Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: daftlad on January 09, 2016, 08:47:02 AM

Title: Seasonal electricity
Post by: daftlad on January 09, 2016, 08:47:02 AM
So I've had enough, toys flying out of the pram going all over the place!
It's time to run for the hills and grow our own veg, build eco houses an stop encouraging those morons we call politicians.
Portugal sounds nice?

Was thinking, maybe a bit of leccy might be nice and quite like the idea of being off grid!
So I was thinking how much leccy do we actually need? Mobile phone, tablet, a few led lights, maybe 50w/h a day well I have a nice big 165 watt panel all I need is a charge controller and a battery, humm, well.... Maybe might want a fridge in the summer?
Convert a chest freezer and it should use less than 200w/h a day?

But then we come accross the big problem........ Tools!

So that got me thinking maybe I should only use tools, washing machine when the sun is out?
Could get 1000watt of panels, maybe 2 batteries a pretty big inverter and as they say Bob is your mother's brother or maybe not.....

So 1000w panels, biggest power tool 2000watt, tools only used for very short durations when the sun is out, my batteries would need to provide 1000watts or more like 1400 on a bad day?

So basically my per day consumption will be pretty low but current draw pretty high for short periods.
I reckon if I use a 24 volt system I am looking at about 60 amps.

How big do my batteries have to be to maintain a high enough voltage that the inverter doesn't trip out?
How big do the batteries have to be so I don't wreck them?
What sort of batteries?

Oh and I don't want to spend much money.....

Hope everyone is well  :norfolk

Title: Re: Seasonal electricity
Post by: biff on January 09, 2016, 11:24:31 AM
Hi Daftlad,
          I am glad to help and I welcome your questions. You will get so many different answers to your query that you will be stumped as to what direction to take.
  Now,,Even you do not know what our daily electricity use is going to be,so it a case of suck it and see.
  Starting with 1000watts is a good way to go, but your battery needs to be forklift or better. Bigger dc voltage is advisable,say 48volt.
  You have the right idea with the chest freezer converted to a fridge,,(massive savings on electricity there) but you can use a 24hour clockwork timer that is adjustable for 15 minutes,,so start off with 15 minutes on and 6 x 15minutes off. This will be very near what you want. Or you can go the proper conversion kit for £24.00 with the sensor in the bottom of the freezer and the meter on the wall.
  It just depends on how serious you want to be about it. 1000watts will not run the washing machine, You will need at least 2kw but you can use hot water from the tank and fill it through the top,then pick a wash that does not use the heater. You are right about using the appliances in midday when the sun is at its best.
  There is absolutely nothing to stop you from getting a couple of PV panels and a few batteries in the meantime, to power your led telly, lights and laptop.This way you will get a feel for the amount of power that you can draw off the batts without crocking them. Batts are expensive so a few small lessons learned at the start will save you mega bucks when your system gets bigger
 You will always need a generator a good reliable diesel keystart, say around 5kw. Keep it fully tanked up with a good battery. You can also charge your batts from the generator thereby doubling your fuel economy. The very best of luck,

