2kw off grid with batterys

[Ucatchmydrift]

Hi, im wanting to setup an off grid 2kw system on my shed roofs. (one shed has a mains supply too)
I have found someone willing to sell me 8 x 250w poly panels for £500 second hand. - german made, cant remember the make but will check this and test on a sunny day as best as i can.

This is a budget build (solar and budget ha ha!), with an aim to power a computer that runs 24/7 and draws exactly 300w.

Doing some maths i figured 2kw solar and 5kw of lead acid deep cycle batteries (varta 110ah x 4 (=£400)) would provide around 3/4 of the power needed each day on average, and i could switch over to mains power at night to charge the batterys off peak when flat.
Turns out i can only use 50% of the battery storage

I was hoping to do the whole build for around £1000. - im sure plenty of you are laughing at that!
I thought i had found an inverter that would be able to switch from power from the panels, to the batterys, then supply power from the grid once batterys are flat. The inverter was an iconica IC-BM2000-24.(£340) Typically it turns out that this has a max solar input of 1200w even though its a 2000w inverter! Grrr.

So, my main question is,, does anyone know of an inverter that will be reliable that is capable of 2000w input from solar, with a built in solar charge controller and normal battery charger that will automatically switch between the 3 sources for under £500? As im struggling to find such information!
Thanks .
Things are never simple.

 

[binky]

Hi, im wanting to setup an off grid 2kw system on my shed roofs. (one shed has a mains supply too)
I have found someone willing to sell me 8 x 250w poly panels for £500 second hand. - german made, cant remember the make but will check this and test on a sunny day as best as i can.

This is a budget build (solar and budget ha ha!), with an aim to power a computer that runs 24/7 and draws exactly 300w.

Doing some maths i figured 2kw solar and 5kw of lead acid deep cycle batteries (varta 110ah x 4 (=£400)) would provide around 3/4 of the power needed each day on average, and i could switch over to mains power at night to charge the batterys off peak when flat.
Turns out i can only use 50% of the battery storage

I was hoping to do the whole build for around £1000. - im sure plenty of you are laughing at that!
I thought i had found an inverter that would be able to switch from power from the panels, to the batterys, then supply power from the grid once batterys are flat. The inverter was an iconica IC-BM2000-24.(£340) Typically it turns out that this has a max solar input of 1200w even though its a 2000w inverter! Grrr.

So, my main question is,, does anyone know of an inverter that will be reliable that is capable of 2000w input from solar, with a built in solar charge controller and normal battery charger that will automatically switch between the 3 sources for under £500? As im struggling to find such information!
Thanks .
Things are never simple.

I think you are looking for a pink unicorn . I've not seen anything that will do what you want, the most likely place to find such a piece of kit would be Victron, but they aren't cheap. With off grid batteries you can have multiple independent inputs with their own charge controllers. That's almost certainly your cheapest option. Is your shed in a windy place? If so I would consider a small turbine to trickle charge overnight, and help cover winter months.

For AC charging, you could just use a standard car battery charger, you would have to switch it on manually when needed. Leisure batteries should be dischargable to around 80%.

 

[Ucatchmydrift]

I think you are looking for a pink unicorn . I've not seen anything that will do what you want, the most likely place to find such a piece of kit would be Victron, but they aren't cheap. With off grid batteries you can have multiple independent inputs with their own charge controllers. That's almost certainly your cheapest option. Is your shed in a windy place? If so I would consider a small turbine to trickle charge overnight, and help cover winter months.

For AC charging, you could just use a standard car battery charger, you would have to switch it on manually when needed. Leisure batteries should be dischargable to around 80%.

Hi, thank for the reply
I found this on ebay last night, seems to do everything that im after at a very good price.. Problem is, its unbranded it seems, and how long would it last?

https://www.ebay.co.uk/itm/28486119...ar=586593776996&widget_ver=artemis&media=COPY
I also found this, which is a bit more expensive, but also seems to do everything:

https://www.bimblesolar.com/offgrid...ever-upower-24v-3000w-100a-lithium-all-in-one
Any thoughts on these would be very mich appriciated as im very new to all of this.

Also, im guessing these are classed as leisure batteries:

https://www.tayna.co.uk/leisure-bat...b4pySFGbUKAOjthSnaHxAhNRd83oUdExoC3FYQAvD_BwE
Does discharging them 80% reduce their lifespan? As i was under that impression?..

