Off Grid build, Need opinions and suggestions!

[wanderinglostadventures]

Hello everyone! So I have an off-grid home in New York and I'm looking at installing my own solar system on my house! So hear is my shot at this!

250w Trina Solar Panel, 12 panels, 4 sets of 3 series runs, 48v 3000w array, one array on south east roof and another on south roof
2 combiner boxes with fuses and breakers
2 Growatt SPF 3000TL LVM 48v all-in-one run in parallel to give 220v service to house
48v 200ah Lifepo4 with BMS controller
7500w Generator with low battery auto start module

Plan to run a dual split duct with a heat pump plus normal amenities

Looking for some feed back on setup and things to possible add or change out!

Thanks in advance!

 

[WYtreasure]

Welcome to the show Long Name.

Two arrays of 12 or 6 panels?
220 volts or 240 volts?
How many 200ah batteries?

Looks like a good start, more info = better suggestions.
Have fun.

 

[wanderinglostadventures]

Welcome to the show Long Name.

Two arrays of 12 or 6 panels?
220 volts or 240 volts?
How many 200ah batteries?

Looks like a good start, more info = better suggestions.
Have fun.

2 Arrays 12 panels each
Array Voltage is aprox 128v, house needs 240v
16 batteries in series

 

[WYtreasure]

2 Arrays 12 panels each
Array Voltage is aprox 128v, house needs 240v
16 batteries in series

Nice arrays. Good answers.

Do you know you do not need to match Solar DC output to your Loads? That's the job of the charge controller. Yours will do it with 48 volts.
and
Everybody and their brother has 220 volt equipment out there. If you should have 240, get 240. Just splitting hairs so you don't split wires.

One of us is really tired. My batteries are running low, yours are HIGH.
Quantity 16, Volts 48 in series does not sound correct.

 

[Hedges]

250W Trina?
Are those dirt cheap, maybe damaged backsheets or other flaws, relatively low wattage per square meter?
You might save on mounting hardware and area by buying newer, more expensive panels. Could be more reliable too.
in other words, are bargain panels worth it? Cost of system is dominated other things.

3kW PV, 10kW LiFePO4

I like more PV in proportion to battery, even configuring system to curtail production so charge rate isn't excessive on sunny days. That lets it make enough power on bad days. PV is much cheaper than battery. In my case, that is PV sufficient to charge at 0.6C, but programmed for 0.2C because I have AGM.

Aim PV strings SE and SW, that reduces peak output to 0.7x as much and extends hours of production, so battery kept full later in the day and starts recharging sooner.

Your battery may be sufficient to last the night, depending on loads. My house with multiple refrigerators would draw 13 kWh if I turn off certain other loads. Find a way to shed some loads at night (e.g. let refrigeration coast until sunup if you have old power hogs like mine.)

 

[Bvillebob]

I built my first two arrays using the 250 watt used panel, a total of 36 panels, and they're working great, but the last array I bought 24 of the REC 370 watt panels from Santan, new panels, not used. They were a but more expensive, but they put out more than 50 percent more power, are split cell, most modern tech and much more efficient being only a couple of inches longer than the 250 watt panels and are actually lighter and easier to handle.

In the big picture the extra $500 or whatever for the newer panels was money well spent to me.

 

[ianganderton]

Have you done a power audit and estimated your daily power needs through the year?

Where are you? Have you checked your solar irradiance averages by month for the year

With your power audit and solar irradiance data do you know if your solar will keep up with your useage through the year?

 

[wanderinglostadventures]

250W Trina?
Are those dirt cheap, maybe damaged backsheets or other flaws, relatively low wattage per square meter?
You might save on mounting hardware and area by buying newer, more expensive panels. Could be more reliable too.
in other words, are bargain panels worth it? Cost of system is dominated other things.

3kW PV, 10kW LiFePO4

I like more PV in proportion to battery, even configuring system to curtail production so charge rate isn't excessive on sunny days. That lets it make enough power on bad days. PV is much cheaper than battery. In my case, that is PV sufficient to charge at 0.6C, but programmed for 0.2C because I have AGM.

