Retired, Want to Go Off Grid Because of High Cost of Electricity

BasspigBasspig Registered Users Posts: 11 ✭✭
We've lived in our self-built retirement home for 53 years now. My first electric bills were $8. By 1972, they hit $28. By the 1990s, $80. In 2002, doubled to $160 when generation and delivery charges were split. 20 years ago, we shifted lighting to CFL, then LEDs when those became affordable. Today we are 100% LED lighting. But things like air conditioning and computers still use the bulk of our power.
For the past year, our electric bills have consistently topped $740 monthly. Next to property taxes, they are our second largest recurring expense. Not something we'll be able to deal with once my wife retires from her job. I get $730/mo Social Security.
I've been researching solar off grid power technology about every two years for the past 20 or so. I'm cautiously optimistic about super capacitors and the new lithium glass batteries. But these are still too expensive to be practical.
Our electric supplier constantly reminds us that we use 3X the power of our equivalent neighbors. That's because I have a recording studio, two video production and animation workstations, a mini IMAX theater with a large venue projector, a 20,000-watt sound system and a full electronics lab on the lower level of the house. Just the computers and recording gear pull a steady 1100 watts.
We have a submerged water pump, a few HP, three 24,000 BTU air conditioners, all electric ceramic cooktops and oven, as well as electric dryer.
My dream inverter would be Aims Power 120kW Pure Sine Wave Inverter Charger and a large bank of super capacitors. The inverter alone is $29,000. The super capacitors would top six figures. And I haven't even mentioned PV cells!
A more practical system would be one of their 15kW inverters, which can be had for 1/10th the price and has a 45kW surge capability. This, powered by a fully populated roof top (36x50') of LG PV panels, 325W each, with a good quality forklift battery, could get us by with careful load management.
We have a 13kW standby generator, which can handle one air conditioner plus light use of the stove, plus the static load of all the computers, LED lighting and shop equipment. It does bog down a bit with the startup of the well pump.
One of the concerns with the smaller Aims inverters is that if you have a short circuit at any outlet in a branch circuit, instead of the house breaker tripping, the whole inverter shuts down. Another concern is impedance. The generator has a high impedance and thus poor voltage regulation and is susceptible to noise and waveform distortion due to loads with poor power factor and switching power supplies polluting the power source.
I'm thinking that for a more manageable start of the project, I might do it in stages: get the computers off the grid, as they are a 24/7 load.
I've already started one small solar project: Two years ago, I removed a 12' sliding glass door and walled off that area. To make up for some of the lost light, I put three 100W PV panels on this south facing wall and built a sconce on the inside with three 12V LED strips. In the winter, when the trees are bare and the sun hits the panels directly, the LEDs are reasonably bright, but not at full output ever. Most of the time, they give off a soft glow during the day but are never really bright. Realistically, I'm getting about 10-12 watts of power off those three PV panels during the 10am to 1pm window where they get the most sun.
Panels on the roof would do better, but we do have snow to contend with in winter and silt from the trees in spring. I had to manually wash down my white EPDM rubber roof with sodium hypochlorite as it had turned dark grey in just one year from microorganism growth from organic droppings from trees. There is considerable shade up there. Some parts get decent sun for a couple hours a day though.
My rough calculations indicate that just to cover a static load of 4kW plus spikes for pump starts and stove usage, I would need 36kW of panels to store enough energy for overnight use from 3-4 hours of available direct sunlight. If I cover the entire roof with PV panels, this goal can probably be reached, but the cost at the current level of tech would be beyond affordability for us.
So I'm back to thinking about smaller scale systems that can be used to handle specific constant loads like our workstations. 
As tech gets cheaper and better, I could think about shifting the entire house to solar, as long as we have the reserve storage to allow us to operate as we do with our 200A utility power. I like to use my sound system at least once a week. It has a quiescent idle consumption of about a kilowatt. The amplifier power consumption for each of the industrial amps varies between about 2 amps idle to 92 amps with full output sinewave test signals. Fortunately, the average draw with music program is 26 amps per amplifier. I have a rack filled with such amplifiers and a large multi channel array of speakers. The power consumption depends on listening volume and content of the program material (duty cycle). I find that my 13kW generator can run the system at moderate volume levels, but at the extreme levels I like to listen at sometimes, the generator can't keep up. I need a stiffer power source in order to be able to use the full capabilities of the audio system. If we lived near the equator, getting enough PV solar would be a much simpler matter, but here in the northeast, the sun isn't as direct and we have dense forest.
So I will probably work the project in steps. Maybe get my web server completely on to solar power for a start. Then expand the system to handle the graphics workstations. Then maybe another system to handle the well pump. etc.
I'm hoping to hear some creative ideas here on the forum.

Comments

  • EstragonEstragon Registered Users Posts: 4,494 ✭✭✭✭✭
    A couple of thoughts...
    First, any shading, even bare trees, will severely limit pv output.  Living in dense forest will mean some quality time with a chainsaw to make solar feasible..
    Second, off-grid power is almost certainly more expensive than grid in the US northeast.  If the objective is saving money, grid-tied solar may or may not make sense, depending on feed-in tarrifs etc locally.

