Living offgrid with small solar system(s)

[Naam]

Thanks..I thought the bushes sounded goid for cooling. Hang some plastic or tarps for a few years until the plants grow. Gotta be right sized plants..we have potacarpas that grow too tall to shade dat window.

Hawaii is same latitude as LoS, so online there must be plenty stuff about landscape shading.

Nice stand alone pool, Naam

i hate stand alone pools in a tropical country and prefer mine integrated in home, i.e. walled, roofed, no sun but shade and pool area airconditioned.

[Muhendis]

Konarain When you are talking about Lithium Ion batteries do you mean LiFePO4's and if so what price are they per amp hour at, lets say 48v where you are?

That looks a great pool and garden Naam. Is it yours?

[Naam]

That looks a great pool and garden Naam. Is it yours?

yes, it's mine. the pool area is our alternate living room from november till mid march. having the area airconditioned during the hot season would be some madness that would exceed even my regular madness by far.

[IMHO]

Talking about pumps @naam,

Plan also to make a swimming pool. Just saw this on internet which i like very much.

Im wondering what kind of pump i need to operate such a relatively small pool solar powered.

The target you want to achieve in an outdoor pool is turning over the complete water volume twice per day.

Let's say that pool is 4M wide, 10M long and an average of 1.5M deep - the means there's 60,000L you need to circulate twice per day - so 120,000L in total. Seeing as you want to run the pump on solar energy only, where you have really only 4-5 useful harvesting hours/day, that means you need a pump and filtration system that can move 24,000 - 30,000 litres per hour / 400 - 500 litres per minute.

Seeing as you only really get about half the flow rate that's advertised on the pump, once plumbing, fittings and filter restrictions are factored in I would think 3-4 HP is what you'd need.

[Naam]

Seeing as you only really get about half the flow rate that's advertised on the pump, once plumbing, fittings and filter restrictions are factored in I would think 3-4 HP is what you'd need.

i think George will find a way to use a much smaller pump which filters 26½ hours a day (no breakfast, lunch or supper break for the pump).

on rainy and cloudy days and during nights) he will power the pump shining an LED bulb (which draws energy from a huge 6.5ah battery) on the solar panels.

[BHW]

Hi

Bit off topic, have a look at rkholdinggroup.com web site all types of solar options there.

Regards

[Muhendis]

Talking about pumps @naam,

Plan also to make a swimming pool. Just saw this on internet which i like very much.

Im wondering what kind of pump i need to operate such a relatively small pool solar powered.

The target you want to achieve in an outdoor pool is turning over the complete water volume twice per day.

Let's say that pool is 4M wide, 10M long and an average of 1.5M deep - the means there's 60,000L you need to circulate twice per day - so 120,000L in total. Seeing as you want to run the pump on solar energy only, where you have really only 4-5 useful harvesting hours/day, that means you need a pump and filtration system that can move 24,000 - 30,000 litres per hour / 400 - 500 litres per minute.

Seeing as you only really get about half the flow rate that's advertised on the pump, once plumbing, fittings and filter restrictions are factored in I would think 3-4 HP is what you'd need.

I think George would be running the system with battery backup for 24 hrs/day in which case surely a much smaller pump would do. I am wondering about this whole business of circulating water. I have a pond/lake 40M x 40M (1 Rai) which when full is 3M deep. lots of mud, fish, algae and other assorted dreadful things in it but it's great for swimming/boating/fishing and I'm still alive to enjoy it again.

[George Harmony]

Its still a mess at my backyard. Here a pict of half of my backyard which i plan for fishponds and above the 2nd fishpond a gazebo. Two-three weeks ago one day heavy rain and its full. Then not so much rain and now its nearly dry. So, more easy to continue to work and make the ponds deeper and make the fundation for the planned gazebo. Next to it there is still enough space for a swimming pool. BUT, when its too difficult to run the pump with solar i pass. Once again my intention is to live off grid with not so big solar system. With wok cooking, microwave and other extras perhaps a system of max 600wp. If with this i also can run a pump for a small swimming pool then ill do it. I thought of making a swimming pool of 7x4m. My premises can not be underwater cause the land is higher than the street and our housing complex have a good gutter system.

