Author Topic: My real-life grid tied solar system with off grid capabilities  (Read 18212 times)

Offline Oregonprepper

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I thought you guys might be interested in my quasi off-grid system.  I have a wife and baby and wanted a system that could run a normal American every-day life, yet provide me with heat, hot and water, cooking and electricity in the event of a grid-down situation.

This past fall I built a new 2000 square foot 4 bed-room house and installed a 3.24 kw solar system,  with 16- Rolls surette s-530 batteries and 14 kw kohler back-up propane generator. 

The trick was to have 2 electrical panels in the house, one for critical loads that would be ran through the inverter, and one for other big loads that would go down in a grid down situation.  Also, because this would be infinitely harder without propane, I just gave up on that fight and put in a 1200 gallon propane tank.  So basically my off-grid capabilities are only limited by the amount of propane in my tank, in which case I always figure to have a minimum of 1 year worth of propane in the tank. 

GRID UP SITUATIONS:

I'm grid tied so I'm net-metered which means that anything the panels are making that I'm not using gets fed back into the grid.  I am surprised at how often I'm feeding the grid, even with the tvs and lights on.  I have a very normal house with a 50 inch plasma tv, electric well pump, electric washer and dryer and I never limit my wife's use of things like curling irons, blow dryers mixers, toasters etc.  We use as many modern appliances as anyone else, although I did try and get as many efficient appliances as possible.  The only difference I would say is that every single light bulb in this house is either LED or CFL.  LED are far better than the CFL for various reasons in my opinion, but either way, I don't care if I ever leave a light on if we leave the house because electricity use from our light bulbs is negligible.  A standard LED bulb only uses about 7 watts an hour.

GRID DOWN SITUATIONS:

If the grid goes down I would lose power to my heat pump/AC and clothes dryer.  The batteries and inverter would be able to run the rest of the house including my well pump for water.  I would have lights, internet, tv, fridge, freezer, appliances, and water, all from the solar and batteries.  If the batteries drop below 50%, then the generator kicks on for a little while and boosts them back up to full.  That is by far the most efficient means of using a back-up generator.  Every watt is used if it goes into a battery bank.  For back-up heating I have an efficient propane fireplace, for hot water I have a propane water heater, and for cooking I have a propane oven/stove.  I'm not even sure if I would notice if our grid went down honestly.  Probably the only way I would notice is if I tried to use the clothes dryer and it wouldn't turn on... in which case I would just use our clothes drying rack.  We could live off-grid like this basically until we ran out of sunshine and ultimately ran out of propane, which would hopefully be 1-2 years depending on how full our propane tank was.  If I wanted to go crazy with the system I guess I could just bury a 5,000 gallon propane tank or something extreme like that.  I can also tie in a wind generator if I wanted to save another $50 a month on my power bills, but I'm not sure if I need to because my goals are already accomplished with this system.


Financial implications:

I think that my 3.25kw solar panels realistically save me about $40 a month on my power bill.  I don't know how much propane I've used so far but I'm guessing I spend about $40-50 a month in propane for hot water and cooking, but I also don't have to heat my water electrically so the propane is kind of a wash I guess.  My first power bill before we moved in and started using heat was effectively 0 dollars.  The next was about $30, then $50 and am now sitting at about $80-100 a month through our freezing winters running an electric heat pump to 70 F degrees in the house.

The whole system including panels, generator, inverter, installation, wiring, labor, etc cost about $33,000.  If you wanted a cost breakdown it would look something like this:  10 grand for panels, 6 for batteries, 4 for inverter, 3 for the rack (which is not on my roof), plus installation and other odds and ends that add up quicker than you would think.  You also get tax credits on everything so long as it's grid tied, and without those it would have been a lot harder to justify.  The payback period on my entire system is horrible, but the payback period on a fishing boat was even worse so....  ;)  And I'm not sure if you can put a dollar figure on the peace of mind you get from a redundancy system like this.  Where I live electricity is only about 7 cents a kw and my power company doesn't do squat as far as solar rebates or any other incentives.  They simply offer net-metering and that's about it.


