I dont think you have to get a geothermal loop inspected but of course you do need septic inspected. Because of soil compaction etc you would likely need the geo loop several feet deeper than septic like 5-6 feet deeper. Same thought though. He has plenty of land just dig 2 sections of trenches one for septic one for geothermal at the same time. Getting the equiptment there and other fees are a lot of the costs. Digging and additional geo-loop would likely cost no more than$1500-$2,000 EXTRA for about 2 days work.He can easily do that himself for about $300-450 Rental fee plus delivery and pickup if he can't pick up which is usually about $150 or so depending on distance. Rent it for a week to do whole thing and about $1500 total cost for excavation. I did geo-loop for 5 ton (about 600feet per ton of loop but can limit to 300 feet or so if space confined by coiling loops etc. If he is going to dig a well he may want to consider drilling a "dry well for a pump and dump geothermal but if the well needs to be deep it will be more beneficial to have closed loop and I would guess wells are deep or poor flow in that area.
30kW "cheap" inverter
- Thread starter BlueSmoke
- Start date
You have received some very good advice. I am in a similar situation except in different area of country. I have 6500 square foot Dryvit home pretty well insulated. I have a pump and dump geothermal but may modify it to closed loop in future. Already had well and a ditch etc.
You already made a great choice with the ICF and great insulation. I would consider 2 inch closed cell foam on inside of ICF also then either closed cell or possible mineral wool for rest where needed. The mass of ICF will help a lot with nighttime HVAC loads. @ story more efficient than 1 especially if 1st is a basement level.
Your loads for all but the @240 V things like HVAC dryer, oven, water heater etc will be relatively low. They are mainly Lighting ,Fridge , freezer, microwave , tv s computers, washer etc. I doubt you would generally use more than average of 1kw at any one time or 2 Kw peak when fridge and freezer and microwave and lights and washer all at same. So this use is very likely less than 10Kwh a day.
Of course the 2 main uses are HVAC and heating water. The biggest problem for solar is HVAC Heating rather than AC since its done at night and winter.
Solar array: yes make it big to reduce storage needed and for more winter availability. I personally would use the max amount of PV input your inverter/s can take. Many large inverters are more restricted on PV input than you might think. For example the Growatt 12,000 watt low frequency transformer unit has a 36,000 watt surge but only 7,000 watt maximum pv input.
Inverter: I also needed relatively high peak Power mainly for HVAC about 25kw and ability to use about 11,000 watts continuous so similar to your requirements.
First limit surge power required.
WellPump : Choose or change to a soft start pump such as a VFD (Variable Frequency Drive which is more expensive along with higher potential maintenance) pump or something like a Grundfus SQEpump or SQ which is what I have gradual ramp up like Inverter HVAC. I would personally only get VFD if I was going to irrigate quite a bit . The VFD s also provide constant water pressure.
The other choice is a direct solar well pump with its own panels since you will store a large volume of water and it should only need to run with sun and Absolutely no surge or power draw on your inverter .
HVAC: Get an Inverter (no surge ) based heat pump(=no surge load) there are geothermal and air to air and air to water heat pumps with these. Generally only the most efficient units are inverter based otherwise the newer units usually use 1 or 2 stage scroll compressors. In many brands of Geothermal only the very top of their lines use inverter compressors such as Waterfurnace 7 or Climatemaster Tranguility 45 but they over year round water heating also not just in cooling use. You could also do what I did. I have a Climatemaster tranquility 30 (because you can't get the 45 from DIY suppliers consider Mr. cool or Climatemaster for DIY or non specialist installer likely much much cheaper). Another choice is Forced air vs mini splits in addition to the radiant floor heating which is nice but it necessitates 2 different systems since you can't cool effectively with it. If forced air use heat pump for AC and ? supplemental or total heating. You can also do what I did and get efficient heat pump with Efficient propane dual fuel furnace . That way you can heat with electric or gas. At least the first and last heating month you can probably heat with almost all PV with the high mass of ICF. You may even want to consider putting the tubing in for radiant heat but not utilizing it until you live in it for a while You may not really need it. So mini splits or Forced air with split units so all ductwork etc in conditioned space not outside only condenser there.