[KonaRain]

About the batteries :

http://www.roadtrek.com/news-events/roadtrek-revolutionizes-rv-travel-with-launch-of-ecotrek-power-technology/

This 129K $ motorhome, sports this handy charging system, to be stored by

Li -On batteries ..so I'm thinking of a way to make something similar to Mr. Musk's system .. if we can part this out, for a lot less money. Lets try and figure this out, shall we.

How many batteries weighing how much..?

more later..

I'll check the LifePo4's..Aloha

Edited April 16, 2016 by KonaRain

[KonaRain]

Ah, the trial is leading to

LiPo4!

http://www.technomadia.com/2011/10/lithium-update-2-the-promise-of-lithium-rv-batteries/

[KonaRain]

Ok..here's da prices in $.

The sure don't weigh a lot, and they talk about taking them apart and reconfiguring. .great idea!

Thanks guys. .

Alohz

http://www.technomadia.com/2011/11/lithium-update-3-lithium-battery-cost/

Edited April 17, 2016 by KonaRain

[Crossy]

Been doing a bit of poking around on aliExpress.

Assuming a 12V system and you don't mind a bit of DIY :-

4 x 125Ahr 3.2V LiFePo cells @ $175 (free shipping) = $700 http://www.aliexpress.com/item/1pc-Lishen-batteries-high-capacity-3-2V-125AH-lifepo4-cell-high-drain-lithium-battery-for-golf/32443391851.html

1 x 12V 60A BMS @ $30 (essential to protect your batteries) http://www.aliexpress.com/item/7s-BMS-12v-lithium-battery-BMS-12v-7s-PCM-for-electric-bike-lithium-battery12v-15a-battery/32316085434.html?spm=2114.01010208.3.38.gkBjX8&ws_ab_test=searchweb201556_0,searchweb201602_3_10017_10005_10006_10034_10021_507_10022_10020_10018_10019,searchweb201603_2&btsid=85e3f303-5e5b-4837-9f9c-7ff1e0ed6af6

$730 gets you 100 USABLE Ahr @ 12V

By comparison, 100 USABLE Ahr @ 12V of lead-acid (300Ahr @ 30% discharge) will cost about $135 x 3 = $405

If the LiFePo cells last > 1.8 times the life of the lead acid you're quids in

[Muhendis]

Been doing a bit of poking around on aliExpress.

Assuming a 12V system and you don't mind a bit of DIY :-

4 x 125Ahr 3.2V LiFePo cells @ $175 (free shipping) = $700 http://www.aliexpress.com/item/1pc-Lishen-batteries-high-capacity-3-2V-125AH-lifepo4-cell-high-drain-lithium-battery-for-golf/32443391851.html

1 x 12V 60A BMS @ $30 (essential to protect your batteries) http://www.aliexpress.com/item/7s-BMS-12v-lithium-battery-BMS-12v-7s-PCM-for-electric-bike-lithium-battery12v-15a-battery/32316085434.html?spm=2114.01010208.3.38.gkBjX8&ws_ab_test=searchweb201556_0,searchweb201602_3_10017_10005_10006_10034_10021_507_10022_10020_10018_10019,searchweb201603_2&btsid=85e3f303-5e5b-4837-9f9c-7ff1e0ed6af6

$730 gets you 100 USABLE Ahr @ 12V

By comparison, 100 USABLE Ahr @ 12V of lead-acid (300Ahr @ 30% discharge) will cost about $135 x 3 = $405