Title: Re: Seasonal electricity
Post by: jonesy on January 09, 2016, 11:37:22 AM
For 2 years, in the south west of France, I ran 1.1kW of pv with 400Ah@24V.  No where near enough.  Inverter only ran when required. I used to run the lights off dedicated 200VDC so the inverter wasnt running overnight (that wastes 24W/day straight away) The router was 24/7 off the battery and at 12W was the biggest permanent load, and the biggest problem.  Fridge, cooking and water heating was gas. Heating was wood. Wind strength is too low for a turbine. Bottle gas is expensive, at about the same price per kwh as grid leccy. I spent €240pa on gas.
I came within a few hours of deep discharging the batteries after 7+ days of no sun in the winter. In fact winter was the biggest challenge; even though the panels are colder and more efficient there is way less hours of sun. Currently seeing 500W of generation on sunny skies/high cloud. Rarely saw more than 800W in the summer. Panels are ground mount due south no obstructions, tilted to optimise/average production throughout the year, so I got less in the summer, more in winter.
I looked at buying more panels to get a total of 3kW, 48V inverter and a battery of around 800Ah@48V which I felt would be enough for a more normal life. In the end the grid connection was significantly less and I put the panels on a GTI under 'self consumption' - IIRC that's ok in Portugal. My annual bill is around €150, or 1.4kWh/day, with all the 'normal' DW/WM/immersion appliances. Gas is down to €80pa. In 4 years on grid we've had 3 power cuts all due to technical, rather than weather issues. I still have a small genny but that's not run in anger for 5 years.
Off grid is a steep learning curve and I rarely had a day I wasn't tinkering, which was fine. However, if I had been ill for any reason, or not around, it would be pretty unlikely a local spark would have been able to fix it.
We grow our own veg, but allow 20-30 hours per week May to Sep, water regularly, and you need to be very creative with cooking. Don't go away if you rely on the food. You have to over produce in case of failure or infestation. Don't buy a freezer, it's diminishing returns and either bottle preserve or compost.
We no longer grow spud as the slugs get most. Brassicas are difficult due to insects. Garlic crop all but failed this year. Tomatoes were ok this year but largely failed last year due to blight, despite being drenched in copper sulphate.
We have around 150m2 of veg and 3000m2 of land (garden). I average about 5 hours per week tending the land strimming/cutting/felling etc.
It's a good life, but you need to be able and fit. Doubt we'll do it beyond 70, as chopping, felling, splitting & stacking fire wood takes a bit longer each year!
Do it, but with a 1kw panel and 2 batteries, you will be dish washing and clothes washing by hand!  

Title: Re: Seasonal electricity
Post by: daftlad on January 09, 2016, 05:42:14 PM
Cheers for the replies.
I have a washing machine that uses 80 wh for a cold wash but (I googled washing machine motor wattages) the motor uses 400, and the water heater uses 2kw? So make sure the heater never switches on and I should be OK? Or maybe not?

So lets look at some numbers?
Let's say a base load after dark of 100wh lights, phone and tablet and during the day another 200wh for the fridge (I wont open the fridge after dark!) so 300 wh a day.
Then there is the other stuff the stuff that will only go on if the sun is out.
Let's say I have another panel giving me 330watts of panels multiply by 5 hours we have 1.65 kw/h per day so in theory after the base load I have 1.35kwh spare, plenty to run the washing machine and some power tools.

If I have 2x 12 volt 100ah batteries will the high current loads ruin them even though they are for a very short duration?
I was also thinking of putting some super capacitors in the system to help with starting the motors up.

So the big question is how much rubbish am I coming out with?



Was thinking of 24 volts so I can do lights phone charging etc without the inverter being on.
I am going to try and avoid the generator, if the sun don't shine we don't have electricity!
I guess the idea of suck it and see is best...

