Off grid solar

JBee

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@ajdelange

Roger on the CHAdeMO, islanding, grid isolation and 240V PV microinverters and how this "box" would have to serve as a gateway for the proposed functionality.

The 10kW PV capacity on the CT was assuming that the onboard inverter would be bi-directional. But thinking about it more would mean that it would be a DC-DC converter not AC-DC inverter. So a separate circuit.

Also I'm still surprised over your energy consumption and that driving is a small proportion of your consumption. I'd seriously be investing on energy reduction rather than production. Obviously building new, like I have, recently, allows for more control of consumption, especially thermal loads. But it can and should be done I think, less is more. When our heat pump is on it heats the whole house with 400W with us inside at 23C and outside at 5C, (with the wind howling at 50kmh avg) but that's mainly because we have 150mm SIPS panels for insulation, and double glazed windows etc.

BTW did I mention our current house (we're starting the next one next year) is actually the same shape as a CT, facing the prevailing wind direction, with the PV on the vault side roof etc which is attached to the 300m² CT garage/workshop of the same design. Once the other one is built this will become the guest house.

Anyways, looks like this is product is about as close as it gets for the proposed gateway box and to use PV directly. Does 50kW and has a PV input option where it suggests the PV nominal power should be at least 2x the max output power. Minimum PV size would be around 14 panels or so (350-600V).

Rather large box I suppose, not sure what the cost is either, or what is actually in the box.

http://www.andromedapower.com/uploads/ORCA_Inceptive_Datasheet.pdf
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ajdelange

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Roger on the CHAdeMO, islanding, grid isolation and 240V PV microinverters and how this "box" would have to serve as a gateway for the proposed functionality.
Note that the gateway is only needed if the house is grid tied as it would be in the vast majority of cases so that would be what a manufacturer who hoped to sell a bunch would design for. There are inverters on the market that can run with batteries or not but the ones I have seen demonstrated on YouTube videos are so small that they tie into the grid through an electrical outlet. Obviously the loads they supply can't be on the same bus as the utility.

In an off grid Powerwall setup the Gateway becomes the transfer switch for the backup generator.

Also I'm still surprised over your energy consumption and that driving is a small proportion of your consumption. I'd seriously be investing on energy reduction rather than production.
I'm really out of opportunities to do that. I've replaced by oil burner with W/W heatpump, cleaned and lined all the ducts and rerouted them to avoid bends where possible, stopped all the leaks I could find, replaced many of the windows and reinsulated the heat losing parts of the house with closed cell foam.

Here's my energy cosumption for year prior to today and the 3 years before that:
34.8 <-- 35.3 <-- 39.3 <-- 39.9 MWh
Note that our winter is in the middle of each of these time spans. All the other work I mentioned above was done after the heat pump was done 3 years ago thus all that stuff saved me about 4 MWh/yr. Not to be sneezed at but my baseline load (the absolute minimum I ever see) is 2.03 kW. Over a year that is 17.795 MWh which is close to half the load in each of the last 4 years. This 2.03 kW is the sum of the loads that NEVER go off. What are these? Ten thermostats and the associated zone controllers, 5 WiFi hotspots, a router, 4 ethernet switches, 4 security cameras, wall outlets with USB and/or night lights built in, WiFi wall switches, TVs, computers and monitors that stay plugged in, UPSs (that trickle charge even when unloaded), printers that stay on line (even though they are Energy Star rated), refrigerators (that draw power for their control circuits even when the compressors are not running), PBX and telephones (whose displays are illuminated at all times), VOIP adapter, control circuitry for the transfer switch, generator controller and generator battery trickle charger, Synology NCS, NEST sensors and range extenders, Instant hot water heater controls and ethernet interface, wall warts that stay plugged in even when not charging the device, Qi chargers and probably a few other things I've forgotten. I keep getting these flyers from the electric company, which I've always laughed at, on how to save electricity and the thrust of most of them is "Unplug all that stuff". Looks as if I could reduce my electric consumption by 25% (8 mWh) if I could get rid of half those gadgets. But, as you may already have come to suspect, I'm a gadget freak and am not inclined to do that.