And presumably the above all in one inverters would be able to charge 4 of them linked together?

Thanks very much

 

[Ucatchmydrift]

Also, good idea about the wind turbine,, im in suffolk, so probably one of the sunniest places in the uk, but liest windy?

 

[Ucatchmydrift]

Plus, after reading a review of a "powmr" all in one inverter, the chap says the minimum voltage to charge the batterys is 150v. So his 8 x 12v batts were not enough!

Does anyone know if the above inverters will charge just 4 x 12v batts? In 24v configuration? Thanks again. This just gets more and more complicated!

 

[binky]

Hi, thank for the reply
I found this on ebay last night, seems to do everything that im after at a very good price.. Problem is, its unbranded it seems, and how long would it last?

Who knows! Some cheap stuff lasts for ages, some dies in a short space of time. DoD can affect battery life, but you should get around 3000 charge cycles minimum.

I would ahve a look on FB for sites that better cover what you are trying to do. Off grid isn't really what most of the members on here work with. I've done one small install, 2 panels and a small wind turbine, but that wasn't trying to run a load 24/7. One thing I will say, you will nedd a pure sine wave inverter, and I would ocer spec that say 500W rather than 300W, they never seem to be able to run at designated wattages.

 

[Ucatchmydrift]

Who knows! Some cheap stuff lasts for ages, some dies in a short space of time. DoD can affect battery life, but you should get around 3000 charge cycles minimum.

I would ahve a look on FB for sites that better cover what you are trying to do. Off grid isn't really what most of the members on here work with. I've done one small install, 2 panels and a small wind turbine, but that wasn't trying to run a load 24/7. One thing I will say, you will nedd a pure sine wave inverter, and I would ocer spec that say 500W rather than 300W, they never seem to be able to run at designated wattages.

Thanks . Ive just gone and ordered the epever 3k all in one inverter above. After using dr google, epever seems a reasonally good cheap make according to some. I also had a conversation with a man from bimble solar and it does seem to do everything i need it to do, with some head room also. So in total the whole 2kw setup with 5280watts of storage will cost £1500 without wire and fittings. Not so bad. .

 

[binky]

Thanks . Ive just gone and ordered the epever 3k all in one inverter above. After using dr google, epever seems a reasonally good cheap make according to some. I also had a conversation with a man from bimble solar and it does seem to do everything i need it to do, with some head room also. So in total the whole 2kw setup with 5280watts of storage will cost £1500 without wire and fittings. Not so bad. .

Bimble have been around for a fair while, so I would think they are quite a reliable source of information.

 

[Ucatchmydrift]

Bimble have been around for a fair while, so I would think they are quite a reliable source of information.

Thats good to know thanks

 

[MarkT]

300W is a lot for a 24/7 computer, are you sure you need that much overnight?
I have an EPEver 4KW off grid inverter (£650 so over your budget) charging 2 banks of 4 130AH "Solar" batteries (cheap truck batteries basically) set as 48V
I have 12 Canadian solar 240/250W panels second hand, probably 10 years old.
They have done at best 2.5kw early afternoon with clear sky, but more often sub 2kW and again around mid day.
I have most of my renovation house running off it, and the night time load is around 100W, and the batteries won't last all night.
The batteries have suffered somewhat, with the use of the washing machine and tumble dryer when there is not enough sun, don't think they have been down to 20% but certainly below 40% a good few times.

I do also have one of the panels on a shed charging 2 80AH mobility batteries through an EPEver 12/24V solar charge controller.
That feeds a WIFI IP Camera, and a 24V bilge pump I use to collect water from a ditch to top up the veggie plot water tank.
I do have a cheap 1kW 24V inverter to power small stuff in the shed if needed.

Have you considered using a mini PC or similar with a brick power supply, and just supply it with a DC-DC converter instead of the mains brick charger?

 

[Ucatchmydrift]

300W is a lot for a 24/7 computer, are you sure you need that much overnight?
I have an EPEver 4KW off grid inverter (£650 so over your budget) charging 2 banks of 4 130AH "Solar" batteries (cheap truck batteries basically) set as 48V
I have 12 Canadian solar 240/250W panels second hand, probably 10 years old.
They have done at best 2.5kw early afternoon with clear sky, but more often sub 2kW and again around mid day.
I have most of my renovation house running off it, and the night time load is around 100W, and the batteries won't last all night.
The batteries have suffered somewhat, with the use of the washing machine and tumble dryer when there is not enough sun, don't think they have been down to 20% but certainly below 40% a good few times.

