Difference in Off Grid Philosophy

Rngr275 · June 2012

Met with a couple installers/system designers since my last post. The one guy was fairly young and has been in business for a couple years. Went to the right acredited schools/training, but doesn't have a lot of experience. I told him that my expected daily Kwhr demand was targeted at around 5Kwhr per day may be a little higher or lowere but this was my target and I want to see a proposal that covered both this value and a little higher and lower Kw PV system. Off the cuff he said I was probably looking at a 2-3Kw PV, suggested a 48V system, 4000w Magna inverter (possible the 120/240 model for future use like a pump). Likes to only us 2 parallel strings and enough batteries for a couple days autonomy. Young but I liked him and he is really trying to establish himself in the area, also encouages my sweat equity.

The other guy really scarred me and was similar to another well know, well established installer who has been doing Off-Grid for a long time. Started out telling my about a system he is doing now that phase one is a huge generator and battery bank (18kw generator), and inverter/controllers and phase 2 will be the addition of the solar panels. Didn't want to talk about a design for me until he gets to see my load evaluation but said that a large generator will be required due to the equalization of the batteries that will be needed a couple times a year. He kept focusing in on my current 1000KwHr a month electric usage even though I kept explaining that my/our goal was to reduce that to less than 200Kwhr per month and that if the system is designed as such then the burden is on us to live within that limit or use the generator more. Also likes big battery banks (800-1000Ahr)

Am I missing something here both well established installers are way off from what I think I want and most here have agreed sounds reasonable.

My current system (In my mind right now) 2-3Kw of PV of say 12 panels @ 200+ watts each, ~4000w invertor,contoller, monitoring (maybe a 120/240v inverter), a couple days autonomy say 8 Trojan L-16-RE @370Ahr (wired for 48V), and a 6-8Kw generator. PV pole mount which I can adjust. IS this a reasonable system to supply enough electricity to support targetd 3-5KwHr a day with the generator available for charging/extra electricity misc. loads like saws laundry etc when needed?

Thanks,
McD

vtmaps · June 2012

Re: Difference in Off Grid Philosophy

I encountered similar divergent philosophies when I met with a few installers a few years ago. Several well known established installers wanted to set me up with a $30,000 system. I think that they were trying to sell me a system so that I didn't have to think about what I was doing. Just buy energy star appliances and plug them in. Use them whenever I want to.

If you go for the system that is in your mind right now, you will have to think about what you are doing and when you do it. You will have to pay attention to the meters. You will have to understand that you are off grid and behave accordingly.
--vtMaps

Volvo Farmer · June 2012

Re: Difference in Off Grid Philosophy

Your proposed system is similar to the one we have been living with for seven years. Laundry and saws are no problem, though we try and load shift laundry to afternoons on sunny days. We even have an 18CF electric refrigerator and small chest freezer. Our location gets over 300 sunny days per year, so your location might affect how much solar or how much battery you need.

People in this forum hammer on newbies to figure out their consumption before designing a system, and with good reason. A lot of folks have no idea the sacrifices and mindfulness it takes to live on 5KWhr/day. However, when I built my system, I went in with your mindset, that I was only going to make this much electricity, and scale my demands accordingly.

Lastly, if you have any interest in maintaining and expanding your system in the future, go with the guy that will let you help him. My installer allowed me to be his helper, and I learned enough in those two days to never need to call in another installer, and I have made several expansions and upgrades since then.

Rngr275 · June 2012

Re: Difference in Off Grid Philosophy

We are going into this knowing that we will beaware of what we are about to do (using electricity) and want to make our children as aware. We are expecting and anticipating a major life style change. Obviously I have no clue how it will all be and how much we will have to adjust until we start but we are trying to be as dilegent as possible. One of the reasons I come to this forum.

Thanks to All!!!

icarus · June 2012

Re: Difference in Off Grid Philosophy

Begs the question,, if you have the grid available, why would you chose to go off grid? I'm us you know that grid tie PV is 1/2 the price with twice the production as battery based off grid, and you can still cut your comsumption as much as you wish if you are grid tied,

Jut saying,,

T.