For Surge from non inverter HVAC units or shop motors etc you can use Soft Start Devices (NOT Hard Start Kits) I used the Hyperengineering unit with my 5 ton geothermal unit with scroll compressor and it reduced starting amps/surge from 100 Amps down to 24 amps and it runs on 16 amps in heat mode. The other unit is 3 ton Inverter dual fuel Fridigaire with IQ drive. The inverter units can usually run efficiently as low as 30% of rating and can increase to 130% of capacity at a little less efficiency. So my 3 ton will produce like a 1 ton or up to about 4 ton of conditioning .With backup dual fuel furnace you have the best of both worlds.
In your case with the high mass you may well not need as much battery capacity for heating as Most.
Dryer: Get a Heat pump dryer takes a little longer to dry but less overall wattage and around 600 watt draw and Some dont require a vent thus less penetrations and air loss so another savings. Drawback not many in larger capacity Solution plan for 2 if needed.
Water Heating: The geothermal or air to water heat pumps if all season or the radiant system +/- the coupled generator, Direct PV heating with backup straight resistance using large volume of tanks and smaller wattage elements= less max draw from inverter or batteries (use one element for house /inverter electric with say 1500 watt element rather than 4500 watt and lower element direct PV) . 1 or 2 stand alone heat pump water heaters and disable emergency heating on them about 500 watts to run and I think all are inverter motors so no surge. Remember they will get heat from surrounding air so Cool surroundings in winter as well as summer consider that in locating. Also no huge wires to run since low amps drawn and you could preheat it with Straight electric as solar dump load direct pv etc. You can also make heat exchanger for direct pv heating such as this video that uses water circulation panels instead but idea is the same.
Water Heater
Maast
Compulsive Tinkerer
Heh, every house built in Utah has a basement and a "cold storage room".
Oven : favor propane but electric doable just another large load to worry about.
HVAC forgot no real choice on cooling but I did and would recommend some ventless gas logs for a fireplace for emergency heat or other ventless unit. This requires no electricity at all for true emergency use. They require NO CHIMNEY either and again no extra roof penetrations.
Water heater: i forgot condensing tankless propane again no roof penetrations if mounted exterior on wall or indoors on wall etc but I think you have this covered and Its more involved if you use preheated water from any source ( need mixing valves / bypass valves etc due to the way tankless works)
Big Points
Overall Efficiency ( recommend view David Poz u-tube Channel House build playlist non ICF, Matt Risinger videos)
Design for Passive solar window exposure etc.
Very high quality Windows and Doors like R5-7 windows
Insulation
Air sealing
limit thermal bridiging
Limit penetrations especially Roof
High House mass
Efficient HVAC
Efficient Appliances
Use other than electric for high consumption or little used (oven)
Consider as much direct PV as possible (well pump if not needed for geothermal)
Avoid high use Electric other than Electric Hvac water heater etc if you want to get close to zero propane and lower overall monthly use ( emergency heat/logs etc and oven)
LOWER LOWER Surge loads as mentioned in each category I cannot over emphasize this
Use Dump loads for excess pv solar such as water geating
Consider at least one Electric Vehicle especially if can daylight hour charge ( summer dump load using its batteries and winter you can charge at supercharger if needed) You can in some cases use the vehicle battery via the vehicle 12 volt battery for a couple thousand continuous watts off power especially at night or true emergency (Will Prowse did video about this on his Tesla)
I will probably think of more
Even with well pump running and fridge, freezer, microwave, lights, TV s , Computers, dryer , two 3 ton inverter HVAC units, water heater like I described etc your max continuous use should be around 12,000 watts. Could be higher depending on your choices and non dump car charging etc.
Generator: diesel or propane size depends mainly on Surges and Continuous use numbers. Remember you can also charge batteries relatively quickly with larger generator avoiding noise at night or during dinner party etc. So you can maximize any size generator over say 8,000 to 10,000 watt generator running more hours or 20,000 watt running half the hours etc. Since they will be charging batteries and running load there is no low efficiency idling.
