Going off grid

[Stere]

Quote

ac inverter/charger and 6kWh of lithium phosphate battery installed late November.

 

What ones did you get?

[openspaceman]

47 minutes ago, Stere said:

 

What ones did you get?

SPA3000TL inverter with GBLI6532 battery. So the inverter will dish out up to 3kW if there is enough in the battery, which means even if there is too little solar power to run something like a kettle for 5 minutes the battery can store enough on aa dull day in dribs and drabs and then release it when needed.

 

I have charted results so far which show that we consumed 6.42kWh per day on average since installation and solar has provided 3.16kWh on average. The graph shows up till 6 Dec solar has exceeded what we draw from the grid.

 

Edited December 11, 2021 by openspaceman
added units

[Justme]

We are totally off grid.

2 x 5kw Victron mkII inverters set up in parallel with Cerbo control system, currently 52kwh battery but just about to double it. Small 1.2kw PV array that we need to extend.

Powering house and soon a static caravan too.

[Logjam]

Interesting range of experiences. We moved into an off grid place a couple of years ago, too far out in the wilds for mains connection to be viable.

Have solar panels linked to lead acid battery bank, diesel genny & Victron inverter. No real issues, top up battery fluid once a month & ensure genny has diesel. Generator also needs normal servicing, oil, filter, coolant etc that is easy enough to do myself. System runs everything, dishwasher, washing machine, microwave etc without any serious issues. Genny cuts in auomatically to balance the load if too many appliances switched on at the same time. 

 

Occasionally power will drop out if batteries are getting down around 65% & high initial load appliance switched on but genny kicks in & everything powers back up. Have learnt to check battery state in advance & manually power up the genny to avoid cut outs. Generator runs most days at the moment with short daylight hours & cloudy wet weather. During summer can go a week with just solar charging the batteries. We mainly use bottled gas for cooking, oil fired boiler for central heating & hot water. Also have solid fuel range that will run hot water, central heating & cooking but needs feeding with logs regularly to be effective so tend to only use it if we're in all day to keep it fuelled up.  Like the fact that we are independent, especially after the recent issues some experienced getting power back on following storms. 

 

Looking at viability of installing a wind turbine to reduce generator use in winter. 

[MattyF]

Interesting range of experiences. We moved into an off grid place a couple of years ago, too far out in the wilds for mains connection to be viable.
Have solar panels linked to lead acid battery bank, diesel genny & Victron inverter. No real issues, top up battery fluid once a month & ensure genny has diesel. Generator also needs normal servicing, oil, filter, coolant etc that is easy enough to do myself. System runs everything, dishwasher, washing machine, microwave etc without any serious issues. Genny cuts in auomatically to balance the load if too many appliances switched on at the same time. 
 
Occasionally power will drop out if batteries are getting down around 65% & high initial load appliance switched on but genny kicks in & everything powers back up. Have learnt to check battery state in advance & manually power up the genny to avoid cut outs. Generator runs most days at the moment with short daylight hours & cloudy wet weather. During summer can go a week with just solar charging the batteries. We mainly use bottled gas for cooking, oil fired boiler for central heating & hot water. Also have solid fuel range that will run hot water, central heating & cooking but needs feeding with logs regularly to be effective so tend to only use it if we're in all day to keep it fuelled up.  Like the fact that we are independent, especially after the recent issues some experienced getting power back on following storms. 
 
Looking at viability of installing a wind turbine to reduce generator use in winter. 

That's pretty much how we run ours, the turbine is great when there is wind but I'll be honest it's not regular.. when we had the storm a few weeks back and was going mad it quickly got to 100% and stayed that way for a while as the inverter had to dump most of it but it gave them a better top up than the genny! All washing machines and appliances got a good work out !
I remember one year one of the springs snapped on the blades and we had to put the break on and lower the tower, was fun when the small tirfor I was using shat itself .. should of got the bigger one on t he case.
We cook and heat off wood though I would not be surprised if we burnt 1.5 cube a week in winter if some one was in the house all the time... I can spend do days a year by myself on the processor rattling out 50 crates I recon that would feed just the house.

[agg221]

On 11/12/2021 at 13:33, openspaceman said:

Yes British gas trialled them  but pulled out. Whispergen made an interesting 3 piston Stirling engined one in NZ and spares are still available but the factory closed after an earthquake. Microgen still do a free piston version at £14k  both were only 1kW and integrated into a boiler. Stirling still makes sense as it can be hermetically sealed , for long life like a fridge compressor. Innovations in battery technology makes a rethink worthwhile. I guess about 15% conversion to electricity but the heat can still be used. PV fits well as during the summer it  works when no heat needed.