PS. At least you are wise enough to know what you are getting into. conserve, conserve, conserve! It may be tougher for your family than you imagine. We have family visit, and they never get the hang of turning stuff off! Even my wife who has been off grid nearly as long as I, but doesn't understand the technology leaves stuff on, and then asks if she can run something, even deter being told how to read the battery monitor over and over again.

T

Eric L · June 2012

Re: Difference in Off Grid Philosophy

My current system (In my mind right now) 2-3Kw of PV of say 12 panels @ 200+ watts each, ~4000w invertor,contoller, monitoring (maybe a 120/240v inverter), a couple days autonomy say 8 Trojan L-16-RE @370Ahr (wired for 48V), and a 6-8Kw generator. PV pole mount which I can adjust. IS this a reasonable system to supply enough electricity to support targetd 3-5KwHr a day with the generator available for charging/extra electricity misc. loads like saws laundry etc when needed?

I think it would work but you may be running the generator a lot during winter or other prolonged cloudy spells. My similarly-sized system (4.1 KW of panel, 360 ah battery bank @48v) gives a pretty reliable 5+ kWh/day (usually much more) at my location if it's at least partly sunny. But rainy, overcast days can see production fall below 2 kWh, and I know the Finger Lakes area enough to know that it can get pretty overcast in the winter.

If that second guy makes a really convincing case that you need a massive generator (which I would really question, but that's just IMO), then you're better off just running the grid to the new place.

One thought: Is it possible the more experienced installer still following the same system design he used when pv prices were $5+ per watt? If so, he needs to be aware that higher panel/battery ratios have gotten a lot more price competitive.

Rngr275 · June 2012

Re: Difference in Off Grid Philosophy

icarus, I would in a heartbeat but the grid is $50-70K away from the house and the neighbor is not very keen on running the poles on his property. $30K away on the other side and 2 neighbors flat out said no. Kind of in a jam here.

erne · June 2012

Re: Difference in Off Grid Philosophy

One thing you want to consider is most homes are wired for 220v and jumping a breaker box can load your neutrals and cause problems or worst. be sure that the young installer understands this danger for you and the future. I am at 8500 feet and produce 5+ kw on most days with 1.3 KW of panels. I seldom need my generator.

waynefromnscanada · June 2012

Re: Difference in Off Grid Philosophy

icarus wrote: »

Begs the question,, if you have the grid available, why would you chose to go off grid? I'm sure you know that grid tie PV is 1/2 the price with twice the production as battery based off grid.
T

I'm sure there are many reasons, and with anyone who knows the comparative costs, it has to do with more than just money. (This is NOT a snarky comment)
For myself, even as a child, I dreamed of having some type of power system, but back then, solar electric didn't even exist. Now, it's as if my childhood dream has come true. Not only do I have solar power, but enough hydro to fill in at night and during the short, dark days of the late Fall stormy season. Having to live with what Nature provides, when she decides to provide it, has been, in hindsight, quite easy for me, and also in a way, connects me to my ancestors. Now, I get terrific satisfaction knowing I harvest the electrical energy I need, on my own, and can likely continue to do so regardless if the grid exists or not. This energy self sufficiency, for me, is a wonderful, amazing thing, worth more than money. I love it and am extremely grateful for it. Like others, I also more or less expect things could get very bad, and even though I'm well aware that I cannot live forever, indeed am nearing the end of my ride through life, I like knowing that energy wise, I'm ready for disaster.

plongson · June 2012

Re: Difference in Off Grid Philosophy

icarus wrote: »

We have family visit, and they never get the hang of turning stuff off!

HAHA!! This is one of the biggest challenges I've had being off grid. My dumb ass relatives who won't/cant'/refuse to understand they need to 1.) Turn stuff off or 2.) Ask me before they turn it on.

My prime complaint is they bring the hair dryer and curling iron. When they walk in the door we have a short introduction to how we provide power for the place, and our limitations.

Next thing ya' know they take a 30 minute shower then I hear the blow dryer...They probably think I lost my mind when they hear me banging in the bathroom door yelling "SHUT IT OFF, SHUT IT OFF!!!"

