Opinion on batteries

[extrafu]

Hi guys,

We estimated our daily power requirements at 10 to 12 KWh per day once our new garage + house will be built.

The construction of our garage starts in the next coming weeks, but the house construction will probably begin in a year from now. So for the next 12-18 months, our daily power requirements will probably be around 3 KWh.

While we'll purchase right from the start the appropriate panels/inverter/charge controllers, we are hesitating on the battery bank. Our ultimate goal is to go with 12 Rolls-Surette 4KS25P (1350 Ah, 4 volts for a total capacity of 64.8 KWh), we are also considering using 8 Rolls-Surette S-605 (468 Ah, 6 volts for a total capacity of 22.5 KWh) to start with and change the batteries in about 18 months from now.

One reason that makes me think about going with the Surette S-605 is that I am new to this and I would prefer going through a good learning and care process with a 3,500 CAN$ battery bank than a 16,500 CAN$ one. Also, our power requirements are low for the next few months and if I happen to take good care of the batteries, I could probably sell them for a fair price after.

Any opinions on this approach?

Thanks!

[Sunking]

OK your plan SUCKS.

Now listen carefully before you get your shorts in a knot, I know WTF I am talking about. You said "your first set is a learning experience right?" Absolutely correct and you wil destroy your first set of batteries learning. Think of of it like a 16 year old first car. Would you buy them an Corvette to learn how to drive? Hell no you would not. You would be a fool to do that. No different here. Rolls are high end, even the 605's and you have no need for that much capacity. I wil save you a thousand dollars.

What you do have right is 48 volts. So two things that are a must right now is selecting the right Panels and Controller to GROW WITH. Controller is easy, you want a good high end 80 Amp High Voltage Controller. Absolutely nothing less than 150 Voc input and higher is better. Panels is the tricky part, and the best building block is either 200 or 250 watt Grid Tied Panels, and avoid PRIME NUMBERS except 1 and 3. Prime numbers of 5, 7, 11, 13, 17 will not work. Well 5 might if the Controller has high enough voltage. You want to run Panel Voltages as high as possible for several reasons. Mostly because it is the most efficient and least expensive. The trick for you is to select a manufacture that wil will still be around when it comes time to expand or warranty claims. Like it or not Solar is over and dying out in the USA. In the next 5 years most manufactures will be gone. So stick with names like Panasonic, LG, GE, Sanyo, ect. I would even avoid LG as South Korea could be gone tomorrow.

Ok for batteries at 3 Kwh per day you are looking at 48 volts @ 300 to 350 AH. No need to go higher. In a pinch you could use up to 5 Kwh in summer. Something like a Trojan J305P-AC a good 3 year battery with 2/4 year warranty. If I were you, Trojan still might be a little to high end for a beginner, and I would look at US Battery models like US 250 HC-XC2, 305-XC2, or US RE GC2H XC2. US Battery is Trojans direct competition but less expensive.

Lastly don't be a Meat Head, get a $10 Temperature Corrected Battery Hydrometer like a DEKA. Learn how to use it and to tell you what the right Voltage is. Now when you are ready to move up. Even better than Rolls is Trojans Industrial Line. There is nothing better and still a little less expensive than Rolls 5000 series.

[Sunking]

Start your own thread, I can shine some light on it.

[extrafu]

Sunking Thanks for your reply. I got all the inverter/CCs part in line - it'll be a Conext XW+ 6848 inverter + 2 CCs 80A/600V. PV is 24 x 305W panels, 12 in series.

As for the batteries, to *start with* and set to be replaced in 12-18 months, the price on the Rolls 605 is very good, I could even lower down a bit and go with the S-550. That would be enough for 3 days worth of usage before going below 50% DoD. The Rolls 505 is priced at 400 CAN$ per battery, same prices I've found (quick search) the Trojan J305P-AC but with a bit more capacity.

As for the ultimate battery bank, I guess it'll depend on the pricing. You might recall in other threads I considered 12 x Trojan IND23-4, but the price right now is about 300 CAN$ higher per battery than the Rolls 4KS25P - and the Rolls has slightly more capacity and based on the specs, a slightly better cycle life vs. DoD curve.

Thanks buddy!

[Sunking]

Sunking Thanks for your reply. I got all the inverter/CCs part in line - it'll be a Conext XW+ 6848 inverter + 2 CCs 80A/600V. PV is 24 x 305W panels, 12 in series.


Thanks buddy!

You are welcome but I see a possible problem. Not sure if you intend on using both CC and all 24 panels initially, if so you have a problem At 7320 watts into a 48 volt battery is 152 amps. Way to much for 605, 550, or any other battery you plan to start with. With either Rolls or Trojan you do not want a charge rate higher than C/6 and that is pushing them a bit. At 150 amps I would not go lower than a 900 AH battery. Of course that is an easy problem to solve, just use half of what you got, and wait until you are ready to grow to install the rest.

Good luck.

[extrafu]

Thanks! I could always use for now the DC disconnect to turn off half of the array. I understand I am getting stuff I don't need for a few months, but would be easier and cheaper to get everything installed at once.

[extrafu]

Or better yet, I can adjust the current on the Conext MPPT 80-600 - Schneider just confirmed me. So if I don't want to go over say 70 Amps for charging the batteries, I could set the max change rate percentage on each controller to 44%. So 44% of 80A == 35.2A times 2 == ~70A.

[Sunking]

Or better yet, I can adjust the current on the Conext MPPT 80-600 - Schneider just confirmed me. So if I don't want to go over say 70 Amps for charging the batteries, I could set the max change rate percentage on each controller to 44%. So 44% of 80A == 35.2A times 2 == ~70A.

OK but that just pisses away all the extra panels with Clipping. It will work, I just wanted to make sure you knew the consequences of having to much charge current. Be sure to get a hydrometer and use it to set the charge voltages. With Solar manufacture recommendations are rarely high enough. Trojan has taken action and done away with 3-Stage charge voltages. Great if you use a AC source of power, but suks on solar. Ac is a constant unlimited hard source 24 hours a day. Solar is unknown for only a few hours a day. Not enough time or power to Saturate a battery as that can take 12 hours.

Edit Note:

Did you check US Battery pricing? I think it would be worth your time.

[extrafu]

Yep, will do purchase an hydrometer and learn how to use it properly. I'll also have a backup generator. Thanks man! I religiously read pretty much all your posts, you're of great help to all the community.