On top of the baseline load I have a walk in cooler from my days when my fascination was with beer. It takes 1 MWh/yr to run that.


Obviously building new, like I have, recently, allows for more control of consumption, especially thermal loads. But it can and should be done I think, less is more. When our heat pump is on it heats the whole house with 400W with us inside at 23C and outside at 5C, (with the wind howling at 50kmh avg) but that's mainly because we have 150mm SIPS panels for insulation, and double glazed windows etc.
Giving you a generous COP of 4 would mean your pump is producing 1.6 kWh of heat which is 5459 BTU/h ( 0.45 ton). If you are in the warmest parts of the CONUS in a tight house the recommendation for heating is 30 BTU/h-ft^2 so 5459 BTU/h would cover 182 ft^2 (17 m^2). For perspective I run an 8 ton W/W heatpump at a duty cycle of 40% for an average of 3.2 tons with the thermostats set no higher than 20 °C but it does get colder than 5 °C outside for sure. Are you sure about that number?




Anyways, looks like this is product is about as close as it gets for the proposed gateway box and to use PV directly. Does 50kW and has a PV input option where it suggests the PV nominal power should be at least 2x the max output power. Minimum PV size would be around 14 panels or so (350-600V).
It says that the required input power should be twice the output power. This is clearly inline with your thought in a previous post about adding more panels to get the requisite juice with lower insolation. So here they want 100 kW or 333 panels capable of 300 W each. The big question is as to whether this scales. Can we charge at 10 kW with 20 kW in i.e. with 67 panels?
 

JBee

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I'm pretty familiar with grid connectivity, the "gateway" functions that can also play a role off-grid functionality. I suppose it all depends on how many connection options are included. These are the inverters I'm using atm on the house that can run batteryless and can be paralleled etc. Efficiency isn't that high, but a few extra panels fix that. Versatility is high instead, and they play nice with various lifepo4 storage options, although some settings can be limiting. (I also have SMA sunnyboy/sunnyisland): https://www.mppsolar.com/v3/catalogs/PIP-MAX.pdf

Apart from protection circuitry the inverter could handle all the switching internally for off grid use. there are hybrid on/off grid versions of the same inverter as well, but I will never have grid here, it single phase and on the otherside of the block 2 miles away.

In regards to your consumption I'm not having a go at you for household consumption, but I thought using 15-21kWh a day in the winter in a rental was high. In the new place we average between 6-12kWh in the house itself, depending on if it's washing day or the HVAC needs to run. I just checked the counter, in the last 225 days we've used 1.7MWh so about 7.5kWh a day avg.

And we still run our PC's (boys are avid gamers, so 2-3hours each other day, with the oldest competing in international esport comps), and I run my 43" 4k HDR monitor off a XPS15 at least 2-3 hours a day for work, plus 2-3hours of TV in the home theatre room. I only have two wifi routers including a pihole as a DNS/adblocker/VPN (1 house 1 in workshop), 1x 24port Gbit LAN, our wireless broadband from our neighbour who has fibre in town (Starlink incoming), and DIY NAS using odroid H2+ running OMV and Docker for bookstack, openoffice etc, which is backed up via VPN to a German, US and Oz VPS, 4 POE ipcams (1x 30x zoom for firewatch), weather station, and probably about 6-7 Samsung phone/tablet chargers plugged in (they're good in standby), along with a selection of smart speakers in most rooms, and USB torches/lights/powerbanks. These are all scheduled and switched off for sleeping hours, except the router/LAN and chargers. Then of course inverter fridge (600l), Heat Pump, water pump (500W on a VSD), all appliances are electrical including induction hob, convection oven, microwave, Thermomix etc, ducted vac, and gas HWS booster (that's not running off solar yet - still have to fiddle with it). Most of the external lights are independent solar, and all the rest are 12V DC straight from a dedicated battery, along with some DC USB PD charging I still have to complete.

Our weather is also very mild here. In the summer we can get up to 40C if we get a strong northerly, but that always crashes back down to around 25C in the evenings as soon as we get the seabreeze in the arvo. That only happens 3-4 times a year though, most of the time it's under 30C in the summer, and not much rain or cloud. In the winter we also get the northerlies which can get us up to the high 20C's in the winter during the day, but most of the days hover around 20C, some going down to 8-10C if we have a Antarctic front come in from the south. At night it can go down to 3-5C, but also only when those southernly fronts come in. This all helps with COP if you schedule heat pumping during the day.

