Great Setup.
Could we know more about your system?
How many Kw solar?
Battery?
best brands of inverters? best bank for the buck?
- Thread starter Jamie.sanders
- Start date
Could we know more about your system?
How many Kw solar?
Battery?
OffGridInTheCity
Solar Wizard
Very kind. In my 4th year - gradually expanding year by year. It's people/sites like this that have made it possible - e.g. real info - can't thank everyone enough.
Off-grid system. Power is fed to the house via ATSs. House is 70-90% powered spring/summer/fall (happy). Winter is the problem - not enough PV to keep house up to warm temps.
12.875kw PV. Its 45 x 285w panels -> 3 x MidNite Classic 150s and generates 18,000kwh/year.
7 x 260ah lithium-ion DIY batteries = 1820ah @ 52v = 94kwh. Operate between 49.5v/cell low and 4.0v/cell hi at 38% DOD yearly average. 1,327 cycles as of this morning.
Future - Plan to add another 4kw of PV + another 30kwh of battery.
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Ampster
Renewable Energy Hobbyist
A lot depends on the rate structure and the trend for NEM policies in your state. My system is an example of how I am hedging against the threat of changing policy in California. When I purchased my current home, I put 7kW of GT solar on the roof. As soon as I got my PTO I installed my Outback Skybox, another 2kW of solar and 42kWh of LFP batteries. All of that is behind the meter and not subject to fees from my power company but complies with building codes.
Also, I think of it as a system, and did not focus on the best brand of inverter. The requirements for my hybrid were entirely different than for my GT inverter(s).
Also, I think of it as a system, and did not focus on the best brand of inverter. The requirements for my hybrid were entirely different than for my GT inverter(s).
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Daddy Tanuki
Solar Wizard
nice been watching your posts for a while. I am fortunate that my needs are small, 7.8 kw of panels and 32kwh of diy lifepo4 power my place seemed to have just enough this winter.... the next challenge is the rainy season. if it makes it through that will no hiccups then I am golden... if not more used panels and batteries. looking at adding another 10kwh just in case as it is.Very kind. In my 4th year - gradually expanding year by year. It's people/sites like this that have made it possible - e.g. real info - can't thank everyone enough.
Off-grid system. Power is fed to the house via ATSs. House is 70-90% powered spring/summer/fall (happy). Winter is the problem - not enough PV to keep house up to warm temps.
12.875kw PV. Its 45 x 285w panels -> 3 x MidNite Classic 150s and generates 18,000kwh/year.
7 x 260ah lithium-ion DIY batteries = 1820ah @ 52v = 94kwh. Operate between 49.5v/cell low and 4.0v/cell hi at 38% DOD yearly average. 1,327 cycles as of this morning.
Future - Plan to add another 4kw of PV + another 30kwh of battery.
I have a backup on a 12 volt system that falls in as a 24 hour backup/reserve for the fridge and freezer and it powers my heating and cooling for both battery packs. its 400 Ah (about 5000 wh) at 12 volts that gets charged by the 48v system and floats at 13.2 which gets cycled daily for cooling and heating though its cycles are quite shallow so I try to keep it at 80% or so as its "full" charge.
Ampster
Renewable Energy Hobbyist
Ha, I wish I could get 94kWh out of 7 cells. It took me 48 LF280s to get 42kWhs.
OffGridInTheCity
Solar Wizard
Just for the record - Its 7 separate 260ah@48v batteries (14s100p each). Total of 7 x 260ah@48v = 1820ah@48v. I use 52v (instead of 48v) because 52 is the average operational voltage
Daddy Tanuki
Solar Wizard
I think he meant that he has 7 packs at 260 amp/hour per pack at 52 volts.
OffGridInTheCity
Solar Wizard
Daddy Tanuki
Solar Wizard
I remember you talking about your packs in the past. you are way more DIy in that regards then I am, I stuck with the plastic cased CALB cells myself.
Ampster
Renewable Energy Hobbyist
Thanks for the clarification. Does that mean you have 7 BMS's?
