Looking for an inverter - which one?

BrigonBrigon Posts: 5Registered Users ✭✭
I've been lurking, reading and learning for a while but will soon be ready to start getting my system up and running. I will be giving more details, and of course asking more questions, once I get my head wrapped around everything, but my question for now is what inverter do I buy. 
Donated to me was a TS mppt 60 and I would love morningstar to have an inverter that was worth looking at for integration purposes, but for what I want to do their inverter does not work.
I am ok making a long term decision that does not involve using my current CC for my main system once I get going because system integration of one manufacturer means things work easier together and makes monitoring easier, but I would like to start off using the CC I have.
I am looking for a 2500W - 3000W  PSW inverter that is 48Vdc input, 120 / 240vac output. I need it to be capable of paralleling as the system grows. I also want a "Hybrid" inverter. I will not be off grid and cannot sell back to the grid so my desire is to use as much power during peak price from solar, and to automatically switch to Line power, if / when the batteries go down to maybe 70% SOC at night when the price is lower.
News out of Midnite solar about a year ago gave me some hope, I am ok buying a classic and their " Little Willy" inverter, ( now titled something else) but no news on LW makes me think it could still be a while away from introduction.
 I do not have any experience with a raspberry PI, but am willing and capable of learning  and connecting that into a PLC / RTU if that is the solution to system monitoring. Talking about system monitoring, I do not want to buy an inverter for $xx, and then find I need to spend half as much again on monitoring equipment.
Is there an option out there that I haven't considered yet.
Looking for suggestions, I have about 3 months to make a decision.

Thanks for all help.

Comments

  • EstragonEstragon Posts: 2,321Registered Users ✭✭✭✭
    Having gear made by the same company can be nice, but I do okay with a mix. My personal preference is to get the best tool for the job, but there's something to be said for integration.

    For the inverter, it may help to know more about expected loads.

    In my case, for example, most loads are 120v and generally not all that heavy. I have a pair of Outback inverters which can be stacked in series for 120/240 or master/slave parallel. With additional units, a combination of series and parallel (or 3bphase) can be done. Rather than have a series stack running to provide 240v only occasionally for a pump, the master/slave setup allows one inverter to sleep most of the time, but still handle occasional large loads. An autotransformer handles my one 240v load. Your load situation may be quite different though.

    Many (most, all?) of the more sophisticated inverters (ie do stacking etc) will need an added component/network not so much for you to monitor, but for you to properly configure them, and for them to work together properly.

    You almost certainly shouldn't need to go the rPi route for routine monitoring. I believe the TS needs a converter dongle for ethernet to monitor with a pc. Some (eg MN classics) have built in for pc and/or web monitoring.
    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
  • Dave AngeliniDave Angelini Posts: 3,698Solar Expert ✭✭✭✭
    Morningstar is in beta now with their first new inverter. If you can wait a bit or call them and ask nicely? I really can't say but it sounds very good!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BB.BB. Posts: 27,440Super Moderators admin
    On the other hand, do a paper design of several systems. For larger systems, integration of chargers and inverters can be pretty nice. Possibly save the Morningstar for a smaller project or to somebody else to use?

    Also, growing systems can have limitations--You are (I think) already looking at a pretty large system. Going towards a 4-6 kWatt single inverter may be an easier system to install and maintain.

    Regarding your grid power--In general, it is difficult to save money with an off grid system (for example) supplying power during utility peak price times.

    In the US, by the time you add up the costs, the losses, and replacing batteries every 7-10 years and electronics every 10+ years, getting much below $1.00 per kWH is not easy (I suggest generally the costs are $1-$2+ per kWH used--One or two folks here, with lots of good shopping skills and using most of the power generated by the sun, perhaps down towards $0.50 per kWH).

    Some utilities are going with a "new rate plan" setup... Basically raising monthly connection fees (from $5 per month to $48 or even ~$96 per month) and then "cheap" $/kWH pricing (very roughly $0.07 to $0.13 per kWH).

    What are your electrical rates and do you have a good handle on hardware costs and energy harvest?

    GT solar is nice because 100% of the available sunlight is pumped back into the grid for credit (use at night, bad weather). Roughly 77% or so of available solar energy (solar panels+GT inverter losses).

    Off Grid solar, a different animal. More or less, very roughly 52% end to end efficiency (solar panels to charge controller to battery bank to AC inverter to AC loads). And since it is difficult to use more than ~65% to 75% of harvested power on average unless you are really managing loads (i.e., sunny days, run water pump to cistern, run A/C system, do washing, etc., and on "gloomy days" cut optional loads until the sun returns). You are pretty much "doomed" to 2x the solar array for a "similar capability" Off Grid system vs a GT inverter system.

    Add that if there are any mistakes (many people "murder" their first battery bank or two) or other issues (nearby lighting strike, hailstorm damaging panels, etc.)--You are responsible for the costs to bring your system back online.

    I am sure there are situations where a "hybrid" GT/Off Grid (battery system) can save money--I suggest that you really look at the financials and see if they make sense for you.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Posts: 7,651Solar Expert ✭✭✭✭
    The moment you add a battery into the system, you are forever loosing money. 
    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 Posts: 3,698Solar Expert ✭✭✭✭
    mike95490 said:
    The moment you add a battery into the system, you are forever loosing money. 
    In some cases this is true!  In many it is not. 