PS: I probably would have gotten a wood fireplace for back-up heat instead of propane heat but my wife didn't want one so that was that  :o

EDIT:  Something that struck me during this process was that for our goals, which was normal every-day living back-up power for at least a year, it's really all about the battery bank and inverter, and more specifically the battery bank.  It's not feasible to run a back-up generator 24/7 for power, but it is feasible to run a generator twice a day for 20 minutes (I'm just guessing with those numbers) to refill your battery bank.  Put some batteries on your house, and a generator to charge them, and you have a fairly efficient and affordable back-up power system.  Batteries do not care how they are charged.  Charge them with a giant hand crank and alternator for heaven's sake lol.  People get too focused on the solar panels for back up power systems when really it's all about the batteries.  The solar panels are just a means to charge the batteries.  Solar panels alone, with no batteries, are kind of a joke honestly... at least for the prepper.  They go down when the grid goes down and offer you zero redundancy.  If you want to throw up some panels to lower your power bill that's fine, but they won't do squat for you without batteries when the grid goes down.
« Last Edit: March 20, 2012, 01:52:27 PM by Oregonprepper »

Offline Mr. Bill

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #1 on: March 20, 2012, 02:15:51 PM »
Excellent informative post!  +1.

Offline backwoods_engineer

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #2 on: March 20, 2012, 02:48:03 PM »
Pictures please, and more detail on your inverter / fuse box wiring.

Offline Oregonprepper

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #3 on: March 20, 2012, 11:21:49 PM »
Photo request granted (these are from just after the install)


The 12 panels (that just survived 75 mph winds thankfully):



Solar comes in that top tube to the charge controller which feeds the batteries.  The batteries then feed the inverter.  The charge controller doesn't really care where it gets the juice from and can easily add a wind turbine to this if needed.  With the wind we've been having lately it's starting to seem like a good idea.



Batteries vented to the outside, which now have a protective box around them. 



Emergency disconnects required by the state.  If I flip the right one it will stop feeding the grid.  It had to be on the outside of the house so that if my house is on fire the fire department can come by and flip the switch so that my system can't overload the grid (or some such nonsense).  My inverter already does the same thing but I guess the state needs a ton of redundancy.  Oh well. 



I don't know everything about the inverter and fuse box but I can try and offer answers to specific questions.

Offline Alan Georges

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #4 on: March 21, 2012, 07:02:52 AM »
Beautiful system.  Thanks for the pics.  And thanks too for the sobering financial assessment of the project.  +1

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #5 on: March 21, 2012, 09:24:32 AM »
Great setup, OP!

I like Rolls S530's.  Does your rack track, or is it fixed?

~TG

Offline DrJohn

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #6 on: March 21, 2012, 10:23:07 AM »
Fab!  We are in the design process of a house and this is very good info!

Offline Oregonprepper

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #7 on: March 21, 2012, 10:36:42 AM »
Thanks!

The rack doesn't track.  For me to have a tracking system built it would have cost more, and gained less, than just spending more to get more panels.  As it is now there are no moving parts at all so there is less to wear out over time.  Those panels are big and heavy and that rack is a serious beast.  I don't know what it would have taken to get it to move with the sun.  On the other hand, I don't think that the technology is super advanced or anything so if you were doing this in a DIY situation it might be something to look into.  But overall I probably would still have just added more panels instead of adding tracking.

I can manually go out there and turn it if I wish to, but I'm not sure it would be worth it.  In the fall I'm supposed to point it down toward the horizon more and in the spring I'm supposed to point it upwards again... there are settings for that.  That's about the only moving I will ever do to the rack.  If the grid was down though I might try and squeeze every last watt out of it and fine tune it's angle a bit.

Offline DrJohn

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #8 on: March 21, 2012, 11:48:41 AM »
Does the Generator come with an auto start?  If so does the solar system charge it's battery, or does it only charge if the genny runs?

Offline Oregonprepper

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #9 on: March 21, 2012, 01:33:03 PM »
The generator will automatically come on when the battery level drops below 50% (which is totally adjustable through my little control panel).  The solar system is charging the batteries whenever it's sunny.  The solar panels are the primary charger of the batteries, and the generator is only a back-up to the solar.  If the grid is down, and it's not sunny, the generator would probably come on after a day or two and charge the batteries.

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #10 on: March 21, 2012, 01:55:12 PM »
The rack doesn't track.  For me to have a tracking system built it would have cost more, and gained less, than just spending more to get more panels.  As it is now there are no moving parts at all so there is less to wear out over time.  Those panels are big and heavy and that rack is a serious beast.  I don't know what it would have taken to get it to move with the sun.  On the other hand, I don't think that the technology is super advanced or anything so if you were doing this in a DIY situation it might be something to look into.  But overall I probably would still have just added more panels instead of adding tracking.

That's my philosophy exactly.  With the low cost of panels right now it just makes sense. 

There is a promising breakthrough in production technology from an American company that basically uses a proprietary "ion cannon" to slice silicon thinner with less waste.  At the point they bring that technology to market, we could see prices half of where they are now, even if energy costs double.  (Making PV solar requires huge amounts of energy to produce silicone.)

