July 29, 2015 at 12:13 am #60709
Wish List for an Integrated Storage System:
Previously I worked as an electronics and communications technician in the military, so I’d like to put my order in to company engineers, for the type of storage unit I’d like to buy:
One system I saw only had one MPPT input. If engineers are going to design the Solar Controllers inside the box, then there definitely needs to be a modular design where additional MPPT/Solar Controllers can be added later. E.g. My house has three small roofs with different aspects and slopes (NW skillion, NW gable and NE gable) and I’d like to add a carport later. I also have a small middle building.
MINIMUM MPPT VOLTAGE:
Another storage system had a high minimum input voltage for the MPPT input. E.g. That won’t work on my house, as the PV strings will be small numbers of panels for small rooftops. I do have a 100 square meter shed down the back, though there will be extra cost and hardware to put a solar system down there.
Another storage system had a 5kW inverter inside. While that’s good for now when working with the grid, later I aspire to be off grid and 5kW of inverter output won’t be enough. The kettle is 2400W and the toaster is 900W and one cooktop plate is 2200W. I don’t want to have to compete with the fridge and other housemates when making breakfast. So I need engineers to design space for another inverter inside, or provide an input to connect another parallel inverter on the outside, or don’t include an inverter in the storage unit in the first place.
With the batteries, I’d appreciate them being able to be added in stages. Good inverters are being made for managing dual battery banks. This is necessary because old and new batteries cannot be connected together, and my budget doesn’t allow for all the batteries being purchased at once. I’d like to transition the house to off peak electricity rates first, then later have the option to be off grid later, if I feel out of sorts with utility companies. So please make the batteries able to be added in stages of at least two battery banks. It also helps for when one battery bank inevitably gets tired, I can add another battery bank, and keep the first to share the load with the new one.
With the Battery Management System (BMS) for the lithium batteries, I’d really like that to be a modular design or so it can be somehow swapped in and out. Since it’s a component worth less than the batteries, please don’t design it so if the BMS goes faulty, the whole storage system needs to be thrown away.
In summary, if the integrated storage system can’t be expanded and repaired with replacement parts, I won’t buy it. I’ll keep searching until I find something flexible or keep the traditional system architecture, designed for individual parts like solar controllers, batteries, BMS and inverter/chargers.
August 1, 2015 at 10:30 am #60823
LG Chem looks good, no included Inverter/Charger or Solar Controllers, means can use anything compatible and cost effective when a replacement is needed. Expandable from 6.4kWh to 9.6kWh to 12.8kWh, although imagine batteries added at a later date would go out in sympathy with batteries bought earlier – like lead acid batteries do. Hence need to make a decision early in the life of the first set of batteries.
6,000 cycles at 90% Depth of Discharge
10,000 cycles at 80% Depth of Discharge
Found some tech specs at http://www.solarjuice.com.au It’s nominal voltage is 51.8V so that’s an easy input voltage to achieve for PV strings. Great it’s supposed to work with Hybrid and Off-Grid Inverters actually on the Australian market with a long track record.
Found further tech info at http://www.bvim.com.au
Operating voltage is 45.2V to 58.1V so looks like any inverter/charger or solar controller that works in the 48V range will be compatible?
Haven’t been able to find warranty anywhere as yet?
August 1, 2015 at 11:06 pm #60831
One Step Off the Grid article: LG Chem pushes Aust. Battery prices further down-
http://www.solarjuice.com.au appears to be exclusive wholesaler $6,898
supposed to be a bit more than $1000 per kW/h ex GST plus inverter solution
http://www.bvim.com.au appears to be exclusive promotion and training org with a network of installers “They will arrange a site visit, quote, delivery and installation” They have a link to find installers in our area.
Full name is LG Chem RESU 6.4 EX
RESU means they are calling it a Residential Storage Unit. In other words, it appears to simply be a battery with a battery management system (BMS). Lithium batteries usually need a BMS to give a low voltage cutout, a high voltage cutout, cell balancing and over temp cutout. BMS usually monitors and disconnects the load if the above conditions happen. Some lithium batteries that are purchased separately have a BMS inside them (think Fusion on eBay) and some have a separate box BMS purchased separately if lithium batteries are added to a solar system later (think Victron).
So the LG Chem appears to provide a box, batteries, BMS and a network of installers to locate and connect box.