    I personally wouldn't use an Aims inverter even if it was free.  These folks make huge 12v inverters, and anyone who would make such a thing is downright scary to me.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • softdownsoftdown Solar Expert Posts: 3,499 ✭✭✭✭
    Unless you live in Hawaii, solar power will likely costs you at least double what grid power costs. 

    You went from $8/mt to $740/mt because of the utility companies? Three 24,000 BTU A/C units in the northeast? I don't know where to begin. 

    You are assured of being gently steered back down to earth.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • softdownsoftdown Solar Expert Posts: 3,499 ✭✭✭✭
    Try looking into Home Nuclear.
    Fusion has been "just around the corner" for decades. Shoot we can now generate 1 Gw of fusion energy while using only 1.5 Gw of energy. Looks pretty rosy. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • mike95490mike95490 Solar Expert Posts: 9,274 ✭✭✭✭✭
    Currently, going off-grid solar will not save you anything.  Off Grid is always more expensive than grid power, because of the recurring battery replacement costs.  Super capacitors are not going to help a bit (well, maybe keeping some of the 120hz ripple under control) but they can't store power as cost effectively as batteries.

    Your best bet is to insulate and make the house envelope as tight as practical.  That will cut down on the air con expenses. Maybe look at the new generation of mini-split heat pumps, they are now getting really efficient for off-gridders.

    Do your mega electronics bring in any revenue, or are they hobbies that will never pay for themselves?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • PhotowhitPhotowhit Solar Expert Posts: 5,575 ✭✭✭✭✭
    You sound like you have run numbers for the size array and inverter capacity. But then speak of a single forklift battery. 

    If you have estimated needing 36kW of panels,  likely you are not counting on the system losses involved with off  grid solar. figure  at  least  50% system losses for every watt used, but  if you are starting with 36kW array, that will produce roughly 29kWhs during solar  noon typically, (about 75-80%), that would equate to 29,000 watts / 58 volts(charging voltage for a 48 volt battery) = 500 amps, this will service a 5000 amp to 6500 forklift battery bank at 48 volts. A 24-85-27 forklift battery weighs in at 4000 pounds and would store about 1440 amphours at the 20 hour rate, so you would want 4 of them, at $7500 each roughly and that is if you have done proper calculations and allowed for 2-3 days for little or no solar energy input. This would be a disposable part of your system, though likely to last 12-15 years.

    Without changes to your lifestyle's energy use, it's likely not possible to beat the grid. What is your current cost per kWh? I know it can be high in the northeast, but it's doubtful to be as expensive.

    I consider myself to be off grid at a little less than the grid electric cost here in Missouri, BUT the cost of electric from the grid is over 30 cents a kWh for a minimal user AND I make adjustments to my lifestyle to deal with long periods of cloudy days because I don't use a generator. 

    We have all heard about Aims horror stories here, but we have also heard at least 1 individual who has set up 2 commercial Aims inverters with good success. I don't even think any of their other inverters carry UL1741 certification for home use. 
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,910 ✭✭✭✭✭
    I  would say consider that many offgrid homes are hard to sell and often not worth what a similar grid home is worth. If that is not a problem then build whatever you want. If it is an issue, build something that is marketable.

    I only uses the Schneider MPPT -80- 600V for solar. it just is too easy to use, wire, and make changes later. Stay with one brand of equipment and your family will like how easy it is to get data from the system and operate it.

    Good Luck!




    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BasspigBasspig Registered Users Posts: 11 ✭✭
    I'll have to ask my wife for one of the electric bills when it comes in next month. It's not the generation fee that's expensive, it's the delivery fee. (They broke up the power companies in 2002 and suddenly our bill doubled, as the delivery charge was almost as much as our total electric bill the year prior). Right now, we're paying about $400 for delivery fees, then there are about 9 or 10 taxes and fees tacked on, then the generation charge. Some of my neighbors travel abroad for months at a time and they flip off their main breaker and they complain that they STILL get a $200 electric bill for each month of no energy use--just for being connected. Another neighbor showed me her $833 bill for last month.

    25 years ago, I used to use electricity with no cares. Had a room full of laser printers and an Agfa SelectSet image setter, a bunch of workstations, used thousands of watts of halogen lighting to light my video setup where I'd record small music ensembles, had 175W outdoor merc vapor lighting that was always on at night, I used to use my large sound system all day long for background music, the well pump had a leak 220' below the surface and would run almost continuously until we fixed it.. and even with all that, the bill rarely broke $100.
    Today, all lighting is LEDs, the laser printers are in storage and we have inkjets now, and my newest computer workstations pull 20% of the power that my last generation workstations did, at least when idle. The outdoor lighting is LEDs and on motion sensors. The well pump no longer leaks.

    I'd love to have my own small nuclear LFTR power plant. That would the ultimate fantasy. But that's all it will ever be. Solar has a chance, especially with the back mirror reflecting types that are in development now and topping 33% efficient with 50% as the target. I watch the progress. We've gone from 3% efficient to a little over 20% now in commercially available PV cells.