What' funny, right now the humidity is around 8%...so low you don't even need a towel, water nearly evaporates coming out of the shower head...

Paul

Cariboocoot · June 2012

Re: Difference in Off Grid Philosophy

a large generator will be required due to the equalization of the batteries that will be needed a couple times a year.

Now there's someone who doesn't know what they are talking about. Equalization doesn't require a lot of Amps, because it is done when the batteries are fully charged. So why would you need a large generator? Higher Voltage; not much current. "a couple of times a year" is a pretty random EQ criterion too.

That one sounds like he's out to sell you a ton of stuff so he makes big $ and you get ... a ton of stuff.

BB. · June 2012

Re: Difference in Off Grid Philosophy

I am a big believer in designing a "balanced" system... If you do it with the generic rules of thumb (~2 days of "no sun", 50% maximum day to day discharge, 5-15% rate of charge, C/2.5 surge current, 5% rate of charge for equalization, etc.), it seems that you will have a cost effective, reliable, functional system for most areas in North America...

In a few cases (such as the desert southwest), you can end up needing more solar panels to support the 5-13% rate of charge than needed to support your daily loads. And conversely, in areas with long/dark winters, you need a lot of panels just to help with daily loads.

Generator wise--You may end up with two generators... One sized to "fuel efficiently" recharge your battery bank (i.e., size your battery bank to your loads first, then size AC charger and genset to bank), and a second one to run the occasional heavy loads (shop, fire pump, backup to first genset, etc.).

An 18 kW genset can easily use 2-3 gallons of gasoline per hour supporting zero to ~9kW of electrical load (less for diesel, more for propane). If it takes 4-6 hours or so to recharge your battery bank (hour or so at "full rate" for bulk charging, and another 2-4 hours at declining rate for absorb charging), that can be a heck of a lot of money out the exhaust pipe every few days.

For my on-grid home, I only average around 200-500 watts of power (excluding microwave, somebody turning on all the house lights and dining room fixture with filament bulbs)... An 18 kW genset is huge and only (seems to me) needed for specific loads (A/C, shop tools, etc.) or charging a very large battery bank.... Try some rule of thumb math (very rough numbers, actual numbers and other hardware issues will modify):

18,000 watts * 1/59 volts charging * 0.80 charger eff * 0.66 typical PF * 1/0.05 rate of charge = 3,221 AH @ 48 volt
18,000 watts * 1/59 volts charging * 0.80 charger eff * 0.66 typical PF * 1/0.10 rate of charge = 1,610 AH @ 48 volt
18,000 watts * 1/59 volts charging * 0.80 charger eff * 0.66 typical PF * 1/0.13 rate of charge = 1,239 AH @ 48 volt

If you have a power factor corrected battery charger (many of the new inverter/charger setups do), then you have 1/0.66 number "go away" and you can recharge a 1/0.66= 1.5x larger battery bank. See this thread on issues of "optimally" charging a battery bank with a "smaller" genset:

Question about battery charger selection with EU2000 generator.

I am on grid--perhaps some folks here can let us know their generator/battery charger/bank configuration and how much run time/fuel per day they use for winter recharging.

The nice thing about a balanced system design--You don't usually have to run the genset for 9+ months of the year--at least keeping your yearly fuel costs a bit more reasonable.

-Bill

Photowhit · June 2012

Re: Difference in Off Grid Philosophy

Rngr275 wrote: »

... said that a large generator will be required due to the equalization of the batteries that will be needed a couple times a year...

This is pretty much, just wrong, if you can reach float maintanance equalizing takes an hour or 2 longer(more direct sun) trouble shooting equalizing for a battery out of balance could take longer but a modest genny would be fine if you don't have the direct sun light.

Rngr275 wrote: »

... He kept focusing in on my current 1000KwHr a month electric usage even though I kept explaining that my/our goal was to reduce that to less than 200Kwhr per month and that if the system is designed as such then the burden is on us to live within that limit or use the generator more....

He may just be realistic with past experiences, it's hard for people to limit their usage and doesn't want you disappointed. I might do the same thing if I were suggesting a system. though...

