Peter Brenner: Help before I buy system

Peter BrennerPeter Brenner Registered Users Posts: 14
Hello,

I know this thread is over a year old but I'm a new guest on this forum. I'm researching the details of an independent power system and solicit the advice of the best minds on this forum.

I'm a power plant electrician by trade with a background in electronics repair. I live in rural eastern Oklahoma, which has gained a wicked reputation for ice storms and extended power outages during the last few years. While off-grid power has been a dream and an intellectual pursuit for several years, it has become more serious lately.

I'm currently overhauling a 1960 25 KW Onan 3-phase gasoline genset with a 232 c.i.d. Ford industrial engine. It may not be the best but an old gentleman gave it to me because I was the only one he knew who could "do something with it." I've recently purchased a 20-acre tract of land and am setting up a small farm so now is the time to lay out the new power system. The property already has commercial power and I've begun to install the manual power transfer switch in the garage.

During the 1990's, I purchased a video tape from a certain Joe Bourgeois of Metamarie, LA. This man had a off-grid plantation style home with a 4500 Watt Dimensions sinewave inverter, a 24 volt 1200 A/h forklift battery, and a 15KW diesel generator. He had successfully used his system for three years before producing his video and never had a power outage. Therefore, I'm convinced Joe's system can be duplicated and perhaps improved.

My objective is to have a fully functional off-grid system to engage with the manual transfer switch. I'm thinking of the 25 KW Onan genset (adapted for natural gas or propane) and an Aims 24 volt DC 7000 Watt 240 volt AC inverter with MSW output.

My home already has wood heat and I have immediate plans to replace the cook stove and water heater with propane counterparts. I'm researching a ground source heat pump for cooling during the summers. These appliance conversions should reduce power consumption to realistic levels for a home-based system. Our water supply is a deep (180') submersible well pump (the reason I need 240 VAC inverter output).

Advice? Constructive criticism? Warnings? Thank you in advance.
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Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    Re: Peter Brenner: Help before I buy system

    Peter,

    I moved your post to its own thread so that the Q&A only applies to your installation.

    Overall, very doable... It will not be cheaper than grid power--but if you have lots of outages, you can make a nice system...

    First, conservation--lots of it. It is almost always cheaper to conserve a watt than to generate it.

    Next, measure your loads. Solar Power is not cheap, and you do not want to build more of a system than you will need.

    Then, define the system type you want/need/will work for your situation...
    • Off Grid--Most expensive. Most people are too far from power lines.
    • Grid Tied--Cheapest and most efficient at generating power. Requires grid connection and a utility that will support net metering or buy your excess power. Will not work during a power outage.
    • Hybrid System--Combines both GT and Off-Grid power. Battery bank and Off-Grid inverter--so you can run without power. However you want to charge your battery bank (solar, wind, water, even grid power). Also, the inverter can perform Grid Tied operation too... For example, your solar panels will feed your AC mains just like Grid Tied. But if the power fails, then you can support off grid operation too.
    The Xantrex XW Hybrid Inverter system sound like it is made for your use. It supports 120/240 VAC split power. 6kW Hybrid Inverter. 48 volt battery bank. And will accept a back up generator for dark days/battery recharging. Even if this is an off-grid installation, the XW Inverter is probably still the best bet.

    Also, regarding the generator set. Most generators operate at a minimum of 50% fuel flow, whether outputting 50% of rated power, or 1% of rated power. From my point of view, most people have way too large of genset and are spending 2-4x or more on fuel that they do not need to.

    So, work out your loads (by season), your needs (grid, off grid, hybrid), and your energy sources (solar, wind, water, propane, diesel, etc.)... Then we can suggest some alternatives.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Peter Brenner: Help before I buy system

    welcome aboard and do some reading as much has changed sine the 90s. also, you may find that home power magazine to be a nice read as well with a free sample issue available on their website.
    http://homepower.com/home/
  • icarusicarus Solar Expert Posts: 5,228 ✭✭✭✭
    Re: Peter Brenner: Help before I buy system

    I'm not clear if your intention is to go off grid for 100% of your power, or just be able to power your homestead when the power is out.

