PowerSwitch Main Page
PowerSwitch
The UK's Peak Oil Discussion Forum & Community
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Questions and advice needed please

 
Post new topic   Reply to topic    PowerSwitch Forum Index -> Solar Power
View previous topic :: View next topic  
Author Message
fumanchu



Joined: 24 Feb 2013
Posts: 16
Location: Scotland

PostPosted: Wed Dec 25, 2013 12:57 pm    Post subject: Questions and advice needed please Reply with quote

Can you run an American f/f on solar power? Or if not, then an ordinary chest freezer? Is it easy and is it not hugely expensive?
We bought this monster because we got it cheap as there is a scratch on one side and they took 300 off the price. A week later, I read that you can get solar powered freezers, and would have preferred one of them Evil or Very Mad
We are very rural here and get a lot of power cuts in bad weather - last 3 days power has been off for 2-3 hours a day - and last week was 12 hours. I worry about the meat in the freezer and am looking for a solution to this, husband thinks solar power is the way to go. Any advice would be welcomed Twisted Evil
Back to top
View user's profile Send private message
woodburner



Joined: 06 Apr 2009
Posts: 3379

PostPosted: Wed Dec 25, 2013 1:52 pm    Post subject: Reply with quote

Happy Christmas fumanchu, Adam2 is the most knowledgable here for almost all engineering topics (:envy:) However, solar power in the UK is not brilliant in the winter, and Scotland will be below the UK average.

There is about 1kW/sqm energy from the sun available in the south, at midday in the summer. It's down hill from there. The conversion efficiency is around 16%, and if it's cloudy the efficiency drops to one tenth of that, so 1.6%. This will let you work out how many square metres you need to run a freezer. Rather a lot.

Even then it is only any good while the sun is up, totally useless at night. For that you need storage batteries. Deep discharge batteries (traction not leisure) are expensive, though they last many years. All told, it is an expensive way to run a freezer IMO. Using a different strategy for food storage might be a better approach. Esp when most food goes into a freezer and is never seen again until it gets thrown out.

For the times when you do have power cuts, could you put a lot of insulation round the freezer? This might give you enough time holding the temperature so the cuts do not matter. 4" Kingspan sheets are very good insulators. Another thing might be a small generator, with a couple of gallons of fuel. (You cannot store more than 10 litres of petrol in a domestic property, but if it's in your car?)

If you do have a solar system it will need an inverter to produce the AC for the freezer, yet more expense.
_________________
If you think the economy is more important than the environment, try holding your breath while you count your money.
Back to top
View user's profile Send private message
fumanchu



Joined: 24 Feb 2013
Posts: 16
Location: Scotland

PostPosted: Wed Dec 25, 2013 2:00 pm    Post subject: Reply with quote

Ok, that really helps. Whatever we do will cost money, unless I take a course in canning. Thanks and happy christmas and a good new year to you too. Cool
Back to top
View user's profile Send private message
fumanchu



Joined: 24 Feb 2013
Posts: 16
Location: Scotland

PostPosted: Wed Dec 25, 2013 2:34 pm    Post subject: Reply with quote

Next question then - if Scotland hasn't enough sun, we certainly have enough wind. Where can I learn more about wind turbines for individual houses? If anybody knows Cool
Back to top
View user's profile Send private message
woodburner



Joined: 06 Apr 2009
Posts: 3379

PostPosted: Wed Dec 25, 2013 3:09 pm    Post subject: Reply with quote

I've no idea,but a minute on a search engine brought up http://www.greenspec.co.uk/small-wind-turbines.php

You will be able to apply for a RHI grant for this, so the rest of us will get charged. There's lots of links.
_________________
If you think the economy is more important than the environment, try holding your breath while you count your money.
Back to top
View user's profile Send private message
fumanchu



Joined: 24 Feb 2013
Posts: 16
Location: Scotland

PostPosted: Wed Dec 25, 2013 3:24 pm    Post subject: Reply with quote

Ok thanks, will give it to husband to read and go and eat chocolate Twisted Evil
Back to top
View user's profile Send private message
kenneal - lagger
Site Admin


Joined: 20 Sep 2006
Posts: 9821
Location: Newbury, Berkshire

PostPosted: Thu Dec 26, 2013 2:41 am    Post subject: Reply with quote

A Happy Christmas, Fumanchu.