    As for my sun situation, I estimate that cells will produce, averaged over the daylight hours, just 10% of their maximum output rating. So I need ten times as many to charge the batteries. A single forklift battery would be a start. We'd have to be careful with energy usage. But over time, multiple batteries would increase our ability to live normally.

    Audio is my reason for living. It's a passion that goes back more than 60 years. That's why I live out in the woods on a mountaintop. The electronics shop was where I designed lots of stuff as an inventor. After retirement, I started repairing amplifiers to supplement my social security, as the property taxes far exceeded my ss payments and my wife will soon be retiring as well. The whole house exists to support my passions, a fusion of audio and video. The sound system I completed construction of in the spring of 1982, beginning in 1976. I've done a few upgrades since then, but remains basically unchanged as far as the foundational parts. A decade ago, I added a projector and screen and turned the whole thing into a theater in addition to music room. I've been a huge pipe organ fanatic since I can remember, and also love pyrotechnics. Reproducing all of these sounds in addition to accurately reproducing a violin solo, consumed decades of my life with research, development and construction of many speaker systems and amplifier designs. 1982 was the inflection point where I achieved my goal. Today, the system consists of two 6' tall Zero racks filled with industrial amplifiers, connected to 240V double breaker. Over the years, my appetite for bass has only increased, requiring me to go from 7,000 watts to 20,000 watts to achieve the same ASMR effect. The house itself had to be sturdily constructed, because ordinary materials would vibrate apart in seconds. Even so, the ground shakes outside when the system is turned up to my preferred listening levels.

    But even when that system isn't powered on, the static load is always minimum of 4kW. We have three inexpensive air conditioners. Originally, we had a York that we'd bought used and it made a good bump in our electric bill, so in '84 we installed Emerson Quiet Kool in both the livingroom and kitchen areas. My studio downstairs also had an Emerson. They used less electricity than the York, but were noisy as heck. So about 5 years ago, I replaced the one in the livingroom and studio with LG models, which use only 1600W each and are somewhat quieter. 

    I'm familiar with the 'mini split' air conditioners, as our apartment in Kamata, Japan has one, and it is silent. I don't think it has quite the cooling capacity though, as I find that by mid July, the apartment unit can barely keep the room below 75°F. I like it at 70°F and no hotter. I looked into this type of AC at Home Depot here in the States, but two things put me off: it's six times the price of a large window AC and you can't install it yourself. Professional installation is additional cost. So $2995 plus whatever they charge to install, compared to $450 for the LG units we ended up buying. But the mini splits can use as little as 550W. This, for only 2 months out of a year doesn't seem like a worthwhile investment. The studio, even though it's in the basement, needs the large AC unit to cool the equipment. The house is very well insulated. In winter, the furnace only kicks on when the outside temps dip into the 20s. The computer and 24" monitor in my daughter's bedroom keeps that room about 78°F during the winter, when she keeps her door shut. We heat with oil and hydronic heat with a separate oil fired hot water tank heater. With six of us living in the house, we use about 400 gallons of oil over a 12 month span. Heating water for bathing and washing seems to use the bulk of the oil.

    I briefly looked at Scheider and they are probably the closest thing to MIL-SPEC quality inverters, but the model I looked at was low capacity and was nearly double the price of the 15kW Aims inverter. But yes, this is an area one cannot cut corners on, so I may allocate more money to the inverter. Back when I serviced broadcast transmission sites, a lot of the newer solid state transmitters have failover protection and are modular. A module fails, the transmitter stays on the air, going from 50kW to 40kW and sending an alarm on the telemetry so the studio is alerted to call me for service. I need only pull the bad module and install a spare to restore system to full operation. Never interrupted the transmission and listeners never noticed. This would be the kind of redundant failsafe system I'd like to see in a whole house inverter.

    I see nowhere but up for electric rates. After the tornadoes that ripped through here last year, 2000 utility poles had to be replaced and it took weeks for Eversource to restore power. My neighbor's house had to be completely rebuilt and it's almost there, a little more than a year later. Now they want to increase electric rates again. At some point we'll be FORCED off the grid just do to inability to pay the bill. Ironically, there are a few towns that have municipal power and guys I know are paying about $50/mo for their electricity. They're HAM radio guys and I don't doubt they use more electricity than average homeowners, too. We know we're being shafted up this way in the rural corner of the state, but nobody seems to be doing anything about it.

    I wish I didn't have this curse of a passion. It limits where I can live. But nothing gives me a 'rush' like building and testing huge subwoofers. Otherwise I'd be living in Osaka, Japan, near where my high school buddy lives.
  • PhotowhitPhotowhit Solar Expert Posts: 5,575 ✭✭✭✭✭
    FWIW - Robbin Gudgel of Midnite Solar, started soldering up Amplifiers for Phase Linear and later started Spectro Acoustics, before doing  Engineer duties at Trace/Xantrex, and later starting Outback and then Midnite…

    Might be an interesting  read for you;
    https://www.midnitesolar.com/pages/frontPage/nwHistory/history.php

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    edited July 2019 #11
    "I've been researching solar off grid power technology about every two years for the past 20 or so."
    well then you should know that with your massive consumption going off grid will cost more not less.

