Demonstration of Generator Support

It is surprising how many people I have talked to (most of whom have Outback inverters and have never heard of it) that do not understand what generator support is all about in an off-grid inverter. And I've talked to other folks who have heard of it but don't think it's all that important to have. And yet others who have heard of it and would like to have it, but have never seen it work in a real live installation.

So I took the opportunity to make a video with a live demonstration of how it works.

[video=youtube_share;KMBdaukbahE]

--
Chris
«13456711

Comments

  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,486 ✭✭✭
    Re: Demonstration of Generator Support

    Chris, thank you for taking the time and posting the Video. This will be a game changer for me on a project I have been working on for 3 years. I'll probably go the OutBack route so I can make it scalable. Thanks again, I hope others will be able to see what this can mean, it opens a lot of opportunities with a small generator and a small inverter and making them work together.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support

    You're welcome.

    I would bet that if you did a random survey and asked people what the most expensive thing is about living off-grid that you would not get the right answer from most folks. It is batteries. Not solar panels, or inverters, or controllers, or generators, or fuel in the generators. Batteries.

    Sandia Labs did a study a few years back on off-grid deep-cycle batteries related to DoD and battery life using Rolls-Surrette batteries. They determined that the amount of usable energy gotten out of a battery over its life is greater if you deep cycle it vs shallow cycle it. I'm sure the study could be googled up for those who are interested. So people who buy extra battery capacity to prevent cycling them below 70-80% SOC are actually spending more money over the long term on batteries than those who deep cycle them to 50% and replace them more often.

    Where generator support in an off-grid inverter comes in, is allowing you to buy the bare minimum in battery capacity to run your normal daily loads and let the generator help with the big stuff instead of just throwing more batteries and solar panels at the problem. Many folks consider it the "pinnacle" of off-grid to not have to run their generator. In reality, that generator fuel is a lot cheaper than the extra battery (and RE generating) capacity it takes to never run the generator.

    In most off-grid homes the normal loads are pretty light, and the heavy draw stuff is very intermittent. Instead of spending the extra money on batteries and multiple inverters to meet the peak demand, generator support is a lot cheaper. So it not only saves you money on batteries, it also saves you money on extra (or bigger) inverter equipment.

    And the last thing it allows you to do is save money on generator fuel. Too many off-grid people have a 10, 12 or 14 (and some even over 20) kW generator on a XW6048 inverter or similar. This is ridiculous. The generator should not be any bigger than required to get either maximum charging amps from the inverter, or C/10 charge rate for your battery bank, whichever is smaller. Running a 8 or 10 kW generator to charge batteries with a 6 kW inverter is like using a semi to haul an armload of wood. Inverters that only have generator pass-thru support are limited to either what the inverter can run, or what the generator can run. And that means if you want to power a 6 kW load with a 4 kW inverter you need a 6 kW generator, and you have to run that 6 kW generator for charging when you only need 3,500 watts to max out the charger in the inverter. With gen support you can save the gen fuel and run your 3,500 watt generator for battery charging, and still power that 6 kW load with ease.

    These are all the reasons why, to my way of thinking, an inverter that does not have generator support in it is not a real off-grid inverter. I know way too many off-grid people who have over-sized their generator because they got Outback FX-series inverters and need to power an occasional heavy load that only the generator can run.
    --
    Chris
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Demonstration of Generator Support
    ChrisOlson wrote: »
    In most off-grid homes the normal loads are pretty light, and the heavy draw stuff is very intermittent. Instead of spending the extra money on batteries and multiple inverters to meet the peak demand, generator support is a lot cheaper.

    Chris, this is one of the smartest posts I've seen on this forum. It just reeks of experience.:-)

    There is another way to deal with a small generator and a FX type of inverter... DC Coupling. Run your generator through a standalone battery charger and draw your AC load from the inverter. Of course, you are limited to the inverter's peak output.

    In my offgrid home (and many others) 3500 watts is adequate for those intermittent large loads. On the very rare occasion when I need more power (e.g. renting a floor sander) I will borrow or rent a large generator.