Title: Re: Seasonal electricity
Post by: jonesy on January 10, 2016, 10:47:30 AM
330watts of panels multiply by 5 hours will not give 1.65kWh, mainly due to the sun not shining at full brightness for 5 hours, if at all.
Based on my array, yesterday, a mainly sunny day, your panels would give 600Wh.  Picking a perfect sunny day in July would give 1.5kWh. IIRC a new battery has an efficiency of 80%, so you'd get out 480/1200Wh respectively. That assumes you have a MPPT charger.  If not, these figures could be substantially lower depending on mismatch between panel and battery voltage.
Current generation is 32W. Current house load 34W. Router & 2 laptops. If I had batteries, they would be getting nothing.
My fridge is A+++ & consumes ~700Wh/day.  This is substantially less that the 3 way (12/240/gas) absorption fridge it replaced. A camping fridge (peltier) is even less efficient and needs power 24/7 to keep food safe. Might get one at 700Wh/day. Have a look at the compressor based caravan fridges if you must have 12V. Half my leccy bill is the fridge, then router, kettle and I just waste the rest (about 20%) on TV, lighting, laptop.
24V doesn't travel well, and volt drops soon stack up. LED/CFL light drops off once you move away from nominal operating voltage.
Bread. Sliced doesnt exist in France, and if you can find it, it last 2 days at best. I used to go to the local bakers 14km in winter, 8km in summer every day. Bread is €1. The true cost of the journey was €7 + 1/ €4+1.  I could cycle, but the altitude difference is around 500m, and I then needed a shower on return. About 50c to heat the shower water by gas. Bought a bread maker pretty quickly, running it every 3 days. Paid for itself in a month or so. But needs leccy.
To run the WM you'll need an inverter of at least 2kVA as otherwise the motor will trip it (that's a current of around 83A @ 24V). The 3kVA didnt trip, but had a huge loss, so only ran it for power tools/ washing machine. 80Wh doesnt sound enough for a WM, as the motor is doing something for 90 mins. I looked at yesterdays run, but the heater kicked in (hot fill machine!) so it took 1kWh. Removing the spike, it's around 600Wh. The old/more abused a battery, the higher its internal resistance; what this means is that it is unable to deliver amps without the volts dropping and the inverter tripping off.
You don't mention a TV, so maybe you intend to stream to the tablet?  You'll need 3-4Mbits ADSL for that which you won't get in a remote area unless very lucky.  Satellite ADSL is expensive and is another appliance 24/7
So the big question is how much rubbish am I coming out with?
The system you describe will probably be ok  May to September, running out of juice some of the time, assuming the sun shines, but once the clocks change it's like turning off a tap. IMO Batteries won't last long. Biff talks sense.

Title: Re: Seasonal electricity
Post by: daftlad on January 10, 2016, 12:20:03 PM
Don't watch much telly so won't miss it...
I realised after writing my last post that it didn't really fit in with your real world experiences. In reality less than 500wh from 1.1kw of panels, didn't think it would be that bad in southern France!
There are people claiming less than 100wh day for the converted chest freezer into a fridge so I thought 200wh day was about right?
There is the 12/24 volt compressor made by danfoss, apparently it is super efficient in a chest fridge but the cost approaching a grand!  facepalm
I will look again at the energy usage of the washer, put the energy monitor on it.
I guess 1000wh day is not unreasonable even if I wash clothes cold, have a chest fridge, don't use routers, computers etc.
On good days I would be able to use tools and the bread maker and washing machine.
On bad days I would have to get the bike generator out!

Will keep thinking..... :norfolk

Title: Re: Seasonal electricity
Post by: todthedog on January 10, 2016, 01:09:57 PM
Hello Daft lad

Simply go for it.
We left the UK 15 years back to move to Finistere in Brittany. :norfolk
No specific plan in mind,just a desire to try and regain control of our lives, but arrived at 'the good life' more by circumstances than good planning.
I would recommend a bit of planning!!

Bought a farmhouse with outbuildings and about 3800m2 of land.
In the interim have raised pigs, turkeys ducks chickens rabbits guinea fowl for our own consumption, and chicks for eggs.
Grew a good percentage of our own veggies, drank the wine and joined in with the community. Really important if you are not going to become 'little england'

Renovated insulated the house and done up the outbuildings. Added PV a wind turbine, solar thermal, and heat pump. Water from a well to water the garden.
We are now positive for energy we flog a bit to EDF and this completely covers the cost of what we use, no monastic life, all the mod cons. Off grid just seemed a step too far! facepalm

Lovely area reminds us a bit of the UK of my youff!!

For us now time for a change we are planning a move to Sweden a change of culture and a new language to learn!  Before we get too old.