I did some work for Microgen a decade or so back. It's a good product but by their own statement it only really makes sense when you have a demand for a lot of heat to keep it running near continuously. Single domestic properties don't really work, but it is excellent for blocks of flats, leisure centres and similar. I have recently been doing quite a bit with a company that has installed a lot of CHP systems in the latter.

 

On 11/12/2021 at 13:33, openspaceman said:

Yes but high purity necessary and there are capital cost issues. Where will the hydrogen come from? Up to 10% hydrogen can go in the gas main before pumping losses cause problems, such a fuel cell could filter hydrogen out selectively and methane then burned.

Around 25yrs ago (worrying!) I used to work for Johnson Matthey developing catalysts for fuel cells. I specifically worked on reformate tolerant anode catalysts. The anode is the side where the hydrogen goes, with oxygen to the cathode. At that time, hydrogen was made by steam reforming, effectively the old towns gas process - water plus carbon goes to hydrogen plus carbon monoxide. The problem with the anode catalyst is that it really doesn't like carbon, which sticks to the platinum, covering it completely, known as poisoning, so there are no sites for the hydrogen to react at. This means the purity levels needed to run a fuel cell are phenomenally high. You can run a reverse reaction to remove the carbon but it takes a lot of power, so the overall efficiency of the system drops the more you have to do it.

 

At the time, one of my colleagues was leading the activity to develop separator membranes. I am not sure that the technology has moved on that far since, as the shift from presuming hydrogen would be reformate to presuming it would be electrolytic and hence pure happened around that time. This means there may well still be some considerable technical development needed to create a cost-effective separation membrane which can run at a sensible flow rate.

 

Irrelevant aside - my first patent was in this field: 

US5939220A - Catalyst - Google Patents

PATENTS.GOOGLE.COM

---

A novel catalyst comprising a Pt--M alloy wherein M is one or more metals selected from the transition metal elements or...

 

Alec

[openspaceman]

1 minute ago, agg221 said:

I did some work for Microgen a decade or so back. It's a good product but by their own statement it only really makes sense when you have a demand for a lot of heat to keep it running near continuously. Single domestic properties don't really work, but it is excellent for blocks of flats, leisure centres and similar. I have recently been doing quite a bit with a company that has installed a lot of CHP systems in the latter.

 

Around 25yrs ago (worrying!) I used to work for Johnson Matthey developing catalysts for fuel cells. I specifically worked on reformate tolerant anode catalysts. The anode is the side where the hydrogen goes, with oxygen to the cathode. At that time, hydrogen was made by steam reforming, effectively the old towns gas process - water plus carbon goes to hydrogen plus carbon monoxide. The problem with the anode catalyst is that it really doesn't like carbon, which sticks to the platinum, covering it completely, known as poisoning, so there are no sites for the hydrogen to react at. This means the purity levels needed to run a fuel cell are phenomenally high. You can run a reverse reaction to remove the carbon but it takes a lot of power, so the overall efficiency of the system drops the more you have to do it.

 

At the time, one of my colleagues was leading the activity to develop separator membranes. I am not sure that the technology has moved on that far since, as the shift from presuming hydrogen would be reformate to presuming it would be electrolytic and hence pure happened around that time. This means there may well still be some considerable technical development needed to create a cost-effective separation membrane which can run at a sensible flow rate.

 

Irrelevant aside - my first patent was in this field: 

US5939220A - Catalyst - Google Patents

PATENTS.GOOGLE.COM

---

A novel catalyst comprising a Pt--M alloy wherein M is one or more metals selected from the transition metal elements or...

 

Alec

Thanks Alec, I was trying to respond on your omicron thread and finding it difficult. I realised from your posts you had an analytical brain but only now appreciate you qualifications, natural science, chemistry I guess.

 

Please stick around this thread and lets talk about the problems of micro generation, especially in relation to the whispergen and Microgen Stirlings. The microgen unit can still be got for £10k but that's a ridiculous price which is why most here off grid seem to stick with diesel.

 

We had a marinised 10kVAPetter running a remote classroom 20 years ago, the water cooled manifold and coolant heated the rooms but it was far too powerful (to meet peak loads) to get more than 20% conversion to electric.

 

If you have looked at my offering up thread you will see I need to "find" 300W for 10 hours to get me independent of the grid. Of course I don't need it as I am in a residential street and quite happy to accepts my Solar PV array and battery will only get me 80% free of imports.