~TG

Offline Insidious

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #11 on: March 21, 2012, 05:16:38 PM »
Texas Girl, are there pics of your setup?

Offline backwoods_engineer

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #12 on: March 22, 2012, 08:22:01 AM »
Very impressive system.  Did you do the installation yourself, or were you required to use a contractor?


Offline Oregonprepper

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #13 on: March 22, 2012, 10:07:07 AM »
I hired it done through a local solar guru who specializes in off-grid applications.  When I was looking around at solar installers it was evident that the vast majority are simply trained to come out and install a little $10-$20 grid tied net metered system with no batteries, designed to throw on business's roofs so that the business can save a little money on their power bill, off-set some taxes and appear to use "green energy".  Most of those companies were also seriously overpriced for what you got.  When you look for a contractor find someone who loves doing off grid applications.  My guy has been doing this entire life and loves everything about his job.  If you are in Oregon and doing this shoot me a message and I'll send you his info.  I wouldn't go with anyone else.

If you do everything yourself I'm not sure you would qualiify for tax credits and incentives as easily, but that's not to put off someone if they really know what they are doing.  The work isn't all that difficult if you know your stuff.

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #14 on: March 22, 2012, 06:18:55 PM »
Texas Girl, are there pics of your setup?

No, I never thought to take pictures of just the solar system.  I'm tearing it down to move right now, but will take pictures when it gets back up. 

Basically, it's a pair of Outback GVFX 3648's on a FlexWare 1000 backboard, set up for 120/240, with 3.4KW (15-225w BP's in 72v nom strings) feeding a pair of FlexMax 80's.  I will be upgrading the battery bank when I move, one of the choices is Rolls S530's (two strings of 8 ea), or maybe the larger 6CS17's which have a longer warranty period.  I'd like to pick up a few more panels and go totally off grid, so I'm leaning towards the larger batteries.

~TG


Offline cidermonkey

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #15 on: August 05, 2012, 02:04:03 AM »
Great post oregon prepper, solid info.  One note though, if you add wind it won't charge thru the same controller.  Each energy source will use its own controller as interface between it and the battery bank.

The economics are so different in every area, completely dependent on what govt / utility programs are available.  Step one for people considering a system like this could be going to this site which lists all programs available by state.  http://www.dsireusa.org/

I design and install systems like this on the Olympic Peninsula.

Offline chrisdfw

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #16 on: August 05, 2012, 11:56:55 AM »
No, I never thought to take pictures of just the solar system.  I'm tearing it down to move right now, but will take pictures when it gets back up. 

Basically, it's a pair of Outback GVFX 3648's on a FlexWare 1000 backboard, set up for 120/240, with 3.4KW (15-225w BP's in 72v nom strings) feeding a pair of FlexMax 80's.  I will be upgrading the battery bank when I move, one of the choices is Rolls S530's (two strings of 8 ea), or maybe the larger 6CS17's which have a longer warranty period.  I'd like to pick up a few more panels and go totally off grid, so I'm leaning towards the larger batteries.

~TG

Just my opinion, but go with the larger batteies. 530's are L16 type, whichb are good, but the CS series is really good. If yu have the ability and a method to deal with the masive size, crown tractive batteies are great.

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #17 on: August 05, 2012, 11:59:30 AM »
Great post oregon prepper, solid info.  One note though, if you add wind it won't charge thru the same controller.  Each energy source will use its own controller as interface between it and the battery bank.

Wouldn't separate controllers need to be networked to work together, so they didn't fight each other?

~TG

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #18 on: August 05, 2012, 12:07:59 PM »
Just my opinion, but go with the larger batteies. 530's are L16 type, whichb are good, but the CS series is really good. If yu have the ability and a method to deal with the masive size, crown tractive batteies are great.

I had considered forklift batteries too, but replacing a bad cell down the road requires quite a bit of skill.  I may be teaming up with a friend to order batteries this week for a quantity discount.  We are looking at an order of 32-40 units.

~TG 

Offline PrepperJim

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #19 on: August 05, 2012, 12:29:19 PM »
I bought batteries from this company and got really good service. They are in Bastrop, Texas.

They may or may not have what you are looking for.

Edit to correct link
« Last Edit: August 05, 2012, 02:27:39 PM by fritz_monroe »

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #20 on: August 05, 2012, 01:04:18 PM »
I bought batteries from [urlhttp://www.centexbatteries.com/]this company[/url] and got really good service. They are in Bastrop, Texas.