This is us,%20&prixMin=100000&prixMax=150000&codeNavigation=0

Anyone fancy a move  ;D ;D ;D whistle

Title: Re: Seasonal electricity
Post by: biff on January 10, 2016, 02:34:24 PM
Exactly Daftlad,!
                   Go for it. You cannot go wrong. It is a learning curve. The satisfaction ,when you start generating your own is immense. No matter how small the amount. Just enough for led lights is a feat in its own and surely that is worth going for.

Title: Re: Seasonal electricity
Post by: spaces on January 10, 2016, 05:35:45 PM
^^ Liking the Varde kitchen units, todthedog! I bought several a few years ago on ebay - superb vfm, s/h prices seem higher now than then.

daftlad, the advice to go for it is good - I lived for a while offgrid and I've dug out the average daily figures (in kWh), ish, for mid-winter, substituting laptop (which used about 25w) for tablet:

0.35    Lighting 50w x 7 hours                               
0.03    Tablet 10w x 3 hours                               
0.42    Desktop with 20" screen 70w x 6 hour (2007 iMac)
0.04    Battery chargers 10w x 4 hours
0.07    Washing machine                                                                         
0.27    Fridge  (1500w startup)                                                             
TV 100w - used when spare electricity available

Space heating was the log burner, food was cooked on it and kettles boiled, saving much lpg, superb! Hot water for showers and bathing was heated by solar for 8 months of the year and by waste veg oil in a boiler which lived in a greenhouse for the rest - this doubled as a superb place to dry clothes.

I looked at buying many PV panels, batteries and a wind-genny but I reckoned it could make better use of the £thousands. Perhaps a good decision, given how the price has tumbled.

Instead, I bought a couple of big 12v deep-cycle batteries and set up a charging system for them in the car - the daily commute charged them most of the way and once every three or four days there was a longer trip which fully charged them! The old Mercedes has a huge alternator and runs on 90-100% waste vegoil, which is/was free. I bought a really good inverter and a small part of what would have been spent went on some solar tubes for hot water.

Not only was this system bloody inexpensive, its impact on the planet was minimal too - the car was already made and was already in daily use, fuel consumption dropped from about 40 to 35, with some vegoil used in heating hot water in the dark months. I ended up using one 230w PV panel which was donated when a local environmentalist saw how little impact on the planet my system had - it topped up the batteries nicely in summer and meant the odd Sunday trip to my business premises/blast around the Moors wasn't needed!

Once domestic energy consumption has been reduced to a low level, it soon becomes clear how much energy is used in transport (whether EV or not!), unless everything is doable on a bike. Running the car on a waste, renewable fuel oil which transported me about while providing an energy store for domestic electricity was pleasing - especially when the same, free fuel heated the domestic hot water in the winter.

I still have the iMac as it's reliable, still fast enough, doesn't use much energy compared with other desktops, stands in for the TV usually and is a joy to use, but it's obvious electricity use could be reduced still further in an offgrid situation if you relied on a tablet most of the time. Projectors use less energy than large screen TVs, especially if connected to the tablet with a wire rather than bluetooth. Taking your annual break in January and February would reduce the demand for energy in these cold, dark weeks.

Title: Re: Seasonal electricity
Post by: Billy on January 10, 2016, 06:25:06 PM
I have 683ah @ C20 and it's not enough. I would double it. My 880 Watts of Pv is not enough. I would quadruple it.  The Turnip @ 600 Watt is not enough. I would treble it. Perhaps then I would not need to fire up the Genny.  We run a "normal" house with DW and all that goes with it. It's fun trying. exhappy:

Title: Re: Seasonal electricity
Post by: billi on January 12, 2016, 04:27:40 AM
In reality less than 500wh from 1.1kw of panels, didn't think it would be that bad in southern France!

Hi Daftlad , according to PVGIS , you can expect  much more  per day (on average) , even in winter ...

If you use the heavy tools,  mainly on sunny days  , the battery then will not suffer so much stress ...

