May 2, 20215 yr My current sorta gel 12V 400Ah off-grid set is 10 years old and down to a sliver of its original capacity. The main controller is a Morningstar SunSaver SS-MPPT-15L with 550Wp of panels. I think 200Ah ish makes sense for a replacement since I'm just not getting the input in winter for much more to make sense, other than possibly to avoid being charged too fast when the sun actually appears. The only mandatory load is a couple of watts of Raspberry Pi server. If it's feeling flush it can take 12W of Internet router off-grid. Sometimes I run my laptop and other loads up to a 100W water heater, but only when there's lots of sun etc. What suppliers and brands would anyone recommend? Rgds Damon Edited May 2, 20215 yr by DamonHD
May 3, 20215 yr Can't help that think that LA is not the way to go. Li xx are pretty cheap, or would you have to buy a different charge controller. I also wonder how efficient DC charge controllers are when the battery is charging up the last 20%. What is the embodied carbon and energy in a LA batter? https://www.sciencedaily.com/releases/2013/03/130308111310.htm
May 3, 20215 yr I use County Battery as they are local to me and have found the Fuller Batteries very good and also have a decent warranty. https://www.countybattery.co.uk/leisure-batteries/fuller-agm-leisure-and-marine-battery-12v-115ah-sealed/ You would need 2, but they have a discount of 10% when you spend over £250. They do a 200Ah Lithium too, but it’s £1500......
May 3, 20215 yr This is an interesting challenge. 24 minutes ago, SteamyTea said: https://www.sciencedaily.com/releases/2013/03/130308111310.htm Is now quite an old piece of research, doubt that much has changed greatly for batteries, but charging sources (Solar / Wind / ???) have moved on so the overall equation might now be a bit better. 7 minutes ago, PeterW said: They do a 200Ah Lithium too, but it’s £1500 However the guarantees have not really kept up with expectations - wonder why this is? Is it because charging / discharging control technology to maintain battery life of these systems is so diverse - and you need care when charging Lithium, so they don't feel able to offer longer as they have no control over the surrounding kit. You cannot expect to need to replace a £1500 battery every couple of years and so having longer term confidence would be a buying decision game changer you would have thought.
May 3, 20215 yr Author 11 hours ago, SteamyTea said: Can't help that think that LA is not the way to go. Li xx are pretty cheap, or would you have to buy a different charge controller. I also wonder how efficient DC charge controllers are when the battery is charging up the last 20%. What is the embodied carbon and energy in a LA batter? https://www.sciencedaily.com/releases/2013/03/130308111310.htm Excellent advice from someone over at fieldlines.com is, if it doesn't have to be mobile, LA is still often the best choice. Relatively cheap and recyclable and little cell-balancing trouble or fire risk. I have LiFePO4 and LA and I think that LA is likely best for this application. And I really like and trust my Morningstar SunSaver MPPT controller, and have integrated heavily with it from my RPi and home-brew power management. Rgds Damon PS: thanks all for the thoughts so far. Though I'm not a newb, well maybe not, it's very good to be able to talk it over! Edited May 3, 20215 yr by DamonHD
May 4, 20215 yr Hello DHD ? Out of curiosity why 12V 200 Ah rather than 2x 12V 100 Ah in series? Smaller batteries to lug around. Thinner wires / lower I2C losses. A lot of automotive grade stuff takes 12-24v these days (LEDs, USB adapters, laptop adapters) or is available in straight 24v (pumps, motorised valves etc). I'm picking up 20 used 195W panels (£230 the lot...) next week and would like to split these / experiment with running hotel load on PV inc overnight via storage. Somebody was offloading 50 panels the other day for £1200. Cut cables slightly sketchy to rejoin but at that price I was half tempted o use 'em as a ruddy fence!
