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diy solar

System for 1900 square foot house.

Pyrofx

Pyrofx

Flux capacitor builder
Joined
Jul 27, 2020
Messages
570
Location
Oatman Az
Guys If you have time, I'd like to pick your brain.
Ultimate goal. 1900 square foot house. Super insulated as I am building it myself. Summer temps 120 degrees in Az.

Fixed mount ground panels. Have 50 , trina 250's so far.

Our households consumption peak month was 2054 kwh.

Batts will be 280 lifepo4, either 4p16s , or 16s4p.
Do you think the guys for sale mp5048 would be a decent start ? My original plan was sma islands.

2 biggest loads are going to be the ac .4 ton ( possible ductless) and 5hp well pump. ( water is at 1100 feet. )

I would welcome your thoughts, as I'll be picking up equipment piece by piece.
 
2054kW/month = 68.5kWh/day

68.5kWh/day / (50*250W) = 5.5h/day of solar hours - pretty reasonable for AZ, BUT

Need to factor in 0.85 efficiency loss, so

68.5/.85 = 80.5kWh/day, so you'll need more panels.

Check link #5 in my signature for actual solar availability in your area. #6 to play with theoretical systems to see what meets your needs.

280Ah * 4*16 (64 cells) *3.2V = 57.3kWh - on the low side, but probably do-able for daily needs. If you're in the true desert where you actually get temperature drops that are livable vs. the heat island that is Phoenix, then that might take some of the load off, but if you're going to run A/C at night... yuck.

MP5048 would likely not run what you need. They have shit surge and might not run your HVAC unless you're going for super efficient low surge options. You're looking at a major investment, and cheaping out on low-end equipment to save a couple thousand is not the right way to handle it. Go with Victron, Outback, midnite solar, Schnieder, Xantrax hardware.

Big concern - you're using existing monthly kWh, but you're applying it to an unbuilt house? Sounds like an energy audit is in order per link #1 in my sig.

5hp well pump is going to be horrifying on its surge current. I wouldn't be surprised if it's around 80A/230VAC, so around 18kW surge. I assume you're planning for above ground cisterns with a separate 1/2 hp pump and pressure tank for household use?
 
We are up here in bullhead.
As for the audit , in using the house here now as a pretty close similar. I built it pretty efficient.
I was thinking same thoughts on inverter but had to ask just in case you thought they would do.
Any live for the sunny islands ?

I don't have and can't seem to find real world data for the splits. The birch is have to supply an evap cartridge for each room.

Yes on above ground storage. 6k gallons. I'm also looking into the Grundfos solar pumps.

At 60 bucks a panel , that's the cheapest thing in the system , and I've got plenty of dirt to add more.
 
Is grid available? or will you be entirely off grid?
That makes a big difference in which inverters, how much battery (if any), which battery.

Insulated, but an air gap with air moving through can help. Attic ventilation, for instance. Maybe double walls, inner insulated and airflow in outer?

5 hp is about 3kw to 4kw, possible starting surge to 20 kW if not more. I suppose sufficient Sunny Islands or other larger inverter could do it.
How about 3-phase pump and variable frequency drive? That would have no starting surge. (Although I think I had a problem with interference between a VFD and a transformerless GT inverter.)
You could do a 3-phase Sunny Island system (especially if off-grid). I think 3-phase will start a pump easier because it provides a good phase offset (compared to starting windings of a split-phase pump.)
But I would view a well pump as an opportunity to match consumption to production. Varying frequency with VFD to consume surplus power would let you get by with less battery, less cycling. Same for a 3-phase A/C on VFD.

Batteries should be somewhere cooler and temperature controlled, possibly buried.

Sounds like you're at least halfway there with PV panels, need to double that to supply 100% and then some.
Orient arrays in multiple directions to spread production over the day.
Panels are cheap, and you don't need as much PV inverter (or charge controller) with multiple angles.
AC couple with GT inverters takes care of separating battery charging current from PV and loads. Not sure if any DC coupled solutions do that well.
(That matters if you use a very undersized battery like I do.)

Sunny Islands are offered for around $2200 right now. Two, three, or four could meet your needs. If you are grid-tied, only 13 kW of PV can pass through relays of two inverters 2S1P (could manually transfer additional GT inverters from grid to island side.) Off grid, you could put 24 kW of Sunny Boy on two Sunny Island (more kW with more of them.)
 