    I see a PG & E guy at the grocery store and he keeps asking if we are surviving without him.
    Over 20 years now and then the price was over 100K to bring power up my mountain. 

    I asked him what the cost is now and he said "we will need your checking account and can carry the loan...
    We have a battery now that will outlive my Wife and I  ;) If the lightning god is good!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • mike95490mike95490 Posts: 7,651Solar Expert ✭✭✭✭
    edited April 10 #7
    The moment you add a battery into the system, you are forever loosing money. 
    modified to
    The moment you add a battery into a Grid Tied system, you are forever loosing money. 

    sorry about the confusion

    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 Posts: 3,698Solar Expert ✭✭✭✭
    Yes mostly always Mike!  Unless there are special medical, poor grid, or fire dangers. The town here had to leave for 7 days during a fire and once they ran out of gasoline during 100F heat they all left. Many camped out in the smoke. It was terrible for them!

    I have sold some battery systems/mini-splits since then, but I hear you!

     Much more sensible to have a propane genset with that 500 gallon propane tank sitting outside your ranch/farm house when the power goes out! 
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BrigonBrigon Posts: 5Registered Users ✭✭
    Thanks for the feedback guys. I suspect most posters do not put all the details in the OP, so here are some more details.
    I will be retiring shortly and need something to keep the grey matter working. Taking into account that fact alone we could say that this would be a pretty expensive hobby, I agree. 

    Luckily, I am in a position that I expect to get regular donations of equipment ( panels, batteries, cable, transfer panels, breakers) as time passes. None of this equipment is new, I have some 50 watt panels that I will series to make 150 watt panels to match the 150 watt ones. Not ideal, but they should work. The batteries are about 3 year old 12v 105 aH AGM batteries, again not ideal, but workable for a while with some careful monitoring.  These batteries may last a year or two, but all I am reading says I am going to screw my first set anyway even if they were new. 
    The only thing I think I will have to buy to get operational is the inverter and fused battery connectors and fuses. I'm sure there will be some incidentals, but hopefully not too expensive.
    So with this in mind, not dismissing all the advice you have given, I will carry on with the installation.

    Estragon, loads will be adjustable depending on what system I end up with. I intend installing a transfer panel next to my existing panel and moving circuits over to the transfer panel as I get more knowledge of what my system could do. This transfer panel will be fed from solar inverter or if this does not work out, from the existing panel. My backup if all else fails is switch back to the utility. 
    Initial loads will be 2 x fridge and 2 x chest freezer. These are on 24 hr/ day and will be the first thing moved. The next thing would be a Grundfos water circulating pump and blower fan for the outdoor wood boiler. 
    Loads after that are discretionary and should grow over time. 

    I know this is not the usual way you would design a system, but I am trying to use as much solar as I can for the equipment I have. (possibly could have in future). I expect this system to be dynamic and the system 2 years from now may be a lot different from the initial set up.

    Dave A, Thanks for that info. I always wondered how Morningstar and Midnite survived without an inverter option. Looks like both are working on it. I will contact both for updates.

    BB, I am in Southern Ontario  and subject to the Wynn government's past, present and hopefully not future electricity policies. I do not have rates handy, but my previous calculations say that I should be able to reduce my electricity bill (after a lot of fine tuning of the system) by about $120/month. I will have the time to play with it.

    My other option is to sell the equipment and spend all day watching T.V.   NOT.

    Thanks guys.




  • EstragonEstragon Posts: 2,321Registered Users ✭✭✭✭
    Running fridges and freezers is a fairly challenging application for an inverter. They have large starting surge current needs to start the compressor motor and to overcome any initial backpressure. Running loads are more modest, and near zero between run cycles. The furnace blower will be similar.

    This means the inverter has to potentially handle surge needs for all units starting at the same time, but also not use too much at idle when all units are between cycles. All 4 units starting at once may not happen often, but it can happen. A 2500w inverter may not be able to handle the surge.

    Something like an Outback radian series (4kw or 8kw) may work well and have been available for some time now. It would need a mate3 display/control ($436 from NAWS) added to the inverter (~$2300-4200). For stacking and/or incorporating charge controller display/control, a hub would also be needed (~$125). They do 120/240, and are stackable. There are similar inverters from Schneider and others shipping now.

    I have a Morningstar 300w psw inverter and it serves its purpose well. No idea what they have in beta. I think Midnite is focussed on getting the "B17" modular inverter/controller product out. I assume the smaller inverter ("little willy / rosie") will be a single inverter module in a non-expandible case, but I don't know. There hasn't been much recently on wider availability, but it must be getting close.
    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
  • Dave AngeliniDave Angelini Posts: 3,698Solar Expert ✭✭✭✭
    Agree on surges. The Outback and Schneider 4KW and up should be fine though. Below are both of the companies monitoring web portals. I am doing some testing now and there are some very nice things coming if you need to control things remotely from the web.
    They both make self consumption software to save grid use, but you really need to stay with one company unless you like headaches!





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

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