    Both gen support and DC coupling for large loads will involve discharging of your batteries. You make the point that battery investment should be minimized (I agree!), but that also limits the usefulness of both gen support and DC coupling. Consider my system as an example. My battery bank (24 volt 370 ah) is more than adequate for my domestic needs. If I need to draw 3500 watts while running my eu2000 (using either gen support or DC coupling) my batteries won't last long supplying the additional 2000 watts.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,486 ✭✭✭
    Re: Demonstration of Generator Support

    VTmaps, I'v used your scheme for 30 years. The only problem with a stand alone charger is that you are limited to the input size of the charger. With generator support, once you set the incoming breaker / generator output ( you chose the load on the generator, say 80% ) it will take the input and charge to the max with power share and make the distribution direct to the inverter. Another consideration is that you have less conversion losses.

    Most of the time I find myself putting 55 Amps dc in and the inverter taking away 10-15 amps dc for it's load, so my net input ends up being 40 amps and thats fixed. The extra head room of the generator is never used. To get around this I'v used a Magnum MM 1512 inverter for it's charger ( 70 amp ) and never hooked up it's AC output. It has a smart charger, but still requires some intervention. Thats a $900 solution for a issue I hope that OutBack will take care of. Time will tell.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support
    vtmaps wrote: »
    Both gen support and DC coupling for large loads will involve discharging of your batteries. You make the point that battery investment should be minimized (I agree!), but that also limits the usefulness of both gen support and DC coupling.

    What the gen support does for us, like shown in my demonstration, is reduce what would be excessive load on our bank to a more normal load of around 10 amps. Your bank still has to be sized correctly to carry these loads because when you throw a 40+ amp load at the inverter you will get severe voltage sag for about 45 seconds while the inverter starts the generator and gets it online to help out. But it recovers right away as soon as the load drops back to more reasonable levels for the bank.

    I did that demonstration with zero incoming RE power and I forgot to show how the bank voltage sags under big load. But as soon as the generator is helping it popped right back up to 80% on our MidNite Battery Capacity Meter with only a net 10 amp inverter load coming from the bank. Our bank will hold and deliver that 10 amp inverter load continuous for 24 hours if it is fully charged. And we don't have a small bank, but it will sack the bank really fast if it is allowed to run a 40 amp load for 2 hours. If we have incoming RE power when this is happening, it doesn't even affect the bank because the power is coming directly from the solar panels or wind turbines to run the inverter's portion of it.

    Gen support is not like battery charging because it's very intermittent duty. The oven in my demonstration came up to 425 degrees to cook the pizza and then the element cycles off. The inverter sees the load went down so it charges the batteries under the reduced load during the delay time before it shuts the generator off. And that battery charging for 15 minutes while it's waiting to see if the load is coming back replaces what was taken from the batteries during the high draw part of the load. All this time the generator is running at peak efficiency under full rated load.

    My wife's new range is a modern one and the elements don't cycle back on to cook a pizza like that - it simply uses the heat that's retained in the oven after pre-heating to do the cooking when you select the "pizza" option on the control panel. So the total gen run time was only roughly 5 minutes to get the oven up to temp, and another 15 minutes of monitoring time while it's waiting to see if the big load is coming back, and then it shuts off.

    So, that's what gen support is all about. I know there are some folks who don't need it. But I also know there are some folks who don't understand what it does. I wouldn't even want to try to figure out how much money we'd have to spend on batteries to try to run the stuff my wife likes to have without it. And she will not allow any sort of gas line to come into our house. So it was a steep learning curve for me to learn how to set it up and how to use it.
    --
    Chris
  • SolaRevolutionSolaRevolution Solar Expert Posts: 407 ✭✭✭✭✭✭
    Re: Demonstration of Generator Support

    Magnum will soon be releasing their MSH (MS Hybrid) inverter line with Gen Support and Grid interactive mode with two seperate AC inputs! Tec support said it will be in the same inverter chassis and so will fit with existing Magnum BOS gear.

    It is still in testing but should be shipping soon. There are a lot of details of operation listed in the 2012 ME-ARC manual.

    -Alex
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support
    Thats a $900 solution for a issue I hope that OutBack will take care of. Time will tell.

    I don't know about Outback. But Magnum sees the light and is coming out with their new MSH4024RE that has it. The MSH4024RE is a 120V inverter with gen support. When I talked to the people at Magnum when we were looking to up our system to 48 volt they told me the MSH4024RE is their answer to the venerable SW Xantrex, which is still the best inverter ever built by any company. These features like gen support actually work in the SW and the lights in the house don't even flicker when it does it. We'll see how well Magnum implements it and if they can match what Robin Gudgel did with the SW when he designed it.