I do also have one of the panels on a shed charging 2 80AH mobility batteries through an EPEver 12/24V solar charge controller.
That feeds a WIFI IP Camera, and a 24V bilge pump I use to collect water from a ditch to top up the veggie plot water tank.
I do have a cheap 1kW 24V inverter to power small stuff in the shed if needed.

Have you considered using a mini PC or similar with a brick power supply, and just supply it with a DC-DC converter instead of the mains brick charger?

Hi, cant believe it was just over two months ago i posted this, seems ages ago now.
Alot has changed since then. Ive been reading and learning alot.
I bought the 3kw epever inverter above, managed to buy 12 x 240w jinko panels for £750 second hand in great condition and squeezed all of them on top of my workshop and shed roofs as planned.
They are in two strings of 6 in parallel as 6 are on on side of roof, and 6 on the other (shallow roofs, get plenty of sun etc).
They make just under 2kw at the sunniest part of the day, so not too bad.
But i decided to go for as much as i can to also run as much of the house as possible due to all the electricity price hikes etc.
Got an off grid setup with a double socket in each room of the house to use for solar which i will be finishing this weekend. Nearly all done now.
Just got to get the most expensive part - the batteries.
Not going for lead acid anymore as i want them to last for 10 years plus, and to do that with lead acid would mean having to use just 20% of their capacity before charging, and having to charge fully each time etc. - just not practical, let alone all the other maintenance etc.
So im going to go for lithium phosphate now.
Expensive, but worth it in the long run. (£3500 for (11.7kw) - 9.4kw useable- based on discharging down to 20% each day) - roamer 24v).
So the setup has gone from £1000 to about 5k lol.
But its been a great project so far and should pay for itself quite quickly. - id rarther pay for this equipment than give all that money to the energy companies! - so thats what im doing...

 

[johnb2713]

So im going to go for lithium phosphate now.
Expensive, but worth it in the long run. (£3500 for (11.7kw) - 9.4kw useable- based on discharging down to 20% each day) - roamer 24v)

Try here for top quality, lower price batteries.

https://www.fogstar.co.uk/products/eve-lifepo4-280ah-prismatic-cell

 

[Ucatchmydrift]

Try here for top quality, lower price batteries.

https://www.fogstar.co.uk/products/eve-lifepo4-280ah-prismatic-cell

Thanks very much for that reply . I have considered doing a diy battery build but have not really looked into it due to not knowing much about how to incorperate a bms. The bms on the roamer batteries seem to be of a good quality according to some.
Batteries here:
https://roamerbatteries.com/shop/p/...b0vSDOMN94TPJJz-QCt2AUKFtDuyL1CRoCGYQQAvD_BwE
The link you sent me mentions 12v bms's that they supply. Do you know of a good quality reliable bms for 24v that would handle 2 x 24v diy packs in parallel? (unless the bms's can run in series to make 24v? - i know nothing yet, im going to have to have a read about it all)

Thank you..

 

[johnb2713]

Thanks very much for that reply . I have considered doing a diy battery build but have not really looked into it due to not knowing much about how to incorperate a bms. The bms on the roamer batteries seem to be of a good quality according to some.
Batteries here:
https://roamerbatteries.com/shop/p/...b0vSDOMN94TPJJz-QCt2AUKFtDuyL1CRoCGYQQAvD_BwE
The link you sent me mentions 12v bms's that they supply. Do you know of a good quality reliable bms for 24v that would handle 2 x 24v diy packs in parallel? (unless the bms's can run in series to make 24v? - i know nothing yet, im going to have to have a read about it all)

Thank you..

Have a look at Seplos, Daly or maybe Victron as well.

Heres a nice video takes you through the whole process.

 

[Ucatchmydrift]

Have a look at Seplos, Daly or maybe Victron as well.

Heres a nice video takes you through the whole process.

Thanks for the video, i shall watch that later.. Looks like somthing that i would really enjoy doing actually.
Only problem that i can see is cost.
For two 24v roamer batteries giving me 9.4kw useable it costs £3500

To diy the bank using the cells you posted above, including daly 200a bms with bluetooth, i would need 16 cells giving me 4 x 12v banks. Run in series and parallel to give me 24v. Im guessing here, but i take it each 12v bank would need its own bms, so i would need 4 of them at £140 each. Cost of 16 cells totals £2880. Total = £3440, thats without the cost of making the boxes to put them in.
I would get a total of 11.5kw which is more than the 9.4kw, but including box parts, it woild probably total about £3700? Roughly.

