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Joshd

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Ok

 

So of you are asking about the load.

 

Well it would depend on whats running as fridge and freezer would be on 24/7. Then maybe once a day a washing machine load and tumble dryer load. Plus one computer in the day. During the evening it would be tv, lights and computer. I doubt that we would meet the peak load of what the generator can do. Yet if we had a battery packs installed etc they could be used first and we could kick in the gene if required.

 

Yes we do have the gene already at house.

 

With regarding the batteries we would take care of them to last and would be looking at the mid-range ones. This might sound a stupid question but how long would a battery last before it need charging kind of thing.

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Hello David and Julie do you mean in a way that it would prvoide the power for the gas boiler which does the hot water as well so i am guessing yes. Which in turn will also put up the power required.

I think they were hoping that there was a cooling circuit, as on most narrow boats, where the waste heat is used to feed a coil in the hot water tank to efficiently warm the water.

Edited by blodger
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Strikes me you have the genny and need to suck it and see now and add to your system what helps.

 

It will be a load of batteries, min 50 amp charger and, 3kw probably sine inverter.

 

I presume you are cooking on gas as well as heating?

 

Do not underestimate your needs when buying in the ancillaries else it will probably cost more in the long run.

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I think they were hoping that there was a cooling circuit, as on most narrow boats, where the waste heat is used to feed a coil in the hot water tank to efficiently warm the water.

I was indeed.:cheers:

 

I was also trying to ascertain whether he intended running an immersion from the genny, but he has now answered by saying he has a gas boiler for the hotwater.

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I'm not sure batteries would save you anything if you're running off a generator only. They're necessary for boaters because we can't run engines/generators from 8pm to 8am, but presumably you can run yours 24/7? You put more power into a battery than you get out, so it'd be cheaper to run the generator on demand even before you consider the initial cost of batteries and the ongoing cost of replacing them.

 

If you're using solar panels, then it might make sense to have some batteries that can soak up any spare capacity, but unless you have enough panels that they are often producing more power than you can use, batteries might still be an unnecessary expense.

 

If you are reliant on a generator for electricity, then solar panels will pay for themselves much, much quicker than they would in a normal household set-up. As an approximate rule of thumb, a 100W panel will give you 100kWh per year - most of it in summer, of course. At £2-3/watt for solar panels and about £1/kWh to generate electricity from red diesel, the panels should pay for themselves quite quickly. But you're renting, so the investment may not be worthwhile for you. It might be worthwhile for the landlord, but obviously he'd expect some of your cost savings to be passed on to him as rent.

 

Whether a wind turbine is useful depends on where you are. They're more effective on a house than on a boat because of the extra height of a house roof, whereas a boat is usually at the lowest point for miles around and often sheltered by trees/cuttings.

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I think they were hoping that there was a cooling circuit, as on most narrow boats, where the waste heat is used to feed a coil in the hot water tank to efficiently warm the water.

Hi Joshd

To claify, as you don't have a boat!

The cooling circuit that Blodger mentions is the same as the heater in your car. On most boats with water cooled engines the same conections are used to feed hot coolant/antifreeze from the engine to a separate coil in the hot water tank (imagine the engine as the boiler if that helps)

Steve

Edited by Eeyore
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Ok

 

So of you are asking about the load.

 

Well it would depend on whats running as fridge and freezer would be on 24/7. Then maybe once a day a washing machine load and tumble dryer load. Plus one computer in the day. During the evening it would be tv, lights and computer. I doubt that we would meet the peak load of what the generator can do. Yet if we had a battery packs installed etc they could be used first and we could kick in the gene if required.

 

Yes we do have the gene already at house.

 

With regarding the batteries we would take care of them to last and would be looking at the mid-range ones. This might sound a stupid question but how long would a battery last before it need charging kind of thing.

 

With that usage you're talking about 4 or 5 kwh per day at least, probably nearer 7 or 8, much more than 2kwh in my original post.

 

Batteries need several hours charging regularly to look after them properly, most of that time will be on a few amps charge, time between charges depends on how large a battery bank you have, with a daily 7 kwh that relates to nearly 600ah @ 12v so you would need at least double that in battery capacity to enable you to do one long charge per day, you really need to consider fuel usage against battery cost especially with a large engine producing a few amps for several hours. As said in previous posts solar panels will help but not much use in winter and you need to be free of turbulence for a wind genny.

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Might be worth looking at 'edge technology's website as they offer off grid solutions and might give you some ideas of costs involved.

tbh, just googling 'off grid power/energy' may well offer you more answers in terms of cost. Bottom line is that the property is rented, it'll be your mondy being invested for potentialy someone elses gain.

Also worth bearing in mind is the fact you may need planing permission for solars and wind turbine.