I also cheat a bit with the house design. Double glazed windows with blinds allow for pretty good sun heating control for the summer, reducing my load, and in the winter they help with insulation at night. So there's a few extra kWh of sunlight gathered through the windows during the day to keep it up. Another big item is that the only thermal mass in the house is the insulated hydronically heated concrete slab that acts as a huge buffer between the night and day time, and is "pumped up" using excess PV power during the day...if I have it running because it is cold enough. But that mass, along with the stratified waterboiler storage definitely helps in evening out and reducing peak load. (a tall boiler where the water is not mixed with household water supply, and is not convected so that coolant temperatures are "stratified" and can be extracted at various heights and therefore at temperatures required for the load)

The trick is not to allow high deltas on the slab temp. There is no other thermal mass in the house on purpose, as I believe the best thermal mass is water, which can be modulated for comfort with a valve to each zone, and stores more heat than concrete per unit of volume. Also cheaper to store heat in a water tank than in batteries, and the circulation pump, when it's on, only uses 15W to boot.

On that subject, if you do have a high HVAC load one thing that might help even with a not so passive house, is a ice heater, that uses the phase change latent heat of water to run a heat pump at better COP. Pretty common in Germany. Depending on how you size it you can actually run it multi seasonal (it's not actually that big), so take summer heat to the winter, and winter cold to the summer. Not much more than a buried concrete/plastic insulated tank that has heating/cooling coils in the center, so that it doesn't expand and crack the tank whilst it freezes. DIY is an option for this.

But back to the box:
I found some prices for the Orca boxes, the 50kW is $25k but they are doing a much smaller Orca Portable with 20kW that will be $6k, so definitely an option if it includes the PV input. Obviously the good thing with this setup is that it can directly negotiate the charge rate with the EV to fit the PV power available. I'll keep on looking to see if I can find some German options too. PV and EV is big there, Mercedes invented the EV after all.... :)
 

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.....

On that subject, if you do have a high HVAC load one thing that might help even with a not so passive house, is a ice heater, that uses the phase change latent heat of water to run a heat pump at better COP. Pretty common in Germany. Depending on how you size it you can actually run it multi seasonal (it's not actually that big), so take summer heat to the winter, and winter cold to the summer. Not much more than a buried concrete/plastic insulated tank that has heating/cooling coils in the center, so that it doesn't expand and crack the tank whilst it freezes. DIY is an option for this.

But back to the box:
I found some prices for the Orca boxes, the 50kW is $25k but they are doing a much smaller Orca Portable with 20kW that will be $6k, so definitely an option if it includes the PV input. Obviously the good thing with this setup is that it can directly negotiate the charge rate with the EV to fit the PV power available. I'll keep on looking to see if I can find some German options too. PV and EV is big there, Mercedes invented the EV after all.... :)
Interesting

Could you provide links to the two items you mentioned

"ice heater"

Orca Portable with 20kW

thanks
 

ajdelange

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In regards to your consumption I'm not having a go at you for household consumption, but I thought using 15-21kWh a day in the winter in a rental was high.
Understood. Can't reaally comment on rentals but presumably they are more or less like other houses and the average consumption in the US is 30 kWh per day. Thus 15 - 21 kWh/da is actually low. But my average year round consumption is more like 96 kWh with over half of that going to my gadgets and HVAC control systems. The other half goes to charge the car, keep my beer cool and run the HVAC,

In the new place we average between 6-12kWh in the house itself, depending on if it's washing day or the HVAC needs to run. I just checked the counter, in the last 225 days we've used 1.7MWh so about 7.5kWh a day avg.

And we still run our PC's...
I recognize that you have lots of stuff on timers etc but I still have a hard time believing, given all the gadgetry you list, that you can get by on 7.5 kWh per day. Our summer place ("cottage" as it is known in the local patois) is not as large as headquarters but it too has its phone system, NAS, TV's etc. The baseline load there is less than half of the 2 kW baseline at home at 880 W. But 880 W is 21 kWh/da, treble what you are reporting for you whole load! The whole load for this house is 58.6 MWh which includes car charging. We never run A/C here and in the winter the interiors are kept at 5°C supplemented with oil and straight electric in the older part where the heat pump doesn't reach. But we also have loads like generator battery and sump heaters.