They may or may not have what you are looking for.

Jim,

I don't believe they carry industrial wet cells.  The gel, AGM's, are more expensive, have less charge/discharge capacity, and a shorter overall life.  I'm shooting for 10+ years of service life, and a spare set that can be mothballed dry for LTS, adding the electrolyte when placed in service.

~TG

Offline Nadir_E

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #21 on: August 06, 2012, 10:05:52 AM »
....The gel, AGM's, are more expensive, have less charge/discharge capacity, and a shorter overall life.  I'm shooting for 10+ years of service life,...

Very helpful info, TG.  What do you estimate the difference between the wet cells and AGM to be?  Is there a trade-off in need for service / venting for the wet cells vs. AGM?

Quote from: TexasGirl
... and a spare set that can be mothballed dry for LTS, adding the electrolyte when placed in service.
Good idea - are they completely inert in that state?  (i.e. no degradation of ability to hold a charge once activated?)

A battery-based back-up system is on my wish-list for 2014 - too many other priorities to do it sooner. :(

Thanks,
-N



Offline idelphic

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #22 on: August 06, 2012, 05:22:53 PM »
Very helpful info, TG.  What do you estimate the difference between the wet cells and AGM to be?  Is there a trade-off in need for service / venting for the wet cells vs. AGM?
Good idea - are they completely inert in that state?  (i.e. no degradation of ability to hold a charge once activated?)

A battery-based back-up system is on my wish-list for 2014 - too many other priorities to do it sooner. :(

Thanks,
-N
AGM - Short term / cycle.  They are sealed (but will vent (BAD) so they can be placed in any location - side, back, upside down.

Wet cell - better for solar and deep cycle operations.  You have to monitor the levels.. but as TG stated,.. they can be stored dry for 'later use.'

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #23 on: August 06, 2012, 06:16:52 PM »
Very helpful info, TG.  What do you estimate the difference between the wet cells and AGM to be?  Is there a trade-off in need for service / venting for the wet cells vs. AGM?
Good idea - are they completely inert in that state?  (i.e. no degradation of ability to hold a charge once activated?)

A battery-based back-up system is on my wish-list for 2014 - too many other priorities to do it sooner. :(

Thanks,
-N

Idelphic nailed it.

I'd say roughly, properly cared for wet cells will run from 7 to 20 years depending on type and discharge cycle.  AGM's are low/no maintenance, but will last from 3-7 years with the same "depends".  But wet cells are much more forgiving with a mistake.  Once an AGM, or gel, is heavily overcharged and the gel electrolyte "bubbled", it's life is over.  With a wet cell, they can be "reconditioned" usually with just rebalancing the electrolyte.

"Dry" wet cells can be stored inert indefinately, but make sure they were not charged then emptied for transit, those will have traces of electrolyte that will eventually deteriorate the plates before they are placed in service.  If dry cells are intended to be stored, it's best to purge them with nitrogen.  CO2 gas might work too, but I'm not sure.

~TG

Offline Nadir_E

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #24 on: August 07, 2012, 04:49:57 PM »
Idelphic nailed it.

I'd say roughly, properly cared for wet cells will run from 7 to 20 years depending on type and discharge cycle.  AGM's are low/no maintenance, but will last from 3-7 years with the same "depends".  But wet cells are much more forgiving with a mistake.  Once an AGM, or gel, is heavily overcharged and the gel electrolyte "bubbled", it's life is over.  With a wet cell, they can be "reconditioned" usually with just rebalancing the electrolyte.

"Dry" wet cells can be stored inert indefinately, but make sure they were not charged then emptied for transit, those will have traces of electrolyte that will eventually deteriorate the plates before they are placed in service.  If dry cells are intended to be stored, it's best to purge them with nitrogen.  CO2 gas might work too, but I'm not sure.

~TG

Firstly, thanks to you both for the education.  I hope you won't mind a few more questions from this neophyte.

Does a charge controller prevent the risk of over-charging the batteries (AGM or otherwise) you mention above?

When you say purge with nitrogen, would this be by just filling the cells with that gas for a few seconds to displace the oxygen, or is it more complex than that?

When Idelphic describes "monitoring the levels" I presume that's water levels - correct?  If so, how frequently does one do that?  Is evaporation of the water a greater concern in higher ambient temperatures, or is it a function of how much use the battery is getting?  I ask because if I go ahead with my plans, I won't have a temperature-controlled place to put them - they'll be in a basement (old root cellar) that gets into the 70's on really hot days (of which we get plenty here in SoCal).

