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Author Topic: My Off Grid System Is Now Complete  (Read 13480 times)
nowty
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« on: July 10, 2012, 10:29:03 PM »

















Some of you may have seen a few of my pics on another thread over the past few months, but as I have now practically finished my off grid system I thought folks might want to see pics of the whole system.

My idea started off to buy a few smallish leisure batteries, a couple of panels on my lower front roof and a very small inverter to run my internet 24/7. BUT, after much reading of these threads, buying some cheap gear off fleebay, getting a bit carried away, etc, etc, it has evolved into quite a system.

All DIY (no FITs facepalm), but I do also have a 4kw grid tie system getting the full rate so I am content overall with the green incentive thing and I have almost doubled my green PV capacity without any DNO issues. Yes I know its not financially viable but nor is paying high green elecy tariffs but at least I know mine is 100% green.  signofcross

Its based on the SMA Sunny Island and the PV is fed into Sunny Boys all AC coupled to it. The Sunny Boys are standard grid tie inverters reconfigured into off grid mode with auto power limiting based on frequency shift from Sunny Island unit when batteries are nearly full and loads are low.

It now runs my big 55 TV, small kitchen TV, main PC, laptop, all internet and network gear, Sky box, telephone base station and above 75% battery at night also my kitchen heated floor, two fridges and central heating boiler.

It started working about 2 months ago and has evolved in operation as I have added more PV, inverters and loads. Even with the rubbish weather we have been having, the batteries have not gone lower than 65% and its now saving me an average of 6 units per day. It is fully automated with auto switch over of loads on/off grid via relays which switch based upon time of day and state of charge of the battery.
« Last Edit: July 10, 2012, 10:42:38 PM by nowty » Logged

11kW+ of PV installed and 54+ MWh generated.
Lithium battery storage of 50+ kWh.
Hot water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground source heatpump.
EV BMW i3 (another 30+ kWh's of storage).
250,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
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« Reply #1 on: July 10, 2012, 11:03:31 PM »

Hi Nowty.....
Really excellent set up......
Well done you are going the way
i wish to be in the future...... genuflect
Please keep us posted as things progress...
CU
CD
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« Reply #2 on: July 11, 2012, 09:06:18 AM »

great

Quote
It is fully automated with auto switch over of loads on/off grid via relays which switch based upon time of day and state of charge of the battery.


Can you explain this part a bit more in detail ?

Thank you

Billi
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nowty
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« Reply #3 on: July 11, 2012, 08:35:49 PM »

The SI has 2 internal multi function relays which can be programmed to switch on by a variety of events and I am using them for the state of charge (SOC) values. To avoid confusion SOC of 100% is full and 0% is empty. Because these internal relays are low power I have them triggering some more powerful external relays which are rated at making and breaking much higher loads and I also needed an extra external relay to add a switch based on time of day. Lets call the internal relay Int1 and the external relays Ext1 and Ext2.

For the load switching I have initially set Int1 at 75% to 90% SOC, i.e. when the battery passes over 90% full the relay is on, when the battery drops below 75% full the relay is off. Ext1 has a grid connection from my main consumer unit to the NC contacts and an AC off grid connection from the SI to the NO contacts. The loads of my heated floor (1.1kw), fridges (0.1kw), central heating boiler (electronics and pump, 0.1kw) are connected to the C common contacts. Therefore the default setting is for grid power for these loads. I utilise another relay Ext2 which is triggered by an external timer so these loads are only powered by the batteries if both the battery condition is good and its also not daytime. This is so my main 4kw grid tie system can still normally power these loads during the day.

I have 3 other low power individual circuits which comprise extension leads running under my floor. These are currently manually switchable between grid and off grid. As winter approaches I will switch some of these back to the grid for the deep winter darkness period.

1)   Sky box, broadband modem, router, network switch, HDMI repeater and network storage unit, telephone base station (0.1kw) and runs 24/7.
2)   Big 55 TV (0.1kw), runs mainly in the evening.
3)   Main PC (0.1kw), runs mainly in the evening.