If I have 2x 12 volt 100ah batteries will the high current loads ruin them even though they are for a very short duration

I would say yes , one can ruin them fast ,... ok  i had 4  250 ah  12 volt batteries   in my first 2 years off grid and  , we managed to destroy the bank with heavy loads and too fast charging   (still 2 are in use for light/soft applications)

Many 12 volt  " leisure " batteries are rated at only C20 or even worse at C100

Much better idea to get forklift cells (2-4 times the cycle life of  "leisure" batteries ) ,  12pc  110 ah  @2 Volt are costing about 450 Euro ex vat  , they are rated at C5   , that then means  for that 2.5 kWh bank ,  the  capacity rating is relating to 5 hours , so  500 watt would be  a rule of the thump of a draw  , sure you could use more watts  for shorter time ... , but that depends on your power tools and time span  of using them ...

220 ah of those at 24 volt or about 5 kWh   are "only"  about 600  ( so not automatically double the price )  

Do not underestimate the system losses  whistle

Have fun


Title: Re: Seasonal electricity
Post by: V on January 12, 2016, 09:00:34 AM
When we started thinking ours through, we bought one of these:

and put it on the Fridge for 24 hours, the extension lead with the computers on it for 24 hours, etc. We had no idea what water pumps might use or lights. We put it on the hoover and cleaned the house, recorded that, ran the dishwasher for one cycle, recorded that etc. We came out with a ball park figure and guestimated it up. We've now been off grid for a year and half and the 6kwH per day stretching to 12 if we do washing, cleaning  etc. seems to near enough the right figure with room to grow a bit.

We are not nearly as electrically able as you are. We have an electrician who may be able to connect or disconnect things for us, but all decisions/troubleshooting are down to us. There are some very scary moments, but that's life, isn't it?

Go for it.

Title: Re: Seasonal electricity
Post by: biff on January 12, 2016, 11:07:17 AM
And of course Daflad,
                    If you are stuck in any way,there is always the Navitron forum. A pen and paper is a start and a small ,say 12 volt system to get going, to show you the basics and give you and understanding of what kind of power you can draw off and show you what you "Must not do" such as over draw and kill your batts.
  I ran the fridge for some 4 years on gas and it was like throwing money away. I remember Paul saying that the gas was a very expensive way to go and he was right. We shelved a chest freezer and put a conversion kit on it . The freezer now runs as a fridge for a fraction of the cost and 2 large gas does us for over a year,s cooking 220euros. (It has come down in price)
  Plasma telly is out, to expensive to run but the led telly is excellent. You can buy a 15" led that runs directly of a 12v battery around about 100euros. (Tesco). The central heating pump used top be an unseen battery killer and could soak up 100watts+ without a bother but now you can buy C/H pumps that run on 25watt and lot less.
 A decent diesel geni is a must, even if you were on grid and living out in the sticks, you have to have a geni sitting in the background ready to rumble at a moments notice.+ a 30mtr extension cable ;D and 2 x 25ltr jars of clean diesel (red). It is no good going looking for these things when you are in the middle of an outage, then you pay way over your nose.
  There is a small Chinese 3kw diesel for sale on fleabay. It is around £350.00 and maybe £50 extra for the keystart version. They are sold under half a dozen different names. They are noisy and rough and ready but they start first time every time and deliver good quality electricity.They are extremely economic and simple to operate. The way to overcome the noise is to bury them in a hole in the ground leaving plenty of ventilation. Run them with at least 1kw load all the time, never let them roar away empty.
 By starting off this way you will be able to tell exactly what it cost you to live off grid, Then as you add solar pv and W/T ;D, You will see your diesel bill go down and down. Coming nto the spring is a good time to get started. The days are getting longer and you will be able to take advantage of the PV better.
 Everything that you buy should be easily resold if you find that the life style is not to your liking. So do not buy junk. I know that Paul and I differ on the quality and longlivity of the Chinese generator. I am aware that there is loads of Chinese junk as well as UK junk ;D. Paul is a believer in Mr Lister and I know he is right. They are good. But you are not going to wheel Mr Lister into position in a few seconds in an emergency. Mr Chang Fa has worked well for me for years . I have several Mr Listers but every time I go near them, I need to reach over and turn the key on Mr Changfa first. The rolls is a great car but you can get there in a Micra a lot easier.
 I am , at the moment trying to set up a battery charging system ,using a small 3kw diesel generator and a 2kw wind turbine Permanent magnet generator. only yesterday, i pulled the bits and bobs out of storage and took the pull start boss on the crankshaft down to my local engineering works to get a 2" V belt pully fitted.(not back from hols) Then i intend to screw the boss/pully back on to the face of the crankshaft and belt it to the PMG sitting on top of the engine. I will open another thread if I can get the crank boss done the way I want it done. The PMG already has its big pully fitted. I believe that this is an ideal way to run  a geni. It is in fact the making of a diesel inverter geni, the ordinary wind turbine controller just takes the juice from the generator and sticks it in the bank. We will see.