Bvim say the LG Chem is matched with:
SMA Sunny Island 8.0H (eBay $6k)
SMA Sunny Island 6.0H (eBay $5k)
SMA Sunny Island 3.0M (eBay $3.6k)
SMA Sunny Island 4.4M
Sungrow Hybrid inverter
I haven’t worked out why these inverters are matched, like does it have an interface cable that talks to the inverter? Would have to read the manual.
Says on bvim, has 10 year manufacturer warranty, remote monitoring, 95% round trip efficiency.
If I become seriously interested in this path, I’d read the manual and begin getting ideas about where I could locate the box, get quotes and want to know why the above inverters are compatible, especially if I had an existing inverter. Most cost effective product I’ve seen though disappointed it seems exclusively marketed etc. I’d also want to know if the BMS becomes faulty can it be replaced.
August 2, 2015 at 3:09 pm #60835
I went with Enphase (inverter per panel for built-in MPPT), and I am waiting to see if their modular battery product will make it out of the R&D lab: https://enphase.com/en-us/products-and-services/ac-battery
August 12, 2015 at 8:20 am #61067
To the original author of the post, my feedback:
1) If you really want a system that is modular, redundant, scaled easily, you are better of sicking to individual pieces and 48v.
2) If you really want a small refrigerator type energy appliance that you just land a couple cables, go with something that Samsung has to offer
I still prefer the first one. Clubbing multiple subsystems into one is not a bright idea, one fails and whole system fails. Imagine one has a dead inverter inside that Samsung because the voltage spike fried the sensor board, now replace the whole system, because Samsung won’t send you the spares. Or wait, the product is no longer supported.
1) I am puzzled if the Enphase approach is good for batteries. I saw them at the show and they said it won’t be able to do back-up. In future it may.
2) Also, what point is buying a battery from an inverter manufacturer, its like enphase taking a Trina module, installing an inverter and selling you an AC panel again. Just a silly way of getting more $$ from installer direct. The battery of 1kWh in their AC battery would cost more than the micro inverter. It would have been better if they stuck to sell micro-inverter and one could go get a 12v golf-cart li-ion battery to snap onto it.
Or atleast I hope the AC battery is really super cheap that I don’t have to do any math on pricing, lol.
August 18, 2015 at 7:06 am #61154
Thankyou for starting this discussion, in addition, for my greenfield
domestic site of a simple cottage of 2-3 Br, Grid available, but not
1) Want a failsafe system – actually build 2x say 5kw arrays + storage,
giving some redundancy if one fritzes, fails, can no longer be
supported by supplier.etc. ?
2) Want actual useful energy storage specified. eg 10% DoD just appears
ludicrous wrt new technology.
3) Want KISS. As simple & straightforward as possible. Should be serviceable
by any competent sparky.
4) Want meaningful WARRANTY. Tesla is only one I have found that states 10
year Warranty. 12 Months warranty on something costing $10K + Forget it !
5) Should be as flexible as possible to allow new/better panels/batteries/etc
to be interchanged in the future.
6) Should be impervious to lightning strike (!!!)
7) Must handle toaster/jug/microwave at brekky time.
8) Must handle induction type (rapid) cooker at teatime.
9) Must be totally reliable in ambients of and up to 45*C.
10) No complications pls – eg Flowbattery basics sounds good but then if it
has motors/fans/pumps whatever hung off it that all equates to higher fail. (?)
11) NO CONTRACTS. Not interested in eg $200/qutr for someone to stare at it !!
12) Prepared to pay for quality upfront, am not prepared for ongoing costs at
or above On Grid.
13) DO NOT want any ongoing or future involvement with power companies at all.
Objective is to get out of their clutches. Entirely.
14) Am prepared to invest in high end efficient refrig, etc.
15) Prefer no component is made in China, or is supported by companies pushing
China FTA / Abbott destruction of Oz working conditions.
Should be pretty easy. Yes/No ?
September 3, 2015 at 6:48 pm #61426
Mr E GuyParticipant
1) A wireless display that is easy to see the SOC
2) A dump load circuit that turns on when the battery floats
3) Multi system balancing. If I have two DC coupled battery systems on different arrays (North and E/W) it would be good to also have the ability to charge one battery from both arrays once one goes into float.
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