Unless i just want a project to do, im not sure its worth it, unless im getting my maths completely wrong, which is quite likely ?

 

[johnb2713]

Not quite right, you would need 8 cells to make your 24v, 210a would give 6.7 kWh 16 would of course double it. The cells from Fogstar 16 batteries would cost £2800 BUT there is a discount code around that will reduce that by 20%. I would use a single BMS to look after the 8 or 16 cells (8S), job done for under £3k

 

[Ucatchmydrift]

Not quite right, you would need 8 cells to make your 24v, 210a would give 6.7 kWh 16 would of course double it. The cells from Fogstar 16 batteries would cost £2800 BUT there is a discount code around that will reduce that by 20%. I would use a single BMS to look after the 8 or 16 cells (8S), job done for under £3k

Ahh ok.... I dont see any 210ah for sale at fogstar? (only 280ah)- if thats what you mean?
But being able to use just one bms for 16 cells would obviously save alot, as would the discount code, which is now 15% (tested and working) instead of 20%, (unless i can find a 20% one that works).
So, 16 x 280ah cells @3.2v each would be 14.3kw - minus 20% = 11.4kw useable
= with 15% discount code: £2447 + say £200 for bms = £2700, so, well worth doing now.
Roamer = 9.4kw useable for £3500
Diy = 11.4kw useable for £2700

Think i will seriously consider this now, assuming ive got it right this time?

 

[johnb2713]

Yes my mistake, big thumbs, small phone keypad, 280A is correct, they also have some cheaper 'B' grade cells, same capacity. The code for 20% was POTV20 which now doesn't seem to work unless it only works once per customer. What I did find is if you setup and account put the batteries in your basket but don't complete the sale, after 2 days you get an email offering you discount!
The DALY BMS is available from places like Aliexpress and there are some on Amazon too, I'm using a Seplos BMS to communicate with my Victron Inverter although comms aren't really needed.
I'm drawing up the battery housing to handle groups of 4 batteries (easier to handle), I will be laser cutting the ply / MDF for the ends, base and sides. If you want a set once youve decided, if you want some cut, cost of materials plus cost of post and I'll cut them for you. I have sourced the sleeve nuts and 6mm screwed rod, again I can give you the suppliers etc if it helps.

J

 

[Ucatchmydrift]

Yes my mistake, big thumbs, small phone keypad, 280A is correct, they also have some cheaper 'B' grade cells, same capacity. The code for 20% was POTV20 which now doesn't seem to work unless it only works once per customer. What I did find is if you setup and account put the batteries in your basket but don't complete the sale, after 2 days you get an email offering you discount!
The DALY BMS is available from places like Aliexpress and there are some on Amazon too, I'm using a Seplos BMS to communicate with my Victron Inverter although comms aren't really needed.
I'm drawing up the battery housing to handle groups of 4 batteries (easier to handle), I will be laser cutting the ply / MDF for the ends, base and sides. If you want a set once youve decided, if you want some cut, cost of materials plus cost of post and I'll cut them for you. I have sourced the sleeve nuts and 6mm screwed rod, again I can give you the suppliers etc if it helps.

J

Thanks for the tip i see there is a 15% off code in my emails already from fogstar this morning , although they are not getting stock untill the 19th october anyway .
Ill have a look at their blog on b grade cells, as not sure on the difference yet..
And thanks for the offer regarding the materials etc.. Ill keep that in mind if i go ahead and mess things up myself ..

Now,, to start reading about bms's.. Seems like a rabbit hole like everything else!

 

[johnb2713]

Thanks for the tip i see there is a 15% off code in my emails already from fogstar this morning , although they are not getting stock untill the 19th october anyway .
Ill have a look at their blog on b grade cells, as not sure on the difference yet..
And thanks for the offer regarding the materials etc.. Ill keep that in mind if i go ahead and mess things up myself ..

Now,, to start reading about bms's.. Seems like a rabbit hole like everything else!

To be fair the DALY one seems straight forward with it's WiFi connection, SEPLOS that I'm getting is better at communication with inverters.