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Author Topic: Backup generator for a low consumption on-grid house?  (Read 16841 times)
skyewright
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« on: December 06, 2013, 03:45:05 PM »

Yesterday's 10 hours off power (& we were lucky - the sign of relief when the power returned at around 4pm just as it was heading toward dark was enormous) makes 3 power cuts in the last 3 weeks (though the other 2 were just a few hours each).

Powercuts aren't usually that frequent here, but they  do happen and in addition to unexpected powercuts, we can reasonably expect at least one "your power will be off from 10am to 4pm on Tuesday next" type notice each year - we've had 2 of those this year.

A big part of me says the answer is nice set of batteries especially as across the year we export more electricity on the domestic circuit that we import, but I've been around Navitron long enough to know that a set big enough to provide 3-5kWh at the drop of a hat (i.e. enough to allow us to keep going normally through a working day) is not something to take on lightly. Some day I would like a "hobby" set capable of running some of our 24/7 things like routers & the weather computer for most of the year from some off-grid panels, but a set up capable of running 50-60W during the summer, & just being "maintained" over winter, is a very different thing to a set capable of supporting a 3-400W demand for 12hr or more at any time of year (our 4kWp grid-tie has only generated about 6kWh total in the last week).

So, getting back to the question, does anyone have recommendations for a generator suitable for a household where the overnight background averages 100W (~80W most of the time,  rising to 150W or so for a few minutes as the fridge/freezer kicks in) and normal daytime use only exceeds 400W if we boil a kettle (& we are not daft enough to want a genny to support  that when a small gas ring can easily be dug out of the cupboard), or put the microwave on (which would be nice, but not essential). In a situation of no mains power we could if necessary cut the overnight to zero, and keep the daytime below 300W, or maybe even a bit less, without stopping normal operations, but nicer if we don't need to.

Taking a look at Pete Power's site (www.petepower.co.uk) it sounds as though LPG might be a good idea? We don't use petrol for anything else other than the car & it's 15 miles to a petrol station, so unless we were disciplined enough to regularly tip the spare can into the car & re-fill with fresh, any fuel is storage is likely to be stale.

On that basis an LPG converted  Honda EU20i might be a thought? The "ECO" setting would cope with daytime normal use but brought up to normal speed it could manage a microwave too. Or maybe that would be overkill? A 600W EX7 would cover most things at less than half the price - but is petrol. (Pete has good words for the EU20i, but not for the EX7...)

Thoughts anyone?

« Last Edit: December 06, 2013, 04:08:40 PM by skyewright » Logged

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David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40°, WSW, Lat 57° 9' (Isle of Skye)
martin
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« Reply #1 on: December 06, 2013, 04:58:30 PM »

Well............. it's the original "how long is the piece of string" thing - IF you're just talking the occasional powercuts you've mentioned, you could certainly "get by" with a relatively tiny generator. We get power cuts, and up to now have survived with running a cable in from the shed, connected to a 300w pure sinewave inverter, run from the battery bank and pv panels in/on the shed - it's more than adequate for a few hours of wifi modem/computer/lights/tv. We have a 1.5kw Honda gennie (£70, local market) in reserve (to give fridges/freezers a quick top up in very long cuts), but have never used it in anger for that.........
I'd go so far as to suggest you could almost get way with an el cheapo chinee 2 stroke for such intermittent use (£59.95, Lidl or Aldi, 3 yrs guarantee) - best run through a surge protector or UPS if running delicate stuff whistlie
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skyewright
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« Reply #2 on: December 06, 2013, 05:25:48 PM »

Thanks for your thoughts Martin.

it's the original "how long is the piece of string" thing
Appreciated.

...local market...Lidl...Aldi...
This is NW Scotland, so those sort of sources aren't something you just pop along to. The nearest Lidl, Aldi & anything you'd call a market are over 100 miles away on the other side of the country. Not been that far for years, I'm glad to say.

best run through a surge protector or UPS if running delicate stuff
No difficulty with that. All the delicate stuff is on UPS's anyway. Living 15 miles down an 18 mile overhead spur our mains is relatively "dirty" too.

