Watts in your Gen Shed?

A great and handy reference for the basics

Build your Independence

Just thought we could have a thread where folks can list what equipment they have put together for their off-grid systems. It may also be educational to know what appliances are used. I’ll start with my stuff.

We live on 1 acre that we had cleared in a rainforest at 1800′ alt.
The average wind speed is 7mph, so no wind turbines here.
Our annual rain fall is 200″. Winter temps are 55°F – 70°F Summer 65°F – 80°F.
Humidity is a pretty consistent 80%
1880 watts of PV controlled by Outback MX60
8 x S530 Rolls Surette 6V batteries strung in series/parallel at 24V
Xantrex TR3624 charger/inverter 3600 watt (square wave)
Kill a Watt CT50:5 metering
Listeroid Metro 6/1 with Utterpower 3K PMG (cooled with Honda radiator and box fan)
We fuel the 6/1 with UVO that we heat to dry out then filter and cut with 10- 20 % Virgin RUG
Yamaha EF2000is ( Fueled with Non-ethanol 89 octane gasoline with 1 oz./ 5 gal TCW3)
Changfa 6 Hp turning a 3K st head (currently fueled with Locally produced Bio-diesel)

Our hot water is supplied by a cheap propane fired Eccotemp L5 on demand water heater
Refrigeration is a 5.cubic foot chest freezer converted with an external thermostat.
Our water is just caught rain water the we treat with chlorine tablets
Water pump is a 3/4hp w/ 5 gallon pressure tank
Lighting is all CFL

Electricity costs on the Big Island fluctuate with fuel prices I think it is about 40- 50 cents / Kwh
Propane is about 4.80 / gallon

Greg West, Hawaii

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26 Responses to Watts in your Gen Shed?

  1. Neil says:

    Still in building stages, but working toward biomass gasifier to power 360 V8 engine coupled to 30 kw ST Generator. No Gasoline. Hopefully to run entire house with some left over to net meter with. We cook and heat with propane and wood. We have an electric hot water heater and i believe a 1.5 HP submersible well with pressure tank.

    winter temps run anywhere from -10F to 60F summers usually run between 85F to 105F. More to come with progress.

  2. Keef Wivaneff says:

    Sounds like a good setup Greg.
    I’m upgrading my system shortly and this time I’ll go with a sinewave inverter.
    I’ve found that the squarewave inverters kill some devices fairly quickly.
    I’ve gone through heaps of plugpack chargers and chargers for battery drills seem to die quickly also.
    That has happened with different brands of inverters.
    Too late to check now but I’m suspecting a DC component on the output might be responsible.

    • Greg West says:

      I hear ya on the sine wave inverter. I actually replaced a control board on a Kitchenaid mixer thinking it was bad but alas it was the dirty power.

  3. Sean says:

    My current setup is a large garden and 24 chickens. It allows me to convert the only true “free” energy we have (sunlight) directly into a fuel source (eggs). The intermediary of choice this year was pumpkins and squash. I put up ~400 # which should last through the end of the year.

  4. Ed Herwick says:

    16 Kyocera 120 solar panels, wired at 48 volts, Outback FX3648 inverter (3600 watt, 48 volt, pure sign), Outback MX charge controller. Formerly, 16 Trojan L16 monster batteries…now 4 USA 12 volt golf cart batteries. Note: I am not a battery fan, but they are obviously necessary. I nurtured and cared for the Trojans with great detail. Essentially they lasted 6 years, less if you factor in some esoteric measuring technique for the rate that they slowly lose their initial capacities. I have minimized the battery death spiral, by just minimizing the size and volume of batteries.

    Our primary generator is a 12 KW diesel made by Imperial diesel of Pennsylvania. This is an Amish group, believe it or not, that assembles superior gensets. It has been a very bright spot in our off grid experience. About 3 hours per gallon with a moderate load of 2500 watts or more…with no failures in 7000 hours over 8.5 years. We also have some small inverter generators for emergency and spot usage, and I am currently experimenting with a 5 HP Lombardini mated to a Redi-Line 1600 watt inverter/generator through an alternator and ONE deep cell 12 volt battery. This combo shows some promise for reasonable power with very low fuel consumption and very inexpensive parts….. but I’m not finished with the final configuration.

    For water, we have a 1000 gallon rain collection tank in the loft of the barn for livestock and backup. The primary house system is a well with a Baker Monitor pump run with a pump jack (electric motor). The well water goes to a 600 gallon storage tank and is pressurized by a Dansk solar piston pump run by a 48 volt DC motor. Hot water is by standard 50 gallon propane fired tank. Initially we did the Bosch “on demand” deal…….but we really didn’t like the performance or quality of that unit. We have a fairly sophisticated water filtration system for water entering the house.