How much water do you need?
For 1100' well (550 psi) are turbine-type pumps the only option, or can you get a positive-displacement one that would maintain efficiency with variable speed?
I think jack pumps are an option (mini oil-derrick style)
 
Grid is 6 miles away.
As far as house build... 2x6 wall. Compressed cellulose. 3" polyiso foam on outside. Vented attic with fans.

The 3 phase on the pump is also what I was thinking to do. All batts and equipment will be in a conditioned insulated block room. It will be kept cool.

Can you point me a good info on setting up the grid tie coupling off grid. I have read through so much over the last 2 years I'm in a fog.

The current workshop was set of with aims lf 24v 3k inverter , 8s 180ah calb , and 2k of panels.has worked like a charm running swamp cooler fridge , micro and coffee pot.
 
Average on water 500 gallons a day. That includes house and all of the trees. Bore hole itself is capable of around 25 gpm
 
And our energy use this past month was not normal.it was about 75% higher. But with the heat we had , we did have to ac cool the chicken coops. I know you got hammered in Phoenix too.
 
500 gallons, 10 hours pumping, 50 gallons/hour, 1 gallon/minute.
My first source for pump data, Graingers, didn't have anything past 600'
But just one data point, 5 hp 375' shows 60 gpm. So 20 gpm if a pump head could supply the pressure you need. That's 20 times as much water as your requirement. So something small and fixed displacement is theoretically possible, with much less load on your electrical system.

Years ago, Real Goods offered jack pumps. I'm not finding any sources right now.

Here's Sunny Island:

Discover the Sunny Island 4548-US / 6048-US! | SMA America

The efficient island manager Sunny Island 4548-US / 6048-US ► Now with 20 % more power! ► Efficient, simple, flexible and durable! ► Check out now!
www.sma-america.com www.sma-america.com
Sunny Boy:

Discover the Sunny Boy 3.0-US - 7.7-US | SMA America

Discover the Sunny Boy inverter 3.0-US - 7.7-US ► PV performance optimization with SMA ShadeFix ► SMA's SunSpec certified shutdown device
www.sma-america.com www.sma-america.com

System example:

There should be two breaker panels. First one has Sunny Boy, then a load-shed relay, then a panel with house loads. That way Sunny Island can disconnect the house if battery gets too low and still have enough left to bring up Sunny Boy when the sun comes up.

You could get three of each (or older model Sunny Boy, available used or surplus) for a 3-phase off-grid system. 17 kW continuous output from batteries at 25C or derated at higher temperature. Up to 23 kW from PV with 3 inverters, or up to 34 kW with six. You can over-panel about 50% if you orient arrays 90 degrees apart like 10:00 AM and 4:00 PM to spread power over the day.

According to SMA, 100 Ah at 48V per Sunny Island, and 100 Ah per kW of PV. So 1000 Ah at 48V, 48 kWh for a 10 kW PV system, more for larger.
But I think you can get away with as little as 100 Ah total, 48 kWh. You just have to set maximum charge current because default settings would allow 0.55C.
The AGM battery I use from SunXtender can supply high currents, but of course Peukert reduces capacity. It would just supply motor starting surge and small nighttime loads.
I sized my bank for 70% DoD, expected to last 500 cycles, more than the number of power failures I expect during 10 year float life.
With AGM, if you sized for 15% DoD, might last 10 years. Not significantly different cost from 70% DoD and replacing every 3 years.

Select lithium with BMS are supported. Other guys here use DIY lithium with Sunny Island.
 
This is the plan I am leaning to.
Now is there any benefit to putting a sunny boy on each island. There seem to be a few takeoff boys available at a reasonable nick.

I will check with my neighbor on the pump he uses. I believe it is putting out about 8gpm. 5hp and was run on a 12kw Chinese single cylinder gen set.
 
Because our attic temps are about 160 degrees.
Tell me about most efficient ac setup that I might use . Just know amana is not an option.
Thanks !
 
In the heat pump arena, Bosch systems are 22 SEER and low cost. They use inverter drive compressor, and electronic expansion valve to maintain high efficiency throughout the home loading...

