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So when we build our new small house (if we can pull it off, still at the dreaming stage) we'd like to start with a new solar system (in addition to the hot water which I think is a separate system (?)and maybe connect with helco as a "backup." The solar we have now in the old house takes SO MUCH maintenance with all the battery checking, filling, equalizing, etc. I've heard the new generation of batteries are sealed/maintenance free (?). What are your thoughts or recommendations - I'm a total non-techie in this area.
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Some nice new stuff out there if you have the money.
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Sorry, Maud, this doesn't help you, but when I saw the subject of your thread I immediately thought you were posting about the discovery of a new planetary system and had to read the post because I didn't understand what new batteries would have to do with anything! [  ]
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I've heard good things about the new Tesla batteries, but they seem to be intended as backup for a grid-tie system.
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Current technologies:
- Lithium-ion ("Tesla"): no maintenance, fewer charge/discharge cycles, currently expensive, nothing is really "packaged" for off-grid applications. Suitable charger/inverters are supposed to be available for Tesla Powerwall (these run at 350-550VDC). High density.
- Nickel-Iron ("Edison"): electrolyte can be replaced every few years, 20-year lifetime, Outback controllers can use these batteries with custom settings. Low-density. Can safely be discharged to 90% of capacity without damage. https://ironedison.com/
- Sodium-Ion ("saltwater"): non-toxic, very low density (~180KWh/pallet), projected to have price parity with lead-acid but last twice as long. http://aquionenergy.com/
- AGM: no maintenance, density similar to wet lead-acid, works with standard controllers/inverters.
- Lead-acid ("wet"): maintenance cycle, suffers damage when discharged beyond 50% (best to keep within 10-20% of capacity). Lifetime of 3-7 years (possibly more) depending on maintenance and charge cycle.
Bottom line: wet batteries are currently cheapest for $/W, work with all standard charge controllers/inverters, and are available from multiple suppliers on-island, usually with 0 lead-time. If you're DIY, you're probably using lead-acid batteries.
Everything else is special-order through an integrator, wait while it's shipped, pay them to install it.
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Stacking, china e-bay has Nickel ion batteries. You pack them in paralleled sets and you're building virtual hybrid batteries. It actually is, save today's computer tech assistance, little more than 1st semester H.S. electronics. Tesla's are Lithium others are Nickel, chose your price target. . Build or buy transformers and converters while hoping Q dot tech can get to market their claims of dramatically increasing viability in solar cell technology before your done building your equipment.
From there, your lap top can import programming to diagnose the sets you built to help locate where and when one of those batteries crystalize so Anny can go get her soldering iron and swap a cell.
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At the moment, if you have the money, the best are lithium iron phophate batteries. They need no water, no equalization, have no gassing. They don't need to be completely charged everyday and are around 96% efficient. You can discharge to 10%-20% from empty capacity and are rated to last 10 years and still have 70% capacity left. If they last as rated then they are cheaper than lead acid.
You can use a regular Outback inverter and charge controller or similar. They are light weight, clean and much smaller than lead acid. They charge fast no long taper but full voltage/amps to end of charge. No voltage drop on high loads like microwave, pump, etc.
Mine finish charging by 1 pm and I take them down to 45% - 50% capacity at night. The lowest voltage my 48 volt system has reached is 51.9 volts, even under large loads, the highest 55 volts. The voltage is just constant.
Now the bad part, they cost a lot up front and they are hard to get here.
They are just boring not much maintainance to do. Did I really say I miss messing with acid, watering, equalizing, worrying about state of charge, monitoring house loads ? I think not.
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Funny, Tom. I would think the dual meaning of the phrase "solar system" would get more confusion than it does.
Hey everybody, a big MAHALO for your responses. I only understand a little of what you all said, but I actually do have others who can read your responses and help me figure it out.
tgalarneau:
[i]"Did I really say I miss messing with acid, watering, equalizing, worrying about state of charge, monitoring house loads ? I think not."
Yes! This is what I want to avoid.
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they cost a lot up front and they are hard to get here
Price? Distributor?
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In Hawaii a new startup is selling Sony's lithium iron batteries. They have a conference center set up in Kona using the technology. They are interested in the whole systems installation along with the profit. I think they are like Tesla using there own software and inverters/controllers $$.
http://blueplanetenergy.com
I'm more of a diy guy along with the cost savings and used my existing equipment. I ordered mine direct from China, where most of the manufactuers are located. They can also be ordered from West Coast from distributers after receiving product from China.
As to cost, it depends on your usage. I use 7 - 10 kilowatt hours per day so calculated 180 amp hour batteries would be sufficient and they are a little more than needed.
Each battery is one cell at approx. 3.5 volts, so needed 16 batteries for 48 volts. FOB China the cost was $210 per 180ah battery. The batteries come in various capacities up to 400ah.
As this technology is fairly new the longevity is still being tested in the real world with some systems so far reaching 7-8 years history. House solar system experience is newer, with more experience in RV and boating systems, as well as in elecrical cars. I notice electrical power tools are switching to this type of batteries, as they don't have the same fire hazard with lithium ion.
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