In operation once the batteries are full the first 25% of the battery will have a heavy load and if there was no sun at all the first 25% would be used up in about 1 day. The second 25% of the battery would last a further 2 days if there was no sun because the load has been automatically reduced. But there is always some sun and even on really bad summer days I believe this 3 days will stretch out to 4 or 5 days. Now we are down at 50%, but are still a few more days away from the disastrous less than 20% level.
« Last Edit: July 11, 2012, 09:34:53 PM by nowty » Logged

11kW+ of PV installed and 54+ MWh generated.
Lithium battery storage of 50+ kWh.
Hot water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground source heatpump.
EV BMW i3 (another 30+ kWh's of storage).
250,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
clivejo
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« Reply #4 on: July 11, 2012, 09:25:07 PM »

Looking good!
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nowty
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« Reply #5 on: December 23, 2012, 01:57:46 PM »

Its now after the shortest day of the year so I thought I would give an update on my system. I was expecting to be shutting the system down or leaving the batteries on float in Dec/Jan, but the system is still working well and is regularly adding 3 to 4 units each day if it is reasonably sunny. To preserve the battery level at this time of year I have limited the depth of battery discharge to only 20%, i.e. it switches back to the grid when battery drops to 80% full and it needs to charge to over 90% full in order to be used the following evening. On standby the system needs about 0.5 units per day to keep the battery level constant and so far it almost always gets at least that much so the batteries dont deplete day after day.

I have estimated that with the extra 3.4kw of off grid PV capacity I have installed and the increased self use of electricity via the batteries, I have increased my annual savings of electricity import from 100 to 400 compared to simply having a standard 4kw grid tie system. With both my grid tie and off grid systems I estimate I will have reduced my electricity import per annum from 6,500 units down to around 2,500 units. Of the remaining 2,500 units, 60% is during Nov to Feb and I think only a wind turbine could make any further impact on that.

Changes I have made since the summer,

1) Replaced the GTI inverters from 2 x SB1200s to 1 x SB4000TL. The advantages are,
a)   Increased efficiency.
b)   I can set a single overall power limit on the SB so this matches the max charging capacity of the Sunny Island and thus lower the risk of overload in mid summer.
c)   I can use SMA Optitrac shade management which has made a big difference.
d)   I made as much money selling my old inverters on fleebay than it cost to buy the new one !

2) I wired in a more permanent second consumer unit to power my off grid circuits and made the system failsafe so if the off grid fails or I manually switch it off for maintenance, the off grid circuits automatically switch back to the grid via a heavy duty power relay with no outage time. This heavy duty relay also replaces a smaller relay which suffered from stuck on contacts on the odd occasion. Pics below.

3) I added my lighting circuits to it, but have taken my heated floor circuit off it. My reasoning here was to have a more lower constant load rather than a few short high peak load.

4) Added some ventilation to the sealed front panel of the Sunny Island which kept filling up with water through condensation which got so bad it shorted out the on/off switch on the front panel and simulated a manual shutdown. This was a most baffling problem which took me a month to diagnose.





« Last Edit: December 23, 2012, 05:32:37 PM by nowty » Logged

11kW+ of PV installed and 54+ MWh generated.
Lithium battery storage of 50+ kWh.
Hot water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground source heatpump.
EV BMW i3 (another 30+ kWh's of storage).
250,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
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« Reply #6 on: December 23, 2012, 04:44:08 PM »

Nice work Nowty  genuflect may the days get longer and longer  Cool
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'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
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« Reply #7 on: January 08, 2013, 08:39:30 PM »

Nowty,
        I have no idea how I missed your thread but it is an exellent setup.It has the hallmarks of a classic little system that could be adapted for use by thousands.When you take into consideration the feeling of independance and the massive relaibility factor then the finance does not really mean that much and it does payback in time.Nice job and like Paul says,May the days get longer and longer  genuflect
                                                                            Biff
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« Reply #8 on: January 18, 2013, 03:39:12 PM »

Bodgetastic! (meant in the nicest way possible).

I haven't yet gotten round to automated circuit switching (preferring to keep separate circuits that I just then swap the loads between manually by selecting a solar or grid 13A socket in the kitchen, etc.).

As you say, it's only on continuous bad runs of black weather that the system bottoms out and you have to run round swapping circuits.

Anyway, congrats on the great work you've done so far and keep at it!
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3.58kWp & 800Ah LiFeYPO4 off-grid(ish). See 'Cobbled together PV in W.Sussex' (in "Show Us Yours")
nowty
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« Reply #9 on: January 18, 2013, 11:44:47 PM »

Having just looked at your website I feel we are on the same wavelength.
Near 30 years ago I did an engineering apprenticeship in the Nuclear industry and gained the proud nickname of "The Bodger" !  sh*tfan

Interesting that you went for lithium batteries as I note that even though yours are less than half my battery capacity, your useable capacity is about the same as you can use more of the capacity and leave them semi charged without worry.
« Last Edit: January 18, 2013, 11:47:59 PM by nowty » Logged

11kW+ of PV installed and 54+ MWh generated.
Lithium battery storage of 50+ kWh.
Hot water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground source heatpump.
EV BMW i3 (another 30+ kWh's of storage).
250,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
nowty
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« Reply #10 on: June 22, 2013, 11:01:47 PM »

My Sunny Island system off grid system with forklift batteries has now been running for about a year so I thought I would share some stats on it. The Sunny Boy / Sunny Island logs (+ some simple maths) have shown,

2316 kWh's have been generated.