Rngr275 wrote: »

... Also likes big battery banks (800-1000Ahr)...

...at 48volts? this is likely based on your current usage. "Didn't want to talk about a design for me until he gets to see my load evaluation" ...this is very sensable, and advice you will find here often!!!

Rngr275 wrote: »

... Am I missing something here both well established installers are way off from what I think I want and most here have agreed sounds reasonable.

They may just be more practical, I like the 2nd guy wanting to see you loads before suggesting a system.

Rngr275 wrote: »

... My current system (In my mind right now) 2-3Kw of PV of say 12 panels @ 200+ watts each, ~4000w invertor,contoller, monitoring (maybe a 120/240v inverter), a couple days autonomy say 8 Trojan L-16-RE @370Ahr (wired for 48V), and a 6-8Kw generator. PV pole mount which I can adjust. IS this a reasonable system to supply enough electricity to support targetd 3-5KwHr a day with the generator available for charging/extra electricity misc. loads like saws laundry etc when needed?

Depends on your willingness to run the generator, that is an open ended power source.

3-5Kw is a large range, I'm setting up a similar system and had started with a 4Kw array and, I feel, a somewhat under sized 800Ah 24 volt battery (I already had the battery for a smaller system and it may be good for 20+ years, just hate to replace it) My loads will be very modest 9 months out of the year, but I run an AC in the summer time, and I will NOT have a backup generator.

Cariboocoot · June 2012

Re: Difference in Off Grid Philosophy

Sure thing, Bill!

232 Amp hours @ 24 Volts.
Honda EU2000i burning about 2 litres a day to run for 3 hours 'cause it's raining almost every day here.
I take advantage of the generator capacity: let it run Bulk (5 Amps AC, about 25 DC) until the current starts to drop off then turn on the water pump and recharge the tank while the gen rolls over easy. When there's no more "opportunity loads" to be utilized and the current is down to 1 Amp AC (about 5 DC) shut it off. It has usually got through most of the Absorb cycle by then (which only totals about 1.5 hours anyway).
Day with sunshine: no gen time at all. 700 Watts of panels Bulk the batteries, do the Absorb, run the opportunity loads, and spend most of the day in Float.
Winter time: forget it. The day is only 6 hours long and only 3 hours of good sun available. We'd be burning gas (and wood) like crazy. Time to turn off the inverter and go back to town.

In Summer those 700 Watts can do 2800 Watt hours per day, and our usage is usually only around 2400. If we ever get a snow-less December I might risk a drive out here and see what they do in the dark days. Likely as not the generator would have to be the major power contributor, and for full use that would mean 2400 Watt hours from a 1600 Watt generator; about 1.5 hours equivalent run time, but at full throttle instead of reduced speed like it is now. Even in the cloudy weather you get something from the panels. Under the right cloudy conditions you can get a pretty steady (albeit greatly reduced from peak) all-day current due to the diffusion of light.

Rngr275 · June 2012

Re: Difference in Off Grid Philosophy

Oh and I bought my Honda eu2000 last night. Going to need it for lots of stuff. Will buy a bigger one if needed for the house and shop or to charge the system when the time comes. Great little generator!

Photowhit · June 2012

Re: Difference in Off Grid Philosophy

I think a couple people have eluded to the price of solar panels is currently low, an extra 1000 watts of array($1000-1500) could save you a lot of gass down the road. Shipping becomes a large expense with these large solar panels, adding 4 to your order now may cost $30-50, but to order 4 more later shipping may be $300+.

A pretty good deal here on SolarWorld(the people who brought you higher solar prices) panels.

westbranch · June 2012

Re: Difference in Off Grid Philosophy

I'm with Tony,

icarus wrote: »

you can still cut your consumption as much as you wish if you are grid tied,

At least you are wise enough to know what you are getting into. conserve, conserve, conserve! It may be tougher for your family than you imagine.
T

My only question is "Why wait for Spring"?

Do it now, CONSERVE! :cool: (good habits begin at home...)

You can see just how and where you will be able to reduce and make some of those HARD LINE decisions and make some mind bending adjustments at will, ...before you HAVE to and don't have a choice...

just a thought.