So something doesn't compute here. In the last 226 days you used 1.7 MWh but you have a 30 kW system capable of generating something like .030*5*225 =33.750 MWh in that time. If you only use 7.5 kWh/da why did you install a system capable of supplying 30*3 = 90 kWh on a lousy (3 hrs FSE) day? And that brings to mind another question. When you batteries get full does your system dump the excess or do your inverters curtail the PV arrays?

Our weather is also very mild here. ...This all helps with COP if you schedule heat pumping during the day.
This is all intersting but it does not explain why your total load is less than 1/3 of the baseline load in my "cottage" and less than a third of the average home consumption.



On that subject, if you do have a high HVAC load one thing that might help even with a not so passive house, is a ice heater, that uses the phase change latent heat of water to run a heat pump at better COP. ..take summer heat to the winter, and winter cold to the summer.
We do that but not with a small water tank but rather a huge one: the aquifer beneath our property. Over the course of the summer we cool it off by perhaps 10 °F and over the summer we warm it up by about the same amount. But thinking about doing it with ice certainly makes the calculations easy. My A/C load is about 3.2 tons. A ton of ice is 2000/8.4 = 238 gallons so for a 100 day cooling season I'd need a 3.2*100*2000/8.4 = 76190.5 gallons of ice. Better, I think, to let mother earth be my tank.


But back to the box:
I found some prices for the Orca boxes, the 50kW is $25k but they are doing a much smaller Orca Portable with 20kW that will be $6k, so definitely an option if it includes the PV input. Obviously the good thing with this setup is that it can directly negotiate the charge rate with the EV to fit the PV power available.
We would hope that it would be able to do that but I did not see in their literature that it definitely could. What we do know is that Tesla vehicles can live with heavily curtailed charge if the charger pulls way back for whatever reason.
 

JBee

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@ajdelange

Sorry I thinks there's a few assumptions in there that are a bit off. First one is the entire building complex has about 30kW of PV (4x 7.5kW) on roofs facing North, including the workshop where the PHEV can be charged. But only one inverter is dedicated to the household loads and has about 7kW of PV connected. I can load share the inverters from the common lifepo4 battery, but there is only one inverter that supplies 240V to the house and has that consumption I gave. I don't have monitoring on the 12V circuits and lighting yet, but will add that at some point, so you'd have to add something there too I suppose.

We are also out of the house working on the farm or in the workshop (separate circuit) most of the day, with only really being actively using stuff between 5-11PM (except for breakfast, lunch and scheduled washing and HVAC during the day) . Because of the weather we have only run the HVAC on about 20 different days so far this winter, it hasn't run in our summer yet, as the house has passively been comfortable enough that it wasn't needed. So the house consumption is probably skewed because of that a bit, but my experience has been that the summer doesn't use as much as the winter for HVAC by far. As before we currently use a LPG gas instantaneous boiler for hot water, that also does the hot water for the front loader, and dishwasher, but even there we're only half way through out second bottle in that same period. (short 2-3min showers and water saving shower heads help, along with thermostat mixer taps)

The inverters curtail the PV at the moment, but hopefully in the next few months our horticulture patch down the hill (45m height difference) will be ready and we'll have our water bore setup up here on the hill with our 500kl water tank. Plan is to use the PV excess to run the bore pump (via a PV excess modulated VSD) and use the tank to buffer supply for the few acres of irrigation down the hill, which then can run whenever the valves open. Obviously the CT would get some of that too....I might even use one of the CT reservations I have for a farm implement use and energy storage. I'm wasting a bit of the PV energy I suppose, but it worked out cheaper to put the extra PV cells up than to do tracking etc, simply because we get $0.42c per watt for the PV we connect up from the gov. So the PV didn't really cost me anything, just had to pay for the inverter/battery and framing as such.

