Off grid new house build.

[Bluedog225]

I’ve been taking care of an fla for the last 10 years. What a gigantic pain in the arse. Never again for me.

 

[Ampster]

I use a LOT of power so I'm curious as to whether I can make this work. I'm currently using 70-80 kWh per day because both my wife and I work from home and I run an electronics repair shop from here. On the weekend I either work on cars, do some welding or build something in the wood shop.

The best return on investment will be energy efficient appliances and other devices. A generator is often less expensive than batteries but batteries do not have operating costs like a generator and it is hard to predict what the price of propane will be. Without knowing details about the location and the weather and insolation of your location it is hard to make a suggestion, I am in a temperate environment and long term am eliminating natural gas. I replaced my gas forced air unit with a heat pump Air Conditioner that is zoned so I only have to heat the zones which I will be occupying. This year i have added more solar panels and will be replacing my gas water heater with an electric heat pump water heater. The oven and dryer are electrick and the cooktop eventually will be replaced by an induction unit. I do have the grid as a back up because my winter electrical consumption is greater than summer.

 

[JayArr]

I’ve been taking care of an fla for the last 10 years. What a gigantic pain in the arse. Never again for me.

Can you be more specific Blue Dog? Is it having to monitor and fill the water or is it more than that? Remember I'll be retired and I'm an electronics tech so checking water levels once a week won't bother me too much but if there is more I'd like to hear.

I'm in Canada Ampster so I need heat in the winter. I'll have one of those 1000 gallon propane tanks beside the house to run the radiant in floor heating as well as the stove/oven, hot water, dryer, hot tub and possibly even the fridge. The generator will run on diesel. We'll get all new appliances so I'll be watching when we buy motorized things like the washing machine and dishwasher, these used to just have straight AC motors in them but newer models have servo and multiphase driven motors that are not so heavy on startup.

I pulled the house plans and I've got 2700 sqft of roof. That's enough space for 148 panels if my math is correct. The roof faces SE at a 5 degree angle and I'm not willing to change my house plans so I'll have to compensate for inefficient angles with more panels. One possible plan is to start with 50 panels and run for a year and analyze how much the genny ran and then add panels as needed the next year.

 

[Hedges]

And that is why I bought AGM.
For a relatively small battery, backup during grid failures only.
20kWh gross, 14kWh usable, $5000, expected 700 cycle life and 10 year calendar life.

For nightly cycling, FLA might have been the way to go. I paid a premium for AGM and get less use out of it to be hands off.

LiFePO4 looks like the way to go now. (the prices I knew about were higher 2 years ago) but various hassles with that too.

Can you be more specific Blue Dog? Is it having to monitor and fill the water or is it more than that? Remember I'll be retired and I'm an electronics tech so checking water levels once a week won't bother me too much but if there is more I'd like to hear.

Look for catalytic recombining caps, automatic (or one push) waterers.
Get an inverter that knows how to maintain and equalize FLA.
One guy (the_colorist) says Sunny Island is very good at that.)

But consider LiFePO4, and find a way to keep it at comfortable temperature. I would also put it where fire wasn't a threat to house, even though relatively safe chemistry.

I pulled the house plans and I've got 2700 sqft of roof. That's enough space for 148 panels if my math is correct. The roof faces SE at a 5 degree angle and I'm not willing to change my house plans so I'll have to compensate for inefficient angles with more panels.

250 m^2 x 200W (STC)/m^2 = 50kW (STC)
That could give a very decent amount of power in the summer.

What do you mean by 5 degree angle? Oriented 175 degrees, almost due South? Or slope of just 5 degrees, virtually flat?
For single orientation, South is best for maximum output, especially in Winter.
For a grid-tied system, slope equal to latitude gives most Wh/year. Off-grid, you care more about when.

The generator will run on diesel.

Electricity will cost you $1.00/kWh from the generator.

Consider using liquid-liquid heat exchanger (available marine) to capture coolant heat for the house. Maybe also after that, put through a radiator, with exhaust gas going over that (or a coil of pipe inside a chamber the exhaust goes through.)
You can get a lot of thermal energy from CHP, better use of fuel.

these used to just have straight AC motors in them but newer models have servo and multiphase driven motors that are not so heavy on startup.

For inverter drive, try to get PF corrected VFD. Straight rectifier/capacitor front ends will cause lower efficiency of your battery inverter. I've also found they upset my AC coupled Sunny Boy GT PV.

 

[JayArr]

But consider LiFePO4, and find a way to keep it at comfortable temperature. I would also put it where fire wasn't a threat to house, even though relatively safe chemistry.

TBH, the "separate building for fire safety" really turns me off. I'm old and old school I guess, FLA is a technology I've been working with for a lot of years. I know how to work a hydrometer and I'm familiar with equalizing processes. I also know how to empty a battery, recondition the plates and fill it back up with new acid. I like that Trojan owns factories in North America and builds the batteries here. Companies that are just an office with a Chinese manufacturing supply chain can disappear overnight.