« Last Edit: December 06, 2013, 05:28:29 PM by skyewright » Logged

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David
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martin
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« Reply #3 on: December 06, 2013, 06:35:08 PM »

Ok - further thoughts - Hondas are indeed beautifully made, go on forever etc., but the newest "i" versions are ludicrously expensive - I've got one of the older "cage" ones - 1.5kw, 4 stroke, starts and runs beautifully, and gives the impression it will go on forever - you should be able to pick up something secondhand similar to mine for £200 - amply beefy enough to get fridges/freezers "over the hump" of starting.
I mentioned the el cheapo chinee 2 strokes because I've long believed they're a load of rubbish from the comments many have made about them, but recently came across a couple going cheap in the local market, so have been experimenting with them, and have been pleasantly surprised..... They're clones of the Yamaha ET650 (or 950), and I would guess come from several different makers in the PRC, and are sold with all sorts of different badges on them (B&Q, Clarkes, Aldi, Lidl etc etc). They're 2 strokes, so are heir to all the usual problems of such engines, but substitution of an NGK plug makes a world of difference, particularly to starting. Because they're so cheap, I suspect many people treat them badly because they don't value them - one of those I bought had the back of the air filter assembly smashed/missing, soon remedied with some bodgineeering involving parts from an old toolbox, pop rivets and silicone. Once fired up and running, they run quite quietly and give remarkably "clean" electricity - I'm running one of them in (I suspect it had hardly been used) and leave it to run when I'm working on my touring caravan, and have a meter in sight connected to the output - rock steady at 50cycles, 239-240 volts when there's a load applied, and only the tiniest of flickers on light bulbs (rather "cleaner" output than I've been getting from a Subaru-built Robin 4 stroke I have) - I'm certainly contemplating chucking one in the boot as "braces" when I go caravanning ("belt" is pvs). I though them worth mentioning for the impecunious and casual users.....
« Last Edit: December 06, 2013, 06:50:53 PM by martin » Logged

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oliver90owner
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« Reply #4 on: December 06, 2013, 10:15:30 PM »

As Martin indicates, but is not specific about, it is your maximum load that is important.

Depending on the type of freezer motor, per eg, you may need a much larger genny to actually get the item started.

With a larger genny, one can always load it up while running, if necessary; but too small is a real pain.  The reduced cost of a good second hand earlier-technology machine may mean a break-even situation for a new high-tech machine is never achieved.

Fuel is not a particular issue apart from safe storage and longevity of some bio versions.  I think petrol stored under very cool conditions and such that the volatiles cannot escape is not too bad, but vented containers soon lose the volatiles.

Sound level may be an important issue for some - a generator thumping or buzzing away is far more noticeable/conspicuous/annoying when the grid is off for everyone else close by.

That Honda you mention would cope easily, I would think.

RAB




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skyewright
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« Reply #5 on: December 07, 2013, 06:29:35 PM »

Martin: Thanks for the observations on the 'el cheapo' units. Interesting, but being so far from a replacement I (& SWMBO) think something a bit more 'solid' would be worth the investment. I'm certainly willing to consider S/H, but buying "unseen" from an unnown source would probably be a poor idea! Pete Power has some interesting looking S/H units, refurbished by someone who knows what he's doing & with at least some guarantee.

RAB: Agree on the petrol. I've had stuff in sealed cans for ages & it has seemed fine when used, but some people seem to make a deal out of it. SWMBO likes the idea of 'clean' LPG. Our F/F is a modern Bosch, not enormous & very frugal on the juice; I believe it has the technology that keeps start up currents fairly reasonable (& unless a power-cut went on for a very long time it could probalby manage okay without power - it shrugged off Thursday's 10hrs easily).
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Regards
David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40°, WSW, Lat 57° 9' (Isle of Skye)
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« Reply #6 on: December 07, 2013, 09:37:51 PM »

my mrs pointed out that our last two power outages (blown up 11kv cable) were only a few hours each. Go to the pub. Save your money. keep fridge / freezer closed. This is a) the 21st C and b) not the third world (contrary to where martin lives, which appears to be the sahara considering his water supply issues... Wink )

I have, for the record, a petrol chinese GMC genny that failed miserably to boil a small kettle during the last power outage, due to it going mad and not revving right, and a PTO genny thats a PITA to rig up currently.
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renewablejohn
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« Reply #7 on: December 07, 2013, 09:59:19 PM »

We live on a farm and the power around us is very unreliable. At least a dozen outages in the last 12 months anything upto 12 hours at a time only about 4 of them actually notified in advance. Having no 3 phase on the farm I bought a 15 kw 3 phase lighting tower with lister engine and had it rewired to be either 3 phase or 1 phase. Now outages are no longer a problem and the amount of diesel used is minimal.
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camillitech
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« Reply #8 on: December 07, 2013, 10:35:44 PM »

I'm not an expert on this by any means SW, My 'redneck' siege mentality says buy a Lister and make a bunker for it  Roll Eyes But realistically in your situation I'd be thinking of a small Honda portable petrol and I really wouldn't be too worried about starting the freezer, sure it'll almost stall and dim the lights if it's not big enough but you'll soon get over it by turning off the TV or a few lights. I dunno how many burger vans and pasta bars I've seen running all day off tiny Honda generators and they all seem to have freezers. To be honest the freezer is the last thing I'd be worried about and mine has always got a fortune inside it. Everyone seems to get uptight about their freezer but most will easily go a few days without power, me I'd just get a 600w Honda and a jerry can  Grin Oh, and unless you're a regular chainsaw or outboard motor user I'd steer well clear of two strokes, mixed fuel lasts weeks not months.

