topic Re: Recommendations for AC solar batteries? in Solar, Batteries & Electrification

Recommendations for AC solar batteries?

thunter — Thu, 03 Aug 2023 02:40:08 GMT

Hi,

What do people recommend for AC coupled solar batteries? Anyone had experience with anything outside of Tesla PW? (I know they're good, just looking into any viable alternatives)

Re: Recommendations for AC solar batteries?

Jerrieclaus — Tue, 08 Aug 2023 03:13:39 GMT

Looking at fault rates and such, it looks like right now you're really best off just going with the PowerWall2

Re: Recommendations for AC solar batteries?

Zues — Wed, 09 Aug 2023 07:00:23 GMT

I have 26 kw of ac coupled batteries from Sunterra and 26 kw of panels

had the system for three years now, have had over $5,000 in credit cheques from AGL

Solar panels are useless without batteries

Re: Recommendations for AC solar batteries?

Caban — Wed, 04 Oct 2023 08:47:50 GMT

Most of the batteries on the market are LiPO based. These are really good for mobile applications as they are very energy dense. This makes them light when you are paying to move them.

Battery installations on a house are not mobile so energy density is not as high a priority. There are other properties which should be considered when making this investment.

Battery stability and safety
Internal impedance of battery
Discharge level
Battery longevity
Expansion options

My original battery set were Lead Acid Gel Cells. This was really the only option that was affordable back in 2013. They had many drawbacks. Namely they had a life expectancy of 8 to 12 years (I only got 6.5 years, just out of warranty) and they do not like discharges below 60% of capacity. One cell failed and that meant the whole bank was not serviceable.

I was looking at a Nickel Iron system. While they are almost bullet proof and can be deep cycled they can have a high impedance when cold. That usually becomes evident when you put on the kettle and/or toaster on a cold morning. I did explore the LiPO offerings too. Although it is rare I did not like the idea of a cell having a thermal runaway as they are almost impossible to extinguish. The other downside is to service life, which is not much better than Lead Acid.

The system I purchased was LTO Batteries (lithium-titanium-oxide) which have many advantages of LiPO for static installations. They are very stable and have no risk of thermal runaway. They can tolerate deep discharge without damage. They have very low internal impedance and can deliver high power and fast charging. They also have a very long life, my system has a 20 year (or 22,000 cycles) warranty that they will be 90% of original capacity. They have an expected life of 50+ years. I can also add extra capacity at any time I have available funds. I currently have 4 units @ 1.93kWh but I would like to add two more.

The longevity of these units mean it has an excellent payback on investment.

My connection fee to the Grid is about $1.76 a day. Due to these batteries and my FiT my latest quarterly bill is under $47. That is because I use very little supply from the grid and export a lot. These are really good batteries and they do not smell of Musk.

Re: Recommendations for AC solar batteries?

Zues — Wed, 04 Oct 2023 09:48:13 GMT

When you say musk, is that the dude with the cordless cars

Re: Recommendations for AC solar batteries?

Caban — Wed, 04 Oct 2023 10:05:23 GMT

That’s the fella

Re: Recommendations for AC solar batteries?

NeilC — Sun, 15 Oct 2023 02:13:17 GMT

@thunter

Hi,

Just in case you don't know, LG Batteries are currently under a recall due to a possible failure.

LG also supplies batteries to other companies.