Aim PV strings SE and SW, that reduces peak output to 0.7x as much and extends hours of production, so battery kept full later in the day and starts recharging sooner.

Your battery may be sufficient to last the night, depending on loads. My house with multiple refrigerators would draw 13 kWh if I turn off certain other loads. Find a way to shed some loads at night (e.g. let refrigeration coast until sunup if you have old power hogs like mine.)

The panels are just something I had aquired for basically 25 panels for $500, Ive tested all the panels on approx high sun during the summer and there is about a 3% degrade in all the panels. As far as my panel direction, these are the only faces I have on my roof and putting them on the ground is not an option due to being on top of a mountain, settled in a valley so sun is limited durring the winter. Wouldnt it be 6kW due to having two 3kW arrays, Thank you for your response its greatly appreciated

 

[wanderinglostadventures]

I built my first two arrays using the 250 watt used panel, a total of 36 panels, and they're working great, but the last array I bought 24 of the REC 370 watt panels from Santan, new panels, not used. They were a but more expensive, but they put out more than 50 percent more power, are split cell, most modern tech and much more efficient being only a couple of inches longer than the 250 watt panels and are actually lighter and easier to handle.

In the big picture the extra $500 or whatever for the newer panels was money well spent to me.

Yes I plan on in the future using better panels but Im trying to keep this low budget as best as I can since the house itself needs a lot of work, we have been running off a generator for 20 plus years and tired of the noise! lol As soon as its realistic i will be upgrading panels and growatt inverters to match. Thank you for your response

 

[wanderinglostadventures]

Have you done a power audit and estimated your daily power needs through the year?

Where are you? Have you checked your solar irradiance averages by month for the year

With your power audit and solar irradiance data do you know if your solar will keep up with your useage through the year?

Thats something I have not done yet, hard to estimate when you only have to power lights and a tv, fridge is propane right now, water heater is propane, stove is propane, really the only things I will really have to figure out is split duct usage and fridge usage along with power used by inverters. Im located near Lake George NY, Thank you for your response

 

[wanderinglostadventures]

Nice arrays. Good answers.

Do you know you do not need to match Solar DC output to your Loads? That's the job of the charge controller. Yours will do it with 48 volts.
and
Everybody and their brother has 220 volt equipment out there. If you should have 240, get 240. Just splitting hairs so you don't split wires.

One of us is really tired. My batteries are running low, yours are HIGH.
Quantity 16, Volts 48 in series does not sound correct.

Yes lol this much I am aware of! I did learn that! but lost everywhere else!!
220v 240v is something im still wrapping my head around, I know my growatt inverters supply 120v and can be run in parallel and the specs say 6000w parallel, the onlything i have thats 220v is my well pump and the split duct im eventually installing. As far as the batteries go I have 16 lifepo4 batteries at 3.2v so 16 batteries in a series gives me 51.2v, Thank again for your response

 

[ianganderton]

Thats something I have not done yet, hard to estimate when you only have to power lights and a tv, fridge is propane right now, water heater is propane, stove is propane, really the only things I will really have to figure out is split duct usage and fridge usage along with power used by inverters. Im located near Lake George NY, Thank you for your response

It is a task that can feel quite challenging but it’s a crucial process in designing a fit for purpose system.

Estimated power audits reveal maximum draws required as well as average daily use for summer and winter.

You may be planning a massively over built system or one that is not fit for purpose.

For fridges many manufacturers provide average energy use data that is useful for power audits

 

[Hedges]

The panels are just something I had aquired for basically 25 panels for $500, Ive tested all the panels on approx high sun during the summer and there is about a 3% degrade in all the panels. As far as my panel direction, these are the only faces I have on my roof and putting them on the ground is not an option due to being on top of a mountain, settled in a valley so sun is limited durring the winter. Wouldnt it be 6kW due to having two 3kW arrays, Thank you for your response its greatly appreciated

$500/25 = $20/panel, so half the SanTan advertised price ($40 cracked backsheet, $60 better condition).
$20/250 = $0.08/W. Can't beat the price. (except a guy in Europe who bought 120W panels for $4 each)

Look up sizes of popular panels on the used market today and new commercial installs. See if you can put rails on your roof (which use top clamps) so if you do upgrade panels in the future (for 50% increase in output) they fit in the same place. But rails/clamps cost more than "L" feet which would probably need new roof penetrations when installed.