May 6, 20215 yr Author Hi The current battery bank is 4x99Ah in parallel. The system voltage is 12V so that I can use standard automotive equipment on it, eg the USB supply for my RPis, typical draw ~1W, so thinner wiring is not really an issue for much of the system! And nothing downstream of the controller that I currently have would like 24V, and the overhead of a converter would likely exceed the normal load. A single battery rather than a bank would simplify the wiring, eg avoid needing the cross straps and running the main feed to opposing corners, but is not the most important consideration. I am indeed using cheap second-hand panels as fence/screening: https://www.earth.org.uk/expanding-off-grid-PV-system.html#20160722 Rgds Damon
May 6, 20215 yr Ah, space constrained rather than supply of panels constrained! I'll need to look for somebody else to split a forklift pack then... https://www.ebay.co.uk/itm/154427926929 (48 V / 500 Ah for 24 kWh nominal @ £1500 - it really wants a full roof and a 2 kW inverter to carry any single appliance except an induction hob)
May 7, 20215 yr On 02/05/2021 at 21:24, DamonHD said: What suppliers and brands would anyone recommend? I've used Trojan t-125 on our boat for some time and found them good value for money. They're 6v deep cycle and do require regular maintenance, top up with distilled water every month. They put up with a lot of heavy use in fork lifts and golf trolleys.
May 9, 20215 yr Author So, from the info here (thank you) and the thread here: https://www.fieldlines.com/index.php/topic,150367.0.html at the end of the summer I'll likely get a 220Ah Victron gel: https://www.tayna.co.uk/leisure-batteries/victron/bat412201104/ or, if being a bit more bold, 1 or 2 Firefly AGM: https://www.macbethenergy.co.uk/#/ I'm likely also to add more to my Enphase grid-tie, and if I can manage it, Sunamp heat storage! We'll see! Rgds Damon
September 5, 20215 yr Author It's all done and installed, thanks for the advice! https://www.earth.org.uk/battery-bank-replacement.html Rgds Damon
September 19, 20215 yr Author For anyone interested, I also increased grid-coupled storage by ~1kWh, and it seems to be strutting its stuff so far: https://www.earth.org.uk/Enphase-AC-Battery-2.html Rgds Damon
September 19, 20215 yr 30 minutes ago, DamonHD said: For anyone interested I am interested. Do you know the embodied energy to make those batteries, and the associated carbon emissions, which are of course regional.
September 19, 20215 yr Author No, though they are probably available, given that the manufacturers are reputable (Victron and Enphase). Rgds Damon
October 28, 20214 yr Author As of today I have gone from ~1.25kWh of ac-coupled Enphase storage ("AC Battery") in early September to ~5kWh today. (Well, configuration isn't complete, but the physical installation is done.) This is for science in the sense that I'm pretty sure that this is larger than optimal, especially in winter, but I want to found out if that is evident from the stats. Rgds Damon Edited October 28, 20214 yr by DamonHD
October 29, 20214 yr On 03/05/2021 at 08:06, SteamyTea said: Can't help that think that LA is not the way to go. Li xx are pretty cheap, or would you have to buy a different charge controller. I also wonder how efficient DC charge controllers are when the battery is charging up the last 20%. What is the embodied carbon and energy in a LA batter? https://www.sciencedaily.com/releases/2013/03/130308111310.htm This is worrying to read and I'll need to ponder on it as I'm deciding whether to opt for battery storage, in due course. Or go the EV route (which we will at some point in any event). I'm vaguely aware of one pumped hydro in Wales. All in it makes me wonder if/when the Bristol Channel barrage decision will be revisited.
October 29, 20214 yr 4 minutes ago, GLPinxit said: Or go the EV route Depending on what you already drive, and how many miles you do, getting an EV will probably be the biggest improvement. We change our partners and vehicles more often than we do our bank accounts, and I suspect that most people will change home battery technology about as often as changing bank accounts. It is much cheaper, for everyone, to get the big boys to install battery storage. Though like @DamonHD, the idea of playing with this technology appeals.
December 5, 20214 yr Author On 28/10/2021 at 16:54, DamonHD said: As of today I have gone from ~1.25kWh of ac-coupled Enphase storage ("AC Battery") in early September to ~5kWh today. (Well, configuration isn't complete, but the physical installation is done.) This is for science in the sense that I'm pretty sure that this is larger than optimal, especially in winter, but I want to found out if that is evident from the stats. Rgds Damon Updated page for the last round of Enphase storage install, including the modified load profile: https://www.earth.org.uk/Enphase-AC-Battery-3-4.html Rgds Damon
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