Desperately seeking off grid solution for sunpower 210 panels!

I recently had this installed:

14 Sunpower 210's in 2 strings of 7
Sunnyboy 3000 grid connected inverter

I was very upset with my installer (who shall remain nameless) when after work had started, the sales weasel informed me that they could not install a battery backup for my new system (I made this a clear requirement during negotiations) due to "Technical limitations".

Turns out he meant nobody builds a disconnected inverter/charge controller for a positive ground panels like Sunpowers, at least not for sale in the US (I hear Xantrex has a disconnected inverter for sale in the EU?).

So, my question to this board is, what do you all think? Is there anything I can do?

BTW, I'm curious about what would happen if I could defeat the anti-islanding feature of my Sunnyboy 3000?
Would it be as simple as wiring something like a Xantrex PH1800 into the grid feeds to simulate an active grid?
«1

Comments

  • mike95490mike95490 Solar Expert Posts: 9,358 ✭✭✭✭✭
    Re: Desperately seeking off grid solution for sunpower 210 panels!
    chopkins wrote: »
    Would it be as simple as wiring something like a Xantrex PH1800 into the grid feeds to simulate an active grid?
    Won't work. In laymans terms, the grid tie inverter trys to "feed" the grid with 250V. The massive load of the grid keeps it at 240V. If the inverter gets much above 245v, it shuts itself down.
    (or whatever the local voltage in your country is)

    I'll withdraw this, folks with more experience than I, have spoken)
    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: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Yes, you can install a good quality inverter (true sine wave recommended) that is rated for the maximum power you expect your solar panels to output.

    Basically, you run the battery powered inverter as grid tie with fall back to off grid operation. And you connect your Grid Tied solar inverter (Sunnyboy in this case) to the output of your battery inverter.

    Turns out that the Sunny Boy should believe that the Grid is "good" and operate as normal. The battery powered inverter will also work in parallel with the Grid Tied inverter... If the power consumed by your loads is greater than the Grid Tied inverter's ouput--the battery inverter will add power...

    If the load is less than the output of the Grid Tied inverter--then it "back drives" the battery inverter and actually charges your battery bank quite nicely.

    Issue is that you need to control the charging of your battery. So additional hardware (or your monitoring) is required.

    Solar Guppy has done this and found it works well (but he is an Inverter Design Engineer) and has recommended the Xantrex XW grid tie capable inverters for this type of installation.

    This is certainly doable--but I have not done the work myself--so I cannot help you with any details.

    There are a few threads here that discuss some of the details--but I was not really able to find a thread with any details on how to do this correctly/safely.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • TelcoTelco Solar Expert Posts: 201 ✭✭✭✭✭
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Sorry to hear about the problems. This is the right place to get it fixed though, even though I don't have a system I've been reading as much as I can so I'll know what questions to ask when it's time to buy.

    Whether you can make them do anything depends on what the contract states. It should have listed what they were to install, and should state that battery backup is a requirement. If it does not state this, then forcing them to fix the problem is not going to be an option. If it does, usually a letter from a lawyer is enough to spur action. Lawyers know how to use the big words like "breach of contract" and "punitive damages" in ways to make business owners wet their pants.

    Might also see if there is a local TV news team that will contact them on your behalf, sometimes the knowledge that everyone in their local area is going to know that they aren't installing what their customers think is going in will scare them into fixing your issues even if the contract states otherwise. Even if they know you're boned, they know that potential customers will see what they did to you, and will be less likely to contact them when they are ready to go solar. It takes a thousand "attaboys" to cancel a single "oh$h!t."
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    The architecture Bill ("BB") described above is called "AC Coupled". OutBack's battery-based off-grid inverters can be applied in a similar manner. While the approach works, there's a big quirk to consider.

    Specifically, power from the battery-less grid-intertie (BL GI) inverter is used to power downstream loads, and any extra is run "backwards" through the OutBack inverter to charge the batteries. However, this charging method is unregulated.

    One solution is to use the OutBack inverter's AUX output to control contactors located in the BL GI inverter AC wiring to disconnect the BL GI inverter when the battery voltage reaches a certain point. This will shut off the BL GI inverter, as they are no longer "grid connected". Once the battery voltage has dropped sufficiently, the BL GI inverter is reconnected, and, after the required 5-minute UL safety period, it'll turn back on.

