solar power information?

Discussion in 'Designing, building, making and powering your life' started by pebble, May 13, 2007.

  1. pebble

    pebble Junior Member

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    Anyone got a good website or online forum recommendation for solar power information? Something that's not too geeky, and that is accessible for women (who generally don't grow up knowing what an amp is) - I find alot of sites assume a level of knowledge I don't have (although I do know a bit).

    I need to get my head around Watts and amp hours etc, so I guess a general electricty site would be ok to start with. And then I need to look at my needs and what is feasible etc.

    I need to set up an off grid system this year based on solar, and a bit of engine generated 12V storage (car/housetruck). Maybe some solar hot water, solar cookers etc. I'm also very interested in passive solar heating but maybe that's a different website.

    I've tried looking online a few times but am wading through too many commercial sites that aren't really helping that much.
     
  2. 9anda1f

    9anda1f Administrator Staff Member

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    Hi Pebble,

    Here's some good places to start:

    Basic Electricity: https://www.eia.doe.gov/basics/electricity_basics.html for terms and science.

    Basic Batteries: https://www.batteryuniversity.com/partone.htm as batteries are the storage medium for solar electricity.

    Basic Solar Electricity: https://www.rerc-vt.org/electric/basics.htm for the concepts behind photovoltaic panels and home solar electricity systems.

    Keep asking questions! There are some very experienced solar users on this site who will work along with you as your knowledge grows and your design comes together.

    9anda1f
     
  3. RobWindt

    RobWindt Junior Member

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  4. arawajo

    arawajo Junior Member

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    Hi pebble,
    I also grew up not knowing what an amp was. It's somewhat frustrating isn't it? These things seem to be innate knowledge in the male of the species. I find it difficult to know what questions to ask in order to get the answers I need!

    Thank goodness for this site and the wonderful posters who can be found here.

    Ta.
     
  5. christopher

    christopher Junior Member

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    The best magazine on the subject is Home Power, which you should subscribe to!

    HP also has a web site https://www.homepower.com, which is well worth looking into.

    There are some good books on the subject, too... and I'll try to remember which one is best... and get back to youy. Home Power would be a good place to start.
     
  6. pebble

    pebble Junior Member

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    Thanks everyone! I'll go have a read and then come back with my questions :)
     
  7. gardenlen

    gardenlen Group for banned users

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    pebbles,

    i'm in the process of gettting hands on info' from those who have actually done it so to say.

    we found that when we wanted to know the nitty gritty there is lots and lots of misinformation out there especially online, and in person just know all that seem more interested in flogging you something. so be careful.

    anyway to date we have one projest listed that may give you some ideas of equipment etc.,. so when you get serious you will have some knowledge.

    the link is on our page here it is:

    https://www.lensgarden.com.au/solar_project_one.htm

    hope it helps.

    it is a pretty basic projest retro fit on a modern type home.

    my opinion in the long term homes are going to need to be designed to run efficiently before renewables will do the job.

    len
     
  8. pebble

    pebble Junior Member

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    Thanks Len. I agree on the need for caution.


    I'm still reading and researching but I have a few initial questions.

    1. I haven't gotten my head around when I need to think in watts or amps. People talk about watt hours and amp hours, and the books on solar are saying to calculate my watt hours, but do I have to understand amps as well (other than to figure out what the watts are)? If the battery is measured in amp hours why am I calculating all these watt hours?


    2. I understand that panels are rated in watts eg 80 watts, and that an appliance uses watt hours, but I don't get yet how the battery in between fits into that. eg if the sun shines for 3 hours what sort of charge is going into the panel and into the battery? How is the power in the battery measured, going in and going out?


    3. When looking at how much power an appliance uses do I go off the appliance or its transformer/adaptor.

    eg my laptop's power: 24.5 V DC 2.64 A (max.)

    the laptop's adaptor's power: input - AC 100-240 V 1.5 A
    output- 24.5 V 2.65 A

    If I wanted to calculate wattage (V x A), which do I use?
     