    If it is the former, it can be done, but it will be expensive,, $5-10 watt or thereabouts

    If it is the latter a 25 kw Onan is a pretty good place to start. Depending on your grid load, 25 kw should power most homesteads with a bit of conservation!

    You might find this link interesting:http://www.smokstak.com/forum/forumdisplay.php?f=1

    This is a forum dedicated to Onans and there are some pretty smart old guys who know a lot about them. Biggest issue in my experience is to exercise them regularly with a good percentage load.

    Tony
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Peter Brenner: Help before I buy system

    Large off grid systems are very possible - they just take a lot more planning to get it right the first time.

    I think the largest we ever did was for a resort in Cabo San Lucas, around 20kw of panels and 16 Outback inverters.
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Peter Brenner: Help before I buy system

    If the current water heater is in good condition, instead of paying to switch it to propane I would research installing the solar water heater with the current setup. From what I've read, that is the quickest payback of using solar energy.
  • myocardiamyocardia Solar Expert Posts: 118 ✭✭✭
    Re: Peter Brenner: Help before I buy system
    icarus wrote: »
    If it is the latter a 25 kw Onan is a pretty good place to start. Depending on your grid load, 25 kw should power most homesteads with a bit of conservation!

    Haha, that's great. He might have to turn off those last 50 "grow your own" incandescents in the basement, huh?:D
    Advice? Constructive criticism? Warnings?

    There's absolutely no reason to be off-grid, when you have grid power available. That goes double when you already own a 25kW generator. You could completely power your house 24/7/365 for the next decade before the cost of the fuel would start approaching the cost of the batteries alone for the system you have proposed. You probably also weren't aware that off-grid is eligible for zero state or federal rebates, were you?

    Go ahead and wire that switch up, and use it for what it is designed to do: allow you to power your house from your generator. Then go to a Batteries Plus store and buy yourself eight Trojan T105 batteries. Batteries Plus sells them for $149 each. Here is their OK store locator: http://www.batteriesplus.com/store_locator/state/OK.aspx Next you'll need a 24V charger for them, available at a good price from our host: http://store.solar-electric.com/ioten25amp24.html

    Lastly, you'll need to buy yourself a pure sine wave 24V inverter. As you can see from this link: http://store.solar-electric.com/sasiwain1.html you can buy a 1,500 watt pure sine inverter for less than $600. That will run your television and satellite receiver, along with up to a 10,000 BTU air conditioner for short periods of time. Well, the inverter will run them for long periods of time, but only eight 215Ah batteries won't.

    This will allow you to have power 24 hours per day while your grid power is down, but not misuse your generator, like nearly everyone who has ever owned a generator does. I.E., it will allow you to start your generator for 1 hour every few hours (to recharge your batteries), instead of running it 24 hours/day, even though for most of the day you're only using a TV and a few lights. As a matter of fact, if you're only running the TV and a fan or two, you could only start the generator once or twice per day. If you decide after trying it out that you're happy enough with the arrangement, then you can spend another ~$2,000 or so, and buy a few large panels, along with a 24V charge controller. That would allow you to not ever need to turn on the generator, as long as it isn't air conditioning weather, and you have bought yourself plenty of CFL light bulbs.

    The smart part of doing it this way is that everything you buy to start with (batteries, charger, and inverter), you will have to have to buy to go along with the solar panels, anyway. This way, it gives you a chance to try out the "lifestyle", and only spend half of the money upfront. Good luck, and welcome to the forum.
    DoD= depth of discharge= amount removed from that battery   SoC= state of charge= amount remaining in that battery
    So, 0% DoD= 100% SoC, 25% DoD= 75% SoC, 50% DoD= 50% SoC, 75% DoD= 25% SoC, 100% DoD= 0% SoC
    A/C= air conditioning AC= alternating current (what comes from the outlets in your home) DC= direct current (what batteries & solar panels use)
  • mike95490mike95490 Solar Expert Posts: 8,370 ✭✭✭✭✭
    Re: Peter Brenner: Help before I buy system

    Abandon the mod-sine, and stick with the pure sine models. And keep the grid connection.
    Personally, I'd install a battery-less Grid Tie system, collect the rebates, and if the grid fails, run the generator.
    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 ,

  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello sub3marathonman,

    You wrote:

    "If the current water heater is in good condition, instead of paying to switch it to propane I would research installing the solar water heater with the current setup. From what I've read, that is the quickest payback of using solar energy."