Sure you can get some piece of Chinese carp from Lidl or Aldi and if your lucky it might even work, of course you've got the three year guarantee to back you up. However that's nay fecking use when it don't start on Christmas eve and the nearest branch is 110 miles away.

Good luck, Paul
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'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
skyewright
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« Reply #9 on: December 08, 2013, 03:15:55 PM »

I'm not an expert on this by any means SW, My 'redneck' siege mentality says buy a Lister and make a bunker for it  Roll Eyes
Naturally. I'd expect no other but, as you go on to point out a bit OTT for my case. Better to leave the Listers for those with a genuine requirement, e.g. V.

...me I'd just get a 600w Honda and a jerry can  Grin
Funnily enough 600W is exactly the size I had in mind before I started looking around.
That would be plenty big enough for what we really need (i.e. enough to allow us to look after business during the day, and give us some light [& iPlayer  Grin] in the evening). It was only when I started looking at actual models that the bigger size like an EU20i (2kW) with it's fancy ECO option for lower usage started to come into the picture as a possibility.

Oh, and unless you're a regular chainsaw or outboard motor user I'd steer well clear of two strokes, mixed fuel lasts weeks not months.
Now I'm a convert to the Austrian scythe I've not used the 2-stroke strimmer for over 18 months.  Grin Grin
You've also reminded me that it was 2-stroke mix that I had in mind as very likely to go stale. Neat petrol in a sealed can should be a different matter.

Sure you can get some piece of Chinese carp from Lidl or Aldi and if your lucky it might even work, of course you've got the three year guarantee to back you up. However that's nay fecking use when it don't start on Christmas eve and the nearest branch is 110 miles away.
... and even the first 15 miles are blocked (quite possible in the two types of weather most likely to lead to an unannounced powercut - heavy snow or a storm strong enough to push a spring tide even further up the loch than usual).  Grin
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David
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biff
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« Reply #10 on: December 08, 2013, 04:31:11 PM »

One of the generators that the German supermarkets have sold in the past 4 years was a 2.8kw 4 stroke.
               Its a petrol jobbie and has just about everything you would need in a geni.
       I would be the last person to buy one of these,since I have loads of diesel generators about me.However a quick look at this particular model which was for sale for 199 euros convinced me that there was enough bits and pieces on the frame to justify twice the price,so I fired it into the boot of the car and its been in my store ever since,That was 4 years ago and its never been out of the box.I know from experience that when you go looking for these things they are nowhere to be found.Not only has the price gone up since i bought it but the specs are not as good.
  I know that this is chinese "Carp" as Paul calls it but I also have to be honest and say that I have always had exellent service out of their power tools,etc.I like to run a geni at about 60% of its load.I would never boil a kettle of a geni,I remember watching the lads boil a kettle of a posh lister one day and that lister was murdered and covered the place in black smoke.It was a 5kw jobbie and these lads did this 3 times a day.The normal job was powering 2 blowers for pumping in insulation into houses.I would not let any engine suffer like that,its pointless,silly.Lecky kettles should be banned.
                                                                            Biff
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« Reply #11 on: December 08, 2013, 05:58:31 PM »

My setup is a Honda EU20i as my generator and an APC SmartUPS 750 XL with an external battery bank.

I have owned several generators, both frame type and suitcase type. I can thoroughly recommend Honda brand. They are reliable, easy to start and spares are easy to find. Chinese ones have always disappointed. One thing that was important to me with my latest generator was noise. The EU range of generators are some of the quietest on the market due to their clever exhaust design and the variable speed engine and inverter. They also sip fuel. My neighbours are single digit meters from me, and I can run my EU20i without disturbing them. You can also get 3rd party accoustic covers to further reduce noise. As the generator is an inverter output, you can run sensitive equipment without worry.

I hear that the EU10i is not the best product and tends to fail earlier than others in the range. I went for the EU20i because i needed portability whilst maintaining sufficient power to start water pumps. My main use was powering either an 850w 2" submersible high volume foul water pump, or a 800w high pressure clean water pump. The EU20i started these with ease even when on variable speed mode, though I tended to be nice and run it at full speed when turning on the pump if I remembered. I no longer need to pump water so dont really need the portablity any more. If i were to choose again I would look at either the EU26i due to it being the questest in the range or the EU30i to give me the ablity to run any 13 amp mains appliance at will. They are also electric start.