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OffGridInTheCity
Solar Wizard
I use Batrium Watchmon (central BMS) with 98 longmons (14s * 7) to monitor the overall battery bank and throw the ABB SACE shunt-trip if any pack gets out of wack - e.g. low/hi volts and low/hi temps in my case.
Amazing, I wonder if its still profitable to do this vs Prismatic. you think your cost was <$0.18/ watt?
Me too!
I paid just under $1000 ($940) for 18x 200AH second hand CALB +BMS, which give me about 6kWhr of storage.
(2 spares so I could chuck the worst performers). No idea how long they will last.
940/6000 = 15.5c/Watt
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OffGridInTheCity
Solar Wizard
I've kept good records over last 4 years... The cost is running ~$196/kwh for 90%+ original spec second hand 18650 cells all purchased from BatteryHookup, Battery Clearing House, Jag35, Power2Spare, (and a few from eBay till I learned my lesson). This includes everything (tools, cell holders, hundreds of feet of various wire, solder, electrical tape, voltmeters, iCharger X8, Batrium/longmons, zip-ties, shelves/galvanized metal for fire reduction, fire extinguisher, shunt-trip, US Tax Rebates... everything except free-labor on my part)
$196/kwh / 1000 = $0.196/wh. So let's say $0.20/wh
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Wow , Amazing
Now Im getting LFP cylindrical @$0.12/wh from china including shipping for que raw cells. I calculated $0.16/wh with everything including busbar holders, barley and fiberglass wrap.
Case & Man hr bring it up to $0.18 / wh
But after seeing your post, BCH has $0.3 / cell 18650. that could change the equation. maybe bringing the cost down to $0.12 wh w/ everything.
The only thing holding me back is the Fire risk. even with metal case & fiberglass wrap.
Now Im getting LFP cylindrical @$0.12/wh from china including shipping for que raw cells. I calculated $0.16/wh with everything including busbar holders, barley and fiberglass wrap.
Case & Man hr bring it up to $0.18 / wh
But after seeing your post, BCH has $0.3 / cell 18650. that could change the equation. maybe bringing the cost down to $0.12 wh w/ everything.
The only thing holding me back is the Fire risk. even with metal case & fiberglass wrap.
OffGridInTheCity
Solar Wizard
It's hard to say exactly - but I agree, I paid (on average with all the discards) more like $1.00-$1.20/cell so $0.30/cell would make a significant difference. The labor to process 12,000 cells (so far) is A LOT but I'm retired/bored so it wasn't a big deal for me. I can see why LifePo4 bricks are popular!!
Cell acquisition is the hardest part. I've found it's best if a 'battery' (~14s100p in my case) is all the same cell type. To get 1,400 good cells I have to more but it's difficult to estimate the keep/discard ratio and then the source is gone if you guess wrong and you don't have enough to do the battery. Then you have to wait....
After 4 years of operation - with 10,000 cells in operation and following thousands of posts - fire is not a worry for me because....
- the cells are BMS'ed with visibility into failing packs so they can be taken offline before serious failure - e.g. its not a 10minute 'thing' but rather multiple days / weeks warning.
- operated in good ambient + cells never get warm (are ambient temp).
- lightly stressed (charge/discharge per cell) - average <100ma/cell with a 400ma/cell max before the master breaker trips - e.g. well within test parameters and the specifications of the cells.
- operating in the middle range (3.5v to 4.0v) for lithium-ion - low stress.
Of course there is some risk, less that taking a drive perhaps, LifePo4 has some risk, lead acid has some risk, but very few things in life are risk free. For me, I believe I'm operating at reduced/acceptable risk thru test/oversizing/low-stress/monitoring/proper-wiring. This is something you have to decide for yourself - I make no claims, just sharing what I'm doing!
Fire Protection: I have corrugated metal (roofing) over top of the battery bank to block flame from hitting the ceiling, cinder block walls on 3 sides, concrete floor, smoke detector right overhead, and a fire extinguisher - but the 4th side is open to the room.
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Daddy Tanuki
Solar Wizard
hyou can only take so many precautions until you are like NASA... afraid to move lest you lose your your retirement...
Very interesting. Will go into detail on your setup over the weekend and get you my analisis.
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