    More information on this architecture is available on the OutBack technical forum at www.outbackpower.com

    HTH,
    Jim Goodnight
    "crewzer"
    Eastern Regional Sales Manager
    OutBack Power Systems
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    In addition to what Jim/Crewzer has suggested, I believe that NEC/Safety would require a second, independent, method of controlling charge on the batteries (if the primary feed back failed to shut down the GT inverter, then a second method that does not use any components of the first would be highly recommended--if not required to prevent battery boiling/failing/or worse) ...

    That could be accomplished by placing a diversion controller on your batteries and have them dump the excess current to heaters (or whatever) to prevent your batteries from overcharging.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    So in theory:

    I wire the AC "outs" of an inverter/charge controller to the grid phase lines (which should be fine all by itself, also I'm assuming the signal is good enough to defeat the anti-islanding of the SunnyBoy or that modifying the grid quality settings in the SunnyBoy would allow this to work).

    The Xantrex PH1800, for example, has a clear separation between the "outs" and the "in's" used for charging the batteries, but for now assume the AC "in" on the Xantrex is disconnected.

    The "outs" of the Xantrex trick the sunnyboy into thinking the grid is up, so it will provide power to the mains.

    So well and good, however, mike90045's post about excessive voltage brings me to the root of it.

    What happens to the "excess" power generated by the SunnyBoy?
    I'm pretty sure the voltage would not change, but what would the SunnyBoy do when it supplies current that has nowhere to go?

    Side note, what is the worst thing that can happen if I actually experiment with this config? (Safety note, I have extensive residential electrical experience and I'm an engineer, but in software…)
  • Solar GuppySolar Guppy Solar Expert Posts: 1,973 ✭✭✭
    Re: Desperately seeking off grid solution for sunpower 210 panels!
    chopkins wrote: »
    So in theory:

    So well and good, however, mike90045's post about excessive voltage brings me to the root of it.

    What happens to the "excess" power generated by the SunnyBoy?
    I'm pretty sure the voltage would not change, but what would the SunnyBoy do when it supplies current that has nowhere to go?

    If the Sunnyboy has more watts than the grid ( Battery powered inverter or real grid ) can sink, the voltage will rise and the Sunnyboy would go offline.

    The issue is, When running the Offgrid inverter unregulated, the battery voltage just continues to rise until either the battery's boil or a high-battery-voltage fault happens, neither is a safe condition.

    With the Xantrex XW as the "Grid" and the GT's feeding the XW's outputs it can be somewhat controlled by as described in the document

    http://solar-guppy.com/forum/download/AC%20Coupling%20Application%20Note%20JE%20Draft4.doc

    The Outback Units are 120VAC only and would require a pair to do the AC coupling feature, the Xantrex XW is a 240V split-phase unit and can be coupled directly, but is an unsupported and un UL approved configuration.

    I only run this way if I lose the utility's and need to run the whole house and use the Xantrex GT's as HV charge controllers, but it requires constant attention ... very handy if a hurricane takes out the grid for a while ...
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    For the "Battery Inverter" think of the UPS type that uses a relay to connect AC input to the AC+Inverter output--And the DC inverter input to your batery bank...

    When AC mains are up--the AC-IN is directly connected to AC+Inverter-Output... So the SunnyBoy's and your AC loads work as normal... If there are more loads, the AC Mains supply the excess energy. If there is more SunnyBoy output than AC loads, the "excess power" is driven back upstream through the relay in the Battery Inverter back out to the AC Mains--and turn your meter "backwards" (assuming you have a Net Metering plan).

    When the AC mains fail, the Battery Inverter opens the relay and starts generating 120/240 VAC output to the AC+Inverter-Output... The SunnyBoy sees this output and may either just continuing to output power, or see the glitch and shut down for five minutes then restart outputting power to the local Battery Inverter Output.

    If there are more loads than SunnyBoy output, then the SunnyBoy and Battery Inverter simply work together to drive the local loads. If there is more SunnyBoy than loads--the power is driven back into the Battery Inverter and it actual "eats" the excess power and drives it back out its DC connections to the battery bank--And now starts charging the battery bank.