If the LiFePo cells last > 1.8 times the life of the lead acid you're quids in

It gets better . LiFePO4's can be happily discharged to 100% (90% is max advised) so the cell capacity is actually greater for the LiFePO4 than the 30% of the lead acid battery. In other words, for the same lead acid usable capacity you need less LiFePO4 capacity. LiFePO4 batteries are good for 2000 - 5000 cycles (if you believe the manufacturers data) which is 3 - 4 times more than flooded lead acid. For a 48v system you "only" need 15 cells. It is essential that the LiFePO4 cells are balanced with a bit of charge shuttling electronics otherwise the full capacity will soon fade. Also the charging regime (three stage), which is very similar to lead acid, needs to include a reliable and accurate low voltage shutoff on each cell otherwise death will come quickly. This is what the BMS Crossy mentioned is all about. LiFePO4's are what I shall be changing to when my FLA's expire so I'm keeping an eye on the prices.

[Muhendis]

About the batteries :

http://www.roadtrek.com/news-events/roadtrek-revolutionizes-rv-travel-with-launch-of-ecotrek-power-technology/

This 129K $ motorhome, sports this handy charging system, to be stored by

Li -On batteries ..so I'm thinking of a way to make something similar to Mr. Musk's system .. if we can part this out, for a lot less money. Lets try and figure this out, shall we.

How many batteries weighing how much..?

more later..

I'll check the LifePo4's..Aloha

One of the first lines in that link advert says that the lithium batteries have iron phosphate in them....Yep. They're LiFePO4's

[Muhendis]

Forgot to mention that the LiFePO4 cells are good at higher temperatures unlike their lead acid pals.

The lead acid batteries are spec'd at 25 deg C and need to be derated in a strange way as the temp. goes up. Capacity increases but cycle life decreases.

On the other hand LiFePO4 cells are relatively unaffected by elevated temps. up to 50 deg C.

[George Harmony]

Interesting @crossy.

I find this one for 1300usd. What i dont undrstand r the specs. Does this battery have a build in charge controller???

Edited April 17, 2016 by George Harmony

[Crossy]

Interesting @crossy.

I find this one for 1300usd. What i dont undrstand r the specs. Does this battery have a build in charge controller???

It has a built-in BMS yes, LiFePO4 batteries are close enough to lead-acid that they can use the same charging system (that's why you can make drop-in replacements) although apparently you won't quite get to 100% charge.

[Gary A]

All the talk about DC appliances is interesting but is really not that practical. Most DC things are 12 volt. That means you need expensive heavy wiring. Since I didn't install my solar system to save money, I ended up going the much simpler way. My battery bank is wired in parallel. This is a simple 12 volts. I am able to run easily available 12 volt fans and 12 volt LED lights directly from the battery bank. The modern pure sine wave inverters are pretty efficient so the house wiring can be used as is and all the appliances are regular 230 volt AC. My small system has 600 watt of solar panels and 4 65 AH AGM sealed batteries. The MPPT charge controller and the 600 watt pure sine wave inverter are Chinese and after three years have never had any problems. I think the entire system cost me about 40,000 baht. I do miss the air conditioner in my computer room during main power outages, but the fans and lights are better than nothing. My computer is happy with the pure sine wave inverter. No low voltage, surges or lightening worries. Basically, I have a super size UPS.

Another advantage of my 12 volt battery bank is the ability to charge my battery bank with a regular automatic 230 volt charger. We rarely have several days of no sun but I can charge the batteries when that happens. On overcast days, the system keeps up pretty well.

ADDED - for the price of a 100 AH lithium battery I can buy a lifetime supply of 200 AH lead acid deep cycle batteries. I also looked at the Tesla batteries but the voltages rule out using standard solar power components.

Edited April 17, 2016 by Gary A

[BHW]

Hi Gary A

You are on the right track, there are so many options for solar power & water pumping, you have sized for what you want, most people don't do this, don't research through people who know the in's & out's. Forums are good to an extent but a lot of miss information also.

As you said Lithium batteries are top shelf, in time maybe more reasonable, Gel batteries bit more expensive than lead acid but much more suited for solar best way keep at around 50% charge then might get 8 + years use.

BHW.