  9. gardenlen

    gardenlen Group for banned users

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    g'day pebbles,

    read that project at our site and write down waht factors she has there.

    most that i have heard work in amp/hours so you need X amount of solar collector panels to supply power to Y amount of batteries all determined on your household use.

    with you laptop or anything you go by the power the actual appliance uses not any adapters that come with them, is all i know.

    over at the living simply board there is a chap over there would be a big help to you as he designs and installs solar/wind in his country, also another lady (they are both going to do esays g\for me)over there is doing me an essay on her project as they all know even in books and especialy online and face to face the so called experts are going to baffle you.

    for me chatting directly to people who have done it and lived the install expereince is your best line of travel.

    also think about running a dual system that is wind and solar, you may always have some wind but you don't always have sun hey? and also look into a generator for thos days/weeks of little sun, with the gen' is it best to charge up the battereis or run the house with it and put a little into the batteries? 2 good questions there but you will need a good gen set.

    keep in mind the built in obscelescences ie.,. manufactured equipemnt has a useby date electronics generally around 10+- years, batteries maybe 10 years, ok solar panels may last from 25 to 40 years but are you going to leave 20 year old solar panel tecknology on your roof when the latest collectors might be a whole lot more efficient and more powerful??

    eg.,. if batteries cost $6k then every 10 years that is your bae cost. oh the one advice i was given and stick with is don't go the way of feeding back into the grid to save buying batteries.

    just remembered christopher from belize is on this board also check down the list you will see his name he is one i suggested you should caht with, but the other lady is over at als her experience could be quiet valuable also.

    len
     
  10. hardworkinghippy

    hardworkinghippy Junior Member

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    Pebble,

    Honestly, it's not difficult.

    I'll explain what we have and say that I did most of the work for our system. I had a lot of books and some great people to help me and it all works OK. You have a lot to learn but it's not difficult, just complicated, so take one step at a time. :)

    We only have a small system, two little 75 watts windgenerators

    [​IMG]

    and eight 75 watt solar panels

    [​IMG]

    So that's 750 watts of power flowing along at 12 volts charging batteries which hold their charge in ampere hours - a measure of Volts and Watts working together.

    Read through this link to understand more:

    https://science.howstuffworks.com/question501.htm

    We've ten 110 ah batteries;

    [​IMG]

    Which go through three controllers to make sure the batteries are always kept at 13.8v even with the sun blasting away and the wind blowing and never go under 11.5v - otherwise they get damaged.

    [​IMG]

    Then a distribution box to feed the wires around the house in very short runs. All with really fingerbreakingly thick wiring (because it's low voltage DC and the cables lose a lot of the power in heat if they're too skinny) to the sockets in the house.

    We've two inverters which change the current from direct (DC) to normal wavy Alternative Current (AC) for appliances that really need AC and we use cheepo car converters to change DC from 12v to almost any other DC voltage. (I'm typing this on 19v DC)

    I have the laptop on a lot, the television at the same time (we've his'n'her systems :twisted:) and I can shear my goats, use a sewing machine and small hand tools, charge our cameras and the neighbours' mobile phones when there are power cuts. We've loads of light everywhere LEDs are great but don't give out much light.

    These photos will give you an idea:

    https://www.flickr.com/photos/hardworkin ... 120244868/

    We use 2D neons and small strip lights for workrooms and reading lights.

    I'm not around an awful lot because it's gardening season, but I can answer your questions if you don't mind waiting - and I'm sure there are other people who can help you with the technical stuff.

    It's not impossible to do yourself and the feeling when you actually turn something on and it works is amazing. :idea:
     
  11. 9anda1f

    9anda1f Administrator Staff Member

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    Hi Pebble,

    Hardworkinghippy points out a great explanation that uses an analogy between electricity and water. To take it one step further, electricity is based on the flow of electrons. A battery stores an excess of electrons at the negative terminal plates and an excess of positively charged ions at the positive terminal plates. When connected into a circuit, the electrons flow from the negative terminal, through the load, to the positive terminal. The load is a resistance to the flow of electrons (if you connect the two terminals of a battery directly together there is almost no resistance and the electrons will flow REALLY FAST, heating up the wire and damaging the battery. It's called a direct short circuit and is very dangerous. Batteries can actually be used for arc welding...the gap that the electrons must jump across serving as the resistance.) When you charge (or recharge) a battery, you are "pushing" those electrons back onto the negative plates and leaving positively charged ions at the positive plate.)