As for your ice calcs I think you might of left out the latent heat component which would make it better?
https://courses.lumenlearning.com/suny-physics/chapter/14-3-phase-change-and-latent-heat/
 
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JBee

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Interesting

Could you provide links to the two items you mentioned

"ice heater"

Orca Portable with 20kW

thanks
This is the Orca website, I haven't found to much about their new Portable product otherwise:
http://www.andromedapower.com/orca-inceptive/

As for ice latent heat storage I only have some links to German sites atm. But you should be able to use google to find them.
 

ajdelange

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I assume nothing but I only know what you tell me. I now understand better how you are set up. I still don't understand how you are able to run a household on less than a third of the normal consumption.

As for latent heat: that term is usually reserved (at least in the HVAC industry) for the head of condensation as, for example, of my 3.2 ton load probably half goes to the latent heat (remove the humidity) and the other half to "sensible heat" i.e. actually cooling the air.

The ton of air conditioning unit is pure heat of fusion. It is based on the amount of heat absorbed in an hour (12,000 BTU/h) by melting a ton of ice over a day. Thus when we talk of a heating requirement of 3.2 ton that refers back to the days of yore when i would have had to order 3.2 tons of ice for each day of the cooling season, put it in the ice house and cover it with straw. In those days the ice was cut from places in New England and Canada and shipped by rail to places like New York city all winter long so that the ice houses were full by the time the summer hit.

Yes, the runoff from a ton of ice is cold and in warming it to room temperature it could absorb more heat but the phase change heat is so much greater than the specific heat that it's not worth considering in calculations involving melting ice.

Because of this history I was quite intrigued by the notion of this ice bank as it is essentially reverting to the 19th century way of doing things. But it would not work in my application because it does not go below freezing often enough or stay below long enough to produce ice where I live. I would have to have it shipped in from up north. Thus I can't move cold from winter to summer but I could move it from Lake Placid to Washington.

Of course its appealing because if I had my 320 tons of ice on hand my air conditioning load would be only that required to run coolant pumps and fans. Second law says that a system that pumps heat from 80 °F to 55 °F should be doing work for me but the realities are that because of inefficiencies I have to do some work to pump heat downhill. Mind you less than I must do to pump it up hill (from 50 °F to 68 °F) in the winter but still quite a bit.

Some systems (those with desuperheaters) capture the "wasted" energy and use it to heat DHW. These also increase the "efficiency" by lowering head pressure so the compressor doesn't have to work so hard.
 
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JBee

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So it appears you have nearly 10x the heat requirements from your HVAC than I do...yikes!

I dunno mate maybe the electrons go faster in the US! Aussie average is 19kWh btw.

I mean I did go around the house and test everything individually, and then got rid of the high standby ones that I could, then put the rest on master/slave boards or a scheduled powerpoint. But its definitely not inconvenient at all to run like this, I don't notice it. I have the kWh meter on the inverter and a wireless one on the feed, and both are within 10% of eachother. I'll have to add up my list to show you what draws what. I'm still in the process of adding individual circuit monitoring.
 
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ajdelange

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So it appears you have nearly 10x the heat requirements from your HVAC than I do...yikes!
So it seems but I don't attach any proclamation of surprise because my numbers fit the size of my house, its siting and my local climatic conditions. The HVAC was designed around those and it is, therefore, completely unsurprising that it draws what it draws.

Now when you say that you achieve an 18° C rise with 450W I may not say "yikes" but I do say it must be a pretty small house because if I work backwards from that number I find that it would be, if tightly insulated and located in Florida, 182 ft^2. But then as it apparently isn't a small house I wind up saying there is something I'm clearly not understanding.

I dunno mate maybe the electrons go faster in the US! Aussie average is 19kWh btw.
Other than Coriolis being in the wrong direction and driving on the wrong side of the street I think everything is pretty much the same.


I mean I did go around the house and test everything individually, and then got rid of the high standby ones that I could, then put the rest on master/slave boards or a scheduled powerpoint. But its definitely not inconvenient at all to run like this, I don't notice it. I have the kWh meter on the inverter and a wireless one on the feed, and both are within 10% of eachother. I'll have to add up my list to show you what draws what. I'm still in the process of adding individual circuit monitoring.
The one nagging thought that keeps coming to mind is that the consumption meter is on only one phase and that it is, therefore, measuring only 1/3 the load. But I am sure that's not the case.

