analysis for an off-grid solar home I'm planning to build starting next year. I came across some information about the NiFe battery as an alternative to flooded lead battery. Does anyone have any experience or thoughts about this type of battery? I've heard they're prohibitively expensive, but their lifecycle costs are better due to lower maintenance cost. Any thoughts would be appreciated.

Kugel


I have no experience with them, but I did some research a couple years back. My thoughts are that it's hard to make a direct comparison between NiFe and lead acid batteries. The main difficulty I have with considering NiFe is the high upfront cost and the limited track record of the actual products and companies that manufacture and/or sell the products.

From what I've seen, the upfront cost of the NiFe is about 5 times that of lead acid for equal capacity. However, I consider that the NiFe battery can ostensibly be fully discharged without damage, so the effective capacity should be considered as twice as high as a lead acid battery limited to 50% discharge. This is good also because it takes nearly twice the weight of NiFe battery to see the same capacity as lead acid. Therefore, the effective energy density is roughly the same for each battery when this dynamic is considered. However, we still have to contend with an effective unit cost that is roughly 2.5 times higher for the NiFe even after this is considered.

If we consider that the NiFe is likely to last longer than the lead acid, then this might change one's mind. However, a good flooded lead acid battery sized to limit its discharge to 50% should last 10-15 years and a lot of evidence supports this. Therefore, if the NiFe battery lasts for 30 years or more, then a reasonable argument can be made for the NiFe since one should see higher reliability during that period and a battery replacement is avoided... and it would end up storing and delivering the same energy per upfront dollar paid for the system as lead acid. However, do we KNOW it will last this long with regular heavy discharge? More important, is there anyone out there with integrity offering a prorated warranty if it doesn't?

There is also the problem of lower efficiency in the NiFe battery that I've heard reported from independent sources. I don't have data, so I can't discuss specifics... but this is one thing you should research.

It seems that the (effective) cost may not be much different between lead acid and NiFe when projected over the long term, but there are too many unknowns to be sure. However, that upfront cost is certainly daunting. Speaking only for myself, I would want to see a lower price, more successful real world examples with data, and a smokin' warranty. If the upfront cost were to fall to about 50% of it's current level, then I would start to show interest. I would be willing today to risk paying twice as much for a NiFe battery of equal capacity as a good lead acid counterpart based on the promise of higher discharge and longer life... but not five times. Of course, that's just me.

NOTE: When I consider a lead acid battery sized to limit discharge to 50%, I do not mean the battery is discharged to 50% every day. Rather, I mean it is never discharged beyond 50%, and that many if not most days will not approach 50% discharge. After all, people don't use the exact same amount of electricity every day, and the exact same amount of electricity is not provided by an off grid energy system. There are also many strategies available to limit battery discharge. One advantage might be considered in favor of lead acid in that, while the system may not be regularly discharged beyond 30% or so, it does have the extra capacity in case one needs it.

NOTE: Another argument in favor of the less expensive lead acid battery is that there is likely more profitable ways to spend the cash required to purchase a NiFe battery. Again, I really think the price on these batteries have to come down considerably before they should be considered.

 
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