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Author Topic: 2017 Off-grid  (Read 2295 times)
heatherhopper
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« on: January 25, 2018, 10:07:51 AM »

2017 summary for anyone who likes numbers



This is for an off-grid, all AC coupled, system. The data is derived from standalone monitoring systems but correlates quite well with data from the integrated system (Sunny Islands, GTIs and generation meters). "System" efficiency is simply an expression of how much generation is consumed both directly and indirectly rather than "lost" - and is subject to <3% error. "Battery" efficiency is rather less reliable I think (there being no DC power flow recording) although it is also in line with SI data. DC conversion losses of the GTIs are not accounted for although standby draw is. DC diversion from overvoltage protection and loss of potential generation due to AC frequency shift when the system is saturated are not accounted for - the ambition is to eliminate or at least reduce these to a minimum without just dumping to atmosphere.

Comment or critique on the "methodolgy" (such as it is apparent in a summary) is welcome.

Has anyone any off-grid data for "System" and/or "Battery" efficiency? Doesn't matter whether it is AC or DC coupled or a mix and the size of system is irrelevant - I need some real world (not theoretical) reference to be able to look at my own system critically. When thinking about replacement batteries in the years to come (and any possible new generation and heating provision) I would like to do so with an appreciation of how well (or not) the current set-up works relative to other possibilities.

In general:

PV continues to be as predictable as ever but is increasingly affected by shading - mostly in winter which is of little concern but also now a bit in summer which may soon require some difficult decisions.

Wind has been oddly consistent both throughout the year and also day to day. However the worst of the year's storms generally missed us so this ended up an average year in total with few periods of sustained high winds to push the numbers up.

I have become increasingly relaxed about generator operation so this has been the highest year since installation of wind generation 6 years ago - I imagine experienced off-gridders will smile knowingly. For example it ran for a few hours Christmas day just so we could use the electric oven uninterrupted for the Turkey - irresponsible on the face of it but when you consider the cost of propane and the inefficiency of our gas oven maybe not so clear cut. Generator efficiency per run varies 2.5-3.5 kWh/lt but I have not really tried to optimise the loading and intend to play around with the economics of this a bit in the future.

I can't help wondering about the optimism for a variable renewables dominated national grid when looking at my own little microcosm of a system. Consumption discipline is critical even with an average excess of generation. Easy enough to achieve in a single household but scale it up to the population in general - mmmm!

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Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
Fionn
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« Reply #1 on: January 25, 2018, 10:58:53 AM »

Very interesting data, thanks for sharing!
What is your PV and Wind generation capacity?
I wouldn't be overly concerned by your generator runtime, it's still a very small proportion of your total consumption.
« Last Edit: January 26, 2018, 12:25:03 AM by Fionn » Logged

6.75kW PV - 2.75kW East, 1.5kW South, 2.5kW West. 3 x Flat Plate Solar Thermal with side arm FPHE on 268L cylinder
heatherhopper
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« Reply #2 on: January 26, 2018, 11:36:43 AM »

Quote
What is your PV and Wind generation capacity?

2.8 & 6 kW (as per profile). PV peak limited to 2.5 by Inverter. Rare but not unknown to be at peak capacity and quite impossible to sustain when it does happen.

Quote
I wouldn't be overly concerned by your generator runtime, it's still a very small proportion of your total consumption.

Not concerned about generator run time (cost is minimal and it will undoubtedly outlive me). More interested in utilising the flexibility a bit better - sadly there is a point at which the sustainability, economics and practicality of more storage and renewables make less sense than (for example) a little bit more diesel. Hence my interest in just how efficiently I am currently using the excess, future battery sizing etc. I think a holistic approach is required rather than just bolting on more and more stuff.
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Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
biff
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« Reply #3 on: January 26, 2018, 01:18:43 PM »