    When the AC Main power is restored--then the Battery Inverter Relay clicks back and all the SunnyBoy (and the local loads) are reconnected back to the AC Mains and all works as normal.

    Think of a large UPS where one of the "loads" is a SunnyBoy Grid Tied inverter.

    The limitations--You want the Battery Inverter to be able to take Maximum SunnyBoy output (less other AC loads--if substantial and continuous)--So typically you would want the Battery Inverter's rating to be greater than the maximum SunnyBoy output wattage.

    Also, you need some what to safely manage the battery charging--so you don't cook the batteries (or cause fire/explosion)--Typically NRTL/NEC would require two independent methods to regulate power to the batteries so that a single point of failure would not cause battery overcharge (hence my recommendation for a diversion charger + whatever other charge controller you use).

    Another issue is that many US battery inverters are 120 VAC and many Grid Tied inverters are 240 VAC... So you end up needing to use an Auto Transformer (Outback has several auto transformers available and application notes) of some sort to connect the two together. Or use a 120/240 volt Battery inverter like the XW line from Xantrex.

    Worst Case experimental issues? You are working with several thousand watts and upwards of 50 amps at 120/240 VAC--not small amounts of energy. Also, you are working with relatively large battery banks--which have 10's of thousands of Short Circuit Amps available.

    Also, you will need to ensure that your local battery bank is not overcharged (and properly vented, fused, wired, etc.).

    Your last issue is that you can only do this testing (legally?) when your current installation has been approved by your local building department and electric utility for your Grid Tried Installation.

    Assuming you are knowledgeable and safe, using appropriate equipment/circuit breakers/fuses/etc.--you should not be unduly at risk.

    You should probably pick your equipment (battery inverter) and post questions here (or at Outback) to double check that the inverter you want to use will work in this application.

    The inverters that I have seen discussed to date have all been True Sine Wave types (high end Outback and Xantrex units)--which are much better devices for powering all types of loads--I don't know how Modified Sine Wave (square wave) inverters would work in this application.

    Perhaps Solar Guppy or Jim/Crewzer would know. MSW would be certainly be cheaper.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Desperately seeking off grid solution for sunpower 210 panels!
    I wire the AC "outs" of an inverter/charge controller to the grid phase lines (which should be fine all by itself, also I'm assuming the signal is good enough to defeat the anti-islanding of the SunnyBoy…
    That’s basically the right idea.
    ...or that modifying the grid quality settings in the SunnyBoy would allow this to work).
    I suspect that this can’t easily be done. Each grid-interactive inverter sold in the U.S. is individually certified to UL 1741 (not just type-accepted), so I suspect they are not easily altered.
    The "outs" of the Xantrex trick the sunnyboy into thinking the grid is up, so it will provide power to the mains.
    Right. I just don’t know enough about the product to be able to tell you if it will work “backwards”.
    So well and good, however, mike90045's post about excessive voltage brings me to the root of it.

    What happens to the "excess" power generated by the SunnyBoy?
    I'm pretty sure the voltage would not change, but what would the SunnyBoy do when it supplies current that has nowhere to go?
    Therein lies the fundamental rub, as they say.

    In the case of the OutBack off-grid inverters, the “excess” power is used to charge the batteries, but in an unregulated state. Once the batteries reach their target absorption voltage, we’re back to the fundamental question: “Where does the rest of the excess power go?"

    One solution would be to place a contactor in the AC lines between the output of the SunnyBoy and the “micro-grid”. When the battery voltage reaches a user set value, the OutBack inverter’s AUX output (i.e., genalert hi/lo voltage function) could be used to activate the contactor to disconnect the Sunnyboy’s output, which would turn it off. Once the battery voltage falls low enough , the contactor would be deactivated and the Sunnyboy re-connected.

    Or, you may want to invert the control signal so that the contactor opens in the event of a failure of the battery-based inverter -- a fail-safe configuration.

    You may find this discussion and the embedded links to be of interest. See: http://www.outbackpower.com/forum/viewtopic.php?f=15&t=2963

    Regards,
    Jim / crewzer
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Chopkins,

    Another thing to consider is just installing a transfer switch and backup generator...

