Newbie looking for an advice

kenzakenza Registered Users Posts: 6
Hi everyone!

I am a newbie here, so please be kind if I ask something stupid.

Short (or not so short) introduction is:

6 months ago I moved into a new house and one of the first things to do was to install my PV system. 12 (I am adding 3 more now) LG 260 watts mono panels with Enecsys micro inverters and monitoring gateway. Installed on the roof without any issues and connected directly to my junction box to a separate circuit breaker. Had to deal with the local utility company but after some time managed to replace the fancy energy meter I had with the analogue one (which now runs mostly backwards during the day).
I planned to have a generator providing power during the grid outages (started automatically via a PLC that detects power outages, disconnects the house from the grid and starts the generator - I have had this system for 3 years in my previous home and it works great).

The problem is:

My new home is in a gated community in suburbs. After 9 PM you can hear a fly at 1km from your home. So, the generator option is not valid anymore. What I did (without too much thinking) is the following: I bought 4 x 170Ah deep cycle batteries and got a 2.2KW Off-Grid inverter (nearly enough to cover my basic needs during blackouts - and the batteries can provide power for a couple of hours, what should be ok). I connected it to the PLC instead of the generator and it works well (in some cases).

As you probably already know, the problem is what to do if there is a blackout on a sunny day - my Enecsys inverters would wake up and send the unused energy to the Off-Grid inverter -> what would result in a loud bang and some capacitors leaving this planet (luckilly the OG inverter still works, and I plan to replace the capacitors soon). I could program the PLC to disconnect the circuit where the panels are connected (with running some additional wiring) but I do not like that choice as it makes no sense to be running the entire house on batteries while I could use energy from the panels.

Any suggestions/ideas on how to overcome this problem without investing in a hybrid (grid-interactive) inverter?

And the second question: for the moment I am charging the batteries using a couple of 12V (smart) car battery chargers. I would like to have a single 48V (smart) charger taking care of the battery bank. Any suggestions?


Thanks in advance for your help!

Wish you all a lot of cold and sunny days ;)

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie looking for an advice

    Welcome to the forum.

    Actually your problem can be solved with a bit of wiring. What is missing is a transfer switch that takes the critical loads off the grid system and puts them on the back-up system. This can be manual (inexpensive) or automatic (expensive) if you need the change to happen without human effort. No AC connection between the OGI output and the GTI at all. If you buy the right sort of inverter this (and the charging issue) is solved automatically. Inverter-chargers have the transfer switch and battery charger built-in.

    Another thing that can be done with the right inverter is to AC couple the micro-inverters so they will provide charging and a bit of extra power in daylight. But I expect you don't want to spend about $5,000+ to do that!

    What exactly do you have for an off-grid inverter? You mention four 170 Amp hour batteries which are probably 6 Volt so that would be either 12 Volt (I hope not) or 24 Volt. You also ask about a 48 Volt smart charger, which would not make sense for either of those systems. Details are important and will help us find the best solution for you.
  • kenzakenza Registered Users Posts: 6
    Re: Newbie looking for an advice
    What exactly do you have for an off-grid inverter? You mention four 170 Amp hour batteries which are probably 6 Volt so that would be either 12 Volt (I hope not) or 24 Volt. You also ask about a 48 Volt smart charger, which would not make sense for either of those systems. Details are important and will help us find the best solution for you.


    Cariboocoot,

    Thanks for your response. Sorry I was not specific.

    Batteries are 12V - 4 x 170Ah (EnerSys Powersafe SBS 170F) and the OG Inverter is ZTE 48V (2.2KW) inverter. On Grid inverters are Enecsys micros.

    Thanks!
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Newbie looking for an advice

    Okay, so you do have a 48 Volt system with approximately 3.5 kW hours of power available.

    Given the equipment you already have the easiest thing to do is to put all the critical loads (those that must be kept running during an outage, like the refrigerator) on a sub panel (or single circuit if there's only one or two). Then you use a transfer switch to connect them to either the grid system or the OGI but never both.

    A few transfer switch examples:
    http://www.solar-electric.com/catalogsearch/result/?q=transfer+switch&cat=0
    http://www.homedepot.ca/webapp/wcs/stores/servlet/SearchView?catalogId=10051&storeId=10051&langId=-15&N=0&Ntt=transfer+switch&Nty=1&D=transfer+switch&Ntx=mode+matchallpartial&Dx=mode+matchallpartial&s=true

    I don't know what you'll have available where you are. I also don't know the output characteristics of your ZTE inverter: it may be pure sine or modified sine for example. In some cases (best/easiest/cheapest) you need only switch the hot leg of a 120 VAC system. You are in Chili so your power standard is European 230 VAC 50 Hz. You'll probably need a switch that is double pole like the 240 Volt examples because you have two hots to change over (and no neutral). Grounding may bring up issues too, depending on what the local requirements are.