    I don't know where you're located, but I lived in the Valley of the Sun (Phoenix) for three years during the 80's and northeast Oklahoma isn't so sunny. A passive solar water heating system is little more than a tax write-off here. Between June and September, the solar water system would be fairly useful but sit basically idle for the other nine months. I've read such systems do quite well farther south in Texas ...

    That's the reason for my consideration of propane for applications like the water heater and cook stove. When the power goes out, I can still have hot water and a home cooked meal. I grew up on a farm about 40 miles away and we rode out many short power outages that way. We stored water before storms, made sure we had enough firewood for the wood stove to heat the house (during the winters) and simply went to bed early like farmers when the power failed. Usually in a day, the rural electric coop restored the power and everything was normal again. That was before the ice storms when entire counties lost power for several days or weeks ...

    The only improvement I'm attempting now is a modest off-grid system to power the well pump, the freezer and refrigerator. It would also be nice to use the clothes washer so the dirty laundry doesn't stack up.
  • icarusicarus Solar Expert Posts: 5,228 ✭✭✭✭
    Re: Peter Brenner: Help before I buy system

    Peter,

    I'm confused. Are you suggesting that Solar hot water is not "viable" in Phoenix? I find that counter intuitive. I have built a number of simple flat plate (read cheap!) hot water collectors and used them in places with way less sun than AZ that yield pretty good harvests. The last one I installed was on a house in the Rainy Pac. NW. It provided a tow person household with ~75% of it's hot water needs on an annual basis. 150% in the summer, ~25% in the winter.

    Please clarify,

    Tony
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello Mike90045,

    You wrote:

    "Abandon the mod-sine, and stick with the pure sine models. And keep the grid connection.
    Personally, I'd install a battery-less Grid Tie system, collect the rebates, and if the grid fails, run the generator."

    Please explain your reasons for abandoning the MSW inverter and sticking with the true sinewave inverters. According to various readings, the MSW inverters can power nearly everything as the sinewave versions, with greater efficiency and little trouble.

    My 1990's video tape "Electrical Independence in the Home" by Joe Bourgeois of Metamarie, LA features a Dimensions 5500 W sinewave inverter which produced 120 and 240 volts AC from a 24-volt DC forklift battery. It appears I might duplicate this system with a few modern upgrades like the Aims MSW inverter.

    I'm specifically interested in hearing more about the Aims Industrial 24V DC MSW 7000 W 240V AC output inverter. I can't find any real world reviews about it. Of course the manufacturer's and retail sales pitches are everywhere on the Internet. I'd like to hear from somebody who has installed this particular inverter and used in in a real world off-grid application, even if only for a few days. How well did the inverter work and did cause any unusual symptoms or damage or destroy anything? Has the inverter technology improved with MSW with greater efficiency and less expense or is MSW a fraud?

    That is one of my main questions for this forum ...
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    Re: Peter Brenner: Help before I buy system

    User "adas" has used some of the larger AIMS inverters at his fabrication business in Hawaii.

    You can search for posts from "adas" or use google and search for:
    • adas aims inverter site:wind-sun.com
    Adas has not been on the board for the last 1/2 year or so--but you could also try PM'ing him and see if he has anything to ad.

    -Bill

    PS: Here are a couple of FAQ's regarding MSW and TSW inverters...

    All About Inverters
    Choosing an inverter for water pumping

    What some people have done is use a smaller TSW for computers and "sensitive" equipment and used MSW for big stuff like well pumps.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello Tony,

    Your response arrived in just a few minutes. Wow!

    You wrote:

    "I'm confused. Are you suggesting that Solar hot water is not "viable" in Phoenix? I find that counter intuitive. I have built a number of simple flat plate (read cheap!) hot water collectors and used them in places with way less sun than AZ that yield pretty good harvests. The last one I installed was on a house in the Rainy Pac. NW. It provided a tow person household with ~75% of it's hot water needs on an annual basis. 150% in the summer, ~25% in the winter."

