Off Grid Solar System, opinions and advice welcomed

Long story short, my wife and I have bought 6.5 acres in South Western Oklahoma. We are going to be starting an off grid homestead, I'm going down at the end of this month (January) to start the ground works. She will be following down later in the spring with our 3 month old son.

I have done a fair bit of research but am not an expert in any way.

The system we have gone for is:

1x 5kW Stackable 48V 240VAC 100A 450VDC Off-Grid Inverter by Growatt (with transformer)​

1x 48V 100AH LiFePower4 Battery by EG4​

8x SanTan Solar T Series 250W solar panels​

This is the first solar system I have ever built so am a little intimedated so would like feed back on the set up.

I'm planning on having all 8 panels in series. Each panel has a VOC of 37.6 therfore the string should produce 300.8VOC. The charge controller/inverter from growatt has a max input of 450v so this should be ok. Right?

The reasoning behind this set up is:

• We need something big enough to power our 5th wheel trailer (major appliances: small fridge freezer, washing machine, propane dryer (winter only), fans, charging battery power tools, small economical window AC unit for a couple of hours a day in the summer, lighting and device charging)
• We dont have a massive budget. It would be nice to have more batterys and solar panels but we cant afford it at the moment
• We can add to this set up as and when we need it. If we need more solar panels then add 4/6/8 more put them in parallel through a combiner box and were good. when we can afford more batterys then add 1 or 2 more. And eventually when we need more watts of power add another charge controller/inverter
• for a complete novice this seems like a straight forward set up. all I need to worry about is wiring up the solar panels and the battery correctly.
• If we dont have enough juice from the solar panels then we can charge the batterys with our generator through the growatt all in one system.

My main questions are:

• is our system big enough for our needs?
• does anyone see any problems with our set up?
• have i missed anything?
• is it possible to charge our batterys with our generator through the growatt all in one system? It has AC input so I think it should be fine. When we bought the growatt inverter through signature solar the guy tried to sell us the battery charger they had on sale at the same time. when I told him I could charge the battery directly through the all in one system he forwarded me to the tech team. I was on hold for a while then the line dropped. So was he just doing his job, selling things or do I indeed need a seperate battery charger.

Thanks in advance, please be nice, i'm new to this. if there is any more infomation i should provide please let me know.

The Voc does sound OK.
If you wired instead as 4s2p, would the Vmp be high enough for the inverter?

You have 2000W of PV panels, 4800W of panels. 2.4 hours of production to recharge 100%.
What I'm thinking is, you might fully recharge battery, then waste PV production, then draw some power, then have a lower state of charge beginning the night.

With 4s aimed South East and 4s aimed South West, you get about 0.7 as high a peak power, 1.4kW. But more hours to (almost) make up for it.
That might keep battery somewhere between empty and full during the day.

2000W/4800W = ~ 0.4C charge rate, typically acceptable for lithium.
Determine what colder temperature is OK at 0.4C (it isn't 0 degrees C, should be greatly reduced current near freezing), and set low voltage charge disconnect accordingly.
If 4s2p as I suggested, then 1400W/4800W = 0.29C, so a bit lower temperature is OK.

Sometimes people have trouble with a generator feeding an inverter/charger because it is picky on frequency. In such case a separate charger can be a solution.

You may or may not need a precharge resistor to avoid 1000's of amps surge when connecting battery, so have some suitable resistor available (I think a 100' or 250' roll of Romex can serve, but most people use a power resistor.)

Use a DMM to double-check things before connecting and before closing switches. Make sure of voltages, polarity, and no voltage before touching terminals.

A DC disconnect if not built in is handy to isolate wires before work. At least, shut off inverter, confirm PV terminals have gone to Voc (no current), then unplug MC connectors for both positive and negative. Then confirm voltage has dropped to zero.

JamesHird said:

The system we have gone for is:

1x 5kW Stackable 48V 240VAC 100A 450VDC Off-Grid Inverter by Growatt (with transformer)​

Click to expand...

This will be pretty power hungry even when it's not providing any loads. They have a pretty high idle burn - about 90W. This will use 2160Wh/day. This is almost 42% of your battery capacity - just being on and providing no loads.