Thanks again for your help,
-N

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #25 on: August 07, 2012, 07:26:03 PM »
A properly installed (and programmed) quality charge controller should manage the batteries charge cycles for you.  That being said, different types of batteries will require different charge settings.  There are several phases of the cycle, so a good controller manages several parameters, including battery temperature.  (Don't skimp with a cheap controller!)  My Outback goes through five different phases with each charge cycle. 

Battery life depends tremendously upon the charge controller and the loading (discharge).  The most common problem is undersizing a battery bank and working it to death, especially the gel/AGM's which shouldn't be discharged as deeply as wet cells.  70° ambient temperature is not a problem for most batteries, 107° could be.   Also, never mix old and new cells, unless you want the new ones to take on the degraded performance characteristics of the older cells.

Electrolyte levels are mostly dependent on the charge cycle, how fast (more voltage) and how long it runs.  Running a generator for a few minutes to fast-charge a bank is much harder on them than a 5-hour solar trickle.  When starting out, you might check the levels once a week for awhile and go from there. 

Purging a dry cell just keeps plate oxidation to a minimum, I don't know how bad oxygen in the air would be versus airborne salts.  I have not seen any hard data on mothballing dry wet cells for 10-15 years yet.

~TG

Offline cidermonkey

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #26 on: August 26, 2012, 12:00:17 AM »
Wouldn't separate controllers need to be networked to work together, so they didn't fight each other?

~TG

Good question, we've just gone past my personal hands-on experience.  I believe however that you can use the settings to give one controller priority (via voltage settings) and shut one down when the batteries get near full charge.  When the batteries are not near full charge, just let them both go full bore.  I guess the controllers that can talk to each other, like the Outbacks or Midnites, would do better by making the charging from each source the same when the batteries got close to full.

Offline Oregonprepper

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #27 on: April 09, 2013, 11:46:07 PM »
I just thought I would bump this up after listening to Jack's last call-in show where he answered someone's question about running a well off of solar power. 

It's not as much about running off of "solar" as it is about running off of a battery bank.  These off grid systems are all about the battery bank which is where you need to put your focus.  You can charge them efficiently from solar, propane or diesel generators or wind power... it doesn't really matter. 

I had a smaller well pump but recently switched out to a much larger pump to handle my irrigation system.  I think it's about a 3hp pump? 

The important thing to look for when finding a pump for off-grid capabilities is finding a soft-start variable speed pump

If the grid goes down I would theoretically only use the well pump for drinking water and the occasional shower which means that the well pump would run with a low power draw.  I wouldn't be irrigating my yard which would save a TON of electricity on my pump.  It ramps up or down based on how much water I'm currently using. 

Let me know if you have any questions about my system and I'll definitely try and answer them.   :)

Offline TexasGirl

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #28 on: April 10, 2013, 02:10:11 PM »
I just thought I would bump this up after listening to Jack's last call-in show where he answered someone's question about running a well off of solar power. 

It's not as much about running off of "solar" as it is about running off of a battery bank.  These off grid systems are all about the battery bank which is where you need to put your focus.  You can charge them efficiently from solar, propane or diesel generators or wind power... it doesn't really matter. 

I had a smaller well pump but recently switched out to a much larger pump to handle my irrigation system.  I think it's about a 3hp pump? 

The important thing to look for when finding a pump for off-grid capabilities is finding a soft-start variable speed pump

If the grid goes down I would theoretically only use the well pump for drinking water and the occasional shower which means that the well pump would run with a low power draw.  I wouldn't be irrigating my yard which would save a TON of electricity on my pump.  It ramps up or down based on how much water I'm currently using. 

Let me know if you have any questions about my system and I'll definitely try and answer them.   :)

Exactly!  +1

I have a half horse submergible well pump, which one would expect to pull less than 400 watts, but the Power Factor is .40 - very inefficient.  It's 120v, and the Honda EU2000i has a hard time with the starting surge.  But amazingly the Outback VFX3648 doesn't even flinch.

On a side note, we had a good solar day recently.  Since it was near the equinox (perfect angle for my array), and was a cool clear day following a cold front, the "4.1 kw"  array produced 4.28 kw/hr at it's peak.  Running a fridge, freezer, and the usual appliances (including electric cookstove) the 800 ah 48v battery bank seldom drops below 90% charge.  We will see how it does this summer with the airconditioner. 

Yes, it's all about the battery bank and inverter.

~TG

Offline Cedar

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Re: My real-life grid tied solar system with off grid capabilities
« Reply #29 on: April 10, 2013, 02:23:26 PM »
I missed this before.. nice set up.

Cedar