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With that usage you're talking about 4 or 5 kwh per day at least, probably nearer 7 or 8, much more than 2kwh in my original post.

 

Batteries need several hours charging regularly to look after them properly, most of that time will be on a few amps charge, time between charges depends on how large a battery bank you have, with a daily 7 kwh that relates to nearly 600ah @ 12v so you would need at least double that in battery capacity to enable you to do one long charge per day, you really need to consider fuel usage against battery cost especially with a large engine producing a few amps for several hours. As said in previous posts solar panels will help but not much use in winter and you need to be free of turbulence for a wind genny.

 

As I mentioned earlier (post #13) it would be better to run the genny when the washing machine or tumble dryer is needed rather than sizing batteries to meet those high loads.

 

I get the impression that Josh does not yet know how to calculate kWhrs, amp-hours, or to work out the necessary size of batteries and all of that stuff. Until he can do all that comfortably, or has an unbiased advisor who can do it, I think he will be at great risk of making an expensive mistake. Its an awful thing to be at the mercy of experts :)

 

One question he might well ask himself (and no need to tell us! ) is whether he can easily afford the £15 per day that he expects running the generator to cost. The other thing is that all of the suggestions from forum members will involve him in an investment of hundreds of pounds - can he afford that? (again no need to tell us ).

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If/when you do a power audit don't forget that most appliance labels state the steady state load. A 90 watt fridge can pull nearly 1.5Kw when the motor starts. You need to factor this in and ensure that whatever you choose can cope.

Also generators tend to quote their output when driving a resistive load e.g. a bulb. If you put an inductive load such as a motor on them they are not capable of providing the same power (google power factor for more info)

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If the OP is serious then a CHP system may be the answer.

Look here :-

http://www.helec.co.uk/Combi%20sheet%20Kwe%207.5.pdf

 

the Energy Saving Trust is also a good source of information.

 

Look here : http://www.energysavingtrust.org.uk/Generate-your-own-energy/Micro-combined-heat-and-power-micro-CHP

 

Keith

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If the OP is serious then a CHP system may be the answer.

Look here :-

http://www.helec.co.uk/Combi%20sheet%20Kwe%207.5.pdf

 

the Energy Saving Trust is also a good source of information.

 

Look here : http://www.energysavingtrust.org.uk/Generate-your-own-energy/Micro-combined-heat-and-power-micro-CHP

 

Keith

 

This still needs either connection to the grid or batteries and inverter/charger.

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Running a genny to provide all the power on demand is a bad idea unless your base load is large (yours is not)

 

So you need a battery / inverter system that provides the base load & then only run the genny when you need peak loads (washer & dryer) or battery charging (pref at the same time).

 

As to system size.

 

The washer will use 1kWh ish per load & have peak loads of about 2kw

The dryer will use about 2kwh per load & have peak loads of up to 3kw

All your other loads will come to less than 3kwh per day & 2kw peak

 

So absolute max peak load (unless you have elec shower, immersion, elec kettle ect) will be about 7kw & daily loads of about 3kwh plus 3kwh for every wash & dry load.

 

Lets say you do all your washing on one day per week (good for that long bat charge you need then too).

 

Do daily you need 3kwh from your inverter & battery bank.

(oh & the inverter needs to be sized to cover your normal loads & NEVER the washer & dryer) so in your case about a 3kw one will do)

 

I would want to only need to run the genny every 3rd day so you need 2 days worth of power out of the battery bank. As you should only use 50% of the total capacity that means you need a bank of 4 times your daily needs. So thats 12kWh. In 12v battery terms thats nearly 1000ah (pref at a low 5C rate even though your usage will be at 20c or more). At this point I would say that you need to consider the voltage of your system. My advice would be to use 48v if you can, 24v is better than 12v but steer away from 36v due to limited choice on parts. The reason to use 48v is that the cables can be much smaller for the same amount of power carried so they cost less & you loose less.

 

So for a 48v system you will need a battery bank of 250ah (when working out battery sizing & volts you can add up one or the other not both, so 4 x 100ah 12v bats can be 1 x 48v 100ah bank or 1 x 12v 400ah bank but not 1 x 48v x 400ah). All hold the same total amount of power.

 

Next,

chargers

 

If you get an inverter with a charge built in then all good & well. But for a separate charger you need to consider the amps. Again on a 12v system you need 4 times the amps to get the same power back in to the bank as with a 48v one. At your level of use I would suggest at least 120amps at 12v & 30 at 48v, more if you can but you do need to watch the charger amps to battery bank ah relationship.

 

From all of the above you can prob tell that to do this even half right with all new items will cost you quite a bit. You & only you can tell if that is justifiable for you.