 

My colleague from our charcoal project went on to solid oxide fuel cells with Rolls Royce, that had promise but never quite got there and was sold to a Korean firm. Luckily Dave was kept on by RR.

[agg221]

11 hours ago, openspaceman said:

Thanks Alec, I was trying to respond on your omicron thread and finding it difficult. I realised from your posts you had an analytical brain but only now appreciate you qualifications, natural science, chemistry I guess.

 

Please stick around this thread and lets talk about the problems of micro generation, especially in relation to the whispergen and Microgen Stirlings. The microgen unit can still be got for £10k but that's a ridiculous price which is why most here off grid seem to stick with diesel.

 

We had a marinised 10kVAPetter running a remote classroom 20 years ago, the water cooled manifold and coolant heated the rooms but it was far too powerful (to meet peak loads) to get more than 20% conversion to electric.

 

If you have looked at my offering up thread you will see I need to "find" 300W for 10 hours to get me independent of the grid. Of course I don't need it as I am in a residential street and quite happy to accepts my Solar PV array and battery will only get me 80% free of imports.

 

My colleague from our charcoal project went on to solid oxide fuel cells with Rolls Royce, that had promise but never quite got there and was sold to a Korean firm. Luckily Dave was kept on by RR.

Responses are not necessary to the omicron thread - that wasn't why I posted. You are correct in surmising natural sciences - chemistry, followed by a rather odd engineering doctorate in materials, based on inorganic chemical synthesis routes.

 

Some slightly random thoughts:

 

Thinking back over the time I have been involved, various significant changes have happened. One of the biggest changes is the shift in the pattern of demand. 20 years ago, light bulbs were still filament, many houses still didn't have a computer and if they did, it was a tower PC with a CRT monitor, using a modem connection for the internet which might be on for an hour or so a day at most due to costs. Mobile phones were becoming common but were by no means universal (snakes anyone?). Houses were built to very poor thermal standards and there wasn't a single Passivhaus standard building in the country. Wood was still mostly worthless - people didn't have log burners and most people would be glad of an offer to remove a dead tree (which is where most of my timber for boat restoration came from, along with the living room floor in my previous house). PV was phenomenally expensive and nobody would have thought of putting it on a house. Solar thermal panels were coming in as the big thing just over 15yrs ago.

 

The changes appear to be in pattern of energy demand as much as in the supply sources. Energy consumption from the basics such as lighting has dropped significantly across the board and modern motors are far more efficient, but the digital world places much more demand on power for devices such as phones and computers, and a lot more electronic connectivity within equipment such as boilers, cookers and white goods. This has probably pushed the base load up. This also relates to lifestyle. Are you able to batch up washing and put the machine on when the sun is shining, making direct use of PV to run washing machine and the weather for drying, or do you need to do a regular family washload at the weekends regardless of the weather and have to use the tumble dryer if the weather isn't good? These have a huge impact on the ability to make best use of an irregular supply vs. the need for more storage. Insulation vs. heat requirements are more tricky to estimate - the difference in heating bills between a brand new bespoke building meeting Passivhaus standards and a Victorian end of terrace with solid walls and no realistic route to insulating it without sacrificing a lot of space in the rooms is huge. That often means that, within very limited ranges, you are stuck with the fabric of the building you have.

 

I wonder if it is useful to break down energy requirements by category. What I was thinking of was low grade heat for space heating and hot water, high grade heat for cooking, DC electricity and 240V electricity. It would then be possible to think about the total requirement for each and consider where that is now and whether that could be reduced in an acceptable fashion. This would be very much down to individual circumstances. I know the options better for canal boats and some of these don't apply, but for example on a boat the water pump can be replaced with a hand pump and a header tank, with a separate header tank for a shower where you pre-blend the hot and cold water. This substitutes manual work for electricity, cutting the requirement. I suppose the equivalent for a house would be using a gravity fed shower rather than a power shower. Whether someone sees that as acceptable or not is a personal choice. Other options might include the use of a pantry for food storage to minimise the size of the fridge, and at this time of year perhaps to substitute its use completely, and storing more food as dried and preserved goods to reduce the amount of freezer space needed. Gravity fed rather than pump fed is also a choice for some heating systems. HVO is not a cheap option, but it does enable both green and off-grid credentials to be met.