    It's one thing to have these features. It's quite another to put it in a package that don't break. Sure, the XW-series has it, but it's not as seamless and programmable as the old SW Plus, nor is the XW is as good of an inverter as the SW Plus. If Magnum Energy can match it, then it raises the bar that everybody else is going to have try to meet and Outback is going to be left choking in Magnum's dust.

    Edit:
    Sorry Alex - your post must've came in while I was posting mine about the new MSH inverter from Magnum. I didn't know they have some info in the ME-ARC manual on it either. That's cool - I'll have to take a look at that to see how they implemented it. Thanks!
    --
    Chris
  • BB.BB. Super Moderators Posts: 26,769 admin
    Re: Demonstration of Generator Support

    The neat thing that Chris is doing is running his generator at something like 80% or so of its rated output near 100% of its run time. The AC generator output either going to supply his large AC loads (range, electric dryer, etc.), and/or the balance goes to charging his battery bank (natural "opportunity" loads). So he is staying >50% load on the genset and being very fuel efficient.

    Much different than firing up a 4kW generator support AC loads that may be only 400-600 watts for much of the time with occasional peaks for Range/Tools/Shop loads.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support

    Bill - yes, that is a good point. A person still has to put the pencil and paper to it to figure out what your loads are and what you need for batteries, inverter power and generator power to run them in the most efficient manner.

    The first gen support system I set up was with dual SW Plus 4024's and a EcoGen 6kW. We had way too much inverter capacity, and the generator was way too big with that setup, which wasted power in running an extra inverter that we didn't need, and fuel to use the generator support effectively. Fortunately I was able to trade that setup for the one we got now while still using some of the other equipment (ACCB and GSM). I hit it a lot closer to ideal when we put in the 5548 with the EM4000SX generator. It still runs all our loads with no problem, the generator burns roughly half the fuel (in cost/hr), and we saved roughly 100 amp-hours a day in running one inverter vs two, doing the same work.

    The only difference with our new system is that I don't do any welding in the shop with it anymore without manually starting the generator first. My Lincoln 225 amp welder is a bit much for the single 5548 if I strike an arc with the welder set on 225 amps. It is impossible for it to get the generator online fast enough to meet that big of load. But with the generator pre-started it handles it with ease.

    So it was not something that I got to "just work". It took me two tries to build a system that does the job at the peak efficiency. On the first try I went by others (mainly the Xantrex dealer that we bought our inverters from) said to do. And make no mistake - it did work perfectly fine. But experience with it showed me the proper way to set it up. Fortunately I was able to apply that experience at not much cost to change it to the way it should've been set up in the first place.
    --
    Chris
  • mtdocmtdoc Solar Expert Posts: 600
    Re: Demonstration of Generator Support

    Great video Chris. Gen support is a nice feature.

    One thing to point out I think is that you are probably on the far end of the curve of off griders- both with your loads (all electric home) and RE generating capacity (with those awesome turbines!). While the essential points of not running an oversized generator or inverter/battery bank for occasional peak loads are very imporatant- I think the more "conservative" off grid setups strive to never have the kind of regular peak loads that an electric range or electric clothes dryer generate. In that case the difference between the baseline load and peak loads is not as extreme and gen support is not as critical. As you point out with your welder example - using a manual started generator for an occasional high amp shop load is a different issue and a reasonable way to do things.

    I'm not off grid usually, but just as an example when the grid is out and I am in off grid mode, my baseline 120 VAC load is 0-2 amps. Typical medium high loads are the dishwasher or clothes washer (5-12 amps) The ONLY really high amp load I have is my septic pump (240 VAC via PSX-240) which will draw up to 30 amps (120VAC) at start up then settles down to 15-20 amps for the rest of its 15 - 60 second cycle. Even with this occasional high surge load, I have never exceeded my Outback GVFX's surge capacity. This is with a modern 3000 sq ft home. I have tested the gen support with my small Honda gens (no autostart) just to see if it works ( it seems to work fine) but I have yet to need it with my setup and think I rarely would even if was off grid 24/7.

    So lots of different scenarios. You seem to have found the ideal, most efficient way to do things in your situation which definitely requires gen support.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support
    mtdoc wrote: »
    One thing to point out I think is that you are probably on the far end of the curve of off griders- both with your loads (all electric home) and RE generating capacity (with those awesome turbines!).

