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Home Forums General Discussion Off Grid, but keeping all mod cons???

Viewing 13 posts - 16 through 28 (of 28 total)
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  • #64669
    NJones
    Member

    Since the suggestion has been made for multiple wind turbines/multiple charge controllers/multiple PSW inverters,… would it be possible to design a modular of grid system?

    I read that there can be issues charging a single big battery bank from many small controllers,.. can this be overcome?

    Is anyone able to recommend specific products (that are available in Ireland or from companies willing to ship internationally) that would be suitable?

    Is anyone willing to post a wiring diagram of how such a system would be implemented?

    #64670
    elnav
    Member

    You say “technically unsound”,.. tell me why it is, & tell me how to fix it whilst retaining the features I need? You say its “wasteful”,… I agree,

    In the first place I asked if you had done a power budget. You did not answer. If you had you would have a better idea of exactly how much power you really needed. Many of my clients live perfectly well on one 3kw inverter. A few want air conditioning so they get two but six invters? that is crazy. In the first place the size of a battery bank needed to support that many inverters at full output would be extremely large. given the quantity of lead involved it would also be extremely large (floor area) and heavy.

    Inverters are unlike any other power source be it solar wind or a generator. They can for a short period handle surges much higher than their continuous rating. This could be 2X or eve 3X

    Inverters all have a small parasitic idling curren. So if they are not delivering power they are still consuming power. That is quite wasteful and carries a penalty by requiring additional solar or wind turbine capacity you would not otherwise need. Having six units online means 6X the wasted parasitic load conmpared to one which is what many homes can make do with.

    My wifes uncle lives off grid on a single Outback inverter and has most of the toys. He doesn’t fell like spending the money for a second unit because the expenditure is not worthwhile to eliminate the minor inconveninece presently imposed by needing to think about load management.

    The technical complications involved with running that many inverters is not that great but does impose construction limitations. This could prove to be more of a headache than you bargained for. Dr. Dave Clark has 30 inverters on Hyperior and the installation has proved troublesome simply due to the number of inverters. Its a three phase system.

    #64671
    NJones
    Member

    I haven’t done a power survey yet,.. I’m working on it though.

    After your comments I did a bit of research & admit that 6 inverters is prob too much even for me,… I really couldn’t survive on one though!

    #64672
    elnav
    Member

    Doing a power budget as opposed to a power survey will at least get you into the ball park. I find that with few exceptions most appliances use less power than the rating plate suggest.

    The biggest benefit of doing the budget up front is that it helps keep you focussed. then as you do actual surveyes you plug in real world numbers and if you have set up the spread sheet correctly you can see if you are ahead of or behind the projections. It never ceased to amaze me that on a 100 foot yacht needing peak demands of 30+ kilowatts of power basic lighting still only consumed 2- 3 kilowatts. Cooking electrically came next in terms of usage but with the modern countertop cooking appliances I find We ourselves are using about one quarter as much nergy as with the older technology stoves etc. We have cooked with gas and even wood in previous homes but electrical cooking today is probably the most efficient. To everyone surprise we found that even solar powered houses with a limited 450 watt of PV panel capacity you can use some electric appliances.

    #64673
    NJones
    Member

    Electrical cooking and heating was something I was expecting to have to avoid (except for a microwave & kettle),.. it probably counts for over 30% of my current electrical usage and the oven & hob are extremely high drain I would have expected?

    #64674
    NJones
    Member

    Slightly off topic,.. but I’ve been reading up on this again today,…

    On the land is a small natural spring,.. really only a trickle of water, maybe 5 litres per minute, so I had discarded the notion of micro hydro generation. There is however nearly 40 mtrs of a fall from the top of the site to the bottom of the field (its on the edge of the valley). All the calculations are factoring flow & head,… can a 40mtr head realistically make up for a tiny flow rate or is there a point in more extreme cases like this where the maths simply doesn’t correspond to the real world very closely?

    #64675
    elnav
    Member

    5 liters per minute calculates out to 7200 liter per day. The micro turbines I know of require a minimum flow rate to be effective. But if you collect the spring water in a storage tank at the top then release the water in bursts of sufficient volume you could generate electricity intermittently. Somehow this is not likely to generate sufficient power unless you are willing to practice some conservation and restraint in energy usage. This was something you made it clear was not acceptable to your wife.

    We must change our ways and begin to exercise responsible stewardship of the resources the earth has for us to use, but not waste.

    The concept is similar to storing the energy from wind that blows 24/7 but never enough at one time to power everything. Generating electricity that can be stored in batteries is therefore necessary. Same goes for solar. Maybe collect solar powe in daytime release water flow at night time.

    #64676
    elnav
    Member

    Someone mentioned that lead acid batteries seldom last more than 5 years. With care they can be kept going about 8 years but rarely as much as 10 years.