    If you can't change your consumption, just move to a place that has better electrical rates. I live on 2.5 acres and I think I pay around 11 cents/kwh. 
    The bass would have to be ridiculous to disturb my neighbors with similar sized lots. 


    Sounds like with your fixed income you will have to make some serious choices on how to reduce your electricity usage, which frankly is probably for the better if you use 3x higher than normal. sounds like turning things off when not used would save a lot of energy right off the batt.

    mr.Cool has minisplits that can be assembled by yourself because the refrigerant is held in with special factory sealed valves.  Only issue is the lineset is about 25 feet long and has to be installed without loops for best effciency
  • mcgivormcgivor Solar Expert Posts: 3,814 ✭✭✭✭✭✭
    Lots of information but no mention of actual Kwh costs or whether there  peak charge rates. With such high consumption it may be possible to reduce consumption or peak shave with solar or diesel but going full off grid would be a monumental task given the load description. The cost of equipment along with storage large enough to span days of poor solar production would exceed grid in most cases, the energy companies know this so they charge accordingly. 


    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • BasspigBasspig Registered Users Posts: 11 ✭✭
    I recall that the rate is around 10 cents a kw/h, but when I divide the number of kw/h used into the total bill, it's around 25 cents kw/h. The base charge for delivery is around $200 here. On our recent bill, delivery charge was $410 and generation fee was $324. Then there are 9-10 taxes, environmental fees and other fees tacked on.

    When the big system gets crankin', the ground outside our house shakes. I've had problems where after an exceptionally loud listening session, our well brings up brown water for a few days. One time I was playing pipe organ music really loud and took a walk up the road with my sound level meter. At the end of the road, I took a reading and the lower bass notes were hitting 97dB and the pressure on the ear drums was about like a Huey helicopter coming in low over the horizon. In 1978, when the system was only about 1200 watts, a buddy of mine and I took a walk to the radio tower about a mile south and we could clearly hear the bass. It's a hopeless addiction. Today I have much better subwoofers and industrial power amps, equipped with 30A twist-lock plugs, to drive them.

    I'll check out the Mr Cool mini splits. My wife and I recently took a 2 night vacation in Narragansett and the hotel had Mitsubishi mini split a/c units which were virtually silent.

    Yeah, I was looking at the 325W LG panels, which probably run close to $800 a piece. But the thing is, we're talking about a one-time cost vs. recurring costs. I can plan for a one time cost. But I cannot plan for reliable income or flat electric rates for the next 20 years. 1966: electricity cost me $8 a month. By 1972: $28 a month. By 1995: $180 a month. Today: $730 a month. In 20 years? Maybe $3500 a month?

    Fascinating read about Robin Gudgel. I've owned Phase Linear amplifiers and Bob Carver is a friend of mine. In 1976, I bought a Spectro-Acoustics 210R equalizer. I still have it, though I no longer use it. Sold the Phase Linear for $3050 back in 2007 to a fellow in Sydney. On a side note, it's funny how we all have lots of hair when we're young, and end up completely bald when we get old. LOL.

  • EstragonEstragon Registered Users Posts: 4,494 ✭✭✭✭✭
    There are some "lumpy" recurring costs for off-grid power.  For planning and LT cost purposes, replacement cycles might run; 5-10 years for (quality, well maintained) batteries, 10 years for components (inverters, etc), and 20-25 years for panels.  Sometimes they last longer, but these are reasonable MTBF numbers to use.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • PhotowhitPhotowhit Solar Expert Posts: 5,575 ✭✭✭✭✭
    Estragon said:
    There are some "lumpy" recurring costs for off-grid power.  For planning and LT cost purposes, replacement cycles might run; 5-10 years for (quality, well maintained) batteries, 10 years for components (inverters, etc), and 20-25 years for panels.  

     ...but these are reasonable MTBF numbers to use.
    I use the same numbers in planning my replacement times, but expect the 'mean time Before Failure' to be a bit longer, I'd expect a quality inverter to last 15-20 years, Though when I ran numbers for costs over 30 years of running my system, I planned replacement every 10 years for Charge controllers and Inverters. It's always nice to be 'money ahead' when planning. 

    My experience with  solar panels has been remarkable, I'm to the point where I only expect failure due to weather, even the degradation of output has be pretty darn minimal. Ran an equalizing cycle on my system and must not have pushed 'send' when reconfiguring my 2 arrays. I also happened to be running a toaster and air conditioner for about 1500 watts, so I was maxing out one array of 2000 watts, during a hot late afternoon. I was pushing over 1600 watts from my 7 year old blemished Evergreen solar panels.  While I never really look at these things, I was checking to see how much energy was goind into the battery forgetting that I had the toaster on. 

    Someday soon I'll have to hook up the Whiz-Bang-Jr, likely when I wire in the additional 1875 watts of array up and my 3rd Classic CC.  Of course I've been putting that off until I need it to run the additional day time load of an air conditioner in the main room... LG has come through and it's available now, of course this late in the season, I'll just wait and catch an end of season sale...lol 

    Dang I'm cheap...