    I agree. This is for the full-time off-grid home. And there are many off-grid folks who live fairly spartan and don't have the stuff we got. I like the all-electric home because it gives us the option to use RE power to run it. We can run the full induction range top on my wife's range totally on RE power, for instance, without gen support. The only time gen support is required is to use the oven part, as an example. But if we had an LP appliance you are limited to only one fuel to run it - LP - with no option to use your RE power to operate your appliance.

    It think the point is that are many folks who believe you can not have this sort of stuff for off-grid because it's too expensive to put in the RE equipment to run it. That's where generator support shines like a beacon in the night. It makes it possible, at very reasonable cost and efficiency, to enjoy the things that people on grid power have.

    And it does take a good generator to make it work right. Our Honda is so awesome I cannot even begin to describe it. It maintains voltage and frequency control that our Generac 6 kW could not maintain on its best day. When I pre-start the generator to do some welding it uses the "iAVR" overload output of the generator to meet the load from the welder. The rated output of the generator is 3.8 kVA continuous, 4 kVA for 30 minutes, and iAVR (overload) output of 5 kVA for 10 seconds. However, that is a conservative rating for the Honda generator. I have seen it in the iAVR overload mode for up to one minute at a time when I'm welding, and it maintains PERFECT 120V and 60 Hz input to the inverter while doing it. It is so perfect that really sensitive loads like CF light bulbs do not emit a single flicker when I strike an arc with the welder. I have worked with megawatt class gensets in my life and I have never seen another generator that can do what these Honda EM Deluxe generators can do. It is the most amazing feat of engineering in generators that exists - at a fraction of the cost of inverter type units.

    Having that grid-quality input to your inverter, I believe, is also a factor in making generator support work properly. The inverter is forced to use whatever the generator puts out. And if the generator drops in voltage and freq under heavy load (which is part of using gen support), the inverter is forced to match it, which reduces efficiency of the equipment you're trying to power.

    So this is all the stuff I've learned about using it. And I just wanted to throw it out there so other folks can see what you can do with it. It opens up possibilities for off-grid living that let you enjoy having some of this stuff without breaking the bank to have it.
    --
    Chris
  • LOTWLOTW Solar Expert Posts: 25
    Re: Demonstration of Generator Support

    Great video. When I bought my system, (which I designed and built myself), I just assumed that the VFX3648 would do this. I was shocked when I realized after testing that it did not. Now I'm stuck having to buy a second inverter and cabling, disconnect as well as a HUB10 for the few times a week when the new septic pump comes on at the same time as the water pump, dishwasher, washer etc....

    If the generator could just come on to assist when the load got up to 3000W or something, it would be perfect and save 2500 bucks at least.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support

    Actually, some time back I was shocked to find out it wasn't in the FX-series inverter. I think it was Volvo Farmer that was trying to run some of his stuff while charging with a small generator and he said if it was charging and his 'fridge kicked in things could get ugly. Ryan Stankevitz (works for MidNite Solar - used to work for Outback) told me it was a feature that boB put in the software in the Mate and they had always intended to implement it, but it never got done.
    --
    Chris
  • inetdoginetdog Solar Expert Posts: 3,121 ✭✭✭✭
    Re: Demonstration of Generator Support
    ChrisOlson wrote: »

    Sandia Labs did a study a few years back on off-grid deep-cycle batteries related to DoD and battery life using Rolls-Surrette batteries. They determined that the amount of usable energy gotten out of a battery over its life is greater if you deep cycle it vs shallow cycle it. I'm sure the study could be googled up for those who are interested. So people who buy extra battery capacity to prevent cycling them below 70-80% SOC are actually spending more money over the long term on batteries than those who deep cycle them to 50% and replace them more often.

    A good analysis for those off-gridders who have an autostart generator or can manually crank up the generator when needed to supplement or charge the batteries.
    The remaining argument for shallow discharge, even with RE batteries designed for efficient deep cycling, is that the extra bank capacity may be required to get the days of independence without sun that the owner needs. But your argument still holds to the extent that using a generator to charge the batteries every cloudy day in that case may be cheaper than paying for the extra battery bank size.
    As always, YMMV.
    SMA SB 3000, old BP panels.
  • VicVic Solar Expert Posts: 2,811 ✭✭✭✭
    Re: Demonstration of Generator Support

    Hi Chris,

    Appreciate your detailed posts and Video on using Gen Support.

    My system IS oversized for almost all loads here. But chose to do Stacked inverters -- a bit of added redundancy, and inefficiency.