Hello HH,
        I know how you feel and can see that you wish to capture and "use" every little bit of energy that you generate in a more efficient way. That means transferring the incoming solar into heat and storing it in heavily insulated tanks but you can only store so much before it all becomes too much and confusing.
  Our losses here are quite substantial because we have an old tired Lead acid bank of 60 forklift cells, but we have learned to live with it and our latest addition to the system,,our 120v pmg charger is quite a game changer. I always intended to be totally diesel free but I realise now that there will always come a time when the Solar and the Wind do not work and I had to have some thing that could top up the bank without needing expensive transfer switches,,sunny islands and all that gear,,So a DC charger straight to the bank with no transformers or AC inverters in between to dilute the charge,,It only has to run for a short length of time and then you can knock it off and go for a 4 hour period without having to worry ,,And of course once the Top 10 ot 12% of the bank are gone,,you start up again,,run for another 100mins and .....
  It is a question of balance, Matching the right PMG to the bank,, In my own case,,I use a 120v x 2kw W/T PMG , I set the rev on the engine somewhere around 1500rpm and with the large pully on the PMG,, it runs at the required 350(approx)rpm,, In starting off on a low bank it dishes out some 12amps@ 136vdc but once the bank starts getting well up,,the resistance pushed the Amps back to 8 or 9 while the voltage is 148vdc, during this time our dump load immersions are working,, There are no transfer switches just the 120v charger starting and stopping..
  It is worth investigating. If we had a new bank, The present one was well hammered before i got it and we have it nearly 9 years but if we had a new bank,,the efficiency would be much greater. But we cannot have everything.. I experimented with different pulleys on the engine,,Too small and the engine would be clattering away with too small a load,,set at 60mm it seemed to be the best of world, The engine got a decent load at the top end,, it started very easy and it as an absolute miser on diesel. I looked everywhere for a horizontal water cooled Changfa but it was only when I used the Yanmar clone and had the project almost finished that i saw one for sale at the right money..I was sorely tempted but I have too many engines and bits and bobs lying about me,,Hiding in little nests around my shed, I do not need any more.
   It sounds to me that a similar project might be what you need.
                                                      Biff
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An unpaid Navitron volunteer,who has been living off-grid,powered by wind and solar,each year better than the last one.
offthegridandy
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« Reply #4 on: January 26, 2018, 02:16:20 PM »

Hi HH and thanks for sharing your data.

I don't keep detailed records like wot you do, partly cos it ain't available ie I have no reliable Amp/hrs or watt/hrs recorded for the WT.  Simply because I've yet to find a meter I can afford that works.  I do know our "house" consumption and have records for 2 out of my 3 PV arrays. And of course I've records for spend on diesel. I'm afraid I can't comment on actual efficiencies I assume 10% as a ball park figure.

Were in the 2 months of the year when the genny runs (more now since I lost the blades on the WT) and I just accept that.

However I'm trying a little test this winter. 

I've now programmed the genny to run for 1 hr every morning at peak load time and have programmed the immersion heater to come on at the same time.  In the one hr run time I get a tank full of hot water so saving on the oil boiler running,  the battery gets an hrs boost, so some 80 amps or so. I often find that breakfast demand can bring the genny on and if it then does a full charge cycle and the sun is out the charge is unnecessary to a degree.

The plot is that after breakfast time the battery is about to get some input from the PV ha ha.  In fact the programmed genny for an hr seems to be gaining me a day of battery time. The Outback can be programmed in a number of ways and I'm using the "must run" facility.  It will be interesting to see how much if any diesel I save, although the equation will need to account for savings on the boiler fuel.

Cheers.

Andy

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8 KVA Lister TS2 Startamatic Genny
24 Volt 1000amp battery bank
Outback VFX3024
4.6 Kw PV array permanently ground mounted
Outback Flexmax 80
2 X Flexmax 30 PV CC
2.5 Kw wind turbine H Piggot design 4.5 Mtr Dia
12 Mtr free standing Tower.
u/floor heating from oil boiler cross linked to 12 Kw
eabadger
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« Reply #5 on: January 26, 2018, 03:00:52 PM »

since our 3 new arrays on the tilt we have minimised diesel usage, the two victron multis dish out 70a each when generator on (throttled back to 110a total), the new generator is 40a rated and i try to load it as much as possible, water electric oil filled rads in shed.
but christmas eve one of my new victrons started to play up and after testing i diagnosed the contactor, been back to victron now for 3 weeks!!
after local dealer qouted €1100 to fix under warranty!

