Author Topic: Batter backed inverter - Off Grid ? ?  (Read 308 times)

RWS

Batter backed inverter - Off Grid ? ?
« on: September 26, 2018, 09:21:16 AM »
I am trying to buy a StoreEdge SE7600A inverter that I intend to run off grid.  There are several reasons for this inverter.  One biggie is it uses Li-ion batteries that run at 400V DC right off the PV string.  The second reason is the customer has a SolarEdge grid tied inverter (batteryless), so the menus, setup, ect are similar.  Third reason is this inverter uses power optimizers which I have already purchased. 

So.  The salesman informed me that even though it is battery backed, the inverter will not run off grid.  Now I have already downloaded the manual and read it.  In order for it to go thru the set up sequence it must get its power from the grid.  Now there is a grid panel across the room I could use for that temporarily.  But it appears this inverter is a one shot.  When the grid goes down, the load go to the battery but the optimizers shut down because there is no grid precluding the ability to charge the battery.  So what stupid engineer designed a one shot? ?  I told the salesman to sell it to me anyway.  I told him I could configure it to support the load solely from battery and to not export to the grid.  Then I could provide 240Vac from a small sine wave inverter using a 120/240vac transformer, 12v battery and single solar panel.  The StoreEdge would be fat dumb and happy.

So as it stands now we have a conference call today at noon with an applications engineer at the factory.
Later......

RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #1 on: September 26, 2018, 01:14:15 PM »
Well I talked to the factory service engineer.  He said that as long as there was sunshine the batteries would charge.  So all I need grid power for is to get the inverter powered up and software loaded and configured.  We will see about that.  Anyway I have a quote on the way.  Hopefully.

John Galt 1

Re: Batter backed inverter - Off Grid ? ?
« Reply #2 on: September 27, 2018, 11:56:03 AM »
I understand that your customer is already committed to a Solar Edge system.       

Too bad the customer didn't consider that Conext already has a inverters that work both on and off the grid and there are lithium batteries designed specifically for a Conext inverter and report through the Conext combox.   http://forum.solar-electric.com/discussion/351297/conext-bridge-for-xw-li-ions-from-lg-and-hoppecke-announced-for-2nd-half-2017     
 I understand there is now a 2nd lithium battery manyfacturer who's BMS reports directly to Schneider equipment.      Other inverter manufactures may also have inverters designed to work offgrid using a lithium's BMS.

I suspect your dealing with a system that was designed to run on grid only and you're now trying to make it do something it was never designed to do.
Yes, you can probably come up with a work-around.

This sounds like anouther example of why I suggest that a person completely design all the components of a solar system before buying the first component.

RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #3 on: September 27, 2018, 12:21:12 PM »
Yes.  I am quite familiar with Connex.  I have a stacked pair of the XW6048s powering my shop with a line to the house.  It is funny.  I already figured I could make it work but have been pricing around.  Every supplier I have talked to I ask if the inverter shuts down the PV on grid failure.  So far my responses are 50% say Yes and 50% say No.  So now I will just have to try one out and see for myself.  Besides that 10KWH LG Li battery looks like I want to try and I can stack 2 for 20KWH.  That's almost what I am running on my 12KW system.

Too bad I can't make the campout this time as I have a conflict.  I think we would enjoy talking solar....  I tell everyone God gave us everything we need.  I am just trying to use up some of it.  The problem is I can't use all of the Sun, there is jus too much of it.  I even get my domestic hot water from the Sun.

John Galt 1

Re: Batter backed inverter - Off Grid ? ?
« Reply #4 on: September 27, 2018, 01:00:58 PM »
Just found the other lithium battery designed to work with Schneider/Conext.
The Discovery AES battery model #48 works directly with Schneider xanbus battery based inverters.

There is quite a movement of people who have installed grid tied only inverters wanting to run them when the grid goes down but thus far I haven't heard of any easy solutions without replacing the inverter.       I run a single 6848 XW+ for the house.      For simplisity and reliability I stayed with LA batteries with a 10 yr warrenty but I went with large ones to minimize the effort of monthly maintance.       

I concidered using solar for hot water but decided that it was too complicated and expensive compared to propane; especially when the local propane company offered me a free instant one propane heater if I agreed to use them for my propane needs for 3 years.     



RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #5 on: September 27, 2018, 02:45:43 PM »
I guess I have always been a little crazy.  In the 80s I built my new home.  Solar electric was in its early start stage.  I just could not afford it.  I was aware of designing for emergencies, so I installed 2 lighting panels.  One I installed in the garage I wired thru a 100 amp DPDT transfer switch so all my critical loads could be powered from a generator.  My 12KW solar system now comes thru the transfer switch.

I did afford solar water heating though.  I purchased a large tank to store hot water and used a line pressure, always had water in it, single collector.  It was all I could afford. Today I use a double pumped, drain back system w/69 sq ft of flat plate collectors.  I installed two wall mounted radiators and pumped hot water to them for an alternative source of heat.  I installed a cast iron wood heater and installed a sst pressure tank inside the fire box.  In the winter with the wood stove running heating the front part of the house and pumping hot water to the radiators I was able to keep warm with alternative energy.  Basically I had a hot water boiler in the living room.  Boy wouldn;t the insurance company like to see that.....
Today I have a 1.5 ton heat pump with 5kw strip running from solar power to heat & cool the back of the house.  I had enough power for a 2 ton, but the hvac guy said 1.5 ton was a better fit.  I did not argue with the expert.

RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #6 on: September 27, 2018, 06:20:07 PM »
I had opened a case with Solaredge asking about the operation when the grid was down.  I got their answer this evening.  The SE7600A will continue to charge batteries and continue to power off grid loads.  Most of the sales people are uninformed.  I made that comment to Solaredge in my reply.

RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #7 on: October 29, 2018, 06:22:36 PM »
So here we go with the install.  The weather was so good today I just had to put some solar panels on the roof.  The panels mount on rails close coupled to the metal roof.  I ran the wires PV+, PV- & Gnd into the building thru a 3/4" weather head.  Each panel on the Solar Edge system uses an optimizer shown mounted to the rail.  The optimizer has 2 functions.  First it acts like a charge controller so you can mix solar panels.  Second it is used to shut down the solar panel voltage for fire safety.  See new NEC. 
Solar panels on left are for existing grid tied system.
« Last Edit: October 29, 2018, 06:41:39 PM by RWS »

RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #8 on: October 30, 2018, 02:08:41 PM »
Finished installing the last of 11 solar panels.  We measured the PV voltage to determine polarity and also to confirm we had 11 working solar panels.  Today we finished the conduit to the grid powered lighting panel and pulled the wire #10 THHN, black,red,white & green.  The panel board is getting populated with equipment.  Shown is the inverter, the auto transformer and the backed up loads lighting panel.  I plan to order the battery this afternoon. 

John Galt 1

Re: Batter backed inverter - Off Grid ? ?
« Reply #9 on: October 30, 2018, 09:29:12 PM »
Nice looking setup but I'm glad I only had to build to NEC 2011 but I mostly went ahead and built to 2014 standards because they weren't much more effort, mostly labeling and some minor conduit differences.        I'd never want to try to build to 2017 standards with the changes to rapid shutdown and more extensive guttering requirements.

What size battery bank are you installing?

I once concidered becoming a solar installer but because I really don't like working of steep roofs I decided it wasn't for me.

RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #10 on: October 31, 2018, 05:51:14 AM »
It's a small battery, 10Kwh Lithium by LG.  The interesting thing is it runs at 350 to 450 VDC  charged right off the solar panels.  This will be a learning experience.  The system will handle 20Kwh, but cost has the customer constrained.
It's kind of amusing.  We set up a schedule to install over a 6 month period to be finished before Christmas so he could claim his tax credit for 2018.  The extended schedule was so he could pay as you go plan.  Now that we have the solar panels on the roof, he has gotten excited.  He wants to finish up right now !  I put the battery on order yesterday afternoon, so it will be 10 days before we can finish.
« Last Edit: October 31, 2018, 07:27:55 AM by RWS »

RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #11 on: November 08, 2018, 12:57:23 PM »
The battery arrived yesterday afternoon.  I had it delivered on a lift gate truck.  I backed my pickup up to the trailer and the driver put the pallet in my truck.  With the lift gate and pallet jack it went in smoothly.  I delivered it on site this morning.  Bad news..  I did not have enough room to install the battery beside the inverter and maintain the 12" side clearance required in the instructions.  I told my neighbor I could move the inverter and auto transformer to make enough room (2 days) or we could add another piece of 23/32" plywood (formerly 3/4").  We added the plywood.  I took over a multi wheeled cart and slid the battery & pallet out of the truck onto the cart.  I took over a piece of 5/16" galvanized wire (radio tower guy wire) and wrapped it around the I-Beam overhead which is part of the building.  Then hung a comealong from the wire loop.  Plan is to lift it off the cart, dragging it up the wall and attaching it to the mounting bracket (214lbs).  I did take a camera this morning, but as I tried to take the first picture the camera shut off.  (Low Battery)  I use rechargeable AA so all I have to do is recharge.  The bad part is I missed some good pictures this morning.  My neighbor is going to paint the plywood this afternoon so it will be ready for my next trip, hopefully with camera.

John Galt 1

Re: Batter backed inverter - Off Grid ? ?
« Reply #12 on: November 09, 2018, 09:08:16 AM »
While I can't see the details of the battery location but that sounds like a lot of work to raise the battery.      Could the battery just sit on a floor jack instead?     One person holds it steady while the other mounts it to the wall?

RWS

Re: Batter backed inverter - Off Grid ? ?
« Reply #13 on: November 10, 2018, 04:34:48 PM »
The lifting handles came last night right at dark.  Tracking said they were out for delivery at 6:30AM and it was 6 PM when they arrived.  I am on the end of the route.  The first picture shows the mounting board starts  23 inches above the floor and I wanted the battery up about even with the inverter.
The second picture shows lifting the battery starting up the wall with mounting bracket in place.
The third picture shows the battery in place with the comealong still hooked up.
The fourth picture shows the terminations cover and latches.  The Solarstore installation cautioned that the wires should be terminated before hanging the battery because it was difficult to get that cover off with it mounted.  SO,  I mounted a 3/4" plywood spacer between the mounting bracket and the mounting board.  This gives better clearance for both getting the cover on and off and maybe it will help air circulation also.
There is enough room on the left for a second battery if he chooses.  Right now $6000.00 is all he is willing to go for now.  9.8Kwh, runs at 400VDC at about 14 amps or less.  That's the first solar battery I have installed using # 10 wire.
I could only work an hour & a half this morning.  I had to take my wife to Spence Field in Moultrie to an Arts & Crafts show today.
« Last Edit: November 11, 2018, 07:35:41 AM by RWS »