Looking to replace inverter with..

fidodidofidodido Registered Users Posts: 9
Hello all, new forum member here and totally new to solar technology, so bear with me! ;)

Here is a little history about my setup: I currently own a small house, on which I use (as a UPS system) a Trace DR 1524 inverter (http://www.wholesalesolar.com/products.folder/inverter-folder/DR1524.html). It does feeds my needs, because I only run a couple of fans and tv and lights off it. I don't run the fridge or pump from it. Batteries are starting to need replacement and I thought "well, why not look into something more solar friendly and give it away".

Well, here is the thing: I have been reading a lot about Solar Panel + Inverter + Batteries the last couple of days, but still have some doubts that I would like you guys to help me out to clarify them. Thing is, I want a new inverter with true/pure sine wave (the trace's a modified sine wave). I've been looking at a few choices, most notable the Samlex SA-2000K-112 (http://www.samlexamerica.com/products/ProductDetail.aspx?pid=128), but then by reading more on the subject, it turns out this type of inverter has no charger nor transfer switch. Let me say that one of the nice things I liked about the trace inverter is its automatic transfer of power: from utility power to dc and vice versa. I almost didn't notice it to be honest. This is a mandatory thing for me as I plan to add to my home several automation devices (camera / light switches / etc).

So, more reading on this, I found that in order to charge the batteries on this type of inverter I will need (obviously) a charger. So, I know I can have solar panels down to a solar charge controller to take care of the battery charge. And that is no problem, I understand that. And for the transfer switch, i know that they sell transfer switches.. but here is the part that have myself confused. One is, how can I retain the automatic transfer switch in place for utility power ? Let me say that I live in a very rural area where utility power is regularly cut. Meaning that during a day, I may have 20-40 minutes of no power from utility. So, I need the inverter to kick in as soon as there is no power from utility, just like my old trace did. It is possible for the automatic transfer switch to do this ? Keep in mind I will be charging the batteries from solar panel and not ac as it used to be on the trace inverter. Also, another question I have is, are automatic transfer switches fast enough to prevent my electronic devices to notice it ? remember I said I dont want my router or equipment to go off.

I am sorry for such a long post for being my first one, just tried to get my doubts cleared before I go and buy something without proper knowledge.

Thanks a lot for you taking the time to read!

Comments

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    An Automatic Transfer Switch (ATS) does pretty much what you would expect it to, namely transfer your house wiring between POCO and some alternate energy source. By default the ATS will transfer when the grid power is lost, regardless of whether the alternate source is currently active and will transfer back, possibly after a configured delay, when the grid power comes back.
    One thing you need to look at is getting an ATS which also switches the neutral wire, since it is likely that your inverter requires a ground to neutral bond on its side and the NEC does not allow two ground to neutral bonds of that sort to be connected to the house wiring at the same time.
    SMA SB 3000, old BP panels.
  • MarkCMarkC Solar Expert Posts: 212 ✭✭✭
    Have you considered a UPS for the few users you want? They would seem to fit a situation where you lose power for short durations several times a day - but not for extended outages. For an efficient unit that can easily be set up with substantial battery backup (48 Volt) consider the SUA3000 (or better, the SMX3000) by APC. They are quite cheap used and are extremely robust units. The SUA3000 would provide many hours of backup power at, as an example, 500 watts if it was tied to a 48 volt battery system of either 6 or 12 volt deep cycles (150/210 AH). The issue then becomes how to charge these deep cycle FLA batteries. IF you normally have a number of hours of grid power after most failures, a standard 120V AC, 48 V DC charger will do the trick - similar to a golf cart charger. Certainly solar panels and charge controller would also do this, but the cost is prohibitive if you are not planning to actually go off-grid - and simply need more reliable power for a few low wattage users. I currently have such a system - but I also have a golf cart, so I have the batteries already. It provides power to three ceiling fans, 6 fluorescent lights, an LCD TV and medium sized high efficiency fridge. Since I have a grid-tied solar system with a SMA Sunny Boy inverter, I can use the golf cart charger off the Secure Power Supply for solar recharge in off grid mode - with a substantial reduction in my utility bill to boot.