    I too am in the SF Bay Area (SF Peninsula)--Unless you live in coastal mountains (or the Marin Headlands where another poster lives--and PG&E takes days sometimes to reconnect their power after a storm) where you may get lots of multi-day power failures--it is a tough call the difference in expenses between justifying a battery+inverter system (battery purchase, maintenance, charging losses, and battery bank replacement every 10+/- years) vs just getting a small generator and keeping a back up supply of fuel (natural gas, propane, or--in my case--gasoline with preservative).

    In the end, for me, I cannot really justify the battery expense issue for the 1 time in 50+ years that I could have used a system for a multi-day blackout. The Grid Tie is the most efficient (both cost and energy wise) Solar Panel power system for homes with grid power (and is allowed by utility/state law).

    And in my case, I choose not to use Natural Gas a my backup--because I am not sure how reliable/quick to restore after the "big one" (earthquake).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I'm down in the pen too (Burlingame).

    I've thought about the generator option, but I reckon if the big one does hit (or something else) and we lose the grid for a long time, I'd be much happier with a self sustaining power system.
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Chopkins,

    Just below you in San Mateo.

    Look at how much (or how little) power you will need in an emergency...

    In the end, a Honda eu2000i and two gallons of gas per day will probably keep me going nicely...

    Fridge, freezer, a few lights, radio and I am around 400 watts. The eu2000i uses about 1.1 gallons of gas every 15 hours at 400 watts. 20 gallons of gas siphoned out of the car/truck will give me at least 10 days of power. Plus a have a few 5 gallon cans of fuel with stabilizer (recycle into the car once per year) and I am good for the better part of a month.

    Water and security are probably going to be as big, if not bigger, problems if the power outages last more than a few days.

    I treat the outages like camping... Stored food (canned goods and dry) and water (plus filter+chlorine), camp stove, sleeping bags, etc. and we are good to go (food storage and fresh water supplies are my two big concerns).

    There are a couple small wells around here--but no good way to get water out of them (no appropriate pump--don't know if water is good anyway--one well has the old pump links dropped down the hole--don't know how deep I can go down for water pumping).

    And, in the end, the extra gas and portable generator may be more use to us if we have to leave than trying to figure out what to do with 20 solar panels and several tons of batteries.

    I have lived here my whole life--and the only multi-day outage on the peninsula that I can remember is a 5-6 day one in Pacifica--and that was over 50 years ago. The rest of the outages--the longest has only been about 4 hours or so maximum.

    If California goes back to the 2000 rotating outages again--setting up the equivalent of a large UPS with a Xantrex or Outback Inverter looks really nice. Since the Inverters also have internal AC chargers in them, and I would only plan on a 6-12 outage at a time--I would, at least first, setup the batteries to be charged through the inverters (and an AC charge from my generator--or use the GEN input on the inverter).

    For now, I just don't foresee the multi-day outages in our near future that make the battery expense/hassles worth it.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Indeed, water and security are the big ones if let's say the grid is shattered and is down for a number of weeks.

    My plan for water (assuming I have power) is to run a few dehumidifiers. There are fancy ones, but the idea is still the same, water from air.

    Worst thing that would happen if the grid goes down for longer than a few days most likely would be all the people…

    I suppose that since I've already installed the GT system, I may just get the Xantrex for a backup "Just in case" system.
    I may only get enough batteries to test the system, batteries being easy to obtain later if needed.
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I would not plan on using a dehumidifier... Real energy hogs. Yes, they will get you water and some "electric heat"... I have a couple and unless it is very humid (I had to dry some wet carpet from a refrigerator Ice Maker water filter leak and I had a damp home in winter until I fixed the drainage and put some under floor insulation in)--I got a few gallons per day at ~350 watts or so input power) you will probably not get the amount of water you expect for the energy expended...

    350 watts * 24 hours / 5,000 Watt*Hours per gallon of gas = 1.6 gallons of gas on a fairly efficient generator...

    2-3 gallons of water per day for over $6 in gasoline (at $4.00 per US Gallon). Basically, that would double or triple my emergency fuel usage (of course--if you have solar--that power is basically "free" in an emergency)

    My plan was to use my water heater as a storage tank... 50 gallons of drinkable water. Probably plan on 2-5 gallons per day per person--perhaps 1 gallon per day if rationed... Family of 4, that 50 gallon water heater goes down to 2.5 to 12 days for a family of four.