HTH

Cariboocoot · June 2012

Re: Difference in Off Grid Philosophy

And then the Mrs. says she has to have the laser printer-scanner.
It sucks up as much power as the water pump - for longer. :grr

westbranch · June 2012

Re: Difference in Off Grid Philosophy

I just remembered to add...

My detailed load assessment of power consumption worked out to 5-6kwh per day,

and that is with a lot of hard nosed figuring

AND there are NO kids in the equation. That rug rat factor may be what the one installer sees as a HUGE looming phantom load, cell phones XBox vid games etc etc etc...

BTW our guests will have their own space in the 1 room guest cabin with separate PV system, (see sig line) with NO AC plugs and just a 600w inverter.

65DegN · June 2012

Re: Difference in Off Grid Philosophy

Lots of really good suggestions on this thread.
I suspect the installer quoting you the big system is being realistic and is speaking from experience as was already mentioned here. I think he is pretty much correct about a large array but not about the big generator for equalizing and a large battery bank. But that is just a difference in design philosophy as his approach is totally a viable design. He is thinking that you need a big battery bank because of your current lifestyle and high power demands even though you intend to change it, it hasn't yet. To charge a big battery bank requires a big generator because it also has to power loads at the same time.
Some people would be able to get by with the smaller system but life will be dramatically different from what you and your family are used to and if you are going to do it later it should be able to happen now.
People always want to hear that all they need is a few panels and something like a 400 watt wind generator on a 20' pole. It almost never works except for weekend cabins.
It does not sound like you will be happy with a 2 ~ 3 KW system. I don't know what your weather patterns are like but if you get a cloudy spell or live at a high latitude where winter days are short 2 ~ 3 KW won't cut it. People almost always undersize their solar array in an effort to save money ! In the long run it will cost you much more running a generator. Thats money that could have bought you the panels you need to not run the gen and not have to replace it when the rings (or whatever) wear out.
My design philosophy is to get the custmer to buy as many panels as they can afford and get a smaller battery bank that will easily get them through the night and a smaller generator to charge the batteries. Those are the two major reoccurring expenses so I like to keep them small. Use as much of the power as possible as it is being produced. A large array will have better odds keeping the batteries charged on a regular basis even on cloudy days without having to obsess over them. Chronic undercharging of batteries is the #1 cause of system problems.

65DegN · June 2012

Re: Difference in Off Grid Philosophy

BB, I have been using a Honda 2000i for about 3 years now and it has been great. Only repair has been to replace the starter rope. I replaced it with a shorter heavier rope and that has worked out very well. We are about in the middle of a 10 acre parcel and with minimum sound dampening the neighbors can't even hear it. My battery bank is 370 AH and I typically charge at 1200 ~ 1400 watts. Starting the charge cycle while the batteries are still at 48 V or higher makes it easier.

ron45 · June 2012

Re: Difference in Off Grid Philosophy

icarus wrote: »

Begs the question,, if you have the grid available, why would you chose to go off grid? I'm us you know that grid tie PV is 1/2 the price with twice the production as battery based off grid, and you can still cut your comsumption as much as you wish if you are grid tied,

Jut saying,,

T.

PS. At least you are wise enough to know what you are getting into. conserve, conserve, conserve! It may be tougher for your family than you imagine. We have family visit, and they never get the hang of turning stuff off! Even my wife who has been off grid nearly as long as I, but doesn't understand the technology leaves stuff on, and then asks if she can run something, even deter being told how to read the battery monitor over and over again.

T

I was going to respond to the original poster but this one nails it for me as to differences in off grid philosophy. When we went off grid in 83 it was to say **** YOU to the entire Matrix and everything about it. Treading lightly is diplomacy speak for the same set of values. Grid tie systems can be attractive. However in a worst case scenario, one can appear, to use the corporate coopted and sullied, `green' and still consume like the bush family. The orininal poster is correct in preparing for a life change. That's what is required to go off grid.

