Solar power for your house

Discussion in 'General Electronics Chat' started by Dawud Beale, Oct 29, 2013.

  1. Dawud Beale

    Thread Starter Member

    Feb 10, 2012
    275
    7
    Ok I have a hypothetical situation for you.

    You know that civilization as we know it is going to end and all the normal things you have access to such as a mains water supply, electrical grid, public transport etc are no longer functional. However you know this 6 months in advance and you have 6 months to prepare your property to survive.

    You choose to get solar panels installed on your roof as an off grid form of energy.

    Based on a currently available and on the market technology, you have to choose some solar panels that you would install, and state how you would use them to survive. Obviously they are DC so I want to know the technical details of how you would use it for things like a cooker, water purifier etc. How would you connect your solar panels to the sorts of devices that you would need to survive. Your house is already well equipped with big spikey iron fences, basic security etc.

    No smart ass comments please, it's hypothetical and I'm asking to understand the solar technology and how it can be utilized around the home. My understanding is that its mainly used for hot water at the moment. Is there new systems that can provide your house with power, what do you need to use in conjunction with it and how do you technically determine how to connect it up to appliances?

    Whats the best sort of system you could hook up to your property to keep surviving off the suns energy and what appliances would you need?

    I know there is always someone who will try to be smart and say "I would just party for 6 months" or "I'd go to the government bases" or something but obviously I'm interested in the technical aspects of how you could utilize off grid energy for your property rather than how water tight the storyline is
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,087
    3,027
    One thing to think about is that the efficiency of conversion to electricity with a PV panel is ~10%, storage in a battery system loses maybe half of that. So collecting and storing electricity to make hot water is hugely ineffective compared to directly heating water with solar energy. Use electricity where you have to, but not for heat.

    There is good, off-the-shelf hardware for PV-battery-inverter systems to power a normal home. I think there are also pretty good 12V DC systems, but a typical home today is not outfitted with 12V appliances. (So go steal an RV if there's a zombie apocalypse.)
     
    Dawud Beale likes this.
  3. #12

    Expert

    Nov 30, 2010
    16,248
    6,745
    I grew up in a place with no electricity and the bathroom was beside the chicken coop. The most important thing for me would be a water pump, and that would fail after you can't buy any more. I guess being near a fresh water supply will be very important. This has nothing to do with solar panels? Solar panels only serve things that run on electricity. When, "civilization" ends, it will be a short time until there are no more light bulbs or batteries, let alone well pumps. I would be spending my time refurbishing the root cellar, stocking up on Mason jars, and studying how my grandparents survived.

    Sorry. I can't seem to stretch my imagination as far as you seem to want.
     
    Dawud Beale likes this.
  4. wayneh

    Expert

    Sep 9, 2010
    12,087
    3,027
    And just to pile on #12's comments, remember that the most valuable, most highly evolved, yet basic use for solar energy is to fix nitrogen and CO2 into food. It's called farming. PV panels might exceed the efficiency of plants for capturing energy, but you still need to eat. Our ancestors had no electricity at all until very recently.

    Raising fish in aquaculture might be a good thing to learn.
     
    Dawud Beale likes this.
  5. poopscoop

    Member

    Dec 12, 2012
    139
    16
    Lets take survival out of the question and ask how you would live in a country without a modern economy and a functional distribution grid. (Think Afghanistan)

    Its possible to purchase equipment, just not as easily as running down to home depot, so many things are DIY, and reliability is king.

    Step 1 is list your priorities:

    1. Pumping water
    2. Refrigeration
    3. Cooking (hopefully gas or propane)
    4. Ventilation
    5. Heating water
    6. Lighting

    Then you do the math of peak sunshine, peak load, average load, average sunshine, storage, etc.

    Then design the system with sufficient overhead for failures.

    If you're redoing your house or starting from the ground up, just build for 24v DC or whatever else you can manage.
     
    Dawud Beale likes this.
  6. #12

    Expert

    Nov 30, 2010
    16,248
    6,745
    I would consider 12 volts because automotive lamps will be available in the cars that don't have gasoline.
     
    Dawud Beale likes this.
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    If civilation is over forget solar power: the first gang of free lance socialist citizens will huff and puff and blow your house down to get your goodies. You want to look poor and as bad off as they are.

    Somehow the human race survived hundreds of thousands (millions?) of years with out refrigeration.

    Gas is great for cooking but is going to run out. An ax can be sharpened and trees grow by themselves.

    You're dead inside a week without water. That is the priority.
     