[George Harmony]

Following last 2 posters. One can choose to be totally offgrid by using solar systems,windenergy or even a genset which needs fuel.

@crossy...thanks. I will save some "ngen" for such batteries cause im not as rich as @naam hehehehe

[Naam]

Interesting @crossy.

I find this one for 1300usd. What i dont undrstand r the specs. Does this battery have a build in charge controller???

$1,300 for measly 108 amp hours?

what am i missing?

[Muhendis]

Interesting @crossy.

I find this one for 1300usd. What i dont undrstand r the specs. Does this battery have a build in charge controller???

$1,300 for measly 108 amp hours?

what am i missing?

You're missing the origin of the advert. America is the home of the big money and there's plenty there stupid enough not to quibble over $1300 for a poxy little cell. They never heard of Alibaba et. al.

[Naam]

Interesting @crossy.

I find this one for 1300usd. What i dont undrstand r the specs. Does this battery have a build in charge controller???

$1,300 for measly 108 amp hours?

what am i missing?

You're missing the origin of the advert. America is the home of the big money and there's plenty there stupid enough not to quibble over $1300 for a poxy little cell. They never heard of Alibaba et. al.

our friend @George@H@rmony is not @merican but finds it "interesting".

[Muhendis]

I think that may be a polite way of avoiding a deprecating remark. Bicycles and endearing politeness all come from Holland

[George Harmony]

LiFePO4 batteries are good for 2000 - 5000 cycles (if you believe the manufacturers data) which is 3 - 4 times more than flooded lead acid.

Very interesting indeed. Like @muhendis, i keep an eye on the prices.

[KonaRain]

108 KW..

I thought I read somewhere that if they were discharged all the way, they were toast. .fini..

Maybe that was freezing, which is a real problem, though not for us at latitude 20..

[IMHO]

For those interested in LifePo cells, make sure you do your research, as you're going to have to give them a nice temperature controlled environment in order to achieve manufacturer claims.

[KonaRain]

http://www.technomadia.com/2011/10/lithium-update-2-the-promise-of-lithium-rv-batteries/

Here's the warning against total discharge. .

Says your whole bank will be useless..

Set your voltage regulator to the right voltage!

[George Harmony]

I plan to "plant" some of such lantarns in my backyard and m very interested to use this 40amp lifepo battery. Perhaps its enough for all my lighting indoor and outdoor.

My question is:

Can i use a module like lm2577 and connect this module between the panel and battery since the battery have a buildin bms???

[Muhendis]

108 KW..

I thought I read somewhere that if they were discharged all the way, they were toast. .fini..

Maybe that was freezing, which is a real problem, though not for us at latitude 20..

Quite right they will be completely useless if the cell voltage is allowed to go low enough. That is why I would put the limit on 90% discharge. However it is not difficult for the BMS to monitor the discharging voltage and send a suitably coherent signal to prevent further discharge. If you are using a programmable hybrid inverter/charger then it is not difficult to arrange for the inverter/charger to be programmed to switch from battery to utility supply before the battery is destroyed. A graphical display of the discharge of LiFePO4 cells shows a very flat voltage output (ignoring the first few minutes) until they are near the end of the discharge cycle. Then the voltage starts to drop off. If it goes too far then the battery will not recover. It is possible either with a BMS or a programmable charger to detect this dropping of voltage and select a voltage (eg 2.7v per cell) at which the discharge cycle is terminated. The safest way is to use a BMS to monitor each cell.

A further advantage of the LiFePO4 technology over lead acid is the opportunity nature of the charging cycle. With the lead acid battery, if the charge put into the battery is less than the charge previously taken out then the build up of sulphur crystals on the lead plates will increase and the capacity of the battery will be reduced. If this happens often enough the loss of capacity will become quite noticeable and action needs to be taken. LiFePO4 batteries on the other hand, don't care if they don't get a full charge. They will give out whatever is put into them without any detrimental side effects. That is why I like to think of them as opportunity batteries.

Edited April 18, 2016 by Muhendis