today the sun has returned and as i write we are putting 3.7kw in from the sun!!
the two tilting arrays are almost vertical, the fixed array is about 40% of the tilted ones, so tilt works well.
logging, i have input data from morningstars but still have not built a ecomcms thing, got the sensors just need some pi now.
the new in May morningstars are showing 1000kwh each so assume that is x3 for input from pv

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
heatherhopper
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« Reply #6 on: January 28, 2018, 11:20:21 AM »

Thanks for the comments gents - always good to hear different perspectives.
There are so many off-grid variants and, with us all a bit parochial, it always seems difficult to draw out the useful little gems that are out there. It is understandable that off-grid data sets are like hens teeth - they are, understandably, not a priority for people. However unless you know the real world numbers talk of working efficiencies becomes just too anecdotal.

Biff
Much as I enjoy reading about your DC charger I can't really see how one would be of benefit to me other than as a interesting project and I don't have any PMGs or engines lying around. If the relative efficiency of such a thing could be demonstrated to me with real world numbers and in the context of the complete system I might be interested for future reference. I'm sure it would be ideal for some set-ups. I have a 9kva  generator already in place with many years run time in it. As configured it provides system failure/m'tce back-up, direct consumption, battery charging at up to 180a (24v) and, under normal operation, a mix of the latter two. Sure it operates through the hateful whistlie Sunny Island and has an external transfer switch for bypass but these are very necessary parts of the whole system with a few functions other than battery charging. I can quantify the efficiency of this set-up quite accurately. It is really the way I operate this generator that I wish to make more efficient - it clearly isn't properly optimised as I see individual run fuel efficiencies varying so much and logic says this is down to the loading practice.

I do think your 120v bank has real merits. Sadly it seems a rare thing and not well supported by the mainstream, please - no mention of the smiling chinaman Smiley. My intention is to move up to 48v when the time comes for renewals  but at the moment I am thinking probably at quite small capacity as I am unconvinced by the merits of very large banks.

Andy
You appear to be only two inputs short of being able to start working out some "efficiency" numbers and join the limited ranks of the very boring. I have a good 24v DC meter from our Bergey days which needs a worthy home - pm me if it might be of use to you.

With the Turbine being my main input I don't have a "diesel season" as such so can not really programme in a scheduled generator run. I certainly see the sense in doing so with a mainly PV based system. I do load up the generator manually with washing machine, tumble dryer, dishwasher, electric oven, various space heaters etc etc but most of these are not constant draw. I could easily have some immersions or space heaters linked in at the battery absorption stage but then the issue is which ones and since they are all subject to the primary (log gasification) heating regime their availability is not guaranteed and the economics become more muddied than even your oil equation. I have been toying for some time with putting in a small electric flow boiler. There are a few available of suitable size, pedigree and cost and I think if I use back-up provision as a part of the justification it might be worth it as another heat source since I have some storage capacity that is not reached by direct electric heating.

Steve
My PV  is very deliberately summer optimised. I looked at the inclination before install and decided, even without other factors, that winter angle gain was simply not worth it. I trusted PVGIS on this. If I were to add in more PV I think this would be targeted specifically at winter sun and E and/or W operation. Adjustable tilt and/or orientation are attractive ideas - but bring their own problems up here. Trouble is I can't justify more PV - this far north more of it simply doesn't stack-up economically.

It would be good to see your data once up and running.
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Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
offthegridandy
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« Reply #7 on: January 28, 2018, 01:16:42 PM »

Hi HH and thanks for comment.  When my new WT goes up I will have the metering for that.  Along with the Tower I also got the Auroa GT inverters,  and I also aquired a Landis meter for the feed in tarrif so long term I should be sorted.