    From reading the cafe on another forum--one person who had lived through multiple hurricane outages suggested that nobody ever had enough liquid soap, toilet paper, paper towels, and plastic garbage bags (for sanitary storage of waste--and even the plastic bags are a problem if you have wildlife around).

    Even though I am relatively prepared, just typing this up makes be want to go get some 35 gallon garbage cans (with lids--to fill up right after the earthquake--use for washing/cooking/emergency water w/chlorine+filter), a box of trash bags, and some more paper towels--and just stick those in the shed/attic--if ever needed. Barrels are better--but garbage cans I can stack for storage.

    I mentioned the 6 day outage we had here 5+ decades ago--of course, those were simpler times and this was only a local electrical outage (storm caused)--but what worried officials at the time was fresh water--we have pumped storage tanks around the hills here--and they were about to go dry without electricity at the time.

    I have thought about adding a well to our backyard--but getting a well company out here was expensive and the county has regulations on where you can install a well (even if it is just for garden watering). We have an over-sized lot with a smallish house--and there is only a small area in our yard where (I think) it is legal to drill (have to be xx feet from sewer lines--unclear if that is all sewer lines or just city/street sewer lines).

    I think I posted this saying here before...

    You can live:
    3 minutes without air
    3 days without water
    3 weeks without food

    And what do we usually have--lots of air and a fair amount of food--but no real water storage.

    Just typing this up--I was thinking the next time I replace a water heater to go up from 40-50 gallons (more than large enough for our usage) to a 75-80 gallon model--just to have more fresh water storage (and you and your's tied down earthquake straps--right?). Or another justification to go with solar hot water (and the 80 Gallon or two hot water tanks that go with it). Save energy and add emergency preparedness.

    My real emergency electrical needs are for the fridge/freezer. The rest, LED flashlights+batteries, solar/crank powered radio, emergency candles, and camping gear (stove, lantern, propane grill)--will keep our family going OK.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I read the doc from Xantrex, very nice.

    To make sure I understand the concepts:
    The system would reply on two safety features to ensure the batteries don't cook.

    Primary is the AUX 12 volt port that is used to control the Sunny Boy in order to shut it down when the batteries are charged, if the system is running in grid-disconnected mode.
    The reference doc was very specific to Xantrex tech though, so I'll need to figure out the best way to do this with the Sunny Boy.

    Secondary systems are the "High batt cut out" on the Xantrex or the Sunny Boys' high voltage detection/grid out of allows params system.
    The variable there seems to be the setting on the Xantrex, which I'm assuming is a straightforward calculation based on the battery array.
    There are a number of knobs on the Sunny Boy that allow for changing the allowed grid params but I have not been able to find a tech doc to help here. Hopefully I do not have to change these.

    For the XW, I'm looking at the XW4024, which has capacity of 4000 watts (1000 > than the Sunny Boy 3000 max).
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I think you have the basics...

    Two points... SG usually recommends the 6kW XW inverter--it is only $700 or so more and a relatively small cost in the overall system. And it will allow you to draw more load and run cooler at the same loads for longer life.

    Second... From an engineering point of view your "two systems" concept still relies on the XW inverter to have all of its "marbles" (engineering talk... :roll: ) as the same CPU and voltage monitoring circuits (probably) will be both signaling the SunnyBoy and making the absorber/high voltage shutdown decisions.

    It would be better (this is one possible solution, others can be done too) if the high voltage shut down be done with a separate controller to monitor the battery bank voltage and force a SunnyBoy shutdown (controlling an electronic contactor in the SunnyBoy's AC output) would work.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I like your idea about the garbage cans. Next trip to the depot I'll be sure to grad a few more.
    Sadly, I replaced my tank water heater with a tankless…

    So this guy:
    http://ecoloblue.com/Operation_manual.pdf

    runs at 450-500 watts.
    My smallish array usually does around 10kwh a day in summer, so I'd still have capacity for the fridge etc. (assuming I'd only run the dehumidifier during daylight hours).