    Often these tradeoffs are a matter of style. While I have generators, would prefer to avoid running them most of the time -- love the Sounds of Silent Solar. And would not use electricity to cook, preferring LP instead.

    Some of the added tradeoffs are regarding weather -- LP may not work well for you folks in the depths of Winter, when we often sunny, mild days here in CA. But we do need some A/C in the Summer (you might as well), and would not consider running a genset to power the A/C, except in the most extreme conditions.

    As inetdog mentioned, I am in the camp of riding out successive cloudy days by leaning on the bank, rather than running the genset daily. More a matter of style, to me.

    Thanks for sharing and demonstrating Gen Support, as no around here uses it, to my knowledge. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support

    In that whitepaper study that I read that one time they didn't really have any cost analysis in there. It was just a study of cycling on deep-cycle batteries to see what the life was vs cycle depth. The life is shorter when you deep cycle them. But the amount of energy was better with a deep cycle because of the inefficiency of getting from 80% SOC to 100%. So if you deep cycle your batteries to 50%, over the long run you'll get better return on amp-hours in vs amp-hours out vs shallow cycling them, for a tradeoff in shorter life (measured in years) and number of cycles.

    They didn't say so in the study - Sandia just presented the data. But one can read into it that if you buy less batteries and work them harder you'll get better return on your investment over the long haul than buying more batteries and shallow cycling them. We could actually use more batteries because ours spend more time from 50-70% than they do from 70-100% SOC, and we can catch them up easily on a good day. But I'm not going to buy any more because if they last me 7 years they're already costing me $100/month.

    I figured it out once and we'd have to increase our bank capacity by easily double to run the stuff we run with inverter, that we presently run with the generator. And then I wouldn't have enough RE capacity to charge the confounded thing. At present, during the worst months of the year we might spend more than $100 a month on generator fuel. But over the year's time, it is about $50 a month for generator fuel on average. So buying more batteries, plus the stuff to charge them, would never pay because the batteries are going to go bad eventually no matter what you do, and then you take it in the shorts with a $17,000 bill (at today's prices) to replace a big battery bank.
    --
    Chris
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Demonstration of Generator Support
    ChrisOlson wrote: »
    The only time gen support is required is to use the oven part, as an example. But if we had an LP appliance you are limited to only one fuel to run it - LP - with no option to use your RE power to operate your appliance.

    Is it worse to be dependent on generator fuel than to be dependent on LP? --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support
    vtmaps wrote: »
    Is it worse to be dependent on generator fuel than to be dependent on LP? --vtMaps

    I wouldn't call it worse or better - just having the option of using RE power for some things that most off-grid folks will tend to use LP gas for. On a good day with plenty of incoming power we can operate the oven in that range without generator support - it does not overload the inverter unless we have some other larger loads going.

    In my demonstration video, even with 700-750 watts load on in the house, it was barely on the edge of the threshold that causes the generator to start. If the house loads would've been 2 amps instead of 6 amps before I turned the range oven on, it would not have started the generator. And that would not be the end of the world because it only takes roughly 5-7 minutes to get the range up to 425 degrees to cook with, then the element cycles off. The battery bank can easily handle that if it's above 60% SOC.

    If the Load Amps doesn't start the generator, then one of the voltage sag timers (either the 2 hour or 15 minute) will start it if a heavy load that does not reach the Load Amps threshold persists. The only reason it started on Load Amps in that video is because the load amps was at the threshold where I like to see the generator come online to help out. And learning where that threshold is requires some experience with your system.

    If you have a LP fired range you do not have that option. You can have a nice day with all sorts of incoming power, the bank floating - you go to cook something and instead of using what you make with solar panels and wind turbines to "fuel" your range - you're burning a fossil fuel. That's why I've grown to like the electric appliances, despite all the advice I've gotten over the years that for off-grid you should use LP gas. The electric appliances are "dual fuel".
    --
    Chris
  • inetdoginetdog Solar Expert Posts: 3,121 ✭✭✭✭
    Re: Demonstration of Generator Support
    ChrisOlson wrote: »
    The electric appliances are "dual fuel".
    --
    Chris

    I like that analysis! :-)
    Just less efficient when running on the LP fuel that a single fuel appliance would be, but you hopefully make up for that when running on electric.
    SMA SB 3000, old BP panels.
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support

    It's less energy efficient by BTU input to the generator when you factor in engine thermal efficiency and electrical losses in the generator and wiring. But it's about the same cost as LP because LP appliances are typically only about 50% efficient where electric is >90%.