    From personal experience in that climate, I'm certain that such a system would do great in Phoenix. Eastern Oklahoma isn't Phoenix and I'm concerned about the lack of hot water from a passive solar system. Your two person household 25% hot water supply during the winter may translate to less than 10% or even 5% for my household of five. Besides, a flat plate system is too easy for an Oklahoma twister to rip off and carry away. This isn't called Tornado Alley for nothing ...
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Thanks Bill,

    I'll try to find "adas" and solicit his specific advice. Also, thanks for the links and advice.
  • icarusicarus Solar Expert Posts: 5,228 ✭✭✭✭
    Re: Peter Brenner: Help before I buy system

    Peter,

    My flat plate system may not be right for you I concede, but it is tiny, home made and not very efficient. An evacuated tube or better flat plate system can be quite cost effective. The pay off for solar hot water is quite quick in most climates. If you live in a climate where you use A/C on a regular basis, a hot water recover heat pump may be a better alternative.

    The issue with solar hot water is how much sun you get, not the typical outside air temperature. Solar hot water is much more forgiving of partial shading compared to a PV system.

    Tony
  • mike95490mike95490 Solar Expert Posts: 8,370 ✭✭✭✭✭
    Re: Peter Brenner: Help before I buy system

    The FAQ's can sort it out more eloquently than I, but I'll be briefer.

    Grid tie systems, with modern inverters, deliver >95% of the harvested PV electricity back to the grid, unwinding your meter. PV panels, on average, deliver 80% of their STC labeled spec. If you install 3KW worth of solar PV, you will produce ~75% of your investment.

    Add batteries, their cycle losses, monthly maintenance, and annual decline and 10 year replacement, and you have lost another 20% of the harvest.

    MSW inverters may appear to be a good investment, but when you depart from running resistive loads on them, motors consume 20% more power and overheat, appliances, lights and motors "buzz". You are not saving electricity, you only saved $1,000 in the inverter cost.

    Pure sine inverters run all appliances, at the stated power levels, after a month, you would find yourself replacing at least 10% of the MSW powered appliances, as they fail. Which 10% seems to vary, some TV's are fine, some cordless tool chargers smoke in minutes.

    If your area has fairly reliable power, and you only need to keep the fridge and TV going for a couple days, a small, 2,000 inverter generator & gas tank siphon, is a better investment, than banks of batteries and the losses.

    That's my rational behind suggesting a pure grid tie install, and a small genset to carry you through the occasional blackout. If you currently expect blackouts with days or weeks duration, than a grid tie system with a small battery backup for outages, would be my suggestion.

    Mike
    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 ,

  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello Mike,

    You wrote:

    "MSW inverters may appear to be a good investment, but when you depart from running resistive loads on them, motors consume 20% more power and overheat, appliances, lights and motors "buzz". You are not saving electricity, you only saved $1,000 in the inverter cost.

    Pure sine inverters run all appliances, at the stated power levels, after a month, you would find yourself replacing at least 10% of the MSW powered appliances, as they fail. Which 10% seems to vary, some TV's are fine, some cordless tool chargers smoke in minutes."

    Thanks so much for the opinion about MSW inverters. That is exactly what I'm looking for on this forum. I hadn't yet found that topic on the FAQ's but I'll search more diligently for those details. I'm more interested in getting good equipment, rather than getting a bargain only to regret it later.

    What do you know about Dimensions power inverters? They are true sine wave inverters with 120-volt and 240-volt output.

    I'm not necessarily trying to save money with a home power system because I know it has some large up-front costs. We're simply too dependent upon the grid, which is far more fragile than FERC wants us to know. I work in the power industry and see some details which the general public cannot. The tree huggers are trying to drive the cost of electricity through the roof and I'm afraid they'll eventually succeed. It's already happened in Europe and North America isn't far behind.

    This is the reason I'm so interested in a permanent home power system. It requires some personal adaptation and changes in habits, but my hero Joe Bourgeois did it with a luxurious plantation-style home near New Orleans. I'm certain I can do it with my modest home and farm.