JamesHird said:

1x 48V 100AH LiFePower4 Battery by EG4​

Click to expand...

Inadequate. See above.

JamesHird said:

8x SanTan Solar T Series 250W solar panels​

Click to expand...

These probably work at about 80% rated, so you have about 1600W of panels. This should get you about 8kwh/day on good days.

JamesHird said:

This is the first solar system I have ever built so am a little intimedated so would like feed back on the set up.

I'm planning on having all 8 panels in series. Each panel has a VOC of 37.6 therfore the string should produce 300.8VOC. The charge controller/inverter from growatt has a max input of 450v so this should be ok. Right?

Click to expand...

Yes.

Note that series panels can suffer from shading. Hopefully, your mounting scheme can insure that all panels remain unshaded from sunrise to sunset.

JamesHird said:

The reasoning behind this set up is:

• We need something big enough to power our 5th wheel trailer (major appliances: small fridge freezer, washing machine, propane dryer (winter only), fans, charging battery power tools, small economical window AC unit for a couple of hours a day in the summer, lighting and device charging)

Click to expand...

That's a big ask for the system you've selected. You really need to use the energy audit spreadsheet in Resources and calculate your needs.

If you have an absorption fridge (ammonia based, propane or AC powered), do not run it on AC. Run only on propane. On AC, they'll destroy you.

JamesHird said:

• We dont have a massive budget. It would be nice to have more batterys and solar panels but we cant afford it at the moment

Click to expand...

Last thing you want is to buy a bunch of stuff and then realize it's no good for you. You've selected an inverter that consumes 40% of your battery capacity before you even get to use it.

Do some more planning with an energy audit.

JamesHird said:

My main questions are:

• is our system big enough for our needs?

Click to expand...

No.

JamesHird said:

• does anyone see any problems with our set up?

Click to expand...

Yes. Mentioned above.

JamesHird said:

• have i missed anything?

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Yes. You have no defined goal that says, "I need to use X Wh of energy per day." Right now, you're limited to about 8kWh/day total with only about 3kWh/day available when solar is unavailable. Since you don't know your needs, you don't know if that will work for you.

JamesHird said:

• is it possible to charge our batterys with our generator through the growatt all in one system? It has AC input so I think it should be fine. When we bought the growatt inverter through signature solar the guy tried to sell us the battery charger they had on sale at the same time. when I told him I could charge the battery directly through the all in one system he forwarded me to the tech team. I was on hold for a while then the line dropped. So was he just doing his job, selling things or do I indeed need a seperate battery charger.

Click to expand...

The growatt AC charger is not typical. It will not act as a battery charger like the solar does - no bulk, absorption, float. It simply turns off below a voltage and stops immediately once the upper voltage is reached, so fully charging is not easy, but you can easily get > 80% charged.

You will need to set the OFF voltage to 58V and the ON voltage to as high as it will go, but under 58V. If your battery is between the on and off values, it won't charge.

Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the Uber-Sun-Hours calculator site to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round ) and help figure out which parts and pieces you're going to want to get.

The energy audit will tell the truth

My wildhat, however, says you need at least 50% more solar and maybe double but probably triple the battery capacity for 24/7 use that doesn’t require a mental health therapist especially when the wifey arrives. Storage overall is your weakest link even at 1600W effective of panels.

sunshine_eggo said:

This will be pretty power hungry even when it's not providing any loads. They have a pretty high idle burn - about 90W. This will use 2160Wh/day. This is almost 42% of your battery capacity - just being on and providing no loads.



Inadequate. See above.



These probably work at about 80% rated, so you have about 1600W of panels. This should get you about 8kwh/day on good days.



Yes.

Note that series panels can suffer from shading. Hopefully, your mounting scheme can insure that all panels remain unshaded from sunrise to sunset.



That's a big ask for the system you've selected. You really need to use the energy audit spreadsheet in Resources and calculate your needs.

If you have an absorption fridge (ammonia based, propane or AC powered), do not run it on AC. Run only on propane. On AC, they'll destroy you.



Last thing you want is to buy a bunch of stuff and then realize it's no good for you. You've selected an inverter that consumes 40% of your battery capacity before you even get to use it.

