what generator required
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Errm, a 4kw one?? [plus a bit for PF etc] 4kw is 4kw makes no difference if you had 4000A at one volt or 1A at 4000v, would still be 4kw..
You do realise that at 12v this would be 333A.. You would need some SERIOUSLY big cables... want to wire your house using welding cable??
Why would you want to try to generate your own power?? How you going to run anything on 12v???
john..
You do realise that at 12v this would be 333A.. You would need some SERIOUSLY big cables... want to wire your house using welding cable??
Why would you want to try to generate your own power?? How you going to run anything on 12v???
john..
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Or does he mean that his total energy consumption for the day is 4 kWh. So at any one time he might only have 2 or 300 W on the go.
I can read his op both ways or is that just me.
I can read his op both ways or is that just me.
A battery powered 230V inverter fed from the LV DC setup would only require conventional wiring methods for household distribution. As to the practicality, ?????
Yes, see what you mean!!
I agree, all seems pointless to me.. Be like trying to drill for oil out your back and think you can make your own petrol cheaper than ASDA sell it for!!
john..
First of all thanks for your help. This is a project of interest as I may be going off grid sometime in the future.
Sorry guys I should have made things a little clearer. Average consumption per day is about 4kwh. I have read elsewhere that an inverter has about 85% efficiency (please advise if you think this is incorrect) when converting to UK mains voltage. I understand that you can only reduce battery levels to about 50% therefore if I wish to cover 4KWh I will require about 9.4kw in terms of batteries.
if i am correct, 9400 watts / 12volts = 784 amps - so about 4 x 200 amp (AGM) batteries.
Therefore, 4000 /.85 = 4706 watts / 24 hours = a generation of 197 watts per hour required. (have I got this correct)?
Allowing for a little more and so the gen would not be at max output, would a 250 watt low RPM brushless alternator with bridge rectifiers to convert to dc do the job?
Thanks
Sorry guys I should have made things a little clearer. Average consumption per day is about 4kwh. I have read elsewhere that an inverter has about 85% efficiency (please advise if you think this is incorrect) when converting to UK mains voltage. I understand that you can only reduce battery levels to about 50% therefore if I wish to cover 4KWh I will require about 9.4kw in terms of batteries.
if i am correct, 9400 watts / 12volts = 784 amps - so about 4 x 200 amp (AGM) batteries.
Therefore, 4000 /.85 = 4706 watts / 24 hours = a generation of 197 watts per hour required. (have I got this correct)?
Allowing for a little more and so the gen would not be at max output, would a 250 watt low RPM brushless alternator with bridge rectifiers to convert to dc do the job?
Thanks
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So what is your peak load at any point in the day likely to be?
As in when you have most items powered up especially high load ones.
This will then dictate your battery requirement, which will then dictate your inverter, charger and generator requirements.
Try and stay away from a 12V setup, cable size will be big unless your peak load is tiny, a 24 or 48V setup is better, higher the voltage means lower current means less heavy cables.
Have you considered some solar on this project?
As in when you have most items powered up especially high load ones.
This will then dictate your battery requirement, which will then dictate your inverter, charger and generator requirements.
Try and stay away from a 12V setup, cable size will be big unless your peak load is tiny, a 24 or 48V setup is better, higher the voltage means lower current means less heavy cables.
Have you considered some solar on this project?
Hi and thanks for responding. I may go for either 24or48 volts but I have a 2000 watt inverter that I use for the caravan with battery cables that are as thick as those you have coming off a car's alternater. Some household appliances I now enjoy may indeed require a greater peak than 2kw so when the time comes, I will have to consider carefully my options.
There is likely to be a mix of solar and other generated sources of supply like hydro.
Life will be much simpler but hopefully more enjoyable living on the Norfolk Broards.
There is likely to be a mix of solar and other generated sources of supply like hydro.
Life will be much simpler but hopefully more enjoyable living on the Norfolk Broards.
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Good place for spotting Otters - I love Otters, and seeing them every morning from a boat on holiday was epic for me!
48V is defo the way forward, and tends to be fairly normal for what you want. I would tend to oversize the inverter, in my experience a 500W inverter can only cope with say 300w constant load, not that I've had much to do with such things. Batteries, you need to check out a thing called 'depth of discharge' which varies with battery technology - do not be tempted with lorry batteries, they may seem cheap for a large capacity, but are only designed to take a large loading for a short time, ie starting an engine. You should be able to discharge a battery safely and reliably to about 80% of capacity. The whole off-grid 'thing' can be quite confusing, especially as you are panning multiple inputs to battery storage. From what I understand of this set-up, you can have a battery charge controller for each input (gives a bit more reliability anyway) Victron seem to be the make of choice for such controls. Might also be worth having a look at the Centre for Alternative Technology in Wales for advice, and certainly worth contacting Victron helpline for technical support.
One other point, batteries don't like getting cold, they are best kept in an insulated box, and certainly off cold concrete floors.
4 kWh is not a lot, a decent set of solar panels would generate that for most of the year with ease - small wind turbine say 500W would be a good addition as this works 24/7 for when the sun doesn't shine, and obviously over night. It's not often we don't get any sun or wind on the same day! This might eliminate the need for a gennie as anything other than a back up, which means smaller unit would probably suffice.
48V is defo the way forward, and tends to be fairly normal for what you want. I would tend to oversize the inverter, in my experience a 500W inverter can only cope with say 300w constant load, not that I've had much to do with such things. Batteries, you need to check out a thing called 'depth of discharge' which varies with battery technology - do not be tempted with lorry batteries, they may seem cheap for a large capacity, but are only designed to take a large loading for a short time, ie starting an engine. You should be able to discharge a battery safely and reliably to about 80% of capacity. The whole off-grid 'thing' can be quite confusing, especially as you are panning multiple inputs to battery storage. From what I understand of this set-up, you can have a battery charge controller for each input (gives a bit more reliability anyway) Victron seem to be the make of choice for such controls. Might also be worth having a look at the Centre for Alternative Technology in Wales for advice, and certainly worth contacting Victron helpline for technical support.
One other point, batteries don't like getting cold, they are best kept in an insulated box, and certainly off cold concrete floors.
4 kWh is not a lot, a decent set of solar panels would generate that for most of the year with ease - small wind turbine say 500W would be a good addition as this works 24/7 for when the sun doesn't shine, and obviously over night. It's not often we don't get any sun or wind on the same day! This might eliminate the need for a gennie as anything other than a back up, which means smaller unit would probably suffice.