What do you mean by 5 degree angle?

The roof pitch is 5 degrees from flat. It's oriented at about 135 degrees from north = SE

Electricity will cost you $1.00/kWh from the generator.

I'm aware, it won't be 24/7 and sometimes you have to trade $$ for convenience. Running the genny a few hours a day also means that I can run my woodworking gear, compressor, welder etc straight off the genny and NEVER off the inverters. I've rebuilt enough RV inverters to know that the surge of heavy motors is a blown power stage waiting to happen. I'd like to find and strangle the salesman that is telling people they can run their AC on the RV with the inverter. LOL

The genny is going to be up the hill at the utility building so probably too far for heat exchange, some of the army surplus units I've looked at are also air cooled. I'm looking at one 10kW Cummins diesel with only 320 hours for $2900.

I've started my "Audit"

16 Channel Vue Gen 2 monitoring everything by the second. I'll collect data for a week or so and then I'll have to move the sensors and do it again because I have more than 16 branch circuits.

 

[Hedges]

TBH, the "separate building for fire safety" really turns me off. I'm old and old school I guess, FLA is a technology I've been working with for a lot of years. I know how to work a hydrometer and I'm familiar with equalizing processes. I also know how to empty a battery, recondition the plates and fill it back up with new acid.

With suitable ventilation for hydrogen, FLA can be safe indoors.
But it will cost $0.25/kWh cycled through it. vs. LiFePO4 can cost $0.05
I went with AGM for a small battery, but cost matters for a large bank.

I like that Trojan owns factories in North America and builds the batteries here.

Consider Rolls Surette, a premium lead-acid battery. Could give you 20 years service.

The roof pitch is 5 degrees from flat. It's oriented at about 135 degrees from north = SE

In other words, essentially flat.
Nova Scotia latitude 45.0, well beyond inclination of Earth vs. it orbit.
Your pitch is far from ideal for winter, especially.

Do you ever get snow? (I guess I read 0C as about the coldest)

I'm aware, it won't be 24/7 and sometimes you have to trade $$ for convenience. Running the genny a few hours a day also means that I can run my woodworking gear, compressor, welder etc straight off the genny and NEVER off the inverters. I've rebuilt enough RV inverters to know that the surge of heavy motors is a blown power stage waiting to happen. I'd like to find and strangle the salesman that is telling people they can run their AC on the RV with the inverter. LOL

Which they do, with a soft start.
But you should see what quality inverters can do. And if you put in 3-phase, could power such tools well (still same surge, but better starting torque)

The genny is going to be up the hill at the utility building so probably too far for heat exchange, some of the army surplus units I've looked at are also air cooled. I'm looking at one 10kW Cummins diesel with only 320 hours for $2900.

With good inverter(s) and a forklift battery, you could get by with drawing about 2kW from a generator.

My biggest feedback is that in winter you'll get almost no PV. Except when it is somewhat overcast, and the glowing clouds illuminate your panels. (Steep angle would be so much better.) So you'll be running the generator a lot then. If only you could capture 40% to 60% of input fuel energy as thermal for the house ...

And second is try to have inverter system able to run everything. Nice to just use PV not generator when possible. PV panels can be so incredibly cheap. Imagine making electricity for $0.025 and storing it for $0.05

Compare that to diesel, which you're going to be using at least most of the winter. 80 kWh/day @ $1.00/kWh = $80/day, $2400/month. vs. PV & LiFePO4 @ $0.075/kWh, $180/month. (if your daily consumption numbers apply 365 days/year)

 

[Nan_wpg]

Thanks Matt, yes we're trading a view from our living room window of Mount Baker in Washington state for four acres and a view of St Mary's bay. Totally different.

Interesting Video Danke, I think I understand that the charge controllers are AC linked to the inverter generators but he doesn't really say. I always imagined DC linking my PV directly to my batteries. I don't know why, I'll have to do some research to decide.

Also: $27KUSD for batteries - yikes! I hope that if I go with FLA that can be charged in the cold I will save some $$?

changed my mind to reply and it wouldn’t go away

 

[SilverbackMP]

I figured I would need an audit of some sort so I ordered a 16 channel power monitor from Amazon, it has current clamps that go on the branch wires at the fusebox and measure/monitor/log what every outlet in the house is usung and when. This may take couple of weeks but I hope to be able to differntiate between household, home business and weekend hobby power requirements.

I suspect you are talking about ESP home. Personally I am going with Iotawatt as I hate, hate, hate cloud based services for things like this. They can go out of business for one. But worse yet, they need a pipeline to the Internet and open up your network (even if it's just a modem).

Edit: On futher reading, I see you've listed Vue Gen 2; I'm not really familiar with that device.

 

[Rednecktek]

The only 2 advantages that FLA has is 1: you can go about anywhere and get a replacement off the shelf for about $100, and 2: the up front cost is the cheapest of all battery options.