    We heat with wood, which is infinitely available here in southern Tennessee. We have been off grid for 8.5 years.

    • George B. says:

      Ed, Sorry to hear you got such a short life out of the L16 trojans, some claim the Trojan an entry level battery.. But I have no clue how they really stack up against the Rolls.

    • Steve says:

      Hi Ed;
      I had never even heard of the Imperial diesel till I read your comment. Would sure like to get any feedback from you or others as we need a gen set. Have a 6/1 Lister but are going to sell our place and need an electric start for buyers. Thank You—-Steve

  5. Bill Knighton says:

    1 acre in North Carolina.
    8 solar world 245 watt panels
    9 bp 160 watt panels
    6 bp 150 watt panels
    2 Outback vfx 3524 inverters
    1 old xp1100 inverter as backup with the flip of a switch
    2 outback mx-60 charge controllers
    1 midnight classic 150 charge controller
    Outback x-240 transformer
    Outback’s excellent psdc and psac breaker boxes on their mounting plate.

    Solar one 1360 amp-hr, 24 volt flooded lead acid battery
    Battery filling system
    Running well since 2005

    Listeroid 6-1 st-5 head
    Honda eu2000i converted to propane

    One of the vfx is only being used as a charge controller for the generator

    Fagor countertop dual induction cooktop – this is amazing for off grid

    Ecotemp on demand propane water heater

    Jotul 602 Wood stove with DIY thermosyphon water heater

    Toyotomi om-22 oil heater – this is especially sweet at around 90% efficiency. Burns diesel/Kero clean.
    I used to heat water in a tank by pumping it through copper coils near the blower output.

    A bunch of 3 phase frequency inverter speed controllers for machine tools. My living is made in a machine shop powered by my off grid setup.

    gas dryer converted to propane

    20 cubic foot refrigerator/freezer rated at only 370 kWh/year.

    Black and decker toaster oven with back extended for large pizza
    I mention this cheap misc appliance because it replaces a full size oven on an alt-e power budget for $50. Real useful. Microwave pizza sucks. Same for pot pies.

    240 volt 3/4 hp well pump on +200 foot well

    A variety of cheap used 4 and two wheel vehicles that get 40-50mpg with care. Except the pickup.

  6. Greg West says:

    I haven’t run the numbers, but my current theory on batteries is that regardless if you spend $4000.00 or $1000.00 on the same V/Ah battery bank, the cost per month is generally the same. IE the 4k bank will last 12 yrs and the 1k bank will last 3 years.

    So, in the end we don’t really buy batteries, we just rent them.

    • Ed Herwick says:

      Good logic! Like I said…I don’t like them……so, I will not trust them again. I now use them as a buffer or stabilizer for fluctuating demands, and a short term solar backup..really short term. I am much happier with several generator choices available at all times. I have been doing that for a bit over a year and I am so much more comfortable with that system. Now, if I was younger and had some serious extra bucks…….I would certainly give the Edison batteries a run, using my current system (no massive battery backup). I could live with that longevity as well as the 1.5 volt per cell conundrum ( I would just add an extra cell).

  7. Richard says:

    OK fellas, You all seem to be missing the opportunity for combined heat and power and it is so easy. If you are running the gensets for only short periods heat big water tanks. I am on grid but using gasifier woodstove heating 2- 200 gallon (2000 litres) used oil tanks, of water in the basement The fire lasts about 4 hours if left and theoretically puts out 120k Btu’s / hour and shuts off when the wood is done. Fire is left out until tanks cool to point we feel cool then re-lit. In cold weather we may keep adding wood. We Use about 6 cords / year. Whatever heat we need is drawn from the tanks as and when required. Forced air via rad in oil furnace plenum. 45 X 12 radiant floor via home brew heat X in one tank and indirect hot water via pump and heat X to conventional electric DHW tank. I have an old Yanma 3 cylinder with 12 kW Stamford direct drive alternator which seems economical since It is used only occasionally for welding and running shop lights and tools or tools across the property if needed. 30 Gals regular diesel with lube supplement lasts all winter.
    On the subject of diesel, a friend from UK was over the last two weeks. He runs a 17 year old Audi diesel and tells me since ESSO started with ( premium diesel ) My description, his mileage has increased by 20%.. Also our local tractor dealers notice a drop in engine performance when imported European tractors change to local diesel.
    I attended a “renewable energy” course at our Community College some years ago and learned that the cost of a deep cycle battery is roughly equal to its lifetime power output value at current , no pun intended, electricity prices. You also have to pay to recharge them so it seems minimal battery capacity with flexible gen capacity is the way to go.
    Good luck everyone

    • George B. says:

      Hello Richard,

      I’ve heard this story about so called premium diesel before, all I want to know is WHERE the extra BTUs come from? Someone need explain the chemistry to me..

