Inverter and battery charger wiring

Mike 870 · January 2017

I'm trying to think of an optimal way to wire a sure sine 300 inverter and an iota dls 30 battery charger into an offgrid cabin. The manuals for these products dont give much detail. Im wiring for both DC and AC loads and was planning to use QO load centers for both.

I haven't wired or even purchased anything yet. I was wondering if I can use a breaker interlock to connect/disconnect the generator loads and disconnect/connect inverter output on the AC side, and another another breaker interlock to connect/disconnect the battery charger output and connect disconnect the inverter input on the dc side. See attached Picture, probably too confusing without it.

I've spoken to tech support at both companies. The sure sine cannot remain connected on the AC side if there is another AC power source. Per Iota tech support, no harm will come from it being connected on the AC side in the abscence of a dc load or connection. I assume it is ok to leave it connected on the dc side because it's hard wire.

The worst I can think of happening in this scenario is I intend to use the battery charger or inverter or generator but forget to switch the interlocked breakers in which case nothing would happen for lack of power. Am I missing something? Probably making it more difficult than it needs to be?

Mike 870 · January 2017

FYI Link to a QO interlock. I've used one on my house to wire a backup generator, simple handy little thing. https://www.amazon.com/dp/B000LDEQ5Q/ref=olp_product_details?_encoding=UTF8&me=

Estragon · January 2017

You DO need an interlock for AC sources, generator source OR inverter source so you have either or none, but not both.

Your charger is an AC load. It could be on a breaker on the interlock panel, but that opens the possibility of running the charger off the inverter to charge the batteries which supply the power for the inverter. Not exactly optimal.

So you could run two AC circuits off the generator. One would feed the interlock panel with appropriate sized breaker to protect that wire. The other would supply the charger, again with appropriate sized breaker (or fuse).

On the DC side you want to be sure to use breakers intended for use with DC. Direct current will sustain an arc better than AC. I could be wrong but I don't think QO breakers are DC rated so wouldn't use them myself. Assuming 12vdc, breaker/switch panels made for this are pretty common in the marine/rv world. Choice of panel will depend on DC loads, of which the inverter will be one.

Mike 870 · January 2017

Yes 12VDC system. Apparently QO and QOB breakers are suitable up to 48 VDC. I was also planning to also use an interlock on the DC side between the inverter input and the battery charger output breakers to prevent the charger from runnimg off the inverter.

http://static.schneider-electric.us/docs/Circuit Protection/Miniature Circuit Breakers/QO-QOB Circuit Breakers/0730CT9801R108.pdf

BB. · January 2017

Here are some transfer switches:

https://www.solar-electric.com/catalogsearch/result/?q=transfer+switch

And a nice solution would be a relay--The relay, when powered by a genset will switch to genset power. When the power fails, the relay falls back to inverter power. Here is one designed for the job:

https://www.solar-electric.com/pomaxpmautrs.html

-Bill

littleharbor2 · January 2017

Square D QOU breakers are din rail mount and as per their specs

"120/240 Vac At 50/60 Hz (Ul/Csa), 48/60 Vdc"
QOB breakers are bolt in and are rated for "240VAC/48VDC 60A" Although Schneider's website only shows 2, 2pole and 2, 3 pole breakers rated at 60 or 100 amp.

Schneider QOB webpage,
http://www.schneider-electric.us/en/product-range/7229-square-d™-qo™-and-qob-miniature-circuit-breakers?N=1483872282+3915173581&Nr=AND(P_visibility:1,OR(product.catalogId:catalog10005),product.siteId:100003)&filter=business-4-low-voltage-products-and-systems&parent-category-id=50300#tabs

Schneider QOU webpage,
http://www.schneider-electric.us/en/product-range/7230-qou-unit-mount-circuit-breakers?N=2735149915

Might be good to note, Midnite Solar breakers are substantially cheaper and are dedicated DC rated breakers. They have breakers with up to a 300 Vdc limit as well as AC breakers.

Midnite PV breaker page,
http://www.midnitesolar.com/productPhoto.php?product_ID=183&productCatName=Breakers&productCat_ID=16&sortOrder=18&act=p

Mike 870 · January 2017

That relay looks nifty. Would be nice not to have to flip the breaker.

wellbuilt · January 2017

I have the sure sine 300 watt inverter 12 v with a 30 amp charger 2 gc 230 hr battery's
I have it mounted in a 27' trailer wile I build my house .
I have some 12 v lights but for the most part I use ac power .
I just run the battery charger off the generator , and the battery powers the inverter for ac outlets that's it .
If there is something you want to run off the generator just run a separate line for it
I don't really run the generator much .
I started running the generator for 11/2 hrs a day in November the solar panels had snow on them .
The last 2 years I didn't even use the generator

Mike 870 · January 2017

Your system is almost the same size as mine, what is your approx location, and how many watts of PV? What solar charge controller are you using?

Inverter and battery charger wiring

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