 

There are then some CapEx vs. OpEx decisions that could be made. When we re-wired large parts of the house I investigated going 12V on the lighting circuit. At the time, knowing what I did, it didn't make sense but now I know more about how to source system components it would certainly be something I will re-evaluate when I come to re-wire the rest of it. Again, learning from boats, a DC circuit can be used to run many devices, including computers and televisions - even fridges and washing machines. If you are running off-grid, so power generation and storage is mostly DC, the more you run equipment on DC, the less energy you lose through an inverter. Many motor-driven devices such as fridges and washing machines are likely to run DC motors anyway, so it is doubly inefficient to step up to 230V AC and then back down again.

 

Once you have got through all that lot, I think it should be possible to run a revised energy audit on what the actual requirements are. Firstly, it may 'find' some of the necessary capacity in savings and secondly the balance of low grade heat/high grade heat/DC/AC will determine what systems are most suitable and at what size. CHP would generally be sized to meet heating needs rather than power needs as otherwise the heat is going to waste, as per your Petter genset. Pure electrical generation without heat is tricky, particularly in a suburban setting. You are pretty much limited to solar I think. There are improvements here which make better use of space and produce more energy per square metre. The double-sided panels are interesting, as are CIGS. I think it is more incremental gains than step change at the moment, but the gains are big enough to be making a difference. However, unless you have enough space to install sufficient solar and electrical storage to cope in winter, you may end up with waste low grade heat.

 

Heat and lighting demand will vary through the year. I doubt the latter makes much difference with LEDs, but the former definitely does, particularly if the electrical generating solution to meet base load generates heat. In theory you could switch between using and dumping it with a simple valve across two parallel systems - again, boats can do this with the engine coolant, varying between radiator loops and a keel cooling tank. What might be more useful is a higher grade heat store - running a coolant with a boiling point high enough to feed into a cooker. It would work on a modified Rayburn or Aga (the latter are already converted to 13A electrical supplies). It's a style of cooking that may or may not fit in with a lifestyle - very much about long and slow rather than nuking it in the microwave, but it does work. Again, a possible compromise.

 

The systems I can think of offhand are internal combustion, external combustion, gas turbine and fuel cell. You have more experience than me of the problems with trying to run a cost-effective gas turbine. External combustion is the Microgen approach - I'm not really sure why it works out so expensive as it doesn't rely on exotic materials. The problem with Stirling engines appears to be that the power is all in the revs rather than the torque, so there are real efficiency losses when you step it down into an alternator. Fuel cells are attractive, but they all have their own drawbacks. PEM runs on hydrogen and works well but poisons up in impure gas streams. It also needs what would soon become a prohibitive quantity of platinum. SOFC as per RR runs on almost anything and doesn't have material supply issues, but it is a delicate piece of kit. The thin ceramic components are fragile, will break if you drop it, and and are not something that can be swapped out as they have to be brazed in place with complex filler metals in a difficult gas environment. Phosphoric acid fuel cells might be worth a revisit. They fell out of favour 30 years ago or so, but actually they might meet the need for cheap and cheerful. However, they are not currently available so far as I am aware, and are not exactly a DIY solution, so that would appear to leave the option of the most efficient diesel genset you can find, with good sound insulation and run on HVO if you want net zero emissions.

 

This has got rather long!

Alec

 

 

 

 

 

 

Edited December 13, 2021 by agg221

[Canal Navvy]

7 minutes ago, agg221 said:

Responses are not necessary to the omicron thread - that wasn't why I posted. You are correct in surmising natural sciences - chemistry, followed by a rather odd engineering doctorate in materials, based on inorganic chemical synthesis routes.

 

Some slightly random thoughts:

 

Thinking back over the time I have been involved, various significant changes have happened. One of the biggest changes is the shift in the pattern of demand. 20 years ago, light bulbs were still filament, many houses still didn't have a computer and if they did, it was a tower PC with a CRT monitor, using a modem connection for the internet which might be on for an hour or so a day at most due to costs. Mobile phones were becoming common but were by no means universal (snakes anyone?). Houses were built to very poor thermal standards and there wasn't a single Passivhaus standard building in the country. Wood was still mostly worthless - people didn't have log burners and most people would be glad of an offer to remove a dead tree (which is where most of my timber for boat restoration came from, along with the living room floor in my previous house). PV was phenomenally expensive and nobody would have thought of putting it on a house. Solar thermal panels were coming in as the big thing just over 15yrs ago.