Yes, 3kW x 2 = 6kW. (I just saw "12 panels", but you meant for one array)

Does the GroWatt have single MPPT input (in which case you do need fuses for 4 PV string), or does it have dual MPPT (in which case, 2 PV strings, 3s2p into each MPPT, doesn't need fuses)?

Trina 37.6Voc x 3 = 112.8Voc for 3s string at nominal 25 degrees C.
145V/112.8V = 1.28, GroWatt limit is 28% headroom, sufficient for any temperature and temperature coefficient.
That's fine.

Yes lol this much I am aware of! I did learn that! but lost everywhere else!!
220v 240v is something im still wrapping my head around, I know my growatt inverters supply 120v and can be run in parallel and the specs say 6000w parallel, the onlything i have thats 220v is my well pump and the split duct im eventually installing. As far as the batteries go I have 16 lifepo4 batteries at 3.2v so 16 batteries in a series gives me 51.2v, Thank again for your response

Growatt SPF 3000TL LVM 3,000W 48V 120Vac Stackable Inverter | 4,500W M - ShopSolar.com

Growatt 48V SPF 3000TL LVM – 3kW 120Vac Stackable Inverter 4.5kW MPPT Charge Controller Split Phase 120V/240V capable with two or more units + FREE Lifetime Customer Support In Stock & Ready To Ship! 100% Authentic. Factory Direct. Lifetime Customer Support. Growatt SPF 3000TL LVM series...

shopsolarkits.com

Looks like two GroWatt stack for 120/240V split-phase.

You just have to consider any motor loads; starting surge is about 5x nameplate power.
Well pump in particular, find its ratings. Or, get a clamp ammeter that records inrush current.
If the GroWatts can't do it, other brands may (at a higher price.)
I think Signeer advertises 18kW surge. Sunny Island 11kW surge, can stack 2x or 4x. Schneider, Outback, others.
Midnight is bringing out a new model inverter, think they've shown it starting a 1.5hp pump.

It will be preferable to run well pump only when sun is out. If well pump presently pressurized tank (or runs on-demand), add above-ground storage and small booster pump.

 

[wanderinglostadventures]

$500/25 = $20/panel, so half the SanTan advertised price ($40 cracked backsheet, $60 better condition).
$20/250 = $0.08/W. Can't beat the price. (except a guy in Europe who bought 120W panels for $4 each)

Look up sizes of popular panels on the used market today and new commercial installs. See if you can put rails on your roof (which use top clamps) so if you do upgrade panels in the future (for 50% increase in output) they fit in the same place. But rails/clamps cost more than "L" feet which would probably need new roof penetrations when installed.

Yes, 3kW x 2 = 6kW. (I just saw "12 panels", but you meant for one array)

Does the GroWatt have single MPPT input (in which case you do need fuses for 4 PV string), or does it have dual MPPT (in which case, 2 PV strings, 3s2p into each MPPT, doesn't need fuses)?

Trina 37.6Voc x 3 = 112.8Voc for 3s string at nominal 25 degrees C.
145V/112.8V = 1.28, GroWatt limit is 28% headroom, sufficient for any temperature and temperature coefficient.
That's fine.

Growatt SPF 3000TL LVM 3,000W 48V 120Vac Stackable Inverter | 4,500W M - ShopSolar.com

Growatt 48V SPF 3000TL LVM – 3kW 120Vac Stackable Inverter 4.5kW MPPT Charge Controller Split Phase 120V/240V capable with two or more units + FREE Lifetime Customer Support In Stock & Ready To Ship! 100% Authentic. Factory Direct. Lifetime Customer Support. Growatt SPF 3000TL LVM series...

shopsolarkits.com

Looks like two GroWatt stack for 120/240V split-phase.