Next post is Inverters.
And ICF homes are very well air sealed with possible exception of roof and penetrations etc.
Keep in mind the dangers of ventless heating, and tight homes... they consume oxygen, produce CO2 AND CO gas, AND they produce copious amounts of water inside... as long as you provide adequate Fresh air exchange, and have other methods of heating that won’t allow moisture to collect and cause issues, you should be ok.
Inverters: The Low Frequency type inverters are generally higher surge and lower efficiency and Higher Priced (about double).
If you minimize surge you dont need to worry near as much about that.
USA made or supported Brand Name established companies Proven not necessarily better like the Sunny Line Schneider Outback etc
Chineese or Taiwan made (not necessarily bad 0 like MPP, Growatt, Deye, Sunsynk, Amen about 1/3 to 1/2 price. MPP and Growatt have some USA support if you buy particular places.
Hybrid inverters USA Solark etc.
I am making choice now : First thought a pair of MPP LV 6548 s 13,500 continuous watts but 115v each.
Then sunny boy and sunny Island etc but much more expensive and little more complicated but for Low frequency units pretty efficient and real Workhorses , Now leaning toward a pair of Deye or Amen 8k inverters advantage still have 240v with one unit and 10k max if one goes out and 16,000 watt continuous output 20,000 generator pass through I think. The Dye and Amen are two for around $4200 imported while you would need 2 Solark 12 units at $6500 or more each for comparable features . You could actually get 4 units and have an immediate backup for less than 2 Solark 12 s.
Make sure if you order import you get duty and shipping included.
Further posts about batteries
Generator I forgot you will
Very True as I said for Emergency use only. Make sure as code would require to have fire alarms and add co2 alarms even if off grid. Also you can always vent them and outside air intake etc.
CO alarms.
Perhaps a low oxygen alarm.
Batteries: The 272- 280 Amp hour Lithium Iron Phosphate cells are very reasonable at present. EVE harder to get at present or the Lishen cells seem to be reliable at present here is a link to one seller ? non proven
Basen Lifepo4 Battery Cell 4 Pieces Lifepo4 3.2v 105ah 200ah 230ah 280ah 300ah 310ah Lithium Ion Batteries Lifepo4 - Buy Lithium Ion Batteries,Lifepo4,Lifepo4 280ah Product on Alibaba.com
Basen Lifepo4 Battery Cell 4 Pieces Lifepo4 3.2v 105ah 200ah 230ah 280ah 300ah 310ah Lithium Ion Batteries Lifepo4 - Buy Lithium Ion Batteries,Lifepo4,Lifepo4 280ah Product on Alibaba.com
offer.alibaba.com
You could also get Lithium Manganese Nickel with cobalt or Aluminum like Nissan Leaf cells but not much if any cheaper are used and less safety due to fire risk. Advantage with smaller battery bank can get much higher amperage from them 540 amps per 7 or 8 cells in series . Parallel a few sets and get as much as you want but since they would need cooling at sustained output like this it would only be for surges etc.
Big Point: I think you will end up wanting 100 to 150 Kwhr of batteries but why start with that. I recommend start with 4 sets of about 272-280 A Hr Lishen cells about 14.3 Kw each for 57.2 Kw (or certainly no more than 7 or 8 sets capacity) in battery bank and try it a while and if you need more simple to add. You can also save initial cost this way especially if you first put into service in late spring to early fall.
The generator is the bigger question . I think 8-10,000 watts depending on difference in price for 20,000 watt neighborhood. You dont want to buy one then upgrade though. A 10,000 watt run 24 hours though is way more than you would need without much surge and you could likely still run it just at convenient times.
Make sure you get a remote start Generator and have a remote start dry contact connection for inverter etc.
So My system will end up being 100 Kwhr lithium MN of chevy bolt and Nissan Leaf batteries ( bought mine before lifepo cheaper and my Bolt batteries 60Kw were Brand NEW not used with lots DIY. Would get all LiFe Po4 now mainly due to safety.