    • Greg West says:

      Well, as far as CHP goes., I shut the window in my office/generator shed to divert heat from the 6/1s radiator fan when the winter temps dip in to the tundra like low 50s to warm me up.

  8. Bill Knighton says:

    I believe the results obtainable from high-quality batteries is disproportionately more than their high price compared to low quality batteries. There have been high-quality battery banks available for decades and some of the better ones have lasted users more than 20 years.
    My usage is built around the practice that there are months where I don’t start the generator. After seven years my flooded led acids recharge to 1.270-1.275, same as when they were new.
    I started with 16 Trojan T-105s and I bitterly regret that waste of money and effort. I received nowhere near a proportional value to what I spent compared to a better bank.
    But I agree that if using them for short term work I may have had a better experience.

  9. Greg West says:

    If I just had a small super efficient generator that would output 100 watts continuous at night, I think that would be the holy grail.
    It could be wind, hydro, gasoline or diesel. I just think that with a smaller battery bank and ample solar during the day, one could size a system to meet their needs with load management.

  10. Bill Knighton says:

    ^I agree. I almost never set the generator to over 1000 watts and if were continuously running it could be much lower. It is too bad that fuel cells and tiny %30 stirling engines like those from sunpower are vapor ware year after year. There has been shown some evidence on utterpower in comments that they exist.

  11. I’m running two Schott 217W panels in series into a 24V battery bank (4 – 6V 100aH flooded lead acid) through a morningstar mppt-15L charge controller. This drives an electric fence charger (connected directly to the batteries via 24-12V power converter) and the charge controller output is set to turn on when the panels see 80% of rated voltage and drive an API RanchPump R2 DC submersible well pump at ~160′ and fills a 5k gallon storage tank on a hill that gravity feeds water to all the farm livestock and the house toilets and outside faucets. I can’t get the wife to agree to running the whole house off the well 🙁 The system will charge batteries even on cloudy days to keep the fence energizer on and all the critters in.

  12. bob g says:

    some years ago, i set up a spread sheet to crunch the numbers to compare so called entry level batteries against the so called premium batteries… using what info i could find from real world installations and a variety of battery resellers to get an average lifespan and average first cost.

    surprisingly the numbers work out remarkably close, that is cost per kwatt/hr over the lifespan of the battery is the same whether it is a trojan or a rolls surrette battery. yes you will get far more life out of a rolls battery, but you pay more for the added life and when the chips are down it all works out to about the same.

    so from that analysis my decision was to just go with the entry level batteries and do my best to take care of the properly. my thinking is the risk factor is lower for the less expensive batteries, and that was the deciding factor.

    now for the stuff

    because of health issues we decided to locate within the city limits of a small central kansas town (pop ~450) and bought a place sitting on 5 lots situated on a corner… leaving me with only one neighbor that is somewhat close.

    we have two hand dug wells, about 32ft deep that seem to be able to provide adequate water for the house and a large garden even through the dry times… although we use city water we could disconnect and use the well for the house too if need be.

    we just installed but have not hooked up six 320 watt grid tie PV panels, the kind that have their own inverters and are plug and play.
    we have very good solar exposure here and i calculate these will offset about 40% of our electric bill (at current rates and with no other conservation) we also have ~2500 watts or pv that would be used to charge a battery bank and drive inverters, but have not installed them yet… but you can bet they will be going up at some point in the near future.

    we have good supply of nat gas here to the property, the house makes good use of that, however i also plan to fuel my cogen system with nat gas as i think i can produce power and heat at near competitive rates with the power company… provided of course the price of nat gas remains relatively low and my need for electrical power is low so that the add on’s increase the true cost per kw/hr significantly above the electric companies 12 cents/kw/hr rate to something over 15 cents/kw/hr, “and” we are able to effectively utilize the waste heat (approx 5 months where we can use the heat)

    i have one of the chinese gasifiers (thanks George) and the plan is to work on getting it operational enough and clean up the gas sufficiently to power ~7kwe in a batch fire system wherein the goal would be to provide for bulk power needed at peak times of the week, and/or when i need more power in the shop… there is a lot of bio mass available here to use in gasification and i believe there is some possibilities for learning here.

    as for batteries and inverters and all that

    i have an insane amount of pure sine wave inverter capability, something on the order of 30 plus kwatts of exeltech mx series which can be setup as 120, 240 single phase of 208 three phase. however it is doubtful i will ever set up more than perhaps 10kw capacity.

    the direction i am going is somewhat unusual to what most folks are or have done, in that my battery capacity is quite limited as it will only be called up to provide startup needs of my loads and maintain them for only a minute or two, the time needed for the cogen to startup and come online, where it will take over the load and provide recharge for the short term draw on the battery bank… this sort of system allows the use of batteries such as those used in golf carts and perhaps even automotive starting batteries. so long as the battery capacity is such that my startup demand is ~5% of installed capacity automotive batteries could be use to good effect with reasonable lifespan… economies of scale allow for a bit better pricing as well.

    btw. i like the book illustrated! i have a copy in my library and i think it is good enough to recommend everyone have one in theirs.

    bob g

    • Russell says:

      Chinese gasifiers?
      Can you tell us more? How do they stack up with GEK?