Do some more planning with an energy audit.



No.



Yes. Mentioned above.



Yes. You have no defined goal that says, "I need to use X Wh of energy per day." Right now, you're limited to about 8kWh/day total with only about 3kWh/day available when solar is unavailable. Since you don't know your needs, you don't know if that will work for you.



The growatt AC charger is not typical. It will not act as a battery charger like the solar does - no bulk, absorption, float. It simply turns off below a voltage and stops immediately once the upper voltage is reached, so fully charging is not easy, but you can easily get > 80% charged.

You will need to set the OFF voltage to 58V and the ON voltage to as high as it will go, but under 58V. If your battery is between the on and off values, it won't charge.

Click to expand...

Excellent reply, just the inverter idling will eat up a big portion of your collected energy.

2 reply's above don't even bother to read the request, how can he energy audit land ???
Anyway yes try to get some idea of what you will power and possible loads.
That inverter is not a USA model, slapping a transformer half arsed onto it does not make it right. Look at a pair of SPF3000 for the correct 120/240 split phase IF YOU EVEN NEED IT. It could be OK to just run all 120V appliances off a single 120V inverter of 3KW.
You will probably need 2x batteries and more panels but you can add those easy later on.

Quattrohead said:

2 reply's above don't even bother to read the request, how can he energy audit land ???

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If you had read it, he wants to power a 5th wheel and listed several items. Those are audit-able.

Quattrohead said:

Anyway yes try to get some idea of what you will power and possible loads.
That inverter is not a USA model, slapping a transformer half arsed onto it does not make it right.

Click to expand...

Use of an autotransformer is a viable solution. Done routinely to get split phase out of Victron equipment.

Quattrohead said:

Look at a pair of SPF3000 for the correct 120/240 split phase IF YOU EVEN NEED IT. It could be OK to just run all 120V appliances off a single 120V inverter of 3KW.
You will probably need 2x batteries and more panels but you can add those easy later on.

Click to expand...

He likely wants split phase because his 5th wheel is a 50A unit and works best with split phase.

I will leave my pre coffee reply up for prosperity LOL
Still don't like using wrong equipment with a hack though.

Quattrohead said:

prosperity

Click to expand...

Make the coffee already. For posterity.

Quattrohead said:

I will leave my pre coffee reply up for prosperity LOL
Still don't like using wrong equipment with a hack though.

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How is it wrong equipment? How is this a hack? It's done by professionals. Common to do with EU spec Multis/Quattros in North America or in Marine applications.

Victron literally has schematics for this exactly:

https://www.victronenergy.com/uploa...-phase-240V-to-120-240V-with-Quattro-240V.pdf (240 inverter to 120/240 split phase)

https://www.victronenergy.com/uploa...hase-240V-to-120-240V-with-Generator-240V.pdf (240 generator to 120/240 split phase)

and to step up a 120V unit to split phase:


Do you regard Victron as stupid or promoting "hacks?"

Factory tested to UL specifications, not a hack job.

A 240V inverter with floating output could be used with a 120/240V auto transformer (center tap grounded) to provide split-phase.

If the inverter puts out 240V single phase with one leg as "Neutral" bonded to chassis, a different type of transformer would be required.

If the inverter has floating output, and an AC input disconnected by SPST relay (only disconnecting hot, not neutral), then with autotransformer on the output the "neutral" input would be driven to 120V, a problem for either AC grid or generator input (if not floating). An input wire with plug (not hot wired) would become a "suicide cord" because it would have hot exposed pins.

Victron may not be stupid or offering hacks, with their inverter and their transformer paired together (they include a ground bonding relay in their transformer if I recall correctly.)

A retailer bundling a transformer with a different inverter may not think of issues we clever EEs come up with.

Quattrohead said:

Factory tested to UL specifications, not a hack job.

Click to expand...

What are you talking about?

You recommend a pair of SPF3000. Are those UL?

How many Victrons are UL listed? Very few.

Hedges said:

The Voc does sound OK.
If you wired instead as 4s2p, would the Vmp be high enough for the inverter?