    You could alternatively use a double conversion UPS that would continuously charge the batteries and make a seamless transfer back and forth to battery power - the APC SURT line - likely the SURT3000 (120 volt model). The battery situation with the SURTs is a bit more contentious as they operate at 196 volts DC and are not the most efficient, but you can add lots of battery backup with relatively cheap used equipment. However, the standard backup battery systems for all SURTs use small AGMs which can be troublesome and limited life - and are not cheap on a watt-hr basis. As an example, the SURT 3000 would give about 3 hours of run time with one extended battery battery pack at 500 watts supplied power. It would then take a few hours for the unit to recharge the batteries - might not work if you have back to back power outages.

    Something to consider?

    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
  • fidodidofidodido Registered Users Posts: 9
    [USER="10919"]inetdog[/USER] thanks a lot for the tip! Will keep an eye on that

    [USER="15438"]MarkC[/USER] while I agree that probably an UPS will suffice my situation, I dont know if these could be hardwired -- remember I already have the circuit configuration as I had a trace inverter in place. Also, while it is true that I will not normally be powering "huge" equiptment off it (named the pump and the fridge), I would as well like to be able to "just in case". Also, the reason I want to go solar is to minimize the use of AC to charge the batteries. I believe that for the litle time these will be used daily (probably 20/30 minutes in average daily), it will be enough to keep them topped of most of the time. What is your opinion on this ?

    Thanks a lot for your answers both!
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    fidodido wrote: »
    [USER="10919"]inetdog[/USER] thanks a lot for the tip! Will keep an eye on that
    I forgot to mention that you should not just get a three phase ATS and use one pole for the neutral if you can avoid it.
    A true single phase ATS with switched neutral will have specific safeguards to avoid ever having the two line connectors hot while the neutral is open. That condition can burn out 120V loads if the two sides are unbalanced.
    SMA SB 3000, old BP panels.
  • semperfi123semperfi123 Registered Users Posts: 6
    I need same advise , I up graded to a AIMs 24 volt 5000 watt inverter from a 1200 watt , what junk !!, what is a good split phase 220 off grid inverter with out breaking my bank? , the aims did work for one day under full sun light ran my washing machine , convection oven and more , unplugged everything from it and it drained my batteries in the middle of the night with no load :(

    Thanks
  • PhotowhitPhotowhit Solar Expert Posts: 5,656 ✭✭✭✭✭
    I need same advise , I up graded to a AIMs 24 volt 5000 watt inverter from a 1200 watt , what junk !!, what is a good split phase 220 off grid inverter with out breaking my bank? , the aims did work for one day under full sun light ran my washing machine , convection oven and more , unplugged everything from it and it drained my batteries in the middle of the night with no load :(

    You pretty much get what you pay for, the least expensive I would trust would be the new Schneider inverters, but you might want to read the reviews, some people have some issues with them, noisy is the one I recall.

    Might put your system info at the bottom of your posts, a 5000 watt inverter will use a good bit of energy. Typically you don't want large, sustained loads on your battery bank above perhaps 1/10th of it's capacity. So if you have a battery bank like mine 800Ah you wouldn't want to draw more than 80AMps for any length of time or 80 x 24v = 1900 watts so with my array (4000 watts 3000 effective) I might use 3000 watts with out drawing down the battery and 4-5000 understanding I have a substantial load on my battery bank.