    So, if the flow of electrons through a conductor is electricity, it is analogous to the flow of water molecules through a pipe or hose. The pressure is similar to the voltage. The higher the voltage, the higher the pressure exerted on moving the electrons. The volume of electrons being moved is similar to the amount of water molecules being moved through the pipe/hose. The diameter of the hose is similar to the resistance of the wire/load to the flow of electrons. And finally, the power of the water flow to move the water wheel is similar to the wattage and is based on the product of the pressure and volume (voltage and current). Finally, the energy of the water (power for an amount of time) will go on until the well runs dry, but a device will consume energy (watt-hours) that will eat into your reserve power storage (batteries).

    This is all for direct current (DC). Note that voltage x current = power. A 12vdc source supplying 10amps will yield 120 watts of power. A 24vdc source supplying 5amps will also yield 120 watts of power. Higher electric current requires bigger wire to carry all the electrons with less resistance . Alternating current (AC) is used to transport electric power over long distances and is what you have in a wall socket, probably 220vac. Those high-tension power lines that run across the country often carry hundreds of thousands of volts, but relatively little current, to deliver large amounts of power to cities far away over reasonably sized wires. In AC, the electrons don't flow from one end to the other, but are instead "joggled" back and forth. This ebb and flow motion of the electrons still contains power and can be used for work, but the equations are somewhat different to take into account the sine wave flow of the current (and voltage). Don't need to know that AC stuff here.

    So, how come almost everything is referenced in watts except the battery? Batteries are chemical devices that can store the electrons (actually negatively charged ions) at the negative plate and positively charged ions at the positive plate. The problem is that batteries don't supply a constant voltage over the course of their discharge, which makes any calculation of their power output vary over time. However, they can supply a fairly steady supply of current and are thus rated in amp-hours instead of watt-hours. A fully charged 12vdc (voltage direct current) battery may measure 13.5vdc (with no load) and gradually decline to 10.5vdc as their charge is used up. A one hundred amp-hour battery can supply 100 amps for one hour or 10 amps for 10 hours or one amp for one hundred hours within the working voltage range of the battery, although the voltage will gradually decline over the period of current draw.

    Solar panels are somewhat the same, in that they are rated for a specified power (watts) when placed perpendicular to the sun on a clear day. If your solar panels are on fixed mounts, they will not generate the rated power except for maybe two hours around noon. If they are mounted on tracking mounts, they will generated much closer to the rated power for a longer period, but even that will fall off in the early morning and later evening as the sunlight must pass through more atmosphere and is scattered.

    So, there are lots of estimations and calculations that must be done to properly size a solar power system, based on your latitude, clear view of the sky from horizon to horizon, type of panel mounting, degree-days of insolation (how much sunshine that you can expect to get, on average, for your climate/weather), and all of the load factors that add up to power the appliances you want to have in your home. But all of that comes later! :lol:

    Your laptop uses about 65-70 watts of power when supplied with 24vdc. The power adaptor uses alternating current power and has a variety of inefficiencies to convert from AC to DC, which is why it will use more power than directly powering with DC. It also tells us something about your system. Battery storage can be of a number of voltages, usually based on multiples of 6 vdc (three cells). In your case (and in many others too) a 24vdc system might be a good choice, as it will supply your laptop with the voltage it needs without any conversions. For you to use your adaptor, you would have to install an inverter (changes DC voltage to AC), then pass that AC through the adaptor to change it back to DC! Both conversions will suffer power losses and inefficiencies.

    Hope this helps a little. Christopher and Richard will find this thread soon and they can help a lot more than I. :D :D

    9anda1f
     
  12. living simple

    living simple Junior Member

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    Solar power

    Hi Pebble,

    I'm just really writing to say good luck!

    I am a 'girl' who lives solely on solar power, but when i have a solar question i just run to my husband! (or if it's really complicated i ring my 'solar power installer man' - who is terrific, and tells me all i need to know!)

    My only big tip is to really check out the appliances you purchase for your home. We don't own an electric kettle, toaster, microwave oven, george foreman griller (tho i'd love one!) or any of those really super duper power sucking devices! We also started out with a Smartdrive Fisher & Paykel washing machine (one of the best for power consumption), then when that died, we decided to buy a Bosch Front loader to save on water - big mistake! The power consumption drained our batteries way too fast - so it's back to Fisher & Paykel for us! I also try to do the clothes washing and vaccumming while the sun is shining brightly! Don't really know if that helps or not, but i like being ignorant sometimes!