 

It will depend on

how long will you be there.

fuel costs

cost of getting mains installed

can you take it with you & will you have a need for it if you can

are you prepared to put the time in to learn about the system & how it all works for best performance / lowest cost

 

You can save by using used forklift cells (my first 6 cells cost £130 ish & are still going strong. But soon to be replaced by 24 used cells that cost £400). Inverters can be found cheaper used & dealer old stock sales. But you will still need a large budget & if you cant do it (and legaly I dont think you can) you will need some one that knows what he is doing to install & set it up & that will cost as well.

 

Each unit of power provided by our genny costs around 55p (compared to about 12p on mains). We manage to reduce that to nearer 28p (on average over the year) by having solar PV charging the battery up. In summer it covers all our usage. We spend about £400 per year on Red Diesel (bought in bulk when its cheap not during winter), your usage is about double ours or more so expect to pay nearer to £1k. If we had no solar it would cost us nearer £750

 

 

 

Edit to add

 

I have had to make some large assumptions on usage, costs & system. Please please do some home work & read up on this. I normally recommend that people come here for advice on battery & inverter systems but as you are here I would check out the Navitron forum as they do have a off grid / battery section.

Edited by Justme
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The current problem with micro CHP is the heat to power ratio. Most only produce 1kw of elec & LOADS of heat, far more than you should be using if your running it 24/7 for the 1kw of elec. Not that you should be running it that long anyway.

 

Ah just checked that link out. Its not really a micro CHP that you would fit inside your house but a water cooled genny with latent heat recovery. They do have a better elec to hot water ratio. I was talking about the sort you get from say BG & the likes to replace the internal boiler.

 

That unit uses 2.5L per hour at full rate. So a large bottle would last 37 running hours or cost £1.35 per hour to run. For the same cost a Red Diesel one would run for nearly 3 hours & give the same heat & elec.

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Each unit of power provided by our genny costs around 55p (compared to about 12p on mains). We manage to reduce that to nearer 28p (on average over the year) by having solar PV charging the battery up. In summer it covers all our usage. We spend about £400 per year on Red Diesel (bought in bulk when its cheap not during winter), your usage is about double ours or more so expect to pay nearer to £1k. If we had no solar it would cost us nearer £750

 

 

Edit to add

 

I have had to make some large assumptions on usage, costs & system. Please please do some home work & read up on this. I normally recommend that people come here for advice on battery & inverter systems but as you are here I would check out the Navitron forum as they do have a off grid / battery section.

 

 

I am impressed by your cost of 55p /kwhr. On a narrowboat I would be surprised to see power costing less than £1/kwhr and more likely it would exceed £2/kwhr - especially after battery losses are taken into account.

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That cost per kWh is actual recorded costs & has stayed stable with fuel costs for the last 2 1/2 years & include regular (in excess of makers recommendations) servicing (but not bat replacements). I guess that due to running a genny instead of a boat engine to provide the power. It also has a self limiter so that its using exactly the fuel needed to provide the power output, using a boat engine & trying to match the revs to alt load can be hit & miss. Prob a good idea to have an amp meter so you can change the revs to match the load. Also making sure that the genny is running under load as much as possible but not maxed out. IE do the washing when the bats need a good charge but wait till the bats have taken a good bit so you dont max out the genny.

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Its up to you to crunch the numbers but I would go for a larger genny, up to 30kva, purpose made in a sound proof container, one thats designed for many thousands of hours use.

 

Register it and install so you can couple up to the grid and export power and get paid for it.

In return, you get the power you want, the Feed in Tariff (FIT) covers your costs, you have heat back from it as well.

 

Sounds expensive?,

NO

 

google and learn.

 

Meanwhile, forget PV and windy gens. You need exceptional location and investment to cover your needs

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Also it is not connected to the grid so you would not get paid. Plus to get mains in would cost in the ten's of thousands.

 

With regard to what everyone else say i will have a sit down and work some stuff out.

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I am impressed by your cost of 55p /kwhr. On a narrowboat I would be surprised to see power costing less than £1/kwhr and more likely it would exceed £2/kwhr - especially after battery losses are taken into account.

 

I am paying about 50p/kWh - this from a communal generator, i.e. 4 boats plugged into a 6kW genni, and not counting capital costs.

 

I agree - at least £1/kWh for a small petrol genni.

 

m@

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Meanwhile, forget PV and windy gens. You need exceptional location and investment to cover your needs

 

 

Not true. Most locations are good for PV & you will get FIT's payments on every thing made. You can even get free installs (but no FITs & not available offgrid).

 

To get FITS on a 30kva genny it must be running on "reclaimed" fuels that you have to have tested for quality.

 

But not good for a temporary rental house.

 

Also it is not connected to the grid so you would not get paid.

 

Not true. Off griders can still get the main 41.3p FIT payment on total production. You obviously dont get the 3p export rate.

(we have signed up but as yet have not had our first payment but have given readings so its coming soon)

Edited by Justme
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