I paid £600 for my EU20i second hand, but in excellent condition with clearly little use - 2 seasons caravanning. I think that was well worth the money. I could sell it again now for about the same.

The Honda can be converted to LPG. I think that it is worth considering as LPG doesn't age unlike petrol, so no need to worry about fuel degragdation.

 My UPS I bought for £2 as "broken" from ebay. Most "broken" UPS are really OK, they just need new batteries. I asked the seller to take the old batteries out and dispose of them to reduce the postage. Total cost was under £10. I partnered the UPS with 4 off 12v 75AH batteries arranged as 24v 150AH. This gives me about 3kWh of energy to play with. Running the batteries flat every now and again is not a problem. Continual flattening would be.

So i can use the generator by day, and the UPS at night.

If you want s frame generator, the EM range from Honda are the quietest * of their product lines, but no where near the EU.

* Edit: by that I mean most acceptable engine tone. Others may be quieter on paper.
« Last Edit: December 08, 2013, 06:32:47 PM by w0067814 » Logged
camillitech
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« Reply #12 on: December 08, 2013, 07:20:12 PM »

One of the generators that the German supermarkets have sold in the past 4 years was a 2.8kw 4 stroke.
               Its a petrol jobbie and has just about everything you would need in a geni.
      

Sure I've got one of those Biff, came out the back of a white Transit van from Ireland right enough and not from a supermarket but just the same, Honda clone engine, 115/230v with fancy switch and a meter. A good sized petrol tank with gauge, rubber mounted in it's own frame and a 12v charging socket, it really looked the biz.

It was a gift to my neighbour from her sister and sat undercover for two years without being used.

The only time she ever needed to use it, it wouldn't work, so she asked me to have a look. It started first pull but made no leccy,



well it wouldn't would it  hysteria  hysteria  hysteria

http://lifeattheendoftheroad.wordpress.com/2010/10/16/the-sheep-hunter/



The next thing that distracted me was a piece of cr4p from China that had been taking up room in my workshop for around a year. The said bit of rubbish being a brand new and unused Honda ‘lookalike’ generator of the kind favoured by men in white vans who drive around selling them to unsuspecting customers after power cuts. This particular one had been purchased around three years ago for my neighbour by her sister and sat unused and under cover until needed a year ago. Of course when actually required it didn’t work and white van man’s mobile phone number had long since been disconnected :-( I had a quick look at it then and whilst it ran fine there was no juice being produced. A look at the external wiring fuses, trips and connections revealed nothing obvious other than the fact that it was incredibly  poorly made so I gave up and used it as a shelf :-)

As she’d hinted recently that she’d like me to get someone to look at it and as I could do with both the space and a portable generator myself at times I started to get serious with it. Not really knowing what I was doing I took off the end plate of the alternator.


I've never actually given it her back as it likes to sit in a dark room as it's allergic to sunlight




all the paint faded whilst under her porch, the fuel lines split, the petrol tap washer perished and now oil is pishing out of it and turning the rubber mountings to jelly.

Buy one good reliable piece of equipment, it's far cheaper than buying half a dozen bits of junk and far better for the planet.

Good luck, Paul
« Last Edit: December 08, 2013, 07:36:30 PM by camillitech » Logged

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biff
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« Reply #13 on: December 08, 2013, 08:16:41 PM »

Hi Paul,
     I have to admitt that one of the little two stroke early aldi yellow generators had a fuel tap exactly like the one you posted and when I qent to turn it on the lever crumbled away in my hand,now that was very unusual.I sent away the dosh and got another one.I replaced the rubber gasket and it is still buzzin away in a garage up the road.He uses it to power a grinder on the move even though it is rated at only 750watt.Outasight bought one indetical at a boot fair a couple of years ago.
   But I will dig that green 2.8kw Lydl one out and see if it is ok,I would be genuinely surprised if it is not in perfect working order.I have it racked away out of reach but when I get time i will give it the once over.You do seem to be very very unlucky with this chinese gear.  Shocked
                                                Biff
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« Reply #14 on: December 08, 2013, 08:37:50 PM »

Remember to leave all your fridges, freezers and dehumidifiers a good 10 minutes before reconnecting, compressor stall creates about 1000 watt draw per appliance until the thermal overload kicks in, this can cause some overloading issues when changing over to a generator/inverter.
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