On the PV side I have one Outback Mate which covers 2 arrays. I also have a Micro mate and have one other array plugged in but can switch it to other array if needed.  I have 4 PV arrays all at differing alignment. The total array is currently around 4.5Kwp ( 2 more 200w panels in store still) but due to alignments I doubt I'll ever see that but I get nearer optimum across more hrs of the day.  It works.

Andy
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8 KVA Lister TS2 Startamatic Genny
24 Volt 1000amp battery bank
Outback VFX3024
4.6 Kw PV array permanently ground mounted
Outback Flexmax 80
2 X Flexmax 30 PV CC
2.5 Kw wind turbine H Piggot design 4.5 Mtr Dia
12 Mtr free standing Tower.
u/floor heating from oil boiler cross linked to 12 Kw
Scruff
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« Reply #8 on: January 29, 2018, 12:27:09 AM »

but christmas eve one of my new victrons started to play up and after testing i diagnosed the contactor, been back to victron now for 3 weeks!!
after local dealer qouted €1100 to fix under warranty!

Shucks, them blue boxes are not all they are claimed to be.
Put the pressure on Victron, squeaky wheel and all that. Give out to them about the 20% of the product's cost price you spent on that warranty making you entitled to a faster turnaround...or your mate Scruff is going to start stir their name with real-world data on products he bought specifically to list their short-comings and failure to meet design spec.

Take for instance this Victron BMV "Precision Battery Monitor" I have here...Is it a precision instrument? No it's a wishy washy thing that rides a line of best fit and automatically re-cals it's drift at arguably accurate data-points. What do Victron say if you ask them about the drift..."oh it's not accurate after a few days without a "full charge"". Is it a battery monitor? Well no it's an interface, I can't read it unless I'm close enough to poke it...I have a monitor..I can monitor my battery on it from across the room...

Could be worse;
ApprenticeVolt take months, ship it around Europe just for the craic and return it underpackaged with chassis damage.
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eabadger
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« Reply #9 on: January 29, 2018, 10:15:19 AM »

they now say nothing wrong with it!!
but as i have two and tested both in standalone mode off same batts and generator, i even scoped the incoming.
but since i re pointed this out heard nothing!!
victron software said mains conected, i could hear a relay click but no transfer no charge, occasionally worked, when i opened the omron contactor had gone yellow, i assume the small relay drives this contactor and the contactor has been faulty a while.

anyway, sun gone again now.

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
Scruff
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« Reply #10 on: January 29, 2018, 03:57:21 PM »

Ask for your 20% back and tell them you can do a better job yourself.   stir
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eabadger
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« Reply #11 on: January 30, 2018, 08:47:14 AM »

sorry for hijack, but scruff what bmv have you got? i was looking at the 712 and a pi running venus.
inverter repair people now re testing given my detailed (again) diagnosis, one worked one didnt all variables identical.

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
Scruff
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« Reply #12 on: January 30, 2018, 04:02:35 PM »

Well it's a 600 I got used and haven't tested yet. I think I'll install it in the motor in the dash because it's not really suitable as a master unit. First impressions I really don't recommend it. The display is too small to read until you stick your face up to it. The charge detection time max is 50mins where my battery likes to hold absorption for sometimes up to 70 hours if I really hammer them.
I have four major problems with the design; The shunt has an RJ45 port, One PCBs shouldn't live in shuntland, Two the cable losses on that muck cable are going to effect the accuracy over any considerable distance.
It's a theme with Victron where they compromise performance for ease of install and manufacturing costs, the upshot of which is I think I can run sense wires to a shunt from the PCB I'll be siting beside the monitor (so why bother right?..dunno) then using a shorter CatV into the back of the display. So actually the ease of install is a right pain in the hoop because I either have to reverse engineer the PCB and make a lower profile one or live with that gak in the back of my centre console.
Three I want to use one shunt and two (different brand) monitors but the BMV won't play nice with standard 500A 50mV shunts outtov the box.
Four as far as I can tell it doesn't display >100% charge which is very useful to me to see cycle efficiency and charger performance, I find it patronising to have a ceiling on a meter and let's face it's less accurate than those that do.