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • EstragonEstragon Registered Users Posts: 4,494 ✭✭✭✭✭
    MTBF may not actually be the right metric.

     Just a guess, but I suspect a curve of failures over time would be bimodal, with a peak in the first few months (defects, shipping/install damage, misconfiguration, etc), then a trough extending out 8-10yrs rising slowly to a second peak around 10-12yrs as installations with more environmental and/or operational stresses fail, then a really long tail where relatively unstressed installations might last a very long time.

    If parts stayed available for longer, some might be usable almost indefinitely?

    I'll have to keep an eye open for that LG, tho not sure if it's available in Canada.  Getting by okay without, but there's usually at least a few days/yr when it would be nice.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BasspigBasspig Registered Users Posts: 11 ✭✭
    I was looking at the Scheider inverters, and apparently the system is modular and can be built  up to over 100kW capacity. I don't know if this system architecture incorporates fault tolerance, but there's a good chance it does. The inverters are in 6kW blocks about $3000 each. Could start with three and build up from there.

    One criteria would be to choose an inverter that I can service with off the shelf parts. Last year, I was in the preliminary stages of designing a 3-state PWM sinewave inverter. I was building it to handle 120kW, which is about double the most power we could possibly use. We currently have 200A utility service and I am targeting to have as close to that capacity for short term loads. The high rating of the inverter would have all components running at a tiny fraction of their Safe Operating Area, hence lifespan would be indefinite, except for capacitors, which would have to be replaced every 20-25 years. I'll likely be pushing up daisies by then anyway.

    My 3 state PWM sinewave inverter would have two banks of batteries of 170 volts each rail, driving it. Essentially, two back to back inverters providing split phase 240VAC output. It would essentially be a giant class D audio amplifier, driven by a quartz oscillator divided down to 60Hz. I could take it a step further and reference it off GPS to lock the oscillator frequency for accurate line frequency.

    I'm giving another look at LifePo batteries. There's an outfit in Reno, NV that makes a highly regarded battery because of the quality of its BMS modules. They warrant the battery for 10 years. Only problem is a 100Ah battery is about a grand. I would need probably 80 of them to make a 48 volt system to drive a commercial low frequency inverter and supply my needs over night.

    I've been thinking about the cost amortization of an off grid super system, and it's actually not as outrageous as I once thought. Even if electric rates were frozen for the next decade, I will spend $80,000 on utility bills over the coming decade. If I invested $80K into solar and batteries and inverters today, I could halt the recurring cost of utility power. The only problem is that, due to my age, I cannot borrow money, as I'm ineligible for SBLI, so we'd have to figure some other way to raise the money. Or get creative and make it a Gofundme campaign and turn the whole thing into a video blog.
  • BB.BB. Super Moderators, Administrators Posts: 31,680 admin
    One thing to do is review your billing plan with the utility... If your place was originally (for example) a working farm... There may have been grain dryers, weld/fabrication shops/irrigation pumps... And you may be paying a fixed monthly fee for a relatively large service that is not used anymore.

    Some of these fixed costs have been so high that farmers will rent diesel gensets for running fans and dryers for a few months, vs the cost of 12 months of large fixed costs (high amperage drop) that is used only a couple months a year.

    You may check on what rate plans are available for your place... Accept shutting down power for a few hours during (for example) heavy energy usage by folks with A/C and irrigation pumps (use a genset for the few days a year you may get interrupted).

    The fixed charges sound high for your place---But it could be real (remote site, high charges to keep utility service).

    We have seen folks that have figure out that disconnecting service and installing solar/genset was cheaper (cabin that is not used during winter, summer weekends, etc.).

    Whatever you decide--Build a spreadsheet model of your equipment and maintenance costs vs energy harvest. In general, a GT Solar system (no batteries) was about 1/4 the cost of a full off grid system (besides the cost of batteries/etc., there is the fact you have to "over design the system" to provide your minimum loads during winter and probably way more power than you need during summer.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,274 ✭✭✭✭✭
    If you want to repair it yourself, you build it yourself:



    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • Dave AngeliniDave Angelini Solar Expert Posts: 5,910 ✭✭✭✭✭
    edited August 2019 #20
    Living offgrid all about doing it yourself!
     You can do as Mike suggests or just have a bunch of XW spares. You probably will not need them either. I have been trying to kill one that was new in 2006. I have lent it out a dozen times and there is more danger of me dropping it than it failing electronically.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • sawmillsawmill Solar Expert Posts: 93 ✭✭✭
    As a solar novice I certainly have nothing meaningful to add to this post.   I  hope the original poster will keep the forum informed step by step as he begins his journey to an off-grid operation.    
  • BasspigBasspig Registered Users Posts: 11 ✭✭
    My property is zoned residential. The deed goes back to 1939, and it shows residential back to the first owner. Prior to that, may have been an Indian burial ground.. who knows..

