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Author Topic: First Battery days  (Read 4334 times)
dan_b
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« Reply #30 on: September 11, 2018, 10:21:54 AM »

Are you able to charge the batteries back from the grid - ie could you get an Economy 7 tariff and then in the darker months when the PV definitely will not get close to giving you a full charge each day, charge it up on the cheap-rate and at least get more use out of the battery whilst buying less expensive off-peak juice...  
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3.06kWp SolarEdge system with a split array:
2.18kWp 10x South facing, plus 4x West facing 880W

Mk1 ImmerSUN DHW diverter
4kW PowerVault Battery
biff
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« Reply #31 on: September 11, 2018, 10:46:01 AM »

In our case Dan,
        We have a battery bank voltage of 120vdc, with a dump load voltage of 138/9 vdc which is low. But then we have 2 x 2kw x 138dc immersions, each with it,s own tank. When I need to boost the bank. I drop an immersion and let the voltage clime up to 146/7 and leave it there for an hour or so. That is what I have been doing for years. The W/T cannot do that but the PV can easily do it.
I can get a lot more power out of the W/T but what we have at present is very civilised and user friendly. Grin. The Original blades used to put the wind up me on a regular basis.
  We have 3 strings of 1100watt and one of 600watt that produce at least one third extra that the rated output. however, The W/T is restricted by the PV once the voltage climbs to 138vdc. In the wet windy weather the W/T comes into it,s own. The driving rain keeps it cool and of course the PV output is reduced so it takes up the slack and ups the amps.
I have no SMA gear or Sunny islands as such. Just  MADE In CHINA stamped in big bold letters on the front of our Hybrid W/T and PV controllers and inverter. I don,t have to phone Switzerland and ask for a code or tap the interface trying to figure out what the "Error "means. Just a little Chinaman,s face on the dash who smiles when all is good and looks dour when the inverter trips. Everything is restarted by simply switching off and on once.
It is the simplest installation on Navitron.
                                     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.
regen
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« Reply #32 on: September 11, 2018, 02:21:12 PM »

I think you are comparing apples with pears here and taking the original thread off track. It was about PV with batteries and a connection to the grid. Any off grid system (as you have) will either need a large battery bank,excess production at all times or a permanently connected genny. This makes both the economics and payback very different.

Batteries may well be part of the future household system (I hope it is) but if based on PV will require considerably more than a 4KW system -Used to be max permissible with a grid connection. At the moment the economics do not make any sense in terms of an add on/retrofit and anybody with a grid connection would be daft to get rid of it as its the cheapest form of back up you can get. It is for the ecowarriors and those who want to point 2 fingers at the leccy companies.

That said if i was just starting and a reasonable fit was available say 18-20p unit then I would be tempted to go for a 6-8kw system and about 6kw battery bank which is what I think the av house would need to stand a chance of a reasonable payback vs the status quo. Problem is that the av house cannot accomadte 6-8 kw panels.

Regen
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3.92w freestanding PV with sb3300 +Imersun
21kw Stratford T70 woodburner
 300litre thermalstore with 3kw and 1kw immersions
 Wall star 25kw oil boiler
  Spring water supply with uv and ro membrane
 Sheep, poly tunnel and approx 80 sq m of raised veg beds.
phoooby
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« Reply #33 on: September 11, 2018, 03:00:58 PM »

Just signed on the dotted line for 10kw of PV and a PW2. The economics are not to everyone's tastes at about 12-13 yrs payback on the PV. This is partially because it is on non optimal roof slopes to satisfy SWMBO. Not really done calcs on the PW2, it was more a case of using every electron we can so may be near 100% PV in summer and charge it with E7 during winter. The warranty on PW is now unlimited over 10 years as it used to be limited to 37mWh over the 10 years. I will be looking to make the most of E7 charging over winter to improve the economics but realistically that is 13.5kw x 6-7p savings per day over 4-5 months of the year which is only (97-140pa). The rest of the savings will come from using PV at night rather than 13p import, so best case 8 months of 13.5 x 13p = 420pa.

420 + 140 = 540 x 10 years = 5400 which is less than it is costing so I hope it lasts beyond the 10 years warranty !.

Another option I have looked at to try and leverage the PW is something like Octopus Go tariff or if I was feeling brave, Octopus Agile which has 30min rates depending on the grid. It looked quite complicated to manage manually but if a gadget became available to manage the data they give you 24 hrs in advance and use this to manage PW charging, then I would certainly look at that.