Title: Re: Seasonal electricity
Post by: offthegridandy on January 12, 2016, 09:26:01 PM
Hi Daftlad,

I have just done a schematic of my set up, I know it's larger set up than your current thoughts, but in winter I guess we consume 8 kilowatts per day.  I keep notes and drawings in a file for when the grim reaper knocks and try to update it.

Oh and our genny is a Lister!!

( (


Title: Re: Seasonal electricity
Post by: daftlad on January 13, 2016, 05:04:07 AM
Wow, lots of info.
I think I would still like the idea of only using leccy when we have it, like vegetables!
So a c20 really doesn't like anything other than low current discharge but forklift batteries will take a bit of a higher current hammer, makes sense really.
Lots of panels will help when the sun is out and some super capacitors too for the motor start up current.
Will have to continue this later.
Funnily enough I am off to some woods now and they don't have any leccy, see you in 11 days!

Title: Re: Seasonal electricity
Post by: billi on January 13, 2016, 10:55:07 AM
Lots of panels will help when the sun is out and some super capacitors too for the motor start up current.

Lots of panels ( can be found for 20 p per watt) can be as well a good building material  :garden   , and as well divert extra surplus  units into a hot water tank  foe a warm wash of the cloth and your skin  exhappy: , makes  it easier with the girls then   :fight

Not so sure about the need of "super capacitors"  , sure the idea is good and  already  combined with lead acid batteries ( like the Ultrabattery ) ,

But i guess its more the off Grid inverter  that has to take the start up current ...., i would imagine  2-3 kw rated one can  run  all  your needs

To be honest  , today ,  i would go for those Taiwan built  Inverters ( PIP-2424MSX) with an MPPT chargecontroler inbuilt  .... for about  £600 delivered one gets a 2.4 kw inverter  including 60 A chargecontroler ...

Years back  prices were high and availability of alternatives low ,  that idea of a Victron 2.4 kw inverter and an external outback MPPt charger , costed me about £2500  , but still working  :D (and still happy )

Anyway ,  seems  .. that you are pretty relaxed  ,  so i can only say , that the battery is the Achilles  from the start ,.... the rest then can be extended   as "Pay as you go"

Have fun


Title: Re: Seasonal electricity
Post by: daftlad on January 23, 2016, 07:01:38 PM
Hi all.
Billi, where do you get your batteries from? I have been looking at bimble solar (crown) and battery megastore (Trojan)
I have confidence that we can get away with our base load being very little, and spaces numbers are very helpful.
We will start out with a couple of panels and a single 12 volt 100ish ah battery (suggestions) and just use it for the lights and phone (a caravan system if you will) and see how it goes.
Once we are settled then I will look to something bigger but I really want to live differently without lots of appliances, having said that we need a washing machine! And a .......   ....etc etc!!!!!