I'm not questioning your methods but there is a disconnect here. I'm just finishing up a 3 car garage. There qre no loads in there except for an ethernet switch, some WiFi light switches and 3 WiFi garage door openers. Workmen were in there 5 days in the last month and opened the garage doors a couple of times and turned on the lights (LED) for a few hours each day. Nonetheless the average load was 1.5 kWh/day. Thus it is surprising that you can run an establishment with refrigerators, stoves, heat pumps, TV's, computers, gaming consoles, modems..... on only 7.5 kWh/da.

It's been an interesting discussion.
 

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@ajdelange

So I'm not claiming that the heat pump is only running at 450W, it uses more when it starts for about 10-20minutes or so, but then stays at 450W average whilst maintaining interior temp. Its a bit more of a dynamic load overall. I will have to put a monitor on it to track it better, and now that you're curious, I too want to know what it is doing and exactly compare that to weather data. Living area supplied by that one heat pump is about 180sqm in a double storey layout. The workshop has its own 3 phase A/C setup and shares a common 80sqm wall with the house.

But it's important to note that I also schedule to run the AC during the day when it's warmest to heat the house up, and when the PV is available to avoid battery cycling. At that point outside is typically never under 15C, meaning the Delta T is lower, and then use the A/C to push it up to 25C or so inside before turning it off, along with the help of the sunlight through the windows with open blinds etc (which can be up to about 18kW of extra heating on a sunny day).

In the winter time it's "warm" during the day inside the house, but you can open a window or turn off a zone if you're using a room during the day if it feels too warm. The house mass retains much of the stored heat and takes longer to cool down that way, because you start with a higher temp in the mid to late arvo, and run at better COP. I modulate the day temp setpoint depending on weather forecast (manually atm) so we don't get too warm (via my phone). Then at night it cools down, and we run it at about 21C or so once it gets there, to maintain the inside temperature until about 11PM until we head off to bed and turn it off. In that period it is all that it draws.

RE electrical: I only have one dedicated inverter and one phase on house supply. All inverters on same LiFEPo4 battery though, so connected on the DC side. House Inverter meter is on 240V output of inverter, and wireless energy monitor is on the same 240V output cable, inside the inverter itself. (Because there was some space in there). Inverter has wifi too, but has a cloud server in China that is flaky, I need to roll my own on a dedicated Pi Zero W server running Graphena and MQTT etc. so I can send automated commands to it as well.

Only the workshop has 3 phase to run compressor, welder, more pumps, vacuum press, drill presses, bench saws, drop saw, table planer/thicknesser, range of Markita 18V powertool chargers, CNC, 3D printers, laser cutter etc. But it is intentionally not connected to the house because I don't want a machine stalling (from low batt or PV input too) and tripping the house and PCs/wifi etc. CT will be charged in garage/workshop of course. It only has the inverter energy monitoring atm. I'm still chasing a decent DIN rail mounted 3 phase wifi enabled monitor with load shedding capability. (I have a few single phase ones in the house)

As you can probably tell, my reason for pursuing "batteryless" CT charging is also so that I don't have to increase my house/workshop pack size to allow for continuous CT charging. But this will also depend on alternative system cost, otherwise adding some more batteries to buffer, or more PV to the DC side of the inverters also works.

I don't need overnight charging at all, my trips are less than 50km a day locally (only 5km from town), intermittently up to 120km (round trip to the next town) a day about 2-3 times a month, and another 2-3 times of 600km one way trips per month for the shopping runs to the big smoke. For the long trips I'd just organise a top up the day before anyway, so long I make it to the nearest SC, that is now being built 400km away, I shouldn't have a problem with a TM. I also have no qualms using a CT inverter as a buffer if needed. Or cycling between the second CT etc. I won't be getting rid of the Crafter van or Merc 16t flatbed truck anytime soon either, so I can always resort to them if needed and I forgot to schedule a charge...or run the 50kVA for a quick charge overnight on farm diesel.

Overall it should be fine, just wanted to make the most of PV charging because PV is cheap (near nothing with gov. subsidy up to 100kW).
 