    I've studied PV's for years and even experimented with some tiny collectors (15W - 45 W) for fun. Basically, this technology is too undeveloped and expensive for most practical uses. Recharging batteries during a campout or hike is one thing, but powering a home is much more serious.

    I currently have a 10 KW gasoline generator, purchased in December 2008 because an Arctic front was predicted to settle over the U.S. for a duration of weeks. Interpreted: ice storms, deep snow, extended power outages, etc. In short, the Arctic front never came and the government enjoyed the economic stimulus at our expense. I'm not sorry for purchasing the generator, but I'm weary with the hype about the weather. An ounce of prevention is worth a pound of cure and that is my basic approach.
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Tony,

    I'm already considering hot water recovery for my ground source heat pump system. Efficiency is my goal and good planning is the key. Thanks.
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    Re: Peter Brenner: Help before I buy system

    Regarding the Dimensions Inverters... I just did a quick look and found that (the ones I saw) were 12 volt units--even a 3,600 watt version.

    In general, that large of inverter at 12 volts is very difficult and expensive to wire up to a 12 volt battery bank. The DC current requirements are huge:
    • 3,600 watts * 1/10.5 volts cutout * 1/0.80 eff * 1.25 NEC safety factor = 536 amp circuit
    The cable, fuses/breakers/switches, paralleling batteries and fuses/breakers for those, etc... Not a small job.

    In general, 1,200 watts is a good practical maximum power limit for a 12 volt battery bank... For a large system, you really need to start with a 48 volt bank to cut the current to 1/4 that of 12 volts. Plus you have less voltage drop issues (1.5 volts of drop, 12 volt appliance shuts down. That is a 6 volt drop at 48 vdc).

    Personally, I also like to keep parallel strings of batteries to a minimum. If you can justify (and move around) large cells for a single string--I like that... In general, I would try and avoid any more than three parallel strings of batteries. You need to fuse each string and ensure balanced current flow among all of the strings. can be a real pain with a bunch of smaller batteries to have equal length cables between them all.

    Also, regarding the Dimensions Inverter design... Most of them appear to uses fans for cooling internals. Fans draw in dust/bugs and will eventually need replacement.

    Some of the newer equipment are sealed and fanless---very nice.

    Have you decided on your electrical loads and if this will be off-grid, grid tied, or hybrid? We can size a system pretty easily once you have the basic requirements down. For emergency power, you don't have to run the whole home... Just the basics. If A/C is a requirement--use a Sanyo mini-split just for one or two rooms--very solar RE friendly. They can operate nicely on low setting (3,000 BTU) at 300 watts:

    Sanyo mini split AC (inverter/variable speed)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • wtwoods_azwtwoods_az Registered Users Posts: 18
    Re: Peter Brenner: Help before I buy system

    Hi Peter. Just a couple of thoughts from my personal experiences (my wife might say "experiments" since I am still in the exploring process....):

    I do live in PHX. I put in a flat-plate collector drainback system 2 years ago. I setup my electric heater to only turn on, if necessary, during low-cost hours. But, it only comes on at all if the home control computer program determines that hot water will be needed and isn't available. I've spent about $50 on hot water since. Got a way to go on payback, but I am on the way.

    I started getting serious about solar PV last year. I always wanted to, even back in my Silicon Valley days, but just couldn't make it make even close to financial sense. But being here in PHX was just too much of a pull to my spirit (if not solar in PHX, then where?). I would suppose I am not too different from most DYI'ers, my system is coming together over time as I make mistakes and learn from them (my 1st tracker rotation design was really weak). It has me happy so far, I saved some $$ during Jan/Feb, the real test will be this summer.

    As part of my system/plan, I have installed 2 Mitsubishi 23 SEER Mini-Splits which are also heat-pumps as well as being inverter systems (really efficient). Again, the real test with these units will be cooling, not heating, but I am happy with what I saved on heating so far. Haven't had them long enough to whole-heartedly recommend them, but I think they'd be worth a look. And, they qualify for the $1500 30% Fed Tax Credit. The Fed EX driver who delivered the second one said it was the 6th same type unit that week.