You have 2000W of PV panels, 4800W of panels. 2.4 hours of production to recharge 100%.
What I'm thinking is, you might fully recharge battery, then waste PV production, then draw some power, then have a lower state of charge beginning the night.

With 4s aimed South East and 4s aimed South West, you get about 0.7 as high a peak power, 1.4kW. But more hours to (almost) make up for it.
That might keep battery somewhere between empty and full during the day.

2000W/4800W = ~ 0.4C charge rate, typically acceptable for lithium.
Determine what colder temperature is OK at 0.4C (it isn't 0 degrees C, should be greatly reduced current near freezing), and set low voltage charge disconnect accordingly.
If 4s2p as I suggested, then 1400W/4800W = 0.29C, so a bit lower temperature is OK.

Sometimes people have trouble with a generator feeding an inverter/charger because it is picky on frequency. In such case a separate charger can be a solution.

You may or may not need a precharge resistor to avoid 1000's of amps surge when connecting battery, so have some suitable resistor available (I think a 100' or 250' roll of Romex can serve, but most people use a power resistor.)

Use a DMM to double-check things before connecting and before closing switches. Make sure of voltages, polarity, and no voltage before touching terminals.

A DC disconnect if not built in is handy to isolate wires before work. At least, shut off inverter, confirm PV terminals have gone to Voc (no current), then unplug MC connectors for both positive and negative. Then confirm voltage has dropped to zero.

Click to expand...

Setting up the panels in 4s2p configuration for the reasons stated does make sense to me, especially with the high draw of the inverter/charge controler. Maybe because of our battery limitations simplicity isn't the key. haha

I was thinking one way of negating the waste of PV production during optimal sunlight hours is to run all our higher draw appliances during this period. such as doing the laundry, charging all the power tool batterys and running the window AC for a couple of hours to keep the 5th wheel cool. This might not be enough though, I may have to rethink the panel set up. Thank you for the input

I belive the battery has a built in precharge resistor. Will did a tear down video on one

sunshine_eggo said:

This will be pretty power hungry even when it's not providing any loads. They have a pretty high idle burn - about 90W. This will use 2160Wh/day. This is almost 42% of your battery capacity - just being on and providing no loads.



Inadequate. See above.



These probably work at about 80% rated, so you have about 1600W of panels. This should get you about 8kwh/day on good days.



Yes.

Note that series panels can suffer from shading. Hopefully, your mounting scheme can insure that all panels remain unshaded from sunrise to sunset.



That's a big ask for the system you've selected. You really need to use the energy audit spreadsheet in Resources and calculate your needs.

If you have an absorption fridge (ammonia based, propane or AC powered), do not run it on AC. Run only on propane. On AC, they'll destroy you.



Last thing you want is to buy a bunch of stuff and then realize it's no good for you. You've selected an inverter that consumes 40% of your battery capacity before you even get to use it.

Do some more planning with an energy audit.



No.



Yes. Mentioned above.



Yes. You have no defined goal that says, "I need to use X Wh of energy per day." Right now, you're limited to about 8kWh/day total with only about 3kWh/day available when solar is unavailable. Since you don't know your needs, you don't know if that will work for you.



The growatt AC charger is not typical. It will not act as a battery charger like the solar does - no bulk, absorption, float. It simply turns off below a voltage and stops immediately once the upper voltage is reached, so fully charging is not easy, but you can easily get > 80% charged.

You will need to set the OFF voltage to 58V and the ON voltage to as high as it will go, but under 58V. If your battery is between the on and off values, it won't charge.

Click to expand...

Thank you for your detailed response. As a few people have touched on the same concerns I'll create a new post that tries to address all of the advice.

JamesHird said:

Setting up the panels in 4s2p configuration for the reasons stated does make sense to me, especially with the high draw of the inverter/charge controler. Maybe because of our battery limitations simplicity isn't the key. haha

I was thinking one way of negating the waste of PV production during optimal sunlight hours is to run all our higher draw appliances during this period. such as doing the laundry, charging all the power tool batterys and running the window AC for a couple of hours to keep the 5th wheel cool. This might not be enough though, I may have to rethink the panel set up. Thank you for the input

Click to expand...