We are off grid running off a generator and PV and a battery set and have several freezers. We run the genny for two five hour sessions a day, when the freezers are on, and the rest of the time we are running off the batteries and the 880W of PV during the day and the freezers are off.

The freezers are run at maximum cold and seem to cope with the intermittent power quite well. They have been off for over a day without any problems but they are chest freezers which don't get accessed very often.

I have a feeling that the large American fridge/freezers aren't as efficient as other models available but I stand to be corrected on that. An upright freezer isn't as efficient as a chest freezer because as soon as you open the door all the cold air falls out. It might not take much energy with it at any one time but it is an accumulative effect so the more that it is opened or if there is an imperfection in the door seal the cold loss builds up and more electricity is used.

During a power cut you should not open the freezer door if you can help it and it should keep frozen for a day especially if you set it to maximum cold although the fridge will probably warm up.

If you are subject to frequent power outages you could always install a battery backup system which would cut in instantly when the power goes off. Our switchover system from genny to battery does so so quickly that my computer doesn't even notice. When the mains is on the batteries are charged but when the mains goes off the charger turns into an inverter and supplies the house with 3kW of 240V AC electricity.

You would have to be careful what you ran when the mains was off, no electric kettles or hairdryers for instance, but the lights, fridge and computers and television would last for at least 4 or 5 hours depending on the size of your battery bank and how careful you were with power usage. We have 920Ahrs of battery and we can make that last for 6 or seven hours of what we call normal usage. If we cut out the TVs and computers and just use the lights and fridges the batteries will last a lot longer.

You are probably looking at a cost of 4 or 5k for a 920Ahr system with a 3kW inverter.
_________________
"When the last tree is cut down, and the last river has been poisoned, and the last fish has been caught, Only then will you find out that you cannot eat money". --The Cree Indians
Back to top
View user's profile Send private message Send e-mail Visit poster's website
fumanchu



Joined: 24 Feb 2013
Posts: 16
Location: Scotland

PostPosted: Thu Dec 26, 2013 10:20 am    Post subject: Reply with quote

That is really helpful, thank you. Husband doesn't know anything about all this stuff but is quite interested. Main problem is that we're both in our mid 60s, and he thinks we're too old to bother. Would have done this for sure if we were younger as it seems the sensible way to go.
Living here for 30 years, we have everything else covered for long power cuts, (our longest was 5 days)- coal fired heating and LPG cooking. But the freezer is the one thing not sorted and that bugs me. I think now the big freezer was a mistake Evil or Very Mad
Thanks everybody x
Back to top
View user's profile Send private message
emordnilap



Joined: 05 Sep 2007
Posts: 13973
Location: Houǝsʇlʎ' ᴉʇ,s ɹǝɐllʎ uoʇ ʍoɹʇɥ ʇɥǝ ǝɟɟoɹʇ' pou,ʇ ǝʌǝu qoʇɥǝɹ˙

PostPosted: Thu Dec 26, 2013 7:17 pm    Post subject: Reply with quote

The solar-powered freezers are desperate expensive, sadly. They ought to be the cheapest, if there was any justice.
_________________
"Buddhists say we come back as animals and they refer to them as lesser beings. Well, animals aren’t lesser beings, they’re just like us. So I say fụck the Buddhists" - Bjork
Back to top
View user's profile Send private message
woodburner



Joined: 06 Apr 2009
Posts: 3379

PostPosted: Thu Dec 26, 2013 7:37 pm    Post subject: Reply with quote

There is justice, in fact, justice in the UK is the best money can buy. Twisted Evil
_________________
If you think the economy is more important than the environment, try holding your breath while you count your money.
Back to top
View user's profile Send private message
kenneal - lagger
Site Admin


Joined: 20 Sep 2006
Posts: 9821
Location: Newbury, Berkshire

PostPosted: Fri Dec 27, 2013 12:50 am    Post subject: Reply with quote

woodburner wrote:
There is justice, in fact, justice in the UK is the best money can buy. Twisted Evil


Not quite right. Sorry, being pedantic again "justice in the UK is the best lots of money can buy"
_________________
"When the last tree is cut down, and the last river has been poisoned, and the last fish has been caught, Only then will you find out that you cannot eat money". --The Cree Indians
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    PowerSwitch Forum Index -> Solar Power All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group