    Ther is a class of batteries that can last much longer but these have fallen out of favour in recent decades. I am talking about nickle iron or NiFe for short. The life span of these is uncertain because 75 year old Edison cells as they were also called are still in use. Recently a few companies have begun to resurrect the technology. Nickle and Iron is far less hazarous to the environment that lead and sulphuric acid. According to use experience from the past the electrolyte in NiFe cells needs to be replaced every decade or so. The plates themselves only need flushing and maybe a scrub cleaning. To facilitate this service the cell tops are removable.

    #64680
    NJones
    Member

    That’s very interesting about the batteries,.. I’ll do a bit of googling about them.

    With batteries being one of the most expensive components of the system I had been thinking that if possible a diy solution is something I’d consider.

    The micro hydro would be a semi reliable energy source & may allow me to reduce the battery bank size, as on dark & windless days I’d still be getting some energy generation.

    #64681
    elnav
    Member

    NJones if you want some real help send me an email

    2elnav (at_ netbistro.com

    #64683
    NJones
    Member

    Thanks elnav,.. compiling a list of questions for you at the moment.

    The batteries look very interesting, but all the examples I’ve seen so far are very small scale,.. nowhere near the capacity needed for a house. Have you any links for large scale projects?

    I’ve been reading the about the amazing hydro installation here: https://ludens.cl/paradise/turbine/turbine.html

    I don’t have the water for something like that, but the high voltage transformers that he made are very interesting & would mean that the battery house could be located next to my tiny hydro installation at the furthest point from the house. :)

    #64684
    elnav
    Member

    NJones

    This web based forum and tiny text window really does not lend itself to lenghty missives. Emails would be better If you like you could post a summary here from time to time. Your posts keep including highly subjective terms like:

    “The batteries look very interesting, but all the examples I’ve seen so far are very small scale,”

    That begs the question. How do you know what your house needs if you have not done a power budget yet?

    Most of my clients who live away from the grid find 800 – 900 amp hours sufficient with 3kW – 6kW inverters capacity. There is also a technical reason not to go too large with lead acid batteries. In fact one of the characteristics of the NiFe batteries suggest a battery of only 600 amp Hour capacity may be better depending on your charger capacity. Unfortunately so far I have found Chinese, Australian and North American sources but none near the UK. or even someplace inside Europe.

    #64719
    njb
    Member

    We have lived off-grid for 10 years, at first in an Airstream while building, and have been in the house 4 years, and we have all the mod cons we need — washer, dishwasher, electric kettle, toaster, hoover, large electric fridge etc. Our cooking and booster water heaters are fueled by propane, about 120 gallons a year. We don’t have TV, but use our laptops with wifi as TV, radio, movie player, music source etc.. My comment is primarily directed towards your wife, in case it is she who will be doing most of the household/children stuff. These comments are functional rather than technical, because if she’s like me she cares less about what makes it work than how it works day-to-day.

    Figure out what you need before you decide how much power to go for, but build in a fudge-factor, as you will surely get more stuff (kids need their own computer etc).

    We did a lot of research, and got very efficient appliances, you can’t just buy what’s cheap and easy in the stores. Washer (Asko, because water as well as power use is an issue where we live), Bosch dishwasher for the same reason, point-of-use propane hot water heater, although most of our hot water comes from the rooftop solar hot water heater (Solarhart from Australia) LG fridge/freezer etc. We are solely reliant on solar, passive siting for heating in the winter, solar hot water panels and solar panels to generate electricity.

    Be aware that you do things differently, even if you have all the domestic machinery. I only run the dishwasher and clothes washer in the day, never at night, and probably not at all for two or three days in a row when we have winter snowstorms come through that leave us cloudy for 4 or 5 days; we shower in the morning, in yesterdays solar heated water, so to speak, so the tank fills and heats for hot water use during the day. Remember that the thermal mass of a large body of water (your pool?) inside the house pulls down the ambient temperature in warm weather, but really pulls it down in cold weather. Friends have found it a net negative, and took out their indoor cistern. It’s common to have 10F weather up here in the mountains, so we have a woodburning stove that we light for 3 or 4 hours to boost the passive gain on those occasions. I use it to put porridge, stew or beans (in separate pots!) on after dinner, leave till the morning as the stove cools down overnight, when I can put them in the slow cooker or stove top. A good free pre-cook. If we have extensive snowy/cloudy weather we’ve rigged a switch so we can switch the fridge/freezer off at night to save 6-8 hours of battery use. It holds its temperature well so long as we don’t keep opening the door, so night is the best time for this.

    All mod cons doesn’t mean the same as it does in suburbia, but we live in great ease and comfort with un-onerous common sense adaptation, so good luck, it’s a great life.

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