Get a TriMetric Steve, far superior unit but no internal relay.
The Blue Sea M2 looks interesting but I haven't tried it.
The ApprenticeVolt BTM I have is also shyte and wouldn't recommend.

If you can't read the display from your seat then it's not a monitor and shouldn't be advertised as one.  wackoteapot
It's a lot like hanging a watch on the wall and calling it a clock...
« Last Edit: January 30, 2018, 10:34:56 PM by Scruff » Logged
heatherhopper
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« Reply #13 on: March 14, 2019, 03:16:21 PM »

2018 was another generally unremarkable year for our off-grid set-up. Below is data for last two years (since 2017 data seems to have disappeared from the original post).

March data for 2018 is missing a couple of weeks and the data that was recorded I have not included in year end figures. This was courtesy of the beast from the east which resulted in a monitoring hardware failure (driven snow ingress to a previously dry location), PV outage (weight of drifting snow snapped a connector and also made a prompt fix difficult/pointless) and there was an unrelated Turbine meter failure. Estimate of unrecorded Turbine output (from wind speed records) would be 200-300 kWh. Lost PV production would have been negligible in the circumstances.

I think I have improved generator efficiency with some judicious loading. Now getting 3.5-4.5 kWh/lt reasonably consistently. The downside is I seem to be burning more diesel in total to make the loading worthwhile. Swings and roundabouts I guess but best practice for generator health is supposedly 2/3 loading so maybe worth doing.

Interesting observation from this data is an apparent "seasonal" efficiency difference. Not exactly conclusive as there are many variables in a months operation but simple logic suggests there is an efficiency drop of some 2-5% as a result of daily battery cycling such as would be the case with a PV only generation. I may try and isolate some appropriate periods without other influences and have a closer look.

This year so far we are back to 2014/15 generation profiles which is what I call proper British Isles weather.



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Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
camillitech
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« Reply #14 on: March 15, 2019, 08:16:08 PM »

Hi HH,

impressive stuff, I'm pretty anal myself about collecting accurate generation data but have no means of accurately measuring my consumption or diversion and whilst I did for many years have accurate wind speed data and average temperatures that equipment stayed at the old house. One thing I was pleased about was that the weather data I recorded over the years allowed me to accurately access requirements for the new house. When I say 'ME' I obviously mean someone else but their calcs on data I provided based on three years observations proved to be remarkably accurate.



You really cannot asses the efficiency of a system without accurate real world data hey. My initial calcs based on my 'experience' suggested we needed another heat source like a wood furnace. I had many ŁK set aside for one, however the 'real world' data and not my assumptions based on how 'roasty toasty' the house was or how many times I'd used the washing machine suggested otherwise. Four years ago we moved into our newly built house which is all electric, completely 'off grid' and yes, it has been 'roasty toasty'. Well actually it's been about 20 degrees all year round  Cool

Don't have all me data handy but 2016 3290kWh PV, 3394 + 2207kWh hydro (two turbines) 5211kWh wind total 13376kWh PA and 22h gen run time
                                             2017 3344kWh PV, 2975 + 2091kWh hydro 3248kWh wind total 11658kWh PA and 37h gen run time

The 6kW Proven isn't included cos I've no meter on it yet and it's just heating a shed. Having said that, it is a shed with a heat pump in it for the UFH so it does provided 'roasty toasty' heat but I've no way of measuring it.

Envious of your data, Paul :-)

edit, the graphs were based on wind data taken from a 7m mast and 2.5kW wind turbine power curve with 1kW PV, we increased PV to 4.75kW and mast height of 3.2kW wind turbine to 11m. OK we still run the generator occasionally but I now have absolutely no qualms about it and care little about the cost, it's a 12kW Lister and burns 4.5lt per hour at full load, that's less than a gallon a week over the year or a 25 mile drive PW in a Land Rover.
« Last Edit: March 15, 2019, 08:26:12 PM by camillitech » Logged

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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