    For us locally, I have plots and schemes to augment our water out of the reservoir up the hill if needed.
    I could ride my motorcycle up and back for a little gas and can carry up to 20 gallons (I've got a big bmw r1200gs), or take the truck and fillup as much as I can carry.
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!
    chopkins wrote: »
    I like your idea about the garbage cans. Next trip to the depot I'll be sure to grad a few more.
    Sadly, I replaced my tank water heater with a tankless…

    Doh... As I read that--slaps head with hand. I too was thinking about going tankless--but their expense for the first install (plumber, repiping gas& flue, and my concern about reliability, noise, and parts pretty much keeps putting me back with the tanked heater or a tankless+solar hot water (which still has one or more tanks) anyway.

    Regarding Water--if Crystal Springs Dam fails--you will have plenty to scoop up into your garbage cans on the "el Camino"... :p

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • sam csam c Registered Users Posts: 16
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    very informative thread, comment, on running a frig off an eu2000, it may start the frig, if nothing else is running, and thats a maybe, normal starting watts are around 3000. but if it does start its best to keep it running, watts around 300, this assumes its not a self defrost machine, the heaters for self defrost are large, one way to keep the re frig running is to put a low watt bulb in it and tape the door SW closed this would gen enough heat to keep it running
    SAM
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I am surprised about the issues with starting a home fridge... My freezer only takes a 110 watts running--so I would have expected the eu2000i to not have a big issue.

    I have talked with one or two people that have run small room A/C's of of a eu2000i too... Typically for these larger loads, you have to turn of the ECO Throttle.

    -Bill

    PS: I should add that this is an Energy Star Freezer with manual defrost--so there are no heater/ice maker loads. But I would not expect huge loads for my Energy Star Fridge either since its average kWhrs is about the same as the freezer (defrost and Ice Maker heaters may be an issue?).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Good point on the 6kw XW, I will keep that in mind (I like building plenty of room into things if it makes sense, sounds like it does here).

    It would be better (this is one possible solution, others can be done too) if the high voltage shut down be done with a separate controller to monitor the battery bank voltage and force a SunnyBoy shutdown (controlling an electronic contactor in the SunnyBoy's AC output) would work.

    Do you have any controller recommendations?
    Does the XW need anything or does it end up just being a case of disappearing "load"?
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I can answer some of your concerns about the tankless at least (a little payback for your own info!)

    Got the heater at the depot for 1000 bucks. I've got a two bath house but got the 3 bath heater (no problems with supply even when everything is running).

    Plumbing the gas line was not that bad, I already had a 3/4 line close by, but for a plumber I'd guess you'd spend 500 bucks at a min.
    Money well spent, but there is no magic to it and if you're willing to take a few trips to the hardware store to get any custom lengths threaded…

    Noise is not that bad. I mounted mine on the garage wall and yes, you can hear it when it's on but it's nothing big.

    Depending on what you have already the flue is pretty straight forward. Just be sure to get the recommended grade of pipe and be sure to include a condensation draining system.
    The depot has nothing, I got the bits online.

    Standard warrantee is 10 years, though I agree it would suck if it did break (that said it's been in a year and we've had no issues).
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Chopkins,

    Thanks for the tankless heater info--did you see your gas bill go down?

    Regarding the controller--several of the Outback and MorningStar solar Charge controllers (and probably others) can be configured as diversion controllers (setup to turn on a 48 volt heater load) and/or you can probably program/setup them to kick of an electronic relay on the SunnyBoy AC output.

    I would probably like to use the solar charge controller because it is temperature compensated (battery voltage falls as they get warm/hot--can get thermal runaway). You could probably setup a FM 80 from Outback with two levels of "safety"... One as a straight diversion controller and the other voltage controlled output to turn off the AC relay.

    Pretty much you would have to download the manual and/or ask one of the various controller experts here (like Jim/Crewzer) on the configuration/programming details.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Ok, from the top I'll try to sum up everything you guys have recommended:

    Xantrex XW6048 as a "master" controller. The 6048 has a little more than twice the capacity of my sunny boy, so there is plenty of headroom to ensure efficient operation.

