- January 26, 2009 at 1:28 pm #160835
Ok, I’m just about to move into a small bedsit/flat where the only thing I have to pay on top of my rent is the electricity to run my devices.
Now the flat has a pre-payment meter, which uses Â£1 (UK Pound Sterling) to give me 1Kilowatt of power.
Could end up being costly, especially as I several things that run off the mains.
My idea is to get a small solar power kit and run my devices off that – I have seen several possible ideas, all of which charge a 12v car battery which you then run your devices off via an invertor – one of such kits I was looking at was this on located on SolarKitsDirect (probably wouldn’t get this actual kit).
Now this is the question (call me an idiot, an Eco Freak or whatever I don’t care as I want to at least try to save myself money in the future which short term, it probably wouldn’t, but long term it could do):
Would I be better off sticking with 1x12v battery or using more than 1 connected like this:Quote:
image sourced from here
With the same example load of 100 amps presented above the new loads on each battery are as follows:
The bottom battery provides 26.7 amps.
The next battery up provides 23.2 amps.
The next battery up provides 23.2 amps.
The top battery provides 26.7 amps.
Now obviously, looking at the above diagram, running 4 batteries that way would make the first and last battery work hardest so I was thinking only of using two batteries so it shares the load.
Now here is a slight problem that I need advice on….there are obviously many different spec 12v car batteries, some with higher ah ratings than others – for example on SolarKitsDirect, they list a 12v battery ranging from 7ah to 34ah – which is going to be the best one for what I would want to use it for?
The devices I will be using would include:
Laptop (run off the mains when at home)
Desktop PC (although not always used)
Bluetooth headphone charger
External 3.5″ drive caddy
External USB DVD+-RW drive
Small bedside lamp
And a few other mains powered devices.January 26, 2009 at 2:08 pm #181344AlfiharParticipant
Someone correct me if I’m wrong, but with running the 4 batteries in that configuration they should all be ‘worked’ the same amount, or rather the load should be the same across all four.
Remember some devices (laptop) actually run off of DC. The inverter will convert the DC from the battery to AC, then the power brick will convert the AC back to DC, this wastes energy. It would be better if you can get a car charger and connect it directly to the battery.
The heater will drain the batteries very quickly and won’t work with the inverter in that kit. Also that small 10W panel almost certainly wont provide enough power to keep the batteries charged enough to run all of the devices.
I’m quite interested to see how this goes.
Are you able to place the solar panels on the roof, or will they be located somewhere where they only get light some of the time (British weather permitting)?January 26, 2009 at 2:32 pm #181346
that particular kit is just an example. and the heater wouldn’t be connected.
Now seeing as most stuff runs on DC, would buying a car battery + charger + power inverter be a better option?
Or is there a direct method of plugging the stuff directly into the car battery?
as for mounting the solar kit, well the only option i have in the flat is to mount in in the window – but i don’t know how much sunlight it would get or how it would effect the kit.January 26, 2009 at 2:50 pm #181350
First off I need to mention that using batteries in the current range you mention will not give you much power.
Car batteries all output significantly more power than the 34 ah max you are looking to.
There are also questions to be asked about the type of battery-Chemistry as some are better than others for the type of deep-cycle use required by solar power systems.Car starting batteries are not designed for this use really and the lifespan is quickly shortened when used this way as opposed to deep cycle models.
Also there can be concerns of battery acid and outgassing when charging although not with just a 10 watt solar panel.
When the batteries are connected in Paralell like you show they will evenly divide the load between them if they are identical batteries and this brings up another concern.
Strictly speaking the batteries should all be the same and all be put into service at the same time.
MisMatched batteries can drastically effect the total system performance.
Around the US Walmart may have the most accessable and lowest priced Deep-Cyle Batteries that are widely available too and they have a very good warranty exchage program as well making them really the default vendor used by those with RV’s here.
If you really want to do this you need to learn a lot more about it and there are resources all over the internet to do so.
In general though Solar Power is no Panacea.
It is Expensive,The Batteries have to be heavy if they offer any meaningful storage and you do not get a lot of power out for the investment until you have had it for a while.
I realize this is not what you want to hear but generating Solar Meaningful amounts of power is just not inexpensive.
Maybe a better alternative would be to use standard Battery Smart Chargers to charge big batteries while you are gone and there is no load placed on them and then use the stored power to run your devices when needed.
I still think this will be more expensive than just buying the power.