    I peeked at your past posts to get an idea of the size of battery bank and array you have and looks like an 800 watt array and unknown battery bank. An 800 watt array would work for about a 4 golf cart battery size battery bank. I would think a 5000 watt inverter is not in balance with your system. Washing machine is likely 120 volt and on a sunny afternoon once the batteries are charge you should be able to run the washing machine, perhaps off your old inverter. Small convection ovens will run off 120 volts as well, but you will definitely be drawing from the battery bank! My small toaster convection oven runs 1500 watts add in the energy to run the inverter and you are looking at @1700 watts or (1700watts/24volt=) 70 amps at 24 volts, if you had 4 golf cart batteries you would have a battery bank of 440 amps you would be drawing energy at nearly 1/6th of the battery capacity. even with a 800 watt array your batteries would need to provide @ 1000 watts or (1000/24v) or 42 amps about 1/10 of it's capacity...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • MarkCMarkC Solar Expert Posts: 212 ✭✭✭
    fidodido wrote: »
    [USER="10919"]inetdog[/USER] thanks a lot for the tip! Will keep an eye on that

    [USER="15438"]MarkC[/USER] while I agree that probably an UPS will suffice my situation, I dont know if these could be hardwired -- remember I already have the circuit configuration as I had a trace inverter in place. Also, while it is true that I will not normally be powering "huge" equipment off it (named the pump and the fridge), I would as well like to be able to "just in case". Also, the reason I want to go solar is to minimize the use of AC to charge the batteries. I believe that for the litle time these will be used daily (probably 20/30 minutes in average daily), it will be enough to keep them topped of most of the time. What is your opinion on this ?

    Thanks a lot for your answers both!

    Unless, I still don't understand your wiring schema correctly, it seems the optimal situation is if you can power a separate breaker box for your selected "off-grid" users and hardwire from the output of the SUA3000 to the breaker box with positive, neutral and ground. The UPS could then be left on-line - but - will require some FLA battery maintenance that is independant of the SUA charging system (since it is designed for AGM charging) to keep them in top condition. I am using my golf cart charger (again I have a golf cart) periodically to do this - which "gasses" the acid for a short period for mixing. This Club Car Precedent "smart?" charger has been used for my 5 year old golf cart batteries that appear to still have the same capacity/voltage characteristics as a new "spare" set I recently purchased. I also have an emergency "generation" system (for longer term outages - have NOT had to use it yet) that is Prius based with a SURT6000 APC smart UPS. Combined with the SURT003 iso-transformer gives me enough power for my 240 volt water pump and 1-1/2 ton Air Conditioner. I chose to separate the systems as the SUA3000 is so much more efficient for the small users that are required 95% of the time. Again, I have the SMA Sunny Boy on-grid inverter that allows me to charge the golf cart batteries directly off the SPS in the "off-grid" mode. Since I'm not truly "off-grid", this setup provides lots of flexibility during hurricane season in Texas while paying for itself 24/7. The Fed tax credit along with my electrical co-op rebate made this possible - which would NOT be economical without these credits/rebates!!

    I wonder if you considered a fairly efficient, medium sized fridge and a small water pump supported by some storage, if you could meet all your needs with a relatively small/efficient on-line UPS style system. Maybe a small generator just in case?

    BTW, converting any "smart" APC UPS to a hardwire output is quite easy since the PDUs are removable and reconfigurable. Also, the "transfer" is inherently safe using these UPSs - cannot possibly shock a lineman if wired correctly.

    MarkC
    3850 watts - 14 - 275SW SolarWorld Panels, 4000 TL-US SMA Sunny Boy Grid tied inverter.  2760 Watts - 8 - 345XL Solar World Panels, 3000 TL-US SMA Sunny Boy GT inverter.   3000 watts SMA/SPS power.  PV "switchable" to MidNite Classic 250ks based charging of Golf cart + spare battery array of 8 - 155 AH 12V Trojans with an  APC SMT3000 - 48 volt DC=>120 Volt AC inverter for emergency off-grid.   Also, "PriUPS" backup generator with APC SURT6000/SURT003  => 192 volt DC/240 volt split phase AC inverter.  
  • fidodidofidodido Registered Users Posts: 9
    [USER="15438"]MarkC[/USER] thanks for the advice. I dont know wether I want a UPS or some type of hybrid inverter. I was leaning towards the conext sw2524. What is your opinion about it ?
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