    The AC outs of my Sunny Boy 3000 will connect to the AC Load of the Xantrex.
    This connection will have relays controlled by a FLEXmax 80 or similar charge controller in order to shutdown the Sunny Boy when the batteries are fully charged is grid disconnected mode.
    Question: when in grid connected mode and the batteries are fully charged, how does this work? E.G., I do not want to shutdown the sunnyboy when in grid connect mode when the batteries are full charged.

    The AC Load of the Xantrex will also connect (upstream of the relays) to a new "off grid" subpanel.

    The Grid connection of the Xantrex will connect to my main distribution panel for sell mode (Grid connected power, anti-islanding).

    The FLEXmax 80 will sit between the DC in/outs of the Xantrex and should control both grid connected overcharge (without shutting down the sunnyboy) and grid disconnected overcharge/undercharge.

    How does that sound so far?
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!
    chopkins wrote: »
    The Grid connection of the Xantrex will connect to my main distribution panel for sell mode (Grid connected power, anti-islanding).

    Just to be clear, the XW inverter will be passive at this point... Just monitoring the AC mains and (if you have it setup this way) will also be charging/floating your batteries (like a UPS in standby)--Using the AC mains power (including from your Sunnyboy when the sun is up).
    The FLEXmax 80 will sit between the DC in/outs of the Xantrex and should control both grid connected overcharge (without shutting down the sunnyboy) and grid disconnected overcharge/undercharge.

    How does that sound so far?

    My suggestion using the FLEXmax 80 would sit in "Diverter Mode" just connected in parallel to the batteries with the XW. Current will not flow through the FLEXmax between the XW Inverter DC Input/output. Instead, the FLEXmax would be between the battery and your diverter load (typically heaters)--monitoring the Battery voltage and turning the Heaters on/off as needed.

    And, I presume (you need to confirm with the manual/Crewzer/Outback) that the AUX output could be configured to turn off the external SunnyBoy relay (or internal Sunnyboy shutdown, if present) based on Battery voltage (or over voltage).

    And--there is where it gets complicated... You have the XW battery charger, and the FLEXmax Diverter/Charger--Operating both at the same time on the same battery set...

    And you could have the following situation--for example, the XW thinks the batteries need bulk/absorb charging at (following numbers are "Made UP" for this discussion)~60.0 VDC--but the FLEXmax monitoring the batteries thinks the batteries should be floating at 56 VDC--so it turns on the diversion loads to keep the voltage at 56 VDC... The XW sees the batteries going down in voltage and then continues the bulk/absorb charging... And you end up with some 3kWatts of heat in your garage/battery shed that you don't know about...

    My suggestion is to "pick" your major components and "wire them up" on paper. Then reading through the manuals and see how things should be programmed...

    This is what happens when designing a complex system... You start having to add additional components (that can fail) to prevent bad feedback loops (and you get into chicken/egg/startup issues and weird failures)... In this case, perhaps some sort of circuit that "turns off" the FLEXmax if there is AC Mains Power--as you know there will never be any reason to use the diversion load if the AC mains are up and running (and the XW inverter is in By-Pass mode).

    Perhaps Solar Guppy or Jim/Crewzer (and/or others) have a good bock diagram/setup white paper that addresses setting up this AC Coupled system.

    I certainly don't have all of the answers--but this is how I would work out the major issues (before I spend the money).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I'll need to catch up on this later this week...

    Regards,
    Jim / crewzer
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    I just want to add, that none of what I was saying the example in my previous post was intended as a complaint against any of the vendors.

    It was just an acknowledgment that the problem of connecting multiple independent "smart" charge controllers (Grid Tie / Off grid inverters and diversion charge controllers) together can get into possibly unsafe situations when using these products in ways they were never designed/tested for.

    How the functional blocks are configured can address some of the issues (for example, the Solar Charge controller could have its float mode turned off). But while turning float off may work well for an emergency backup situation (Grid Tied Inverter Charger controls battery voltage); it may not work well for the same setup in an Off-Grid type situation with generator backup (the diversion controller without float may tend to overcharge the batteries during periods of light load and lots of sun).

    You get into questions of which device (inverter or diversion controller) do you want to control the backup generator--

    And you would probably want to have some alarm conditions to alert the owner and possible shutdown something if certain conditions occur (such as diversion loads "on" while the inverter is charging or the generator is operating/charging).