    The high electric rates are a problem in our region. A neighbor posted a photo of her $833 electric bill. Another was living abroad for months and shut off the main breaker and still received $200 monthly bills just for delivery and connection fees. Just fifty miles from here, are a group of towns that have municipal power. I know a HAM radio guy who uses a healthy amount of power. He says his bill is around $50 a month. Go figure.

    I did some research on those Mr. Cool mini splits. It's a pretty clever system they have, where the freon is stored in the lineset and the condenser is pre-evacuated. The lines get connected and then a valve on each line is opened with an allen key, allowing the freon to flow into the condenser. Slick. Reviews are all five stars, but I can't find anyone that's had a unit more than a year. HVAC techs claim it will last 3 years and crap out and you'll have to buy a new one, but I think that may be sour grapes and not necessarily true.

    That inverter project looks pretty interesting. But it uses a transformer. My idea was to avoid the transformer and maximize the efficiency to 95% using a 3 state PWM controller, gate drivers and HEXFETs, all running off series battery strings of 170V DC. The design involves use of a tiny amount of resistance in series with each HEXFET and a large and parallel number of them to deliver the current, while maintaining tolerance for short circuits. My approach is to build everything MIL-SPEC with parts rated for 5-7 times the voltage, so as to tolerate spikes from inductive loads coming online, etc. Also needs to be a low impedance source, to prevent poor power factor and noisy loads like switching supplies from polluting the power, like it does with generator power.

    I don't have the money to do it all the way I would like at the moment, but I plan to experiment with making smaller systems and putting some of my 24/7 loads on that source. If I can get my web server on solar, that would be a good start. Then the network hardware plus the server. As the system grows, I can get my two workstations and mixing board and MIDI music production gear on to solar. All this stuff pulls a bit over a kilowatt now, according to my P3 which is plugged into the UPS master plug and monitoring total load.

    I need to do something about the air conditioners soon. My relatively new LG window unit, which is installed in the wall near the ceiling replaced a 30 year old Emerson unit, but after 4 years, the compressor relay has welded itself shut, so I have to turn the unit on and off at the breaker panel. So much to do.. so little time left in my hourglass!
  • BB.BB. Super Moderators, Administrators Posts: 31,680 admin
    Square wave and modified square wave can be very hard on some devices... Induction motors run hotter, and so do many "less expensive" power supplies.

    Having a pure sine wave inverter can be much "easier" on your devices.

    It is difficult to guess which devices will run well on MSW or not. Probably the old 80/20 rule... 80% of devices will run fine, 10% will have an early death, and the other 10% will work but be noisy and/or hot.

    One thing I used to recommend is to use a Kill-a-Watt type meter and measure the power factor of the load... In general, loads with poor Power Factor don't like to run on MSW inverters (great PF is >85%, medium PF around 90-90%, power PF less than 60%--In my humble opinion). You can plug your load in at home on AC mains and then on MSW inverter and see if the PF is worse on MSW (another possible indication of poor MSW operation).

    MSW does not work well with transformers (they run hot). Also, without an isolation transformer on MSW inverters, you cannot run typical Hot/Neutral (ground referenced Neutral). 120 and 120/240 VAC split phase power systems.. If you ground reference the DC battery bus, you will have a short circuit when you try to ground reference the AC "neutral" (the MSW has "two hots" outputs).

    So--if you are trying to follow the correct method for circuit protection, you should use a two pole circuit breaker for even 120 VAC MSW circuits (especially when you are designing multiple kWatt output MSW inverters).

    Also be careful with your 170 VDC bus--Make sure you use fusing/breakers that are rated for 170+ VDC and >several thousand amps of current interrupt. DC current is much more difficult to stop (tends to sustains arcs very nicely) than AC current systems.

    I would humbly suggest you look instead at figuring out how little electric power you can get away with. Roughly 3,300 WH per day (or ~100 kWH per month) can give you a reasonable off grid life (Full size energy star refrigerator, LED lighting, Laptop computer, LED TV, clothes washer, and "solar friendly" well pump).

    Since you have utility power today--It would be interesting to see how low you can get your daily power usage (read meter daily, check utility bill, etc.). If you have electric heat/cooking/hot water, and/or a home that is unlivable without A/C (poor insulation, poor window placement, no shading of south/west facing walls, etc.)... You may not "win" this competition.

    A 3.3 kWatt off grid power system is a "medium size system" (just adding a refrigerator moves you from small to medium solar power system)... And have natural gas/propane/wood/other fuel source for cooking/hot water/heating, you can do OK.

    If you need heating and don't have access to wood/other fuels, a Heat Pump system will be 2-3 times more efficient than an electric heater 9at least until you get below 50F to 32F or below)... And they can give you some A/C and humidity control in the summer. Of course, you probably would have to upsize your solar system to support that.

    More or less, most people in the USA pay around $0.10 to $0.30 per kWH... And off grid power costs probably in the range of $1-$2+ per kWH (even a genset will cost you $1+ per kWH just for fuel).

    Use those numbers to figure out what each device costs you to run. Can you live without? Can you find a more efficient/less costly device. Can you use alternative fuels? Like Crock Pot Cooking, use an (typically Asian) large thermos (you bring the food to a boil, and put in thermos for 2-4 hours to "cook" without using more fuel).