In short, the economics are not quite there yet but then they weren't with EV's for a long time and I only chose a leaf in 2015 because of a cheap finance deal which was a no brainier. Perhaps my return and investment will become more viable if energy costs increase above inflation which I think they are likely to do in the next 10 years with possibly a kick start on 29/03/2019.

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10.2kw Solar Edge PV. Tesla PW2, Myenergi Zappi and Eddi
Nissan Leaf 24 (gone)
Tesla Model S
Nissan env-200
65k ev miles and rising
6kw WBS
biff
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« Reply #34 on: September 11, 2018, 03:35:57 PM »

 Congratulations Poooby,
                       Well done.
                                   Biff
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biff
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« Reply #35 on: September 11, 2018, 04:06:39 PM »

Hi Regen,
         You are right. i did go off topic, so apologies there.
  4kw would be the maximum that we could cope with from mid June to mid August. This year,during the very sunny weather, I disconnected 2 x 1100w strings.The heat in the house was just too much. I would hate to think of how we would roast with 6kw. Normally none of our PV is wasted. The excess is stored in 500ltrs of water and the heat is exchanged and pumped around the house into the rads and the stove to cool the tanks. 6kw would be out of the question.
We do have the large bank but no permanent connected generator. We have a charger that lift the bank as it runs the house, the most direct and economical way possible. It is only ever used if dense fog and no wind conditions hang about too long. I do have a 5kw diesel geni as well but it is only used in anger to power heavy tools and never connected to the house.
  I wanted a system where we were totally fossil fuel free but it is not to be. We have a 2 ton bank with a reserve for 48 hours no problem but the fog can creep in from the sea here and hang about for weeks. It does happen. Usually after Christmas or into February and rather than drain the bank below 123vdc, I run the charger for 100mins and that provided another 4 hours still keeping well about 124vdc. It is never too late to give it a go. I was 56 when I started building this house and wandered off grid Grin. I still had a property on grid. To put this place on the grid, it would have cost me one pole. I was quoted 1180 punts at the time. I did not move in till 2 years later and in that time i had decided to give off grid a chance..
  After a storm,when there is local outage, I switch on every light in the house.. Me Bad.
                                                        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.
pantsmachine
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« Reply #36 on: September 12, 2018, 12:27:20 AM »

Go for it Biff, there are so many variables regardless, its all good to hear! Throwing wind turbines in and E7 is a good example. Never heard of Octopus so will have a learning moment on their site.
There is also a fit & forget aspect to these pylontech batteries which may appeal to some, it did to me as I work away for a month at a time and KNEW that lead acid check and top up would not fly at my house. The Boss has her limits!

We have already talked about extending the PV system as we have another roof that could take another 2.5 to 3.5kw's or so. Understand that this will depend on DNO ok and will be for our use/storage only and will not qualify for FIT. There would defo be a 3rd battery then. I'll see what our first Scottish freeze and beyond does to the figures.

As people have pointed out below but i'd add that for anyone looking to add storage they have to take a close look at their own specific needs. Very few of us will share the same tech set up and where we see 'value' in our properties.

'Batts are for those wanting to fight the system and the eco warriors', I like the sound of that, off for my cape! Smiley

I do like the kids coming back to the house with HUGE bags of washing, they get a crack at the benefit of solar experience as well instead of increased bills at their properties. Makes me very happy and means a lot to me. A different kind of value and they are learning.

The batteries continue to yield 5kw or so each day on a 12+kwh PV day and I can now see an added benefit on high/higher PV generation days of doing all high load works through the day and leave the batteries to reach max SOC later in the afternoon. That way the batteries would provide the excess above PV as demanded thru the day and still have time to max out for evening use without touching the grid. Obvious I know but still thinking my way around the system and working out how to use it to its best.
« Last Edit: September 12, 2018, 05:51:25 AM by pantsmachine » Logged

HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
dan_b
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« Reply #37 on: September 12, 2018, 09:37:02 AM »

Last year, with my 4kW Powervault, I diverted 864kWh from the Solar panels into the battery for discharge later to cover my domestic consumption - all of that would have been exported and then re-imported otherwise.

This year, with the same Powervault, but also using E7 to add some charge to the battery overnight on low rate, I've so far discharged 1100kWh with 3 months of the year still to go.  I've been fiddling constantly with the settings; initially I was putting 3-4kWh in overnight in the dark months, but then since April I have dropped that to 0-1-2kWh in order to allow the battery to capture as much from the sun, depending upon weather forecast.  I'll try and work out how much I have managed to "save" from the differential between the two electricity tariffs at the end of the year.

We had a powercut here a few weeks ago for about 4 hours in the evening and it was also pretty cool to be able to run some lights from the emergency power socket the Powervault has.