    What makes it pencil out even better is that the cost/BTU of LP is higher than gasoline or diesel fuel. Delivered propane cost here right now is $2.72/gallon for 91,700 BTU. Winter blend gasoline is 110,800 BTU/gallon and the cost is currently $3.09/gallon here. So LPG figures out to 3 cents/thousand BTU. Gasoline is 2.8 cents/thousand BTU.

    LPG is usually highest priced during the winter home heating season and it drops in price during summer.

    Gasoline goes the other way and usually get more expensive in summer due to more people driving and higher demand. But winter time is when we use this feature the most because we can't use the clothes line to dry clothes outside, and we tend to do more cooking with the range where in summer we will use the charcoal grille outside to do the majority of our cooking. So for most of the summer our generator is in retirement and the inverter starts it about once every two weeks for 30 minutes to exercise it. In the long run, according to the figures I've come up with on it, it competes very favorably with using LPG appliances in actual out-of-pocket cost.
    --
    Chris
  • mtdocmtdoc Solar Expert Posts: 600
    Re: Demonstration of Generator Support
    ChrisOlson wrote: »
    What makes it pencil out even better is that the cost/BTU of LP is higher than gasoline or diesel fuel. Delivered propane cost here right now is $2.72/gallon for 91,700 BTU. Winter blend gasoline is 110,800 BTU/gallon and the cost is currently $3.09/gallon here. So LPG figures out to 3 cents/thousand BTU. Gasoline is 2.8 cents/thousand BTU.

    Wow - regional differences. LPG is less than $2.00 a gallon here now. Regular gasoline is about $3.30.
    LPG is usually highest priced during the winter home heating season and it drops in price during summer.

    True. Having a large tank helps - buy when prices are cheapest.. With a 1000 gallon underground tank and only our gas range burning propane - I can go 10 yrs without a fill up.8)

    Chris, how are you heating your water?

    Water heating is the crux of being potentially self sufficient for us now. I originally planned to put up some direct solar water heating panels for summers, a wood stove coil and with on-demand propane as back up. This past summer I bough a Nyle Geyser heat pump water heater and in the summer I can run that off my PV as well as all our house loads. In the winter it's a different story.. I have a wood stove coil but haven't installed it yet. Waiting to see if I need the on-demand propane heater...

    If I had 20+ Kw wind potential as you do - the heat pump water heater would probably be sufficient even in winter.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Demonstration of Generator Support

    wow, that gasoline is cheap compared to here as down the road from me it is $3.539/gal. not sure what the propane is up to lately and i will need to find that out before firing up the grill again this spring, but if the weather improves any more here i may want to get more propane now as it's going into the 60s here. that's weird for this time of year.

    anyway, you guys may like to check area gasoline prices where you live or where you plan to visit and i found this site below to be very nice.
    http://www.automotive.com/gas-prices/
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support
    mtdoc wrote: »
    Chris, how are you heating your water?

    We heat all our water with electric 240V power. We have two 55 gallon heaters in series, and all the standard 4500 watt elements have been replaced with 2,000 watt. The top element in the primary heater is set to 125° F and power always on from the inverter. The bottom element in the primary and both elements in the preheater are controlled by my Classic controllers using the Waste Not Hi mode on Aux2 output with SSR's. The Classic turns on 240V power to the elements as necessary to regulate charging voltage and/or keep the power sources at full rated output when there is excess over what the bank needs for charging.

    Those three elements are daisy chained with the same type of thermostats that are used in a standard DWH to switch from the top to bottom element. The stats are set to the max on the three elements so when the primary heater gets up to 155-160°, the stat clicks and the power is then diverted to the top element in the preheater. When the top in the preheater gets up to 155-160 the stat clicks and sends the power to the bottom element.
    --
    Chris
  • mtdocmtdoc Solar Expert Posts: 600
    Re: Demonstration of Generator Support

    Oh yes, of course. I had forgotten you were doing that with the the Classic Aux - yes very nice.

    Well - you obviously have a very well designed system there and are able to run all electric with modest generator run times. But I guess it does depend on your incredible wind resource which few others will have.