Probably 2 Amen 8k inverters in parallell.
12,600 watts panels now plan on increasing to around 20,000 watts or more when get Electric vehicle.
I am on grid but use it primarily for backup . I normally was using about 1800 Kwhr per month but higher in winter if use the second HVAC on all electric. I do have generator hand start etc but only would use in grid out and no solar/ battery available.
Yep My bad! Good Catch
Q-Dog
¯\_(ツ)_/¯
Many, maybe most, new natural gas heaters have low oxygen shut down. If I were relying on such a heater as a main heat source I would make sure to have that feature.
Maast
Compulsive Tinkerer
What he'd need is called a "heat exchanging ventilator". It's an absolute must for all tightly sealed homes for just the reasons stated.
PS. I'd warn you against going above 250v DC PV input. Even 150v would be better. Not so much for the technical difficulty as for the sheer expense and difficulty sourcing the 'Balance Of System' parts and pieces such as breakers, combiner boxes, etc. I'm building a 250v system and it's pretty much kicking my ass finding DIY parts that'll meet NEC 2017 code.
Also, before you start buying stuff READ the NEC code article 690 and associated bits for your area, then read it again, then a third time. Then redesign everything you already thought you had figured out. I'm finding out the hard way it ain't easy _at all_ to meet code and satisfy all the requirements.
And finally, I'd argue that going straight electric for everything is a pretty good idea, especially in sunny Utah. By the time you figure out how much propane, storage, and installation gas would cost you you realize that just making your existing PV and storage a little larger to meet your requirements - with a diesel genset for the holiday season actually would cost the same or less and would be simpler.
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Hedges
I See Electromagnetic Fields!
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- Mar 28, 2020
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Pretty easy to get 600VDC disconnects and fuses with touch-safe holders. This gives you about 2500W per string of panels.
You can get 600VDC MPPT charge controllers, but of course I recommend AC coupled like I have. The inverters can have separate MPPT input per string.
You can get 600VDC MPPT charge controllers, but of course I recommend AC coupled like I have. The inverters can have separate MPPT input per string.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
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This one is 600V AC/DC, 30A, 3 pole.
Mine are around 480Voc under nominal conditions, and 380Vmp
www.solar-electric.com
You can also pick up used ones for less on eBay. Make sure you get raintight 3R if that's what you need.
Being 3-pole, it opened one leg of 3 circuits in my application (code at the time.) for both legs it would only open one circuit.
Once current is interrupted I can open fuse holders on both legs of a different inverter (which has rotary 2-pole DC disconnect included)
Mine are around 480Voc under nominal conditions, and 380Vmp
Square D 600 Volt 30 Amp DC Array Disconnect 3-Pole
Square D 600 Volt 30 Amp DC Array Disconnect 3-Pole
www.solar-electric.com
You can also pick up used ones for less on eBay. Make sure you get raintight 3R if that's what you need.
Being 3-pole, it opened one leg of 3 circuits in my application (code at the time.) for both legs it would only open one circuit.
Once current is interrupted I can open fuse holders on both legs of a different inverter (which has rotary 2-pole DC disconnect included)
You could also consider direct PV mini splits that could also run from inverter if need like they would from grid just put power from inverter to grid input. T
I am certainly not against all electric but for emergency like no solar and generator breaks down then you have NO HEAT SOURCE at all and Battery may not last long heating at night . I would feel much better with propane for emergency heat and since its there the oven also especially if chef desires gas rather than electric stove/oven.
Another VERY IMPORTANT POINT make sure whatever Inverter you get produces US 240 volt single split phase electricity and not 230v European style single phase NON SPLIT PHASE POWER that is not compatible with US msold Appliances etc.
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Wow you guys, keep going with your thoughts. It will be about a week before I have time to get back to this, but I'll read everything and do a mega post to respond. We're in the middle of moving to get out to Utah permanently to get this project started for real.
HateGrid
New Member
Hope some of it helps. Just make sure you evaluate what works best for your situation. Good luck with the move!