Opportunistic usage is definitely viable for maximizing solar and minimizing battery.

I doubt a couple of hours of a window AC unit will do much besides keep you comfortable while you're sitting in the draft of its output...

We have about 3kW of solar and great sun in AZ. We can run the rooftop AC for about 7-8 hours when we need it, and that thing gobbles 1500W or so. Given that panels are cheap, I'd get more panels to make that happen. Double your array to 8S2P. Split it with one half facing SE and the other half facing SW for more uniform harvest for longer.

sunshine_eggo said:

How many Victrons are UL listed

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In practice UL isn’t necessarily a “specification” anyway: from my understanding it’s an approval that certain conditions do not exist; that nothing violates NEC/NFPA; and that any legislative or jurisdictional requirements for X class of device are met. NEC references “UL-1234” but UL requires nothing of NEC.

I’ve bought things that advertised “manufactured to conform with UL1234” that don’t have any UL approval.

Things don’t get sent for UL approval because of cost, or sometimes a manufacturer doesn’t want liability and leaves ‘off-label’ applications as the responsibility of the end user.

That doesn’t necessarily make things unsafe imho

sunshine_eggo said:

Opportunistic usage is definitely viable for maximizing solar and minimizing battery.

I doubt a couple of hours of a window AC unit will do much besides keep you comfortable while you're sitting in the draft of its output...

We have about 3kW of solar and great sun in AZ. We can run the rooftop AC for about 7-8 hours when we need it, and that thing gobbles 1500W or so. Given that panels are cheap, I'd get more panels to make that happen.

Click to expand...

I'm building a roundwood timber framed structure with an earth roof over the 5th wheel with a 16' porch on the front. this should provide full shade from the sun and great insulation. Runing the AC for a couple of hours during the day wont make it a fridge but should take the edge off slightly. Where we are in Oklahoma it only really gets hot for a couple of months (July and August)

JamesHird said:

I'm building a roundwood timber framed structure with an earth roof over the 5th wheel with a 16' porch on the front. this should provide full shade from the sun and great insulation. Runing the AC for a couple of hours during the day wont make it a fridge but should take the edge off slightly. Where we are in Oklahoma it only really gets hot for a couple of months (July and August)

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I grew up in central and NW OK, and now that I'm in AZ, all I can remember is how miserable 95°F was in that humidity...

"dry heat" at 115°F is less uncomfortable.

PV panels are cheap ($0.025/kWh amortized over 10 years).
Batteries are expensive ($0.50/kWh by end of cycle life, for AGM or top-name lithium; FLA $0.25/kWh, recycled or DIY can reach $0.05/kWh)

Therefore, I favor over-paneling, and limiting charge current to what is health for battery. Cheaper to throw away unused power.

I'll try and provide a bit more infomation on what we are wanting and expecting out of our solar set up.

By going off grid and building a homestead we are wanting to get closer to the land to live a more simplistic and independent lifestyle closer to nature. We will be working with the flow of seasons. Waking up and going to sleep with the sun. Our aim is to reduce our energy consumpion to a minimum. Obviously we are not going Amish and want some of our modern comforts, especialy with a young son.
We want to be conscious about our energy consumption. Instead of having the mentality of being able to do whatever, whenever we want with our electricity we would like to work within our means.

Most of our time will be spent outside. Our main electrical consumption will be from fridges and chest freezers and this will be reduced by the construction of root cellars and keeping blocks of ice in our freezers.

Our habitations will be constructed with insulation from the heat and cold in mind. As our property is flat and fully forrested the trees we cut down to clear a couple of acres to build on will be used in the construction of these structures. Roundwood timber framing with earthen roofs is what we are going for. very strong and great insulation. especially with 2' thick straw bale walls.

Our property is in South Eastern Oklahoma. Oklahoma has a sun index of 0.98 and is ranked 6th best state for solar potential. Winters are dry and sunny. the rain happens mostly in the spring and a bit in the fall.

Our property has full southen exposure and the panels can be located with no obstruction from sunset to sunrise, even in the winter.