    All the best in your endeavours,

    Cheers
    Lyn
     
  13. gardenlen

    gardenlen Group for banned users

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    g'day lyn,

    how would you go using a twin tub we at the very least find they are the most water efficient way to wash by a longway.

    so wonder how their power use compares?

    len
     
  14. christopher

    christopher Junior Member

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    Hahahahaha, Thanks, 9anda1f! Not much to add. Your explanation was perfect, clear, good analogies, and with your informative post, and in the rest of this thread, there is plenty of information to digest. Any further information from me will muddy the water....

    Hardworkinghippy, those wind turbines you have, are they Ampair wind turbines? I have one in a box that lost its tail, somewhere, (long story of opportunistic scavenging), and use an AirX turbine, which I like, but would like to get a larger wind turbine.

    There are so many good wind generators out there, especially in Europe.
     
  15. christopher

    christopher Junior Member

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    BTW, Pebbles, we are hosting a solar design and installation course here starting May 21st through May 26th, it costs USD375 for the 6 days, delicious organic food and lodging in spartan but comfortable solar powered housing included, and we will be installing a 625 watt solar array on a 800 amp hour batter at 12vdc. If you take the course, you'll know what that means!

    You are probably too far away to take it, but....

    The course is described at https://mmrfbz.org/solar.html
     
  16. pebble

    pebble Junior Member

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    A winter trip to Belize - that's very tempting :D :wink:


    Thanks everyone :), I've obviously come to the right place 8)

    I need to have a good read through what everyone has said, and then I thought I'd post more about my situation so I can get a bit more specific (eg my situation is relatively 'low end')

    I'm busy for a few days I think but should get back to this this week.

    cheers,
    pebble.


    p.s. arawajo and Lyn thanks for the heads up about 'girl power' :wink:
     
  17. pebble

    pebble Junior Member

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    Still making my way through all the info and getting my head around the system I have and need to set up.

    I'm going to be living in a series of small, basic buildings (probably 3), one of which is a housetruck that needs independant electricity for when I am on the road. I'll need 240V at some point but to start with I'm trying to get the housetruck set up, so am focussed on that in the meantime.

    It currently has a 12V system for lights and the water pump. There is a PV panel; one deep cycle battery with 85aH @20hr capacity; the truck battery which will charge the deep cycle one when the engine is going; a voltage sensitive relay module; a solar controller; and inside the house a voltmeter and a very basic junction box with one fuse between the battery setup and the house wiring.


    One question I have is:

    How can I tell the wattage of the PV panel? It doesn't have any labelling on it at all. All I can tell you is that it's around 1350mm wide and 440 high, and within that are 36 panels 150mm W x 110 H.

    Can anyone tell from that? Or can I measure the watts? (I have a multimeter, but am not sure what I am meant to measure).


    The other question is:

    Can I put a switch between the battery setup (under the house) and the house wiring so that I can turn the wiring off easily (like a mains switch in a 240V house)? I got two switches in town today - one toggle switch 20 amp @12V, one 'double pole' 10 amp switch that I think is for 240V (it's for 3 wire). No-one I spoke to in town really knew what I needed.

    Do I put a switch before the fuse or after (i.e. between the fuse and the house wiring)?
     
  18. pebble

    pebble Junior Member

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    Another question - in general can I use switches, fitting, wiring and the like from 240V systems in 12V ones?

    And can I use, or rewire to use, things like lamps that are 240V in a 12V system? (assuming I have to change the bulb).
     
  19. gardenlen

    gardenlen Group for banned users

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    pebble's,

    switches and power points etc .,. will be ok bulbs etc that is anotehr thing, thought reckon they will ahve to be specific 12 volt bulbs thgought eh sockets could be standard 240 volt if they are compatable with the bulb construction? not sure about circuit breakers etc.,?

    len
     
  20. hedwig

    hedwig Junior Member

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    Hi Pebble, I didn't follow the thread but I would like to ask if you want to built it yourself? How much money do you want to spent?
    And could you please let us know how your project is going?
    Do you want to feed in the grid? And you want to prodce all of your electricity on your own?
     

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