      • bob g says:

        the chinese gasifiers are not the same as the GEK
        the chinese gasifier is suitable as delivered to produce cooking or heating grade gas, but would need a lot of filtration in order to make an engine run.

        it might well need other modification? not sure, but i plan to find out.

        bob g

  13. Bill knighton says:

    It is difficult to find data on some batteries to make a precise comparison. Trojan gives an expected kWh total lifetime discharge for their batteries. For example 438 kwhrs for a t105.
    If I compare that to a premium battery rated at 2100 80% discharges at a listed watt capacity of 32.5 kWh(%80) it would require 155 t105 batteries to match.
    At today’s best prices I can find for each it is $8800 shipping included for the premium battery and $23095 for 155 of the t105 without shipping.
    But it’s not a fair comparison because I would expect the size of 80% discharges the premium battery was rated at to diminish greatly towards the end of its life.
    I would not be able to numerically trust homeowner or installer data as other than anecdotal for these reasons, which would be impossible to verify
    – 20 years of precise discharge measurement
    – 20 years of competent maintenance
    – 20 years of adequate full recharges at required current
    This requires honest lab data from the manufacturers to understand the potential lives with precision enough to draw strong conclusions about value.

    • bob g says:

      i couldn’t agree more!

      having a homeowner maintain a set of batteries to a high level of consistency is just not within reality,

      hell i don’t know if i trust myself to do so either, not without a certain amount of automation to take over and provide the basics at least.

      bob g

  14. Craig B says:

    Been off-grid for a few years, and each year, many more new things are learned. As for the stuff that makes life work around here, there are all sorts of gensets & genset projects, all the main ones are diesel, it’s just easier to store fuel. Some small gas sets are used for portability. Batteries are a definite weak link, no matter how well you take care of them, they just don’t last all that long. Probably at the 5 or 6 year mark, this set will need to be replaced. The US Battery L16’s @ 420AH, aren’t living up to expectations. It gets worse of course when the cold sets in.
    A couple things I’d pass along, a regular electric fridge is a must as opposed to a very expensive “barbie” fridge. Propane is only used for cooking and a dryer if you want it. That way your solar setup can run everything for most of the year, as opposed to being locked in to buying propane for appliances. Put your fridge & deep freezer on quality timers, have them shut off at night and you’ll save lots of energy, and they’ll never know it even happened. Been doing it for years.
    Xantrex inverters work great and have been trouble free.

    • Ed Herwick says:

      Just to be clear on my comment: My batteries were Trojan L16H 6V batteries and not US batteries….although I use US 12V Golf cart batteries now. The current data that I’ve read seems to show that at 50% discharge, virtually all current batteries will have less than 2000 cycles available, some far less…and a couple with a bit more. So, if you cycle once per day or thereabouts, you can see the short life. This does not account for the declining power of the batteries as they cycle from 1 to the 2000th cycle. Is there such a phrase as geometric deterioration??(or maybe advancing entropy??) That would describe my experience.

      • Craig B says:

        I’ve also done quite a bit of study on batteries, cycle rates, output vs temp, etc. We’ve always cycled in the top 30%, maintained water, equalized and so on. With an auto-start on the genset, the batteries are guaranteed not to have been over-cycled, or run to zero. Short of shunts in the lines to track input/output Ah’s, this is the best a battery will ever see imo.

        It really comes down to a trade-off between genset run-time (& associated costs) vs battery life. There are very few ways to store energy and batteries seem to be the weakest link in off-grid living. I wish we had some sort of hydro, as that’s consistent and persistent. I did speak to someone that used old railroad switch batteries and were over 10 years old, but as to whether golf-cart batteries, or any other style is more suitable, I’ve just not seen a quantifiable difference.

        If you have any good results, it would be great to hear them. At $400/L16, it’s a big pill to swallow every 6 or 7 years. Perhaps the answer is the application of a reliable anti-sulphating system which can extend the life of the plates. There are at least a couple of such systems on the market, if they work or not, isn’t clear.

        Finally, one last anecdotal bit for potential off-gridders. Most females have an energy footprint the size of king kong… just something to consider. 🙂


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