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charitygardener
Joined: 17 Sep 2013
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vegplot
Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd
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RichardW
Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales
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charitygardener
Joined: 17 Sep 2013
Posts: 4
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Jam Lady
Joined: 28 Dec 2006
Posts: 2506
Location: New Jersey, USA
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 Posted: Fri Sep 20, 13 9:54 pm Post subject: |
 
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We sometimes go off-grid when a storm knocks out the mains electricity for anywhere from an hour to 14 days (the record, and one I'm not eager to repeat.)
When the outage occurs we use a generator. Different models run on propane, diesel, or on gasoline - that's petrol for you.
Now keep in mind that we're trying to keep the freezer frozen, refrigerator cold, and well pump supplying necessary water in addition to lights etc. You just want to run a few lights on gloomy days
A small portable generator might be just the ticket - small enough to transport in a car, useful for what you want.
I Googled using "camping generator sizes" for the search term and one web site had this: "Lightweight, compact generators provide up to 1000 watts of power. They are ideal for powering TV’s, electric razors, gaming consoles, and small lights and fans."
It also said that the noise would be comparable to a normal conversation. So perhaps this might work for you. |
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charitygardener
Joined: 17 Sep 2013
Posts: 4
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Tarrel
Joined: 17 Nov 2012
Posts: 18
Location: Ross-shire, Scotland
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| Posted: Mon Sep 23, 13 7:34 pm Post subject: |
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You really shouldn't have any problems in putting in a solar-powered system for what you need.
The basic setup you need is:
- A solar panel (Your input)
- a charge controller (controls when your panel is charging the battery)
- a leisure battery (your energy store)
- an inverter (to boost the power up to mains voltage)
- some low energy lights
Over a period of,say, a week, the amount of energy produced by your solar panel should equal the amount used by your lights. The storage in the battery will even out the peaks and troughs (say you have a cloudy day in which you use the lights a lot but produce little solar energy, followed by a sunny day when you don't need the lights but produce loads of electricity!)
so, in more detail:
Lights:
In our large kitchen diner we use 5W LED lights to replace the 50W halogens that were there before. The LEDs easily produce as much light as the halogens. For your cabin, I guess you might need four light fittings, each with two directional halogen-style lights. If you use 5W LEDs that's a total load of 40W (8 x 5W). If you ran them for, say, five hours, you would use 200 Watt-hours of electricity.
Inverter:
A cheap 150W inverter will cost you about £20 and will be quite sufficient to run your 40W worth of lights. Halfords, etc, supply them to plug in to your car cigarette lighter.
Battery:
You need a Leisure Battery. You can get these from Caravan stockists, or places like "Go Outdoors". A leisure battery is designed for deep discharge, i.e. regular charging and discharging. A normal car battery on the other hand is deisgned to be constantly topped up. It will be damaged by regular deep discharging. A 75Ah leisure battery should cost around £75. (Ah = "Amp-hour", a measure of the battery's capacity. It means it can deliver 75 Amps for one hour, or 7.5 Amps for 10 hours, etc. it will do this at 12 Volts. Volts x Amps = Watts, so a 75Ah battery will deliver around 900 watt-hours. In other words, it would run your 40W lighting set-up for around 22 hours without recharging).
Solar Panel:
Panels are measured in Wp (Watts peak). So, an 80Wp panel will deliver 80 Watts in full sun. On a cloudy day, or if the sun is low in the sky, it could deliver a lot less. So, in full sun for, say, six hours, your panel would deliver 480 Watt-hours, enough to half charge your battery, and more than twice what your lights will have used when kept on for 5 hours. So, on a sunny day, you'll be putting more energy into your battery than you are using with your lights.
An 80W panel is around 100cm x 60cm in size, and is easily moved around by hand. You could keep it in the cabin and bring it out when you open up. You could make up a wooden stand for it, ideally angled at about 45 degrees to the sun. Alternatively, it would look fairly unobtrusive on the roof, and would be collecting energy whenever the sun is up (e.g 5 am on a summer morning!). By the way, the folding "solar briefcase" things are good, and they come with a charge controller, but they are only 13 Watts.
Expect to pay around £1 per Watt for a solar panel.
That basically leaves the charge-contoller. This manages the relationship between your panel and the battery. If you were confident that your panel would never deliver more energy than your battery can hold, you wouldn't really need one, but it's better to have one. They come in different ratings, according to the size of the panel you are using. Ebay or Navitron are useful sources, but Google "solar charge controllers" and you should get some decent sources.
IMHO a generator will be overkill for what you need, it takes fuel, creates pollution and noise.
Another possible solution taht occurs is to just have the leisure battery running the LED lights and take it home every 2-3 days and charge it off a battery charger!