 

[SilverbackMP]

The only 2 advantages that FLA has is 1: you can go about anywhere and get a replacement off the shelf for about $100, and 2: the up front cost is the cheapest of all battery options.

3. works out of the box with all the premium inverters. No jacking around with BMS and communication. Less hoops, less unknowns.
That being said, I don't think I would want to go back.

 

[Hedges]

2: the up front cost is the cheapest of all battery options.

What is the cost of 100 AH 48V FLA? Or 225 Ah?

 

[Rednecktek]

What is the cost of 100 AH 48V FLA? Or 225 Ah?

About $400 after tax and core charge.

WalMart DC29 battery, 110ah. Even if you calculate 50% loss that's still $800 for 120ah 48v usable power. Yes, not as much life span as FLA, but you can charge it below freezing and it can be purchased off the shelf a LOT easier than you can buy a 48v LFP battery.

 

[MrM1]

3. works out of the box with all the premium inverters. No jacking around with BMS and communication. Less hoops, less unknowns.
That being said, I don't think I would want to go back.

I don't think premium inverters and change controllers need communication. I've been running LFP with Midnite solar Chargers and a Schneider inverter for 18 months, no communicating. No problems

And my BMSs have been set it and forget it. And it's much easier to check on the cells from my bed via Bluetooth, than having to run out and dip a hydrometer in acid.

I'm never going going back.

 

[Hedges]

About $400 after tax and core charge.

WalMart DC29 battery, 110ah. Even if you calculate 50% loss that's still $800 for 120ah 48v usable power. Yes, not as much life span as FLA, but you can charge it below freezing and it can be purchased off the shelf a LOT easier than you can buy a 48v LFP battery.

Oh, "marine". How many cycles?

"122 amp hour" "58.7 lbs"

Half the weight of SunXtender, quarter the price.

I was going to say LiFePO4 was cheaper now (at least for usable Ah), but you did beat it in purchase price.

 

[Rednecktek]

Yeah, that's why I stated up front cost. Lifespan-wise a LFP will be a better value more often than not than FLA over 10+ years as long as you don't do something to damage them like charge below freezing or the like.

I use a lot of those WallyWorld batteries because of how easy they are to replace and how cheap they are. Because my camp and small systems don't get much cycling I've only had to add about 2 cups of water between the 7 batteries over the last 6 years.

Plus, I like to say if you might destroy something, destroy something cheap!

 

[SilverbackMP]

I don't think premium inverters and change controllers need communication. I've been running LFP with Midnite solar Chargers and a Schneider inverter for 18 months, no communicating. No problems

And my BMSs have been set it and forget it. And it's much easier to check on the cells from my bed via Bluetooth, than having to run out and dip a hydrometer in acid.

I'm never going going back.

I'm using SMA so no charge controllers. I think the Outback AC coupled system benefits from it too.
But I'll be using a couple of old Xantrex and Outback 12volt inverters as UPS units so I'll get to explore this in the future.

 

[JayArr]

Vue is also cloud based but I'm only interested in using it to audit this house, not on a permanent or long term basis.

My biggest feedback is that in winter you'll get almost no PV. Except when it is somewhat overcast, and the glowing clouds illuminate your panels. (Steep angle would be so much better.) So you'll be running the generator a lot then. If only you could capture 40% to 60% of input fuel energy as thermal for the house ...

Am I missing something?I know my roof angle is non-optimum but this chart (Made for Halifax a couple hundred miles away) says that aimed SE at 135 degrees with a 5 degree roof pitch, I'm still going to pick up 86%. That's not enough of a loss to spend a lot on mounts that tilt the panels or mounts in the ground. I get a much nicer yard and only lose 14%. I don't want people to drive up to my house and the first words out of their mouth are about the solar array. It's a house on a bluff overlooking the ocean, I want them to tell me what a fantastic view I've got. The solar has to blend into the background and be as invisible as possible.

 

[Hedges]

Am I missing something?

What season is that graph for?

 

[Rednecktek]

If that's for winter you could easily compensate that 15% loss with more panels and would probably be cheaper than the racking involved at tilting it up.

 

[JayArr]

It's an efficiency chart resulting in ratios so it should apply to all seasons.

I start to see what you're all talking about. I need 25kW of PV and 70kWh of battery.

Let's assume I put 25kW of PV on the roof, not a problem, I have room.

The number of kWh available changes by season so in Jan I should get 86% of 66kWh/kW * 25kW = 1419kWh. If I get my consumption down to 35kWh/day that is 1085kWh so I don't need the genny unless I get two or three days in a row with no solar. If my battery bank is two days long that improves my odds of not having to use the genny but that extra insurance is $7k-$10k extra.

Nova Scotia​

The average solar power system in Nova Scotia will produce approximately 1090 kWh of energy per kW per year.

Is my math OK?