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So I'm not claiming that the heat pump is only running at 450W, it uses more when it starts for about 10-20minutes or so, but then stays at 450W average whilst maintaining interior temp. Its a bit more of a dynamic load overall. I will have to put a monitor on it to track it better, and now that you're curious, I too want to know what it is doing and exactly compare that to weather data. Living area supplied by that one heat pump is about 180sqm in a double storey layout.
O.K. Now things are starting to make sense. The recommendation for a house your size, well insulated and in a climate like Florida's would be 58104 BTU/h (4.8 ton). That's 17 kW which, with a COP of 4, would mean 4.25 kW of electric input. But that's only when it is running full bore. The way you describe things it is certainly running full bore less than 10% of the time and that means average power consumption of less than 425W. My house is larger, the climate much more severe and one of the heat pumps is A/A meaning I don't get COP 4 consistently so that it is no surprise that my average consumption is 5 times yours. I think the circle is closed!


The workshop has its own ...
I'm always intersted in learning what people are doing so I appreciate your taking the time to post all that.



I'm still chasing a decent DIN rail mounted 3 phase wifi enabled monitor with load shedding capability. (I have a few single phase ones in the house)
It may be obvious from the pictures in Nos. 5 and 9 that I am using eGauges for this. They are 3 phase capable and while they don't have WiFi built in they do have several advantages. They store data for the life of the unit at 1 minute intervals going back a year and then 15 minute intervals for data older than that. They require an internet connection (which can be done over the power wires if an ethernet port isn't handy and will record data from either 15 or 63 CT's. The main interface for most is a website but there is an API which might let you plug an eGauge (or eGauges) into your automation system. I don't, probably, have to tell you that they are rather dear.



As you can probably tell, my reason for pursuing "batteryless" CT charging is also so that I don't have to increase my house/workshop pack size to allow for continuous CT charging.
More battery buys you more flexibility for sure but you have to pay for it.


As for ice latent heat storage I only have some links to German sites atm. But you should be able to use google to find them.
You can't use ice to store heat because ice is made by removing heat (the heat of fusion) from water. The heat you remove is stored in the ambient (air, a pond, something like that). Then you can return the heat to the ice (melt it) when energy is needed. So here's how to charge your CT any time you want to without more batteries.
1)Add PV in quantity sufficient to cover your driving needs
2)Use the energy, all of it, from the extra PV to make ice using a water cooled ice machine. Run the output from the ice machine into a pond.
3)Connect one side of a Stirling engine to the pond and the other to the ice reservoir.
4)Use the Stirling engine to operate a generstor which charges the car.

The energy is really stored in the pond (or in the air if you use an air cooled ice machine). The ice just serves as the cold reservoir for the Stirling engine.

Neat, no? Of course I am kidding because while this is theoretically possible the maximum thoretical recovery from the pond or air is only 100*(1 - 273/(273 + 40)) = 12.7796% of the heat stored in air or pond if their temperature is 40 °C.

Now this does make some sense if what you need the energy for is air conditioning as you can recover the cold for only the cost of running fan and pump motors, There was a company in California selling this technology for use in places where electricity is super expensive at the times of day when A/C is needed but much less expensive at night when it isn't. They made ice an night and melted it during the day. Supposedly this saved money and would, if many adopted it, level loads. AFAIK they went TU.
 
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JBee

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I remember stirling engines well. Flew out of Ann Arbor through Newark NYC, 2 days before 911, after looking at STM Stirling there. Brilliant machines, but ended up being too small and expensive as we got methane powered generators in the MW range from EU instead.

Thing is you need a higher Delta T with Stirlings to get the efficiency up carnot. Won't do much from ice. Unless its nitrogen!
I actually designed a tracking tripod and concentrator for the hybrid solar/methane STM back then to overcome the battery storage problem for baseload. Solar at daytime with methane boost, and for running at night. Using renewable biogas of course from food scraps. Been meaning to ping EM about using that to fuel Starship lol...cow manure powered spaceflights to Mars. Brilliant! :)

As for "ice heating" I know its a misnomer, just a poor German translation.


But if you do come up with even better CT charging solutions for outback Joe, let us know! :)
 
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