Hope this makes sense. Any questions, do ask. |
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RichardW
Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales
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| Posted: Mon Sep 23, 13 8:55 pm Post subject: |
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| Tarrel wrote: |
You really shouldn't have any problems in putting in a solar-powered system for what you need.
Agreed
The basic setup you need is:
- A solar panel (Your input)
- a charge controller (controls when your panel is charging the battery)
- a leisure battery (your energy store)
- an inverter (to boost the power up to mains voltage) optional if you use low voltage lights & you will save on the energy used
- some low energy lights
Over a period of,say, a week, the amount of energy produced by your solar panel should equal the amount used by your lights.
Wrong it will need to exceed it by the charge cycle efficiency (about 1.2 times) & any inverter efficiency (80-90%) if one is used.
The storage in the battery will even out the peaks and troughs (say you have a cloudy day in which you use the lights a lot but produce little solar energy, followed by a sunny day when you don't need the lights but produce loads of electricity!)
so, in more detail:
Lights:
In our large kitchen diner we use 5W LED lights to replace the 50W halogens that were there before. The LEDs easily produce as much light as the halogens. For your cabin, I guess you might need four light fittings, each with two directional halogen-style lights. If you use 5W LEDs that's a total load of 40W (8 x 5W). If you ran them for, say, five hours, you would use 200 Watt-hours of electricity.
Inverter:
A cheap 150W inverter will cost you about £20 and will be quite sufficient to run your 40W worth of lights. Halfords, etc, supply them to plug in to your car cigarette lighter.
Battery:
You need a Leisure Battery. You can get these from Caravan stockists, or places like "Go Outdoors". A leisure battery is designed for deep discharge, i.e. regular charging and discharging. A normal car battery on the other hand is deisgned to be constantly topped up. It will be damaged by regular deep discharging. A 75Ah leisure battery should cost around £75. (Ah = "Amp-hour", a measure of the battery's capacity. It means it can deliver 75 Amps for one hour, or 7.5 Amps for 10 hours, etc. it will do this at 12 Volts. Volts x Amps = Watts, so a 75Ah battery will deliver around 900 watt-hours. In other words, it would run your 40W lighting set-up for around 22 hours without recharging).
No it wont, well ok it will but not for many times. You can kill a battery by one full discharge cycle. Far better to stick to 50% discharge or less
Solar Panel:
Panels are measured in Wp (Watts peak). So, an 80Wp panel will deliver 80 Watts in full sun. On a cloudy day, or if the sun is low in the sky, it could deliver a lot less. So, in full sun for, say, six hours, your panel would deliver 480 Watt-hours, enough to half charge your battery, and more than twice what your lights will have used when kept on for 5 hours. So, on a sunny day, you'll be putting more energy into your battery than you are using with your lights.
True but most likely you wont need 5 hours of lights if you had 6 hours worth or full sun. Try doing the same calc for when its not summer. Think in terms of 1 x panels worth of energy all day IE 80Wh when you need 5 hours of lights. Times that up by a weeks usage & see how the system copes.
An 80W panel is around 100cm x 60cm in size, and is easily moved around by hand. You could keep it in the cabin and bring it out when you open up. You could make up a wooden stand for it, ideally angled at about 45 degrees to the sun.
Try 90 degrees to the sun.
Alternatively, it would look fairly unobtrusive on the roof, and would be collecting energy whenever the sun is up (e.g 5 am on a summer morning!). By the way, the folding "solar briefcase" things are good, and they come with a charge controller, but they are only 13 Watts.
Expect to pay around £1 per Watt for a solar panel.
Your a bit out of date. Try nearer 50p per watt. Just dont go for "off grid" type panels. You can just about get a full on grid install for £1 per watt now days
That basically leaves the charge-contoller. This manages the relationship between your panel and the battery. If you were confident that your panel would never deliver more energy than your battery can hold,
(Rubbish, its not what it holds but how much you have used that would matter)
you wouldn't really need one, but it's better to have one. They come in different ratings, according to the size of the panel you are using. Ebay or Navitron are useful sources, but Google "solar charge controllers" and you should get some decent sources.
IMHO a generator will be overkill for what you need, it takes fuel, creates pollution and noise.
Another possible solution taht occurs is to just have the leisure battery running the LED lights and take it home every 2-3 days and charge it off a battery charger!
Hope this makes sense. Any questions, do ask. |
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Tarrel
Joined: 17 Nov 2012
Posts: 18
Location: Ross-shire, Scotland
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RichardW
Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales
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charitygardener
Joined: 17 Sep 2013
Posts: 4
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mark
Joined: 14 Jul 2005
Posts: 2191
Location: Leeds
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dpack
Joined: 02 Jul 2005
Posts: 45460
Location: yes
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