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3.06kWp SolarEdge system with a split array:
2.18kWp 10x South facing, plus 4x West facing 880W

Mk1 ImmerSUN DHW diverter
4kW PowerVault Battery
pantsmachine
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« Reply #38 on: September 13, 2018, 12:33:00 AM »

Dan b, does the powervault have a built in charge controller or do you do it manually or thru a 3rd party controller? My system is automatic through a separate charge controller and I am still getting my head round it. Basically its sun-panels-solaredge-charge controller and the charge controller is set for house demand-batteries-export with the Iboost catching anything over 300watts to charge water tank before finally exporting.

There are a couple of generic complete system settings i can choose on the charge controller app but that's about it. I can't go in and force it or tweak specifics (yet).
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HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
Iain
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« Reply #39 on: September 13, 2018, 08:50:38 AM »

Hi
Dan b, Phoooby,pantsmachine

Have you seen this tariff?

https://www.greenenergyuk.com/Tide

It is on the Tariff section of my Powervault, seems quite interesting.
I am seeing how the solar manages before looking more.
I have a permanent circuit fed from my emergency outlet,
central heating, solar thermal,cooker/oven ignition, router,1 light & TV. Worked well when we had a 6 hour power cut for overhead work.

Iain
« Last Edit: September 13, 2018, 08:52:25 AM by Iain » Logged

1.98kWp PV (11 x Sharp 180 and SB 2.5)
20 x 65mm Thermal and 180ltr unvented
Powervault 4Kw - G200 Lithium-Ion (LiFePO4)
9000ltr rainwater storage   Plymouth
andrewellis
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« Reply #40 on: September 14, 2018, 07:29:20 PM »

Hey Pantsmachine, it's been interesting following your posts.  I live just down the road from you and have finally taken the plunge to put a ground mounted system in the garden largely due to your figures posted.  I've found them very useful for my spreadsheet which helped me to justify the install in my head.

I was wondering if you did the battery install of the Goodwe yourself or did you use a company?  Although I won't put them in straight away I think a diy install would make a big difference to the numbers.

Cheers
Andy
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6.48kw Solar PV JA (300W)Panels, SolarEdge inverter
Borehole -> Nibe F1255 12kw GSHP -> Radiators
Nissan Leaf
dan_b
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« Reply #41 on: September 14, 2018, 10:41:45 PM »

Yes the Powervault has automatic charge control up to 1200w charge and 700w discharge. It works alongside my ImmerSun pretty well.
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3.06kWp SolarEdge system with a split array:
2.18kWp 10x South facing, plus 4x West facing 880W

Mk1 ImmerSUN DHW diverter
4kW PowerVault Battery
pantsmachine
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« Reply #42 on: September 14, 2018, 11:01:35 PM »

Hi Andrew, welcome onboard.
Glad to be of assistance (Agghhh, pressure)!  Grin My install was in truth a tad messy. The original installer botched the battery side of things and follow up. I had to pursue that side of the install to completion myself but got there in the end and now have two contacts who I will PM to you if you send me a message? I would not install the charge controller myself but you could for example have it installed with one battery and then fit further batteries yourself later as that is simple and the app for controller is easy enough to use to add further batteries to the system.

Not sure how local you are to The Shire but I found that the inflicted oil tax by local trades is massive and without naming exact figures I managed to have the entire system installed (admittedly across 3 months due to the battery install instead of 1 day) for nearly seven grand less than quoted in our area. That's not a typo.
Go outside the area and bring people in, the further South you go the better it will be!

We have been up and running since 8th June for solar and batteries are only online for a fortnight so far, we also changed suppliers end of August and applied for the FIT in June (what a slow palaver that is). Anyway, ran the figures and with the new power costs, reduced power purchase from grid and the FIT figures we have seen a 4.15% ROI to date. I am surprised at the figure, especially as its not been a clean run with all factors contributing since install date. Its been a good if slightly buckled start and looking forward to seeing what the dry bright Winter days bring.  fingers crossed!

Dan, good to hear, the water heater units are very cool. Actually very impressed by their simplicity and the thought behind them.
« Last Edit: September 15, 2018, 12:44:25 AM by pantsmachine » Logged

HUGE insulation depth.
5.12 kw PV system with Solar edge.
4.8 kw Pylon tech battery storage.
All Low energy bulbs.
Solar I boost charging 210 ltr OSO system tank.
Balanced & zoned CH wet system & Hive 2
Wood fired thermosiphon cedar hot tub.
Masanobu Fukuoka inspired veg garden & fruit trees
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