Anytime you are using one power source to generate another there are just wasteful ineffecienies involved and mains power really is not too bad a deal.
I am involved in both Emergency Communications and RV systems and have some experience here and I wish it were otherwise.
EdJanuary 26, 2009 at 3:13 pm #181347
so basically I’m better off sticking with the pre-pay meter?
darn…January 26, 2009 at 4:18 pm #181351
I have no idea if the price you mentioned above that you will be charges for mains power is low or hi?
I do not really even know what a “bedsit/flat” is?
So without any frame of reference at all to compare to I can only assume that you feel the price they will charge is high?
I guess I would restate that Solar is not a quick short term Eco fix.
The materials can be pricey and very large and heavy too.
Unless you have really good sun exposure and can track it with the panels I feel you may be surprised by how little use a small system will provide.
It can certainly be a challenge and entertaining to attempt to live “off the grid” to understand the realities of it and the unique challenge it can provide but I think it could easily provide more Challenge than reward.
I have a Solar System( not the Solar System!) in my small RV and it serves to keep my Batteries charged or Topped off depending on the needs I have at the time and the Sunlight available which varies of course.
If I just use the Batteries to provide some LED Lighting and Laptop Charging and very little Furnace Powering(The fan) I am usually OK overnight.
If I try to power an heater as described in your list I doubt I would get even 1 hour with my 2-100 amp hour batteries.
I do have fun trying though.
EdJanuary 26, 2009 at 5:15 pm #181342jezMember
I do not really even know what a “bedsit/flat” is?[/quote1232990007]
Like a one bedroom apartment. A bedsit is traditionally just one room in a larger house with a kitchen area, bathroom in a self contained unit. A flat might have its own bathrooms, kitchen, living room, etc. So I’m guessing Bluebird’s new pad is a cross between the two. I hope he is moving out on his own for the first time rather than the other reason people end up in a bedsit – their wife has booted them out of the 5-bed town house.January 26, 2009 at 5:51 pm #181348
what I got is a Bedsit, and the reason I’m moving into one is cos it is smack bang next door to work @ the right price per month – and my current landlord whose house I share is getting married so needs the room back.January 27, 2009 at 3:05 pm #181352
So if I understand this,you only will pay for the power to light your room and charge devices but not really to cook or heat?
The more minimal your needs the less it will costt either way.
Also please tell me,is the price you mentioned Higher than usual where you are?
EdJanuary 27, 2009 at 4:43 pm #181349
i only pay for what devices i plug in – the main lighting is covered in the rent.
and as for whether the price is higher or lower I have no idea as my current rent includes bills as well.February 13, 2009 at 1:13 pm #181354scoboMember
I have a setup which might fit your needs.
I use a Xantrex power pack which I charge with 3 solar panels totalling 70 watts.
The power pack (Â£80) sounds expensive at first until you consider what it can do.
It has a 20ah sealed lead acid 12v battery with built-in 400 watt inverter, 250 psi air compressor plus a 12v DC socket (same as a car cigarette lighter socket) and can also be used to jump start a car.
It has a built-in charge controller which you would need to buy separately if you were charging a normal 12v battery. This can charge the battery from a solar panel or with the included mains charger.
So it basically has everything required in one unit saving the need for loads off extra devices and cables. It charges my Samsung NC10 about twice when fully charged.
The solar panels give me enough power to charge the Xantrex to about 75% in a day during the summer but only provide enough to keep it topped up in the winter.
I got the power pack here … http://www.qvcuk.com/ukqic/qvcapp.aspx/app.detail/params.item.556114/walk.yah.UKGD-U083
They also have a smaller 175 watt pack at Â£65.April 6, 2009 at 6:54 pm #181353Jonny BlondMember
Â£1 per kwh is ludicrous. I pay 12p per KWH i have similar equipment to you and economy 7 heating for a two bed flat. over the cold winter i used 4000kw over 4 months. i would just change suppliers using you-switch to find the cheapest. they will usualy fit a new meter free of charge.April 6, 2009 at 7:14 pm #181345TCMuffinMember
There has been a lot of discussion recently about power companies over charging for pre-payment meters and Â£1 per KWh does sound excessive.
I’ve just checked with moneysupermarket.com and using my postcode (which is in Cardiff) I get e-on as the cheapest pre-payment meter with a standing charge of Â£0.34 per day and usage charges of Â£0.102585 per KWh. Might be worth checking out 😕April 7, 2009 at 8:30 am #181343
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