The system we are setting up is by no means the end goal. We want to start with a decent foundation that we can build on over time. It would be nice to have more solar panels and battery capacity but with all of the money outgoing on the purchase of the land, buying a trailer to live in during construction and development of the land this is all we can afford right now. By the end of the year we will be able to upgrade our system so this really is quite temporery.

The transformer is sold as part of a kit with the growatt inverter/charge controller from signature solar based in texas. It is so we can run a single phase 120v system.

We dont ever see ourselves needing more than a 10kw system. As and when money comes in we will invest in more batterys and panels.


This is my very basic Power audit: Please don't laugh

10cu.ft. Fridge/freezer 810wh
Hood vent 90wh
4xfans 720wh
laptop 500wh
cell phones 50wh
lights 180wh
water pumps 120wh
outdoor lights 80wh
power tool charging 800wh
Window AC 2200wh
small chest freezer 1500wh
Washing machine 500wh
propane dryer 500wh

8050wh

This is a power audit for all of our electrical need (maybe a few small things missed). We will not need to run all these appliances every day.

For example: the fans and Ac unit will only be required for a couple of months out of the year and this will be during optimal solar conditions.
The propane dryer will only be needed during the winter when AC and fans, etc wont be needed.

The only big draw essential items on this list are the Fridge freeze and chest freezer and lights. These use 2310wh per day.

All the lights, extractor fans and pumps on the 5th wheel are on a 12v system. energy efficient led bulbs are used. The only AC appliance in the 5th wheel is the 10cu.ft. fridge freezer. and the wall outlets.
The water heater is propane, we have a wood burning stove installed for heat

We aren't opposed to running the generator for an hour or two a day to suppliment the solar system. If there are days of bad solar we can charge the batterys with the generator. We would take advantage and while the generator is running charge our power tools, do laundry etc.

I cant emphasize enough that this is a stepping stone system that is intended to be built upon.

It is clear that the battery capacity is our biggest weakness. Followed by the solar array.

What do people think our next step should be? Cough up $1500 and double our battery capacity or spend $500 on panels and double our array.
What added costs are there in a 8S2P array? do i need a combiner box?
would splitting the panels half facing SE half SW compensate for our battery capacity?

Thanks for all of the input, I appreciate the time people have spent in helping us out.

Links to solar components:

5000W LVM- ES Off-Grid 240V Growatt Inverter with Solar Charge Controller + Growatt Split Phase Transformer for true 120V/240V Split Phase Electricity!

48V 100AH LiFePower4 Battery by EG4​

8 x SanTan Solar T Series 250W​

Specifications:​

• Rated Power: 250W
• Open circuit voltage (VOC): 37.6 V
• Max power voltage (VMP): 30.3 V
• Short circuit current (ISC): 8.85 A
• Max power current: 8.27 A

JamesHird said:

This is my very basic Power audit: Please don't laugh

10cu.ft. Fridge/freezer 810wh

Click to expand...

Sounds reasonable.

JamesHird said:

Hood vent 90wh
4xfans 720wh

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While fans are very beneficial in a residence allowing one to run A/C less in off-grid, they are pretty brutal. These are about 15% of your total battery capacity.

JamesHird said:

laptop 500wh

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Seems high unless you're running 10hr/day.

JamesHird said:

cell phones 50wh
lights 180wh
water pumps 120wh
outdoor lights 80wh
power tool charging 800wh
Window AC 2200wh
small chest freezer 1500wh
Washing machine 500wh
propane dryer 500wh

Click to expand...

JamesHird said:

8050wh

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Well, you just covered it with your 8 panels. Better in summer. Worse in winter.

JamesHird said:

This is a power audit for all of our electrical need (maybe a few small things missed). We will not need to run all these appliances every day.

For example: the fans and Ac unit will only be required for a couple of months out of the year and this will be during optimal solar conditions.
The propane dryer will only be needed during the winter when AC and fans, etc wont be needed.

Click to expand...

Diminished loads in winter.

JamesHird said:

The only big draw essential items on this list are the Fridge freeze and chest freezer and lights. These use 2310wh per day.

Click to expand...

Yep.

JamesHird said:

All the lights, extractor fans and pumps on the 5th wheel are on a 12v system. energy efficient led bulbs are used. The only AC appliance in the 5th wheel is the 10cu.ft. fridge freezer. and the wall outlets.