    Myocardia, if you happen to read this, would you tell me where you found out that off-grid systems are not eligible for tax incentives? I didn't know that, doesn't apply to me, but I am curious. Obviously, off-grid would not include utility rebates, but I didn't know about the tax credits.
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello Bill,

    I'm currently reading about the Airpax/Dimensions 24/5600DN sinewave inverter. The cryptic code means 24V DC input and 5600 Watts 120/240 Volts AC output. I found the Airpax web site and downloaded the owner's manual today for curiousity. I'm aware of the tremendous currents at 12 VDC, and have at least decided upon the 24V version. This beast can draw 280 ADC at full load and requires (I assume) fine stranded welding cable sized between 3/0 to 4/0, depending upon the distance from the battery. Knowing me, I'd probably use 4/0 anyway.

    Several months ago, I pinned down a battery dealer who could get me used forklift batteries. I want a 1200 A/h single battery, but might have to settle for two 600 A/h in parallel. I also know of the crossing method of connecting parallel batteries to prevent non-symmetrical current flow.

    I didn't specifically know of the Dimensions inverter design, but I'm not surprised about the muffin cooling fans. At the power plant, I maintain the 20 KW and 30 KW units there, and have changed many cooling fans during my career. I can change muffin fans in my sleep and the inverter design might allow this task without turning off the power. I'm also prone to install a filter for the cooling fan, if it is mounted to draw air

    I have an extensive background in electronics and can troublshoot circuit problems to the component. I still have a fully functional electronics workbench at home, complete with an o-scope. If Airpax/Dimensions will cooperate, I'd also like a complete electronic schematic of the unit I purchase.

    You wrote:

    "Have you decided on your electrical loads and if this will be off-grid, grid tied, or hybrid?"

    I intend to convert two appliances to propane: the water heater and cook stove. This will shed about 13 KW of load from the electrical system. I also want to replace the conventional A/C unit with a ground source heat pump with hot water option. This should shed another 2.6 KW of load. I've already converted the home lighting to tube flourescent and CFL. I wasn't aware of the split load Sanyo A/C unit. Thanks for the link - I'll look into it some time.

    Regarding the overall design of the system, I'm thinking of the worst case scenario - off-grid. This entails an inverter, battery, battery charger, and genset. I have some power outage and generator experience, already. The inverter and battery should be an interesting learning experience.

    Does anybody know where I might find a used Dimensions 4800 W or 5600 W sinewave inverter? I'd love to find one and if the price is right, I might not care if it works. Unless the unit was burned in a house fire, I could probably repair the electronics ...
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello WT Woods AZ,

    I lived at the west end of Glendale Avenue (Luke AFB) for thee years during the late 80's. I remember the area and it's frequent sunny days (300+ per year). Your solar collector should do well. I saw several of them on the house roofs.
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: Peter Brenner: Help before I buy system
    My objective is to have a fully functional off-grid system to engage with the manual transfer switch. I'm thinking of the 25 KW Onan genset (adapted for natural gas or propane) and an Aims 24 volt DC 7000 Watt 240 volt AC inverter with MSW output.

    How are you thinking to convert that 3-phase to DC for charging batteries? Why not 48V DC system instead of 24V? Also, solar panels are really getting cheap these days, you can get good quality stuff for $1.74 per Watt for off-grid use to offset your generator run time. Are you planning to disconnect from the grid? Or is this all just for emergency use?
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello AntronX:

    You wrote:

    "How are you thinking to convert that 3-phase to DC for charging batteries? Why not 48V DC system instead of 24V? Also, solar panels are really getting cheap these days, you can get good quality stuff for $1.74 per Watt for off-grid use to offset your generator run time. Are you planning to disconnect from the grid? Or is this all just for emergency use?"

    All right - let's see if I can explain my preliminary plans. I'm a power plant electrician by profession so I know a few things about 3-phase loading. The generator is wound as 3-phase Wye so I have three 120/240V outputs available. I'll call them A-B, B-C and A-C. My electrical system can use A-B, and I can use B-C and/or A-C for battery charging. I've not worked out the details about specific battery chargers, yet.