You just have to consider any motor loads; starting surge is about 5x nameplate power.
Well pump in particular, find its ratings. Or, get a clamp ammeter that records inrush current.
If the GroWatts can't do it, other brands may (at a higher price.)
I think Signeer advertises 18kW surge. Sunny Island 11kW surge, can stack 2x or 4x. Schneider, Outback, others.
Midnight is bringing out a new model inverter, think they've shown it starting a 1.5hp pump.

It will be preferable to run well pump only when sun is out. If well pump presently pressurized tank (or runs on-demand), add above-ground storage and small booster pump.

Growatt is a single string PV but I have a 4 string combiner box with fuses and circuit breaker

Im not 100% sure about the well pump but it is being replaced this year along with wiring, my well is only 34 feet deep. So im thinking only a 3/4hp well pump and I am adding a grey water tank system as well for back up

 

[Hedges]

If water level sufficiently < 32', may be able to have a slow, fixed displacement pump above ground.
That, or some other pump that doesn't have a large induction motor, could make it easy.
I've seen the suggestion of suspending a SurFlow pump down hole but above high water level. Corrosive environment, of course.
Ideal could be motor above ground, shaft to a submersed fixed-displacement pump.

Shallow-well ejectors can be used, but of course much less efficient. OK if you can start the motor and have excess PV. Not a deep well at all in this case, so inefficiency is a smaller total consumption.

On the surface, a (clean, not "grey") water tank and small booster pump could supply water at night.

 

[wanderinglostadventures]

If water level sufficiently < 32', may be able to have a slow, fixed displacement pump above ground.
That, or some other pump that doesn't have a large induction motor, could make it easy.
I've seen the suggestion of suspending a SurFlow pump down hole but above high water level. Corrosive environment, of course.
Ideal could be motor above ground, shaft to a submersed fixed-displacement pump.

Shallow-well ejectors can be used, but of course much less efficient. OK if you can start the motor and have excess PV. Not a deep well at all in this case, so inefficiency is a smaller total consumption.

On the surface, a (clean, not "grey") water tank and small booster pump could supply water at night.

Well technically the entire water system is grey, we dont drink the well water. Our drinking water gets filtered with the 5micron then to a 3micron then runs through an RO Filter system

 

[WYtreasure]

Well technically the entire water system is grey, we dont drink the well water. Our drinking water gets filtered with the 5micron then to a 3micron then runs through an RO Filter system

I thought that was a great way to go, for a while, BUT then realized I was not getting the minerals from Mother Earth. Food for thought ?

 

[12VoltInstalls]

adding a grey water tank system as well for back up

I didn't really think you meant gray water…

I’m curious, though. Why wouldn’t you drink the water from a well on top of a mountain?!

I’m in northern vermont. Due to everything else freezing up in the winter I’ve been getting my water on my way home 18 gallons at a time from one of two “public” springs where water just runs out of the ground. One has been ‘piped’ to the roadside since around 1820, the other literally is some rocks stacked in the hillside and some 20’ iron pipe stuck in it. 6-10 gals/minute.
I drink water from those springs and don’t worry- a 30’ dug well on top of a mountain should be better.
People didn’t have 5micron filters until just the last few minutes of history.

 

[wanderinglostadventures]

I didn't really think you meant gray water…

I’m curious, though. Why wouldn’t you drink the water from a well on top of a mountain?!

I’m in northern vermont. Due to everything else freezing up in the winter I’ve been getting my water on my way home 18 gallons at a time from one of two “public” springs where water just runs out of the ground. One has been ‘piped’ to the roadside since around 1820, the other literally is some rocks stacked in the hillside and some 20’ iron pipe stuck in it. 6-10 gals/minute.
I drink water from those springs and don’t worry- a 30’ dug well on top of a mountain should be better.
People didn’t have 5micron filters until just the last few minutes of history.

I had the water tested, you can drink it but just had to be really filtered, for someone reason since im on top of a slate mountain there is very high manganese level and the turbidity levels are extremely high as well. Im sure if I had the well dug deeper I could fix that issue, but an addition was added on and the well head is against the house now! So we have never used the water for drinking!