 

The changes appear to be in pattern of energy demand as much as in the supply sources. Energy consumption from the basics such as lighting has dropped significantly across the board and modern motors are far more efficient, but the digital world places much more demand on power for devices such as phones and computers, and a lot more electronic connectivity even within devices which may previously not have really had any electronics, such as boilers, cookers and white goods. This has probably pushed the base load up. This also relates to lifestyle. Are you able to batch up washing and put the machine on when the sun is shining, or do you need to do a regular family washload at the weekends? These have a huge impact on the ability to make best use of an irregular supply vs. the need for more storage. Insulation vs. heat requirements are more tricky to estimate - the difference in heating bills between a brand new bespoke building meeting Passivhaus standards and a Victorian end of terrace with solid walls and no realistic route to insulating it without sacrificing a lot of space in the rooms is huge. That often means that, within very limited ranges, you are stuck with the fabric of the building you have.

 

I wonder if it is useful to break down energy requirements by category. What I was thinking of was low grade heat for space heating and hot water, high grade heat for cooking, DC electricity and 240V electricity. It would then be possible to think about the total requirement for each and consider where that is now and whether that could be reduced in an acceptable fashion. This would be very much down to individual circumstances. I know the options better for canal boats and some of these don't apply, but for example on a boat the water pump can be replaced with a hand pump and a header tank, with a separate header tank for a shower where you pre-blend the hot and cold water. This substitutes manual work for electricity, cutting the requirement. I suppose the equivalent for a house would be using a gravity fed shower rather than a power shower. Whether someone sees that as acceptable or not is a personal choice. Other options might include the use of a pantry for food storage to minimise the size of the fridge, and at this time of year perhaps to substitute its use completely. Gravity fed rather than pump fed is also a choice for some heating systems. HVO is not a cheap option, but it does enable both green and off-grid credentials to be met.

 

There are then some CapEx vs. OpEx decisions that could be made. When we re-wired large parts of the house I investigated going 12V on the lighting circuit. At the time, knowing what I did, it didn't make sense but now I know more about how to source system components it would certainly be something I will re-evaluate when I come to re-wire the rest of it. Again, learning from boats, a DC circuit can be used to run many devices, including computers and televisions - even fridges and washing machines. The more you run DC, the less energy you lose through an inverter. Many motor-driven devices such as fridges and washing machines are likely to run DC motors anyway, so it is doubly inefficient to step up to 230V AC and then back down again.

 

Once you have got through all that lot, I think it should be possible to run a revised energy audit on what the actual requirements are. Firstly, it may 'find' some of the necessary capacity in savings and secondly the balance will determine what systems are most suitable and at what size. CHP would generally be sized to meet heating needs rather than power needs as otherwise the heat is going to waste, as per your Petter genset. Pure electrical generation is tricky, particularly in a suburban setting. You are pretty much limited to solar I think. That means you may end up with waste low grade heat.

 

Heat and lighting demand will vary through the year. I doubt the latter makes much difference with LEDs, but the former definitely does, particularly if the electrical generating solution to meet base load generates heat. In theory you could switch between using and dumping it with a simple valve across two parallel systems - again, boats can do this with the engine coolant, varying between radiator loops and a keel cooling tank. What might be more useful is a higher grade heat store - running a coolant with a boiling point high enough to feed into a cooker. It would work on a modified Rayburn or Aga (the latter are already converted to 13A electrical supplies). It's a style of cooking that may or may not fit in with a lifestyle - very much about long and slow rather than nuking it in the microwave, but it does work. Again, a possible compromise.

 

The systems I can think of offhand are internal combustion, external combustion, gas turbine and fuel cell. You have more experience than me of the problems with trying to run a cost-effective gas turbine. External combustion is the Microgen approach - I'm not really sure why it works out so expensive as it doesn't rely on exotic materials. The problem with Stirling engines appears to be that the power is all in the revs rather than the torque, so there are real efficiency losses when you step it down into an alternator. Fuel cells are attractive, but they all have their own drawbacks. PEM runs on hydrogen and works well but poisons up in impure gas streams. It also needs what would soon become a prohibitive quantity of platinum. SOFC as per RR runs on almost anything and doesn't have material supply issues, but it is a delicate piece of kit. The thin ceramic components are fragile, will break if you drop it, and and are not something that can be swapped out as they have to be brazed in place with complex filler metals in a difficult gas environment. Phosphoric acid fuel cells might be worth a revisit. They fell out of favour 30 years ago or so, but actually they might meet the need for cheap and cheerful. However, they are not currently available so far as I am aware, and are not exactly a DIY solution, so that would appear to leave the option of the most efficient diesel genset you can find, with good sound insulation and run on HVO if you want net zero emissions.

 

This has got rather long!

Alec

 

 

 

 

 

 

Good read (as always) Alec.

Interested in your views on Phase change materials 😉🙂

 

[Stere]

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