    I prefer 24V systems because I know 24V forklift batteries are readily available. I know that 48V systems use smaller wiring because of Ohm's Law, but I don't know of any larger sinewave inverters that use 48V DC input. Before Bill (I think) shed the light upon the msw power quality problems, I was considering an Aims 7000W 24VDC 120/240VAC MSW inverter. Now it appears I would do much better to get a Airpax/Dimensions 4800W or 5600W 24VDC 120/240VAC inverter.

    Solar panels still appear to me as a very minor auxiliary source, rather than a serious producer. I could fill a five acre field with panels to power my house but who could afford it besides King Solomon?

    I'd probably first use my system for emergency power outages and begin the learning curve. Then I'd turn off the grid power for extended periods to learn how to live without it. I'd probably use the grid power for my off-grid emergencies. Eventually, I'd disconnect from the grid permanently. I won't boast because it could take a few years to fully adapt to off-grid life. However, my off grid hero Joe Beorgois did it during the early 1990's in Louisiana. If utility rates go through the roof, I could step up the pace.
  • BB.BB. Super Moderators, Administrators Posts: 29,489 admin
    Re: Peter Brenner: Help before I buy system

    Peter,

    48 volts is pretty common for Solar RE systems... You can get a pretty sophisticated 6kW/12kW surge 48 VDC inverter/100 amp charger/Off Grid/Grid Tied/AC Transfer switch/Generator AC2 / 120/240 split phase for $3,400 or so (plus $$ for generator controller, pre-wired box, etc.)...

    I did not find a quick price on the AP/Dimensions 4,800 watt unit... So, I do not know the difference in costs.

    At this point, off-grid is going to remain more expensive than grid power for the near future anyways.

    Have you figured out your fuel costs for your genset? Usually when I try--I get somewhere between $0.50 to $2.00 per kWhr and if you use an inverter/battery for light loads (use genset to charge bank during day and for A/C use--And use battery bank for evening/night/winter when power requirements are less--Which even adds more costs...

    If you can get used inverters/chargers and used batteries--perhaps you can cut the cost curve down some.

    Although, I am wondering about your off-grid power source--Since you are not planning on solar PV at this time--Is the generator your prime power source? Do you have natural gas on your property? Otherwise, your fuel costs will not be cheap either... I can see planning for emergency backup power, but off-grid does seem to be sort of expensive as planned right now...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: Peter Brenner: Help before I buy system
    My electrical system can use A-B, and I can use B-C and/or A-C for battery charging. I've not worked out the details about specific battery chargers, yet.

    Are you worried about load mismatch between phases?
    I prefer 24V systems because I know 24V forklift batteries are readily available. I know that 48V systems use smaller wiring because of Ohm's Law, but I don't know of any larger sinewave inverters that use 48V DC input.

    Outback Power VFX3648 3600 Watt or Xantrex XW6048 6000W inverters run on 48V. They charge batteries too. Is you preference for forklift batteries is cost based? Or are you getting them used for cheap?
    Solar panels still appear to me as a very minor auxiliary source, rather than a serious producer. I could fill a five acre field with panels to power my house but who could afford it besides King Solomon?

    Lets see, 5 acres would be roughly about 1000 KW system. You really need this much power? :p
    I'd probably first use my system for emergency power outages and begin the learning curve. Then I'd turn off the grid power for extended periods to learn how to live without it. I'd probably use the grid power for my off-grid emergencies. Eventually, I'd disconnect from the grid permanently. I won't boast because it could take a few years to fully adapt to off-grid life. However, my off grid hero Joe Beorgois did it during the early 1990's in Louisiana. If utility rates go through the roof, I could step up the pace.

    I am curious how will you fuel your generator. Do you live on natural gas well? Or you know where to get it for free?
  • jeffkrusejeffkruse Solar Expert Posts: 205 ✭✭✭
    Re: Peter Brenner: Help before I buy system

    I would go with the Xantrex XW6048. It looks like the best fit for what you want.
  • myocardiamyocardia Solar Expert Posts: 118 ✭✭✭
    Re: Peter Brenner: Help before I buy system
    wtwoods_az wrote: »
    Myocardia, if you happen to read this, would you tell me where you found out that off-grid systems are not eligible for tax incentives? I didn't know that, doesn't apply to me, but I am curious. Obviously, off-grid would not include utility rebates, but I didn't know about the tax credits.