Ventilating attics is not the most efficient way to handle them; spray foaming the roof deck, and using radiant barrier in the roofing... far more efficient for the entire home.

Amana doesn’t make bad equipment, and their lifetime condenser replacement warranty is a pretty good deal...
 
Pyrofx said:
And our energy use this past month was not normal.it was about 75% higher. But with the heat we had , we did have to ac cool the chicken coops. I know you got hammered in Phoenix too.
Click to expand...

My usage was pretty typical over the last 3 months. Mostly just delayed reaction for us. June/July were less horrific than usual. August was a month's long suckle at Satan's sack.
 
Pyrofx said:
This is the plan I am leaning to.
Now is there any benefit to putting a sunny boy on each island. There seem to be a few takeoff boys available at a reasonable nick.

I will check with my neighbor on the pump he uses. I believe it is putting out about 8gpm. 5hp and was run on a 12kw Chinese single cylinder gen set.
Click to expand...

There is a benefit to generating AC from PV on the phases where loads also consume power. Some efficiency loss to have one Sunny Island convert AC to DC, and another DC back to AC. There is also a maximum AC <--> DC capability of Sunny Island, but you can have twice that much from Sunny Boy --> load while Sunny Island just watches.

Probably two of those 7.7 kW Sunny Boys would take care of the panels you've got today, and a third would handle the additional PV you might add.
For 3-phase, you're actually going to put each Sunny Boy across two Sunny Islands (208V)
There are also some Sunny Tripower which will work for 3 phase, but most (all?) are 480V so would require 3-phase transformer.

Check the compatibility list from SMA, make sure the Sunny Boy you're considering works for off-grid. You may need an unlocking code from SMA for each serial number and an installer code to change their settings. Then once you've configured things, test with some loads and make sure they smoothly adjust power output according to frequency.
 
Supervstech said:
In the heat pump arena, Bosch systems are 22 SEER and low cost. They use inverter drive compressor, and electronic expansion valve to maintain high efficiency throughout the home loading...

Ventilating attics is not the most efficient

Amana doesn’t make bad equipment, and their lifetime condenser replacement warranty is a pretty good deal...
Click to expand...

We have separate amana systems. One has crapped out once , one of them twice. And a third one 3 times. All in 2 years .
The warranty might sound good , but at 75 bucks a pound for 410 , not covered by the warranty, I'm done with them.

Yes the new roof will be shot with foam , and 20" of blown in.
 
Hedges said:
There is a benefit to generating AC from PV on the phases where loads also consume power. Some efficiency loss to have one Sunny Island convert AC to DC, and another DC back to AC. There is also a maximum AC <--> DC capability of Sunny Island, but you can have twice that much from Sunny Boy --> load while Sunny Island just watches.

Probably two of those 7.7 kW Sunny Boys would take care of the panels you've got today, and a third would handle the additional PV you might add.
For 3-phase, you're actually going to put each Sunny Boy across two Sunny Islands (208V)
There are also some Sunny Tripower which will work for 3 phase, but most (all?) are 480V so would require 3-phase transformer.

Check the compatibility list from SMA, make sure the Sunny Boy you're considering works for off-grid. You may need an unlocking code from SMA for each serial number and an installer code to change their settings. Then once you've configured things, test with some loads and make sure they smoothly adjust power output according to frequency.
Click to expand...


So , the island creates the false grid , and the boys help out by converting PVC straight to ac? Sounds brilliant.
That was what we thought we could do 2 years ago when we picked up 25 emphases micro controlled. Still got the damn things

I'll start digging around on the local guy with 3 sunny boys. He wants to much for then at 750 ea and 10 years old. But if noboady else wants them , they are only worth what I'll give him.
 
Pyrofx said:
We have separate amana systems. One has crapped out once , one of them twice. And a third one 3 times. All in 2 years .
The warranty might sound good , but at 75 bucks a pound for 410 , not covered by the warranty, I'm done with them.

Yes the new roof will be shot with foam , and 20" of blown in.
Click to expand...
You cannot blame the equipment for that kind of service results...

The installation is 99% of the ac functionality and longevity.

That kind of result is a serious installation issue...
 
Yes it is. You get no argument on that. It's not covering 410 when its 3 bucks a pound .

Do you recommend the Bosch split over the ductless ? Not real keen on having to run evap cartridge in every damn room
 
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