    Again, great video on generator support. It will be interesting to see if Midnite Solar offers this feature on their upcoming inverters.
  • BB.BB. Super Moderators Posts: 26,769 admin
    Re: Demonstration of Generator Support

    I still believe in figuring out a rough $$/kWH (or whatever units you like)--Without some sort of numbers--It is very difficult to understand where to put your efforts (and money) for an "optimum" solution.

    That also includes sizing a system too... Even if your off grid solar set is able to output 1,000 kWH per year at $0.50 per kWH (using PV Watts)--If you only really use 500 kWH per year (live there part time, cannot always take 100% of available power every day, etc.)--Then the cost has doubled to $1 per kWH.

    Whether that is conservation, wind, solar, or generator (or a mixture).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support

    Like I explained in another thread here on the forum, the cost/kWh doesn't really matter to us. It's fun to try to put a pencil to it and figure it out. But every kWh we consume easily costs us 3x what people on grid power are going to pay for electricity. It's the part about being independent that we enjoy. We selected our place where we live because we like it and we're not going to spend $168,000 to get a single phase line run to it. After living here for 11 years this coming June without utility power we enjoy what we have built over time, we enjoy where we live, and we would not trade it for someplace with grid power. So whatever it costs, it costs. Living cheap is not what we were after. But we DO want to live comfortable and we have spent a LOT of money to get there.

    And also like I said in that other thread, nothing really irks me more than somebody that doesn't know us that comes to our place and sees what we got, then thinks we "got it made". My reply that I've come up is "yeah - spend fifty thousand and you can 'have it made' too."
    --
    Chris
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,258 ✭✭✭✭
    Re: Demonstration of Generator Support

    I can see your point Chris and I can also see Bill's point in asking for a rough dollar per KWH metric. As a business person I sometimes have get to number with some clients.
    Many are like Chris in that it is just the cost of living offgrid. Sometimes the place where they live is so special that the thought of bringing power in would ruin it. Power lines can bring undesireable results. Offgrid folks are all different! Some live in places and can control their usage to where there is not a generator to support. I liked the song by Chicago that was playing in the video. Spring is coming!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support
    I can see your point Chris and I can also see Bill's point in asking for a rough dollar per KWH metric. As a business person I sometimes have get to number with some clients.

    I've always told people that if they are trying to save money by generating their own power with solar and wind that they're barking up the wrong tree. Hydro power, I think (according to the numbers I've come with on it), is different and you can actually beat grid power cost with a well designed hydro power system. The only thing that has made solar or wind power viable for a lot of folks is government subsidies or income tax credits, etc.. Without those, you are not saving any money.

    To me, this photo embodies what off-grid living is all about, and you can do it with the most basic system that gets you by or by going extravagant and living in style - all it takes is money. But you have control over it, do not send a check to a smoke-belching power plant someplace every month, and you are independent and own all your equipment.

    Attachment not found.

    --
    Chris
  • Dave AngeliniDave Angelini Solar Expert Posts: 3,258 ✭✭✭✭
    Re: Demonstration of Generator Support

    Nice! Nice! Nice!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail offgridsolar@sti.net

  • ChrisOlsonChrisOlson Banned Posts: 1,807 ✭✭
    Re: Demonstration of Generator Support
    inetdog wrote: »
    I like that analysis! :-)
    Just less efficient when running on the LP fuel that a single fuel appliance would be, but you hopefully make up for that when running on electric.

    The other thing my wife uses a lot is her 120V slow cooker. She's cooking our supper right now at lunch time - chicken and it sure looks good :D

    Attachment not found.

    I really think those slow cookers are quite efficient. I think the thing draws about 1350 watts until it gets up to temperature and then it cycles on and off thru the day to maintain the temp. And the cycle-on time to maintain temperature in it is very very short - usually less than a minute at a time. Our system doesn't even appear to know it's there but it will cook supper for us this afternoon and I'll bet it don't use more than 1.5 kWh of electricity to do it.

    For whatever reason, this is another thing that I've told other off-grid folks that we know, that we use, and they can't believe it. They have the mistaken notion that their system could never run such a thing. But we used to use the slow cooker even with our old low-powered 12V MSW system that we had for years, and it never seemed to affect it much on a windy sunny day. Batteries still got charged up and we had supper cooked at the same time, many many days.

    I've tried to convince folks of this for years - if you're off-grid use electric stuff for pete's sake instead of gas. Your equipment doesn't make gas - it makes electricity. So use it :cool:
    --
    Chris
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