    To measure your loads... A Kill-a-Watt type meter works very well:

    https://www.amazon.com/s?k=kill+a+watt+meter

    For 120/240 VAC loads (larger/hard wired loads), there are whole house meters too:

    http://www.theenergydetective.com/

    For you utility power--It sounds like you are running into a billing/rate plane that I saw coming. Basically, keep the cost of power relatively low ($/kWH) at $0.10 to $0.20 per kWH, and make your monthly connection fees high--Over the years have read here about $48 and heading towards $96 per month. If your fees are running in the $100-$200 per month range--Then GT Solar (if legal) and conservation become almost useless... One person is very efficient at 300 kWH per month ($30 for power costs) vs 1,000 kWH per month ($100 for power cost)--A $200 per month connection fee "swamps" the actual kWH costs... (around $230 per month for a light user vs $300 per month for a "heavy user in my "made up" example).

    With high monthly connection costs, disconnecting and going with a small off grid solar power system (call it 100 kWH per month or ~$100-$200 per month "real" out of pocket costs for power--I.e., $12,000 system / 120 Months or 10 years operation ~ $100 per month, all paid up front).

    And disconnecting from utility power may have other complications... It may be hard to get homeowners insurance, your city may red-tag your home for no utility power, you get a nearby lightning strike and have to "fix" your power system, your batteries fail after 3 years because "something went wrong" and you need a new battery bank, you get old and cannot service the system yourself, your die and your wife/family cannot keep the system going, you cannot sell the home in 10 years because no utility power (and if you are in a rural area, the utility may have removed the poles--Leaving a buyer with a huge $$$/mile cost to bring in utility power), etc....

    Being your own power company is not cheap or easy.... If you can reduce your energy needs, that will help both your utility bills and reduce the size/costs/ongoing costs of an off grid power system too.

    Sorry to be such a downer on going off grid... Yes, many people do go off grid and love it. But if they already have utility power, there is usually very little reason to cut utility power--And any such decision needs to be made very carefully.

    Just trying to watch out for you and your family.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BasspigBasspig Registered Users Posts: 11 ✭✭
    edited August 2019 #24
    I own a MSW inverter (Xantrex 2000W) which I've used for running my recording hardware out in the field, but I would never accept MSW for a whole house system. The system I'm proposing offers < 3% THD pure sine wave output. It operates like a class D audio amplifier, being pulse width modulated sine wave at 60Hz, then fed to a low pass filter to remove the switching noise. The output of two back to back inverters would share a common neutral to the breaker panel. The batteries could float.

    The purpose of the scale of this project is precisely because I refuse to give my my passion for extreme audiophile sound and the need for watts to the speakers. The sound system is the biggest load I have. Four years ago, my temporary (for fifty years) 100A service was upgraded to permanent 200A service and the improvement in punch and power reserve was noticed immediately. The sound system is why I'm living in a house on a mountaintop instead of an apartment in Tokyo. It's the #1 priority. The house exists to support it. So it's a no-compromise situation.

    The rest of the house.. hot water and furnace are oil fired. If we had dry summers, air conditioning would not be so necessary. However, I have 24,000BTUs of ac in my studio because the equipment produces a lot of heat. Also, with very high sound pressure levels, the air friction quickly heats the room, almost instantly in fact. Despite the size of the AC unit, it can be challenging to keep the temperature at 70°F in the room with all the gear operating. March to October can see ac use in the studio due to not enough air flow from windows. In the winter, the studio uses no heat whatsoever, because the equipment keeps the room warm, even when outside is 10°F. And in 95% humidity summers, ac is a must. I often just run it a short time upstairs and keep windows and doors shut, just to dry the place out. Else mold becomes prolific.

    I'm trying to get the wife to hang cloths outdoors. However, many days it is raining here, so she uses the electric dryer a lot. Mostly on weekends though.

    I built this house myself back in the 1960s. It was never really "finished" and I bought used barn lumber and other materials on weekly paychecks and hauled them up here on the back of a 1948 Dodge pickup I'd gotten for $100. So the play never had a CO and never qualified for homeowner's insurance. Anyway, I can't afford insurance after the last two tax revaluation cycles placed taxes a little higher than ability to pay. Currently about a grand a month goes to town taxes. But electricity is dead second in terms of largest expense. If electric rates were to magically remain flat over the next ten years, I will pay approximately $80,000 to Eversource during that decade. That could buy me decent off grid solar components to build a capable system. 40 LG 330W solar panels, a dozen forklift batteries and a monster inverter. Or a lot more of the Richsolar 100W panels which tested impressively on that RV solar guy's Youtube channel. I could get scores of them for $40,000 or that $80,000 investment.

    The only problem is cash flow. I don't have $80K now in one lump sum.

    We once had a woodburner, but when my boss's house burned down in 1981 due to a woodburner, I got rid of mine. Also, the soot on the walls was a problem. I've since made efficiency improvements to the furnace and we now use under 500 gals of oil in a 12 month period with six people in the household and a lot of hot water usage.