1709 kWhs has been used to charge the batteries and the batteries have supplied 1524 kWhs which imply a battery efficiency of 89% which I find quite impressive. It will be interesting to see how this efficiency drops in future years as the batteries age and inevitably sulphate.

The system has allowed me to self use around 2000 kWhs and around 300 saving on my elecy bill and saved 1.2 tonnes of CO2. This is in addition to the circa 150 elecy savings and 2000 FITs income I get from my main grid tie system.

The batteries have used either 10 or 15 litres (cannot remember) of de-ionised top up water.

Percentage of total running time at Battery SOC levels
SOC            % of Time
100%          28%
90%            42%
80%            24%
70%            4%
>60%          0%

The SI gives also gives a battery State of Health (SOH) (%) indicator which is the current measured battery capacity expressed as a percentage of the original capacity of the batteries as manually inputted on commissioning. My current SOH is 96% after dropping to 94% over the Winter period. Interestingly the highest it has ever been is 96% when I first commissioned the system. I think this is because I slightly overestimated the capacity @ C10 discharge rates. The batteries were sold to me as 1000Ah @ C20. Using the SI adjustment table I re-calculated them to be 917Ah @ C10, but I have since seen from the battery data sheets that the capacity should have been slightly lower @ C10. So looks like the batteries are still like new.

I am toying with adding some more panels as a facade on my ESE facing rear fence. Not strictly legal without planning permission but they would hardly be noticed by anyone. This would not add much overall capacity but it would help in early spring and late autumn when the sun is low. I have found that you need more charging power in the morning when the batteries can take a higher bulk charge to give the batteries more chance of completing the slower absorption charge later in the day when excess power is wasted by the Sunny Boy severely power limiting.
« Last Edit: June 22, 2013, 11:18:51 PM by nowty » Logged

11kW+ of PV installed and 54+ MWh generated.
Lithium battery storage of 50+ kWh.
Hot water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground source heatpump.
EV BMW i3 (another 30+ kWh's of storage).
250,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
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« Reply #11 on: June 22, 2013, 11:16:07 PM »

Quote
Percentage of total running time at Battery SOC levels
SOC            % of Time
100%          28%
90%            42%
80%            24%
70%            4%
>60%          0%

thanks for sharing this info

i wonder , what is the total lifespan of a good lead acid battery , ok mine is 10 years old and still   doing ok  , similar cycles like you seen over the year

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1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
nowty
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« Reply #12 on: June 22, 2013, 11:25:11 PM »

I would add that the batteries have actually been lower than 60% on a few occasions but the system must not register it if its less than 1% of the time. Fifty something % on maybe five occasions and forty something % on two or three occasions and then only for a very short time period.

When I set the system up I told myself that if the batteries only last 5 years I would be disappointed and my experiment would be a failure.
If the batteries lasted 7 or 8 years I would be satisfied.
If the batteries lasted 10 years or more I would be over the moon, so here's hoping.
« Last Edit: June 22, 2013, 11:29:13 PM by nowty » Logged

11kW+ of PV installed and 54+ MWh generated.
Lithium battery storage of 50+ kWh.
Hot water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground source heatpump.
EV BMW i3 (another 30+ kWh's of storage).
250,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
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« Reply #13 on: June 23, 2013, 06:19:47 AM »

Excellent and interesting stuff Nowty,

my FLA's are exactly eight years 'out the box' and still doing OK, certainly nothing like the new performance but still perfectly adequate. I reckon 25lts PA and mine are certainly cycled deeper than yours through the dry months, as I tend to switch off 'autostart' if the forecast is for wind. Though having just fitted 940w of these http://www.navitron.org.uk/product_detail.php?proID=664&catID=135 on the roof I'm just waiting for the wind and rain to stop and the sun to come out  Cool

http://lifeattheendoftheroad.wordpress.com/2013/06/14/all-i-need-now-are-the-panels/



Yes I know my battery top is a disgrace but that's a plastic sheet and conveyor belt ontop.
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
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« Reply #14 on: June 23, 2013, 02:46:17 PM »

Hi Paul,
         Good choice of panels.You will be wishing you had had the PV installed years ago.The fuel savings is massive.Cyril will now be taking a back seat and I can guarantee that your oil filled rads will be getting very hot indeed.
   The pv really is the business,
                                Biff
   
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