    Charging is going to require something like this Iota: http://www.solar-electric.com/iota-dls-54-13-48-volt-15-amp-regulated-battery-charger.html But again it will need to be a model with the Euro standard input.

    Hopefully that will give you some idea of what you should be looking for at least. These different power standards all over are a pain, but it would be impractical to change every country to one spec. Besides they'd all argue over which is better. :p
  • kenzakenza Registered Users Posts: 6
    Re: Newbie looking for an advice

    Thanks for you help!

    I am aware that I can connect the house to either the off-grid system or the on-grid one, but I kind-of do not like the idea of using the battery power on a bright day and waisting all the solar power I could be using for something else. :)

    Thanks for the info on battery charger. Do you know if there is a 220V 50Hz version of the Iota?
  • South AfricaSouth Africa Solar Expert Posts: 295 ✭✭✭
    Re: Newbie looking for an advice

    I have similar issue as you, kenza, that I do not like batteries, grid is cheaper, and I am not allowed, yet, to go grid tie.

    So, as the guys mentioned, get a switch box. But take it one step further.

    You need batteries to connect it all in order to be able to carry on when there is a power failure. But if there is sun, use that, with grid as backup to the sun and batteries as backup if there is no sun and no grid.

    So modify a switch box to auto transfer your power between sources, sun first, grid second and batteries if there is neither.

    Just one caveat, if you switch between sources, make sure you have a 8-20 millisecond break to protect the equipment, because the sine waves WILL not be in sync and over time you will damage the capacitors in your electronic devices. A old toppie that has been in the UPS industry for many many years, gave me that little gem.
  • kenzakenza Registered Users Posts: 6
    Re: Newbie looking for an advice
    You need batteries to connect it all in order to be able to carry on when there is a power failure. But if there is sun, use that, with grid as backup to the sun and batteries as backup if there is no sun and no grid.

    Actually the order would be:
    1) sun +
    1.2) grid (if available)
    1.3) batteries (if grid is not available)

    But, in order to do this well, I need a device that would be permanently monitoring energy harvested from sun, entire house consumption, grid and would be able to redirect energy from all possible sources (sun, grid, batteries) to every possible consumer (house, chargers, even a dummy heater in case the grid is off and batteries are full).

    Is there anything like that? :)
  • South AfricaSouth Africa Solar Expert Posts: 295 ✭✭✭
    Re: Newbie looking for an advice

    How I did it:
    - All devices I hold dear, is on a dedicated circuit. Stove, microwave, oven, geyser, heaters etc, do NOT bother with that.
    - If batteries are 100% charged, switch off the utilities power, run 100% off solar power.
    - If batteries are drained by 10%, switch back to grid.
    - New enhancement, if there is no grid power, and no sun, switch inverter back on and let it run till the batteries are dead, grid is back on, or sun comes up, whichever is first.

    Then I realised that I can use the batteries at night for lights, which is the easiest if you have LED's, and your family switches them off when not in use.

    To trigger the switch between solar and grid, I use a Victron battery monitor to measure the SOC of the batteries, by using its built-in relay as the main relay.

    Wiring, off the top of my head:
    - The lights, I had a electrician remove the wires from the DB board, and had them installed in separate small little board, which is connected to the inverter 24/7.
    - You can go separate circuits OR identify what circuits run where, and transfer them out of the DB board onto a separate DB. It is actually quite easy, IF you are a electrician. :-)
    - For these 'solar' circuits, remove the wall plugs and install special computer type sockets to stop someone plugging a vacuum cleaner into them. :-)

    Goal is to use the sun to power stuff that is on all the time.
  • mike95490mike95490 Solar Expert Posts: 8,753 ✭✭✭✭✭
    Re: Newbie looking for an advice
    Just one caveat, if you switch between sources, make sure you have a 8-20 millisecond break to protect the equipment, because the sine waves WILL not be in sync and over time you will damage the capacitors in your electronic devices.

    The high end inverters with internal transfer relays, will sync themselves to the grid or generator, and not have the sync issue. (that's how my inverter assists the generator with high loads)
    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 ,

  • OliverHevvyOliverHevvy Registered Users Posts: 2
    Re: Newbie looking for an advice

    Why is the generator not an option? If the utility can't provide you with power, you might very well NEED a generator. Tell them your poor dear mother is in an iron lung or something.... ;-)

    I can appreciate people might not want a generator running all the time, but they do have lawnmowers, etc. Also, if you build a sturdy "doghouse" for it, it won't be too noisy.
  • kenzakenza Registered Users Posts: 6
    Re: Newbie looking for an advice
    Why is the generator not an option? If the utility can't provide you with power, you might very well NEED a generator. Tell them your poor dear mother is in an iron lung or something.... ;-)

    I can appreciate people might not want a generator running all the time, but they do have lawnmowers, etc. Also, if you build a sturdy "doghouse" for it, it won't be too noisy.

    I agree that a generator is a solution for longer blackouts. But I would say 99% are shorter than 1-3hrs and batteries are ok for that. Thanks :)
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