    Not to scare anyone off--but this is a fairly complex setup with lots of unknowns, dealing with fairly high energy devices, and the risks to life and property is not zero if something goes wrong.

    I think that "AC Coupled" Grid Tie plus Off Grid inverters is a very interesting idea--and I am looking very closely and thinking about how it could work in my home (I have Grid Tied Solar myself)--This is something that nobody should jump into without understanding the issues, risks, and realizing that they may be one of the early guinea pigs trying to setup a true fully automated and safe "AC Coupled" system.

    It is possible that my idea of using the "diversion controller" may not be a good one for this application. Using a "simple" charge controller (or temperature compensated controller to monitor the battery bank--which may not yet exist) controlling a solid state AC relay in the Grid Tied Inverter's AC output plus a "wire or'ed" control signal from the AC mains that also turns on the AC Relay (on the Grid Tied Inverter) when the AC Mains are "on" would be the best.

    And use the Off-Grid/Battery connected inverter to control the backup generator (if there is one). Or, possibly use a Battery Monitor with programmable outputs to controller the backup generator would be a neat idea (since a battery monitor "knows" the % state of charge of the battery bank).

    For the second "emergency backup" control--you would have to look at the battery inverter and verify that it will "shutdown" if the battery voltages exceed the appropriate XX volts when the inverter is being "back-driven" by the Grid Tied inverter...

    And/or you may just put a second Charge Controller + AC relay in series with the first on the Grid Tied Inverter's output to have your redundant/independent shutdown.

    Not building a life critical (space/medical) system here--but we do want it to be safe so that no single point of failure will put property and people at risk.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    We did see it go down, quite a bit (about 2/3).
    BUT, our old one was about 20 yrs old and had no isolation…
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Humm.

    So I need to be able to:

    Detect if the Xantrex considers the grid up, either through an existing XW interface or by monitoring the grid connection.

    If the grid is up and the XW is doing a pass through charge of the batteries from the power generated by the GT, will it correctly charge the batteries?
    (previous post seemed to indicate that is would not).
    If that is the case, the secondary charge controller is needed between the XW and the batteries to actually handle the charging duties.
    If that is NOT the case, the XW will handle all the battery charging duties and the secondary is then in parallel and is only used to detect battery overcharge (backup).

    Use the XW grid state (grid up or down) to build GT out control (via AC relays) like:

    Grid up do nothing on the AC relays.
    Grid DOWN and either the XW 12 volt signal says the batteries are charged or the secondary charge controller says they are charged, cut the AC from the GT.

    So, it seems like the next step is to figure out what will handle:

    Grid state detection
    Take the 12 volt signal from the XW
    Take the signal from the secondary charge controller

    Can then operate the AC disconnects from the GT.
  • System2System2 Posts: 6,290 admin
    Re: Desperately seeking off grid solution for sunpower 210 panels!

    Ah, answered one question.
    The XW does not regulate battery charging when in disconnected mode.

    So the secondary charge controller could be set to signal slightly higher than the XW would cut out the battery charging when connected, so it would only signal when the XW is not actually controlling the battery charging (as in disconnected mode) and would not be in parallel but inline.

    Does that config make sense? The XW would control charging in connected mode and the secondary would control in disconnected.

    I could then use the secondary signal to control the GT inverter AC cutouts.

    Unlike its behavior when in charge mode, the XW does not regulate charging when power is flowing from its AC output to the battery. This will not pose a problem if the battery is sufficiently discharged. However, if the battery is already full and there are no loads on the system, there is potential that if the GT Inverter(s) continue selling power to the AC bus, the battery voltage will rise until an over voltage fault condition (“High Batt Cut Out” setting) is reached and causes the entire system to shutdown completely. This may also damage the battery if the “High Batt Cut Out” is set too high for the battery.

    To prevent this from occurring, the system can limit the current injected into the batteries by using the XW’s AUX 12V port to signal the GT to shutdown before an over voltage condition exists. The XW aux output activates an optocoupler that in turn shorts pins 1 and 4 on the GT’s 3Phase port. When these pins are shorted the GT(s) immediately shuts down. Once the pins are un-shorted the GT waits its time to reconnect. In this way the XW can signal the GT to shut down without interrupting the power flow.
Sign In or Register to comment.