    Dawud Beale likes this.
  8. MrChips

    Moderator

    Oct 2, 2009
    12,415
    3,354
    While I can anticipate such end of civilization senarios, I believe what the OP is asking is what is the best way of utilizing solar energy via solar panels.

    I agree with wayneh. Use solar collectors to heat water directly so that you don't have to take cold showers.

    Use solar PV panels to charge lead acid batteries to power small appliances and night time lighting, not for the cooking range, oven or clothes dryer. You are going to dry the laundry on the clothes line. Not sure what you are going to use for cooking.
     
    Dawud Beale likes this.
  9. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,906
    2,159
    Due to several outages in my location in the past few years and as a hobby I designed and built an off-grid solar energy system. (600W of panels, 4 225Ah 6V golf-cart traction batteries for 12vdc output , a high quality 2kW true-sine converter with a backup in storage and a custom PIC18/32 controller system) I've installed a isolated backup 120 AC system in the house with ORANGE Hospital Grade Receptacles in several critical locations so we know not to use them for normal power. I also have an 2kW isolation transformer and transfer switch to send emergency power to the furnace blower/controller/thermostat for the gas central heating system. Most of the critical electronics (some indoor and outdoor LED lighting, phones, CCTV, servers and network switches, satellite TV) in the house are powered by a 1.5kW on-line industrial quality UPS that my solar controller diverts excess AC power to instead of grid power when the batteries are full charged.
    It's been my experience that using standard 120AC for home solar energy has worked better than trying to send 12vdc around the house. The parts and wiring are common, UL/NEC approved and usually cheaper than 12 RV equivalents, plus modern energy-star rated equipment is usually lower in energy usage for the same size capacity. I have a small Honda eu1000i and utility charger to keep the batteries full when the weather is bad. (Most of the time in an Oregon winter)

    http://farm9.staticflickr.com/8087/8430398032_37f977ebda_h.jpg
     
    Last edited: Oct 29, 2013
    Dawud Beale likes this.
  10. Dawud Beale

    Thread Starter Member

    Feb 10, 2012
    275
    7
    One of the main problems I see with solar is that the mains are 240V AC, so most household appliances are designed for this. How do you connect a 12V battery to your fridge or cooker or water purifier? Surely they are designed for a totally different energy source???

    Also, do hand winded battery chargers exist currently? A dynamo that lets you hand wind it whilst it gradually charges up batteries? Since in a zombie apocalypse you'd naturally need flashlights and things. Well in the movies you do anyway lol. If they don't currently exist, how easy would it be to make a hand winded battery charger? Maybe attached to a bike wheel and pedals toget faster winding speeds.

    I guess we have two aspects to this. 1 how do you utilise solar power for energy. 2 how do you survive with the collapse of civlisation. Since both are interestign and related topics, I guess we can just discuss it all.

    So in response, I agree, food is essential. So a plot of land in the garden where fruit n veg is grown, along with a rain collection system, would be really useful. A bit barrel that collects rainwater. You would still need an electric water purifier to purify the water though from the barrel so what would you buy off the market and how would you adapt it for solar power?

    Of course naturally you would also store up a load of bottled water, tinned food, dried carbs like pasta and rice etc. but you would need a cooker etc.

    So whilst I agree that you would need other stuff, energy isn't a complete waste of time in this scenario IMO.

    You'd need good security too, so your water storage and veg would need to not be visible, so spikey fences should also have high hedges. There is no real way to disguise solar panels on roofs so you;d have to take a gamble but as they are more and more common in the UK, I think you'd have good chances of people not looting yours. Its no guarantee. But I doubt the looters would know how to hook up some solar panels anyway and with all the solar panels in the country you have good statistical odds of them not stealing yours since every neighbourhood has a few solar panels and the zombie films usually only have maximum two or three mobs per city. So your odds are good. Maybe you can increase them if your panels are at the back of the house away from the street but that would depend on where the sun rises and sets.

    So on the electricity issue, what kind of systems would you set up, what appliances would you link them to, how would you adapt to the difference in AC/DC, voltage, frequency etc?

    On the issue of lightbulbs etc. I disagree that they would run out. Its an apocolypse. Most people are dead. The shops get looted within a few days, trucks stop brining food into tesco, most people die or flee the city. There will be an abundance of lightbulbs. Withe energy saving bulbs last 10 years and a load of vacant houses in the city, you'd have supplies to last centuries in your city alone. You'd have to go scavanging now and then for new supplies, maybe "burgle" a few empty houses for light bulbs and other useful things like fuses, wires, roof tiles, whatever was needed for your little fortress. But I think you'd manage.

