Off grid new house build.

[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?

 

[Doggydogworld]

The number of kWh available changes by season so in Jan I should get 86% of 66kWh/kW * 25kW = 1419kWh.

With 5 degree tilt your loss will be greater in winter than in summer. You can put your lat/long into PVWatts and play around with different tilt angles. For Halifax and 135 SE / 5 degree tilt and the default 14% system loss it shows me (per kW of panels):



That 40/32/40 in Nov/Dec/Jan is your issue. 50 degree panel tilt gives a bit less annual power but 50% more in December:



You'll need to a better tool to study daily variation. There's a big difference between every December day hitting the 1.6 hour average vs. getting all 49 hours in a couple of 3 day sunny stretches separated by weeks of darkness.

 

[Bluedog225]

This would be my concern with fixed flat panels (what doggy posted). Also, low slope panels will need to be cleaned. I’d plan for access.

Or a second set of panels oriented for winter max.

On the batteries, it sounds like you have a handle on the maintenance required. For me, it was fine at first. Then as the years went on, less so. I’ve got other things to do and the absolutely zero maintenance of lithium is nice.

This panel is on a 1:12 slope. The water pools at the bottom and collects pollen/dust. Some panels (very few) have a notch molded into the frame to let water out and minimize the issue.

btw-you are way ahead of the game by analyzing this ahead of time. We get a bunch of folks who buy first them come looking for advice.

 

[SamDeleted]

$40k

Just spit balling here but I reckon $40k would be enough to get your set up permanently off gird

 

[Hedges]

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.

No way it is for winter, with 45 degree latitude of Nova Scotia. His panels 5 degrees tilted will be almost edgewise to the sun on winter solstice - 23.5° south of the equator, so 68.5 off normal to the sun. Cos(68.5) = 0.367 as much light. (and then of course attenuated by long path through atmosphere.)

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

I don't think so. Cosine of an angle isn't linear.

Is my math OK?

Math maybe.
But 52 in January, 112 in July is likely light intensity, not considering angle. Or power harvesting by panel of a fixed angle oriented for maximum year round.
Your 5 degree tilt is sub-optimum in July (maybe 15% reduction which is OK as you say), but 64% reduction in winter.

The chart Doggy posted is more like what I expect.

Besides the inobtrusive panels on roof (maintaining good appearance of property), can you cover the WSW facing wall with panels?
(Probably not, given the forest I see which likely shades the wall in winter).

View attachment 141494

 

[Bluedog225]

There’s a post here recently about a big install of vertical panels (Finland?). May be worth a look given your location.

 

[upnorthandpersonal]

There’s a post here recently about a big install of vertical panels (Finland?). May be worth a look given your location.

My 44kW vertical and bifacial set in Finland plus now 15kW roof mounted too.

New to the forum, new to the solar energy. Have 63 Bluesun bifacial 700W N-type shingled panels, 22 old electric poles, shit load of underground cable, 51 x 6m 40x40x3mm marine grade aluminium, 2 Bluesun 15kW on-grid inverters, 2 Deye 15/12kW hybrid inverters, 30kW lead acid battery and 4 x 5kW...

diysolarforum.com

 

[JayArr]

OK, got it. The PVWatt site asks for my tilt angle so it's probably summing it with the sun's angle before calculating COS.

Say I configure the PV to be 100 panels at 250W each for 25kW.

even in the short month of Dec I'll get 669kWh and my genny will need to make up 416kWh.

If I use all of my roof and put up 37.5kW of PV I can get 1003kWh

I think what I need to build now is a spreadsheet with a bell curve ven diagrams where I can put in cost per kW of PV, cost per kWh of battery and cost per kWh of diesel powered genny. Then amortize the whole thing over 15 years and see where the money is best spent.

The engineer I work with mentioned something interesting this morning. Digby NS is notoriously windy, there is a wind farm right across the bay from me. I may be able to generate power in the winter months with a wind turbine.

 

[JayArr]

BTW..

The results of only one day of audit pointed me directly to where all my power is being used. The business JRElectronics has a shop where we repair industrial circuit boards and the business also has a server rack full of old HP Proliant servers that run the phones, serve the finance software and keep archives, there is also a firewall and routers, switches etc.

The Business is accounting for more than half of the power we use and the server rack is the largest part of that. I need to upgrade my servers to more energy efficient for now and when I retire I won't need them at all anymore.

This means that I can run the house on 25-35kWh per day easily! I don't need 70-80kWh I've just been wasting that much.

I think THIS is using 35kWh per day!

 

[Rednecktek]

Oh yeah! There's your problem. Back when I was in IT and I ran my own servers in my house, the furnace closet was right next to the server rack. When my furnace died on me I just tore it out and put a huge fan in the floor, cut some holes in the closet wall, installed some vent covers, and let the servers heat the whole house.

I think you'd be surprised just how much power you can save with even semi modern hardware over what's in those racks. I'm guessing old Xeon 2011's or P3's and SCSI drives in those racks? Ouch!

 

[Hedges]

You also will be living on a wood lot. You could go the old fashioned carbon-neutral way, split firewood and let it dry over the summer to heat in the winter. Add ashes to garden compost.

I'm guessing old Xeon 2011's or P3's and SCSI drives in those racks? Ouch!

Xeon? My laptop has dual Xeon.
But I think it is graphics chips which burn the most.