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12V achieved via 48V to AC to 12VDC will be about 70% efficient.

JamesHird said:

The water heater is propane, we have a wood burning stove installed for heat

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Nice! Was wondering about heat.

JamesHird said:

We aren't opposed to running the generator for an hour or two a day to suppliment the solar system. If there are days of bad solar we can charge the batterys with the generator. We would take advantage and while the generator is running charge our power tools, do laundry etc.

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You really want the generator to be the outlier, i.e., when weather is just trash OR if you really have high demand items it doesn't make sense to power via solar. My friend used to have to run his generator every time he wanted to pump out of his 700' well - a couple hours a few days a week.

Given the cost of panels, another $400 to double the size of your array is hands down the best bang for the buck.

JamesHird said:

I cant emphasize enough that this is a stepping stone system that is intended to be built upon.

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"Building upon" needs to consider the end goal. Unfortunately, without that level of planning, you may find that this is system #1 and will be replaced with system #2. It's probably not in your case, given the scalability of the unit.

JamesHird said:

It is clear that the battery capacity is our biggest weakness. Followed by the solar array.

What do people think our next step should be? Cough up $1500 and double our battery capacity or spend $500 on panels and double our array.

Click to expand...

This by an order of magnitude. More battery doesn't help you when you're consuming more than you can replenish. The battery just limits you on power expended between charging. You already have the generator to make up for that. I see it this way:

$1500 for 5kWh of capacity
$500 for 8kWh of solar

JamesHird said:

What added costs are there in a 8S2P array? do i need a combiner box?

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That's generally how it's done, but with only 2P, you don't NEED one. You technically don't even need fuses/breakers on 2P - only 3P and more.

Your ground mount will be double, but DIY can be pretty cheap.

JamesHird said:

would splitting the panels half facing SE half SW compensate for our battery capacity?

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Not so much compensating for it, but it helps. It makes power use more flexible in that it would widen the hours in which you will be producing elevated power at the expense of peak power at noon. It would look like this:



Red horizontal line is max array. Blue/red bell curve is a south facing array (jagged stuff is clouds). Red lumps are SE + SW arrays.

sunshine_eggo said:

Sounds reasonable.



While fans are very beneficial in a residence allowing one to run A/C less in off-grid, they are pretty brutal. These are about 15% of your total battery capacity.



Seems high unless you're running 10hr/day.





Well, you just covered it with your 8 panels. Better in summer. Worse in winter.



Diminished loads in winter.



Yep.



12V achieved via 48V to AC to 12VDC will be about 70% efficient.



Nice! Was wondering about heat.



You really want the generator to be the outlier, i.e., when weather is just trash OR if you really have high demand items it doesn't make sense to power via solar. My friend used to have to run his generator every time he wanted to pump out of his 700' well - a couple hours a few days a week.

Given the cost of panels, another $400 to double the size of your array is hands down the best bang for the buck.



"Building upon" needs to consider the end goal. Unfortunately, without that level of planning, you may find that this is system #1 and will be replaced with system #2. It's probably not in your case, given the scalability of the unit.



This by an order of magnitude. More battery doesn't help you when you're consuming more than you can replenish. The battery just limits you on power expended between charging. You already have the generator to make up for that. I see it this way:

$1500 for 5kWh of capacity
$500 for 8kWh of solar



That's generally how it's done, but with only 2P, you don't NEED one. You technically don't even need fuses/breakers on 2P - only 3P and more.

Your ground mount will be double, but DIY can be pretty cheap.



Not so much compensating for it, but it helps. It makes power use more flexible in that it would widen the hours in which you will be producing elevated power at the expense of peak power at noon. It would look like this:

View attachment 79256

Red horizontal line is max array. Blue/red bell curve is a south facing array (jagged stuff is clouds). Red lumps are SE + SW arrays.

Click to expand...

Thank you so much for your responses. You are making things clearer for me.
It sounds like the first thing we should do is get more panels, put them in 2p and face them SE and SW. This kind of makes up for our low battery capacity and high draw inverter. (widens the hours of producing power therefore less time of just draw from the inverter)