    Thanks for all sharing your interpretation and opinion of the scenarios. The different takes on it made for interesting reading

    p.s. aquanponics is a useful concept for the developing world but not sure if you would have enough space in your garden for it. Could you make a sustainable pond in the garden that you could actually eat the fish from whilst growing food? Wouldn't it need an air pump? Can garden ponds self sustain and can you put edible fish in there?
     
    Last edited: Oct 30, 2013
  11. MrChips

    Moderator

    Oct 2, 2009
    12,415
    3,354
    There are too many inconsistencies in your post.

    "you would also store up a load of bottled water, tinned food, dried carbs like pasta and rice etc." - how long would your supplies last?

    "trucks stop brining food into tesco, most people die or flee the city" - how does one survive in or out of the city?

    "a load of vacant houses in the city" - where did everyone go? You went with the rest.

    You need to consider two scenarios:

    1) a short term interruption of services and infrastructure,

    2) end game apocalypse.

    Nothing you have described will allow you to survive scenario #2.
    You will have to build a castle surrounded by a moat and much more.

    If you are contemplating being energy independent and living off-grid there are many approaches that you can take starting immediately.

    12VDC to 240VAC is not an issue. There are many solutions available off the shelf.
    I would begin by analyzing all your electrical energy needs, categorizing them into essential and non-essential. Your goal would be to reduce and minimize all energy requirements and improve efficiency.

    Use passive solar heating to heat your living space and bath water.

    Use solar PV panels to charge 12V lead acid batteries. Convert all lighting to efficient LED lighting. Convert all small appliances to run on 12VDC.

    Yes, there is such a thing as a wind up generator. It is called a generator or alternator. You drive this from a petrol engine, water turbine, windmill, or a human pedal machine. You can convert an exercise bicycle to do this. A hand cranked generator is not going to supply enough energy to be worth it.

    As others have suggested, your primary concerns will be water, food and warm shelter.
    You need to focus on water conservation and rain water harvesting into rain barrels, growing vegetables in your own garden and passive solar heating for the home.

    Just as important, you need to be able to provide some skill or product that you can trade with others for things you cannot provide yourself.

    A good place to start is to join a Transition Initiative in your area. There are many all over the UK.

    http://www.transitionnetwork.org/
     
  12. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,906
    2,159
    We need to stick to #1 because if #2 happens the best thing to do is to hide for 6 months or until most of the people have died as any location less protected than Fort Knox will be attacked and ransacked in cities.
     
  13. Dawud Beale

    Thread Starter Member

    Feb 10, 2012
    275
    7
    I don't agree that every single house will be ransacked in an apocalypse. There must be tens or even hundreds of thousands of houses and buildings in cities. Most people would die within a few weeks if the mains electricity and water stopped and the indefinite stream of tesco lorries finally stopped and the shelves emptied and the cafes had no food etc.

    Others would flee the city to get to the countryside where it would be easier to survive. More wild animals to hunt, land to plant food etc. Concrete jungles would be living death traps if the petrol ran out and utilities stopped and shelves emptied. Humans panic and when people started dying in the cities, and people started realising how much of a deathtrap the city is, people start fleeing. We can see that in war zones where the people go into a mass exodus. Same happens in drought stricken regions, earthquake and hurricane areas etc.

    I do think a few roaming gangs will still stay in the cities but the odds of them coming into your house of all houses is low IMO statistically. Plus you'd prob have some arms to protect yourself. Obviously guns are illegal so most people wouldn't have them but swords, bow and arrows, baseball bats etc are all readily available.

    Mr Chips, what type of generator can you cheaply buy that can be attached to an exercise bike and used for power? How would you calculate the voltage and current and frequency its producing and how would you use that info to connect it to an appliance such as a battery charger? Are battery chargers DC? Do they have rectification inside and would the generator AC be easily converted by the battery charger? How would you connect water purifiers and cookers and things to it and fridges?

    Also how would you know when it's best to use solar power and best to use a generator since its better to use up the suns energy that burn your own energy? So I guess the system is two tiered. One aspect if converting the DC solar energy to power your appliances and one is using the AC energy of the generator.

    I'm sure between the two sources you'd have all your energy needs.

    To get fresh water you'd have a barrel and something to collect the water and put it into barrels. As it would be some sort of guttering and you'd get all sorts of crap in the barrel outside, you'd need a good water filtration system too.

    For growing crops, you prob wouldn't need any energy I think.