    Since the utility split generation and delivery fees, it was an end run around the DPUC regulations on generation costs. The Delivery Fee has been going up and up and up and is now more than the regulated part of the fee.

    Lots of people have grid tied solar here.. 1 in 10 homes in the surrounding neighborhood a mile north of me have solar panels on the roof. But it is a diminishing return and some people report higher cost now that the have to pay the solar company AND the electric company.

    Last night, I used 13kWH just listening to my stereo at high volume levels for about an hour. I don't run it wide open, but even so, when I reach levels that shake the concrete slab beneath my feet, the lights are dimming on the bass notes. When I had 100A service, my mains at the panel would drop to 95V each time a bass note would hit. With pipe organ music, the current draw is more sustained. Trying to limit line sag through heavier gauge cables supplying power has been my approach to this point. I have two sets of 4AWG wire, in parallel, feeding 240 V AC to the equipment racks 26' from the panel. The crest factor in music is a saving grace, since most of the transient power comes from banks of capacitors in the amplifiers, and is replenished by the mains milliseconds later at a slower rate. But there's no question that for best performance, it needs a robust and low impedance source of mains power.

    We normally use north of 80kWH per day with all the computers, studio gear and shop test equipment running, in addition to the stove and oven, which get a lot of use. Our inlaws love to cook and that's what they do all afternoon. I come into the kitch around 1:40pm and they are already starting to use the stove, which is on continuously til about 6pm when dinner is ready.
  • EstragonEstragon Registered Users Posts: 4,494 ✭✭✭✭✭
    I don't think 80 grand is going to do it for a battery based system.

    Setting up off-grid ~5yrs ago, my daily energy budget was < 1/20th yours.  Costs won't scale absolutely linear (may actually curve up in this case), and some costs (eg panels) are lower.  There are also some things I did (eg independant 12v system, plan for little/no summer generator use) which you may not.  Still, my system ended up being ~$20,000USD (not including structural for panel racking, or generator backup for winter/bad weather).

    Order of magnitude WAG would put it at more like 20x$20,000=$400,000.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • mike95490mike95490 Solar Expert Posts: 9,274 ✭✭✭✭✭
    Build a HV battery bank to power the amplifiers + & - DC buss.  Forget trying to do it with power supplies, which will always be hitting some odd limit.
     Use low impedance super caps too
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.BB. Super Moderators, Administrators Posts: 31,680 admin
    Watch supercaps... They can have pretty narrow operational/peak voltage ranges, and 5 year or less life.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,910 ✭✭✭✭✭
    I just did a system for a guy. My standard power system, an XW, a mppt, 6kw tracked, and a battery. After the federal credit it will cost him about 21K + his labor.
    If I did the install, it would be about 90K. I don't do many anymore unless they are in Hawaii.  ;)

    I also send folks in Arizona to the store here because there can be state and local incentives. They are good folks!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • littleharbor2littleharbor2 Solar Expert Posts: 1,599 ✭✭✭✭

    I also send folks in Arizona to the store here because there can be state and local incentives. They are good folks!


    For out of state online orders , not having to pay sales tax can save  a fair amount of money. nearly10% in my case.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    edited August 2019 #30
    Basspig said:  . . . .
    A few notes:

    Four years ago, my temporary (for fifty years) 100A service was upgraded to permanent 200A service and the improvement in punch and power reserve was noticed immediately.

    It's likely that a small inverter/battery system could have done the same thing, by providing a lower impedance source for the amp.

    1 in 10 homes in the surrounding neighborhood a mile north of me have solar panels on the roof. But it is a diminishing return and some people report higher cost now that the have to pay the solar company AND the electric company.

    Sounds like a poor deal for them.  Not an issue if you pay for the system up front.

    You might take a look at the Midnite MNB17-5.  It's a new inverter system that can handle 10kW per rack, and the system can handle several racks.

    But as others have said, you will pay more for off grid than you pay for on grid power due to battery replacement.
  • BasspigBasspig Registered Users Posts: 11 ✭✭
    That new system from Midnight Solar looks like just what I need. Up to 40kW of power. I wonder what the short term surge capacity is like? Looks like a new product and no pricing yet.

    Low impedance is important for keeping noisy devices from polluting the power to the rest of the building, but current delivery is also necessary for handling the power demands. The QSC amplifiers can draw up to 126 amperes from the line at full power output. There have been a few incidents where the system tripped the dual 50A breaker feeding 240V to the racks. The PL 9.0 is Class G and idles at 315 watts draw from the line. Now imagine a rack filled with them and you get the idea. Now you can see why I have 24K BTU of AC for that 960 sq ft studio/sound room.

    I heard about the hybrid technology where the system consists of conventional batteries plus super capacitors for meeting surge demands. I though the idea of super capacitors was million + charge cycles? That's certainly more than five years.

    Sales tax is a problem now. Seems that no matter where I buy from, sales tax is added to the order.

    There's no sensible way to power the amplifiers from batteries. They run off power factor corrected switching supplies have have five voltage rails per side, ranging to 154 volts for the high rails, and four lower rails for lower power operation, depending on signal levels. The power supply adjusts dynamically with the program material.
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