    After much digging, it seems to depend on the state where you live, not an overall federal rule, like I had at first thought: http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=MN09F&re=1&ee=1 Then again, once you see how few dollars are available for rebates these days, you'll realize you didn't have much of a chance of getting one in the first place.;)
    DoD= depth of discharge= amount removed from that battery   SoC= state of charge= amount remaining in that battery
    So, 0% DoD= 100% SoC, 25% DoD= 75% SoC, 50% DoD= 50% SoC, 75% DoD= 25% SoC, 100% DoD= 0% SoC
    A/C= air conditioning AC= alternating current (what comes from the outlets in your home) DC= direct current (what batteries & solar panels use)
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello AntronX,

    Thanks for responding. I'll try to address your questions:

    You wrote: "Are you worried about load mismatch between phases?"

    Actually, I am concerned about that. A mismatched load isn't just an electrical problem, but a mechanical concern as well.

    You wrote: "Outback Power VFX3648 3600 Watt[/URL] or Xantrex XW6048 6000W inverters run on 48V. They charge batteries too. Is you preference for forklift batteries is cost based? Or are you getting them used for cheap?"

    Thanks for the inverter reference. I don't know much about Xantrex inverters, yet. That's why I'm up to my elbows in homework on the topic. I'm climbing the learning curve as quickly as possible, but it's still a curve...

    My preference for forklift batteries is based upon two reasons: less expense and durability. My video mentor Joe Bourgeois used one in his system and I've read of others whom are using the same batteries for fifteen years or more. I'm not interested in making scrap lead. Several months ago, I called a battery warehouse and can get a used 600 A/h battery for $400. The same man estimated $500 or $600 for a 1200 A/h battery. While these batteries can't power a forklift for an eight-hour shift, I hear they do very well in off-grid systems. If you have another opinion, I'm all ears ...

    You wrote: "Lets see, 5 acres would be roughly about 1000 KW system. You really need this much power? :p"

    Okay, pardon my spouting. Solar panels have improved during the last ten years, but not nearly enough to impress me to buy 10 KW. Besides, I really need the pasture space for livestock.

    You wrote: "I am curious how will you fuel your generator. Do you live on natural gas well? Or you know where to get it for free?"

    I'll use gasoline at first when I get the genset running but that is bad economics for the long term. I'm planning to retrofit for natural gas/propane. Oklahoma is a gas producing state so the fuel is available locally.
  • Peter BrennerPeter Brenner Registered Users Posts: 14
    Re: Peter Brenner: Help before I buy system

    Hello again AntonX,

    You wrote: "How are you thinking to convert that 3-phase to DC for charging batteries? Why not 48V DC system instead of 24V? Also, solar panels are really getting cheap these days, you can get good quality stuff for $1.74 per Watt for off-grid use to offset your generator run time. Are you planning to disconnect from the grid? Or is this all just for emergency use?"

    In an earlier posting, I described the 3-phase output as A-B, B-C, and A-C. My electrical load could draw upon A-B, and I could have battery chargers on B-C and A-C. Since I can only charge the batteries with the genset anyway, this connection scheme appears best for load balancing.

    I've not considered 48V for a DC system, yet. I've heard of this type, but didn't know it was used much.

    Harbor Freight Tools has a sale (I don't have the flyer before me now). They're selling three large panels for $200. What do you think about this offer? Is it reputable or cheap Chinese junk?

    My initial plans for the home power system are for emergency use with a farther goal to disconnect from the grid. I need to master the art of electrical independence before breaking the commercial power connection...
  • icarusicarus Solar Expert Posts: 5,228 ✭✭✭✭
    Re: Peter Brenner: Help before I buy system

    Why would you buy Harbour Freight Panels, when you can get name brand panels from reputable solar retailers (Including our site sponsor) for under $2/watt?

    Tony

    PS My guess is that 3 HF panels you mentions are 3-15 watt panels for at total of 45 name plate. (the reality with these panels is a net of maybe 30 watts) so $200/30= $6.66/watt for a no name, POS panel.
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