    What sort of LED lighting can be connected to a 12V battery? Perhaps that would be a use for the solar energy, to charge up the 12V battery and use it for lights at night time. I guess you could have several appliances running off of the battery but would need to know how to calculate the maximum appliances that can run off of it without damaging the battery.

    You also need heating and hot water I guess.

    I haven't seen much in the way of technical information on these replies so far :p

    I'm watching the walking dead at the moment. I'm on season 3 where they start building civilisations again and it's really interesting how they try to bring back all these useful things without public transport, energy grid, water supply etc.

    So I wanted to work on a few projects at fizzpop, trying to create technology that can work without relying on anything from a centralized infrastructure. I'm thinking about ideas at the moment for what would be essential and how it can be technically be achieved.

    I'm hopefully going to start working on some projects soon once I know what sort of projects I would need. Should be interesting anyway.

    MrChips the things you pointed out werent inconsistencies.

    Yes the supplies wouldn't last forever but they would help you to hold out for a few weeks or months until things quieten down and give you time to prepare to start looking for materials etc, planting crops and so on and so forth.

    Yes people generally do flee cities during disasters. Look at any city in Syria currently. Look at hurricane katrina in america. The floods in pakistan. The drought in east africa. You get mass exodus during disasters because cities are only inhabitable when all services run smoothly. But for the well prepared person they would be able to survive long term and prob have an abundance of things to scavange from peoples houses once most of the city was uninhabited. No I didnt go with them as they all fleed to the countryside of neighbouring countries or trying to find military bases etc but I didnt need to since I had all my supplies and was well prepared

    I agree that a trade is useful and also having gold and silver for use as currency since I doubt the pounds and dollars will be much use. it might even be an economic collapse that caused the whole mess your in. So having tangible wealth with intrinsic value would be useful. I'll have a look at your site
     
    Last edited: Oct 30, 2013
  14. wayneh

    Expert

    Sep 9, 2010
    12,087
    3,027
    You need to be more specific in your question to get better feedback, IMHO. Pick a more narrow topic - like a human powered bicycle generator - and get started. I can recall detailed discussions of that topic in this forum. Solar to AC is also widely discussed here. Just pick something.

    One thing at a time.
     
    Dawud Beale likes this.
  15. Dawud Beale

    Thread Starter Member

    Feb 10, 2012
    275
    7
    Sure thing, will do. I think the wider topic is an interesting one that adds an interesting dimension to it. I will reference links here when discussions get underway

    Feel free to share any links to threads etc for topics you feel may be useful
     
  16. Dawud Beale

    Thread Starter Member

    Feb 10, 2012
    275
    7
  17. strantor

    AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    IMO the only solution for scenario #2 is to train yourself in the art of survival with nothing, both urban and wilderness. If you can walk into the woods with nothing but a pocket knife and emerge months later still healthy, then you can laugh in the face of an apocalypse. if you can survive on nothing, and have nothing, then nobody has any reason to mess with you... Unless people turn cannibal. That's my beef with the show Doomsday Preppers; they have only ever interviewed two survivalists that I'm aware of and they gave both low scores for not having water storage, a basement full of canned goods, and a cache of weapons - these survivalists are the only ones with a chance outside of the millionaires with underground missile silos and 180years worth of canned goods.

    For scenario #1, a couple of weeks worth of dry or canned food and drinking water, several hundred gallons of non potable water for bathing, and a gun to protect it all.

    IMO the best solution is to prepare for both scenarios.

    I would just use solar backup for vices like DVD player while I wait out scenario #1.
     
  18. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,906
    2,159
    I completely agree with you, remove yourself from people as soon as possible in that scenario,
    I've seen people turn cannibal in few weeks during a hopeless situation.
    http://jonswain.org/articles/articles/articles/Vietboatpeople.html

    Everyone one should be ready for a few weeks on your own in case of a local emergency, how elaborate the plan is for electrical energy is a good topic but that's completely different from living in a period where there is nobody to come to your aid and having to revert to a tribal society.
     
  19. MrChips

    Moderator

    Oct 2, 2009
    12,415
    3,354
    You can build energy harvesting gadgets and take conservation efforts on your own. But in any kind of regional, national or global catastrophe that lasts for an extended period (more that 4 days) you will need help from the rest of the community who will all be in the same state of desperation.

    Besides taking your own efforts you need to build resilience in the community.

    The website for the Transition Initiative in Sheffield is:

    http://www.transitionsheffield.org.uk/
     
  20. Dawud Beale

    Thread Starter Member

    Feb 10, 2012
    275
    7
    Ok then so lets rephrase the question and make it a smaller scale local emmergency where you may need to live off grid for a few weeks
     
Loading...