The was no installer when we got to the mt.s in central New Mexico. Where we live there is still a criminal lack of understanding of how much energy can be saved if one orients his home to capture and store passive heat and photo volteic energy. But it has improved some over the years. But the overwhelming majority here is clueless. I'm sure there are grid tie people who DO want to conserve energy and change their way they life. It's a big step in the right direction.

T's query about why not use it if it is there has plenty of merit. I know a guy with a big system in Las Cruces who gets good sized monthly checks from the electric company. And it makes sense in cities or urban areas to do this if it suits you.

What about when the grid goes down? You are like the yuppie with an electric pellet stove. No elecky no stovie. Some people have wind systems with the grid suppling voltage to supply the turbine windings or some part of the system. The national grid is a pathetic hodge podge. And biddniss interests [greed] won't let them change it. Again, I don't think grid tie is always the wrong way to go. It's just that they leave to door wide open to keep on keepin' on bleeding the planet. That's how the difference plays out for me.

Ron

2kw pv w/mixed source panels hence, two out back and one Classic charge controller 200v. Outback 3524 inverter and 12 Surrette S530 batteries and 12 trojan L16s in two separate banks. Three Zomeworks Trackers. Wind is too erratic here for practical use.

BB. · June 2012

Re: Difference in Off Grid Philosophy

One of the things to watch for when "conservation" kicks into high gear... We have a problem in California, that whenever the customers conserve "something", the prices for those things end up increasing...

We have been on a major water conservation kick for 10-20 years out here, water rates are now about 4-5x higher today (partially to make up for lower water usage, and needing more funding to address 100 year old infrastructure).

Or, garbage rates--Implemented major recycling efforts here, and most people are now using one size smaller "garbage" can (we pay for garbage, but not for the two recycling can pickups). Now they have to raise to make up for the expense of people using smaller garbage cans (which subsidize the green waste/paper-plastic-can recycling).

Electricity, roughly 1/2 our bills out here are for infrastructure--If usage falls by 1/2, they will have raise the kWH billing to maintain the infrastructure payments even though we will be using less power.

So--staying ahead of the crowd will hopefully help preserve your cash.

-Bill

ywhic · June 2012

Re: Difference in Off Grid Philosophy

I hope to be 'off-grid' by next spring/summer in TX.. I've got my 725W of PV and my controller.. the inverter and battery bank 12/24V is still up in the air..

I could have gone on the grid for like $40/month out here.. I have 11 acres on a road with power lines..

But the co-op wants $400 just till tell me yes or no.. thats after a $50 trip charge to see the 'site'..

Now doing panels and such works on paper to about $1700 and then the battery bank TBD..

Granted I know in 3 years I'll be getting new batteries and in 5 probably a new inverter and charge controller..

I just want NO BILLS.. I own the property outright and the 12x24 building outright and taxes are $35/year...

Granted I will end up with a cell and internet bill and PO box bill and car insurance/reg bill.. but thats all I want..

Maybe in 2-3 years I double my PV then in case the panels loose there juice in 15-20 years I can still run that darn A/C I keep ranting about.. LoL

solar_dave · June 2012

Re: Difference in Off Grid Philosophy

I seriously considered off grid when I did my setup, but found way to many issues getting it done.
1) the Utility rebates were about half for off grid and it was questionable if they would pay anything at all if the grid was available. BTW their rebate paid for about 45% of my system.
2) Having a large battery bank in the AZ desert heat could be an issue.
3) size of the battery bank to run multiple 3 ton AC units and cool this beast is huge even with the insulation upgrades we did anyway. ( we used 115 kWh yesterday, generated about 72 kWh of those and hit the credit bank for the rest. )
4) we were considering plug in cars when available, again another large load item.

All that being said our utility power is really reliable and cheap off peak. The Grid lets me over generate from Jan - May and get those watts back literally for free (long term battery). Then from mid Sept - Dec or over generation ends up being a credit on our Jan 1 bill, last year enough to not pay them a dime until like May. This year with the plug in cars the first bill was in March. Still we only paid them $24.50 last month and of that only $5 was off peak generation. The rest were fees and taxes, read really cheap battery.

As much as I wanted to cut them out of my wallet it made no sense to do so financial.

Difference in Off Grid Philosophy

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