First Draft: Shack in the Woods

[MHouser]

I am brand new to solar and brand new to this site. I am trying to design a system that will support starlink, my laptop, a second monitor, a couple of lights and be able to charge my phone and flashlight. I drew this today. Looking for any input anyone is willing to offer. Shack is in Ontario, Canada and I will be there for the months of September and October this fall.

 

[Mattb4]

Looks good. A bit overkill for the few loads you mention. But it ought give you headroom for bad weather and adding other items. About all I would mention is you may want a larger inverter.

ETA: One other thing to be aware of. Possible freezing of the batteries. Lithium can not be charged at below freezing temperatures.

 

[HRTKD]

To minimize generator runtime, I would look for a charger with a higher amp output. That AC-DC charger should pull a bit over 10 amps from the generator.

There should be a fuse between the battery bank and the switch. Class T fuse is recommended.

Your 4P PV configuration requires fuses between each panel. Consider wiring it as 2s2p and you don't need fuses.

A switch to turn off PV power to the solar charge controller is helpful. A dual pole DC breaker of an appropriate amperage is what most of us use.

 

[MHouser]

To minimize generator runtime, I would look for a charger with a higher amp output. That AC-DC charger should pull a bit over 10 amps from the generator.

There should be a fuse between the battery bank and the switch. Class T fuse is recommended.

Your 4P PV configuration requires fuses between each panel. Consider wiring it as 2s2p and you don't need fuses.

A switch to turn off PV power to the solar charge controller is helpful. A dual pole DC breaker of an appropriate amperage is what most of us use.

So you think I should look for a charger greater than 50a? Do you have any recommendations?

What size fuse would I use between the switch and battery?

I forgot about the Panel fuses thanks.

I will replace the PV switch with a breaker.

 

[HRTKD]

If you get an inverter/charger (combo device), then you can get quite a bit more charging amps to the battery. That type of device is more expensive, but on the upside, is one device instead of two. My Victron Multiplus 12/3000 can charge the batteries with up to 120 amps, but I've never pushed it that hard.

Before you go down the road of increasing your AC-DC charging, consider if you'll really need much more. I often run my RV off of the same amount of PV you have in your design and I rarely need to fire up my generator. Only if I run the air conditioning do I need the generator. Unless you have really poor sunlight, I think you're going to find that you don't need the generator.

A 100 amp Class T fuse between the battery and switch is about right. 1200 watts / 24 volts / .85 (inverter efficiency) x 1.25 = 73 amps. This is the current that you would expect to see when running the inverter at full blast.

 

[MHouser]

A 100 amp Class T fuse between the battery and switch is about right. 1200 watts / 24 volts / .85 (inverter efficiency) x 1.25 = 73 amps. This is the current that you would expect to see when running the inverter at full blast.

The inverter is rated at .91 efficiency so I divided by .91 instead of .85 which gave me 68 and change. I rounded up to 70. That's the method I used to calc the fuse size for the positive inverter wire fuse.

I am very new to all of this so please excuse my question... why do I need the fuse between the batteries and the switch? All the
other components connected to the positive bus bar already have 70a fuses on them.

Also, I don't have the 50a charger yet, I was simply estimating what I thought I may need. I have a very cheap 10a 24v charger and am looking for one with higher amperage. Do you have any recommendations? The high amp ones get very expensive.

 

[HRTKD]

I am very new to all of this so please excuse my question... why do I need the fuse between the batteries and the switch? All the
other components connected to the positive bus bar already have 70a fuses on them.

The batteries have the highest current potential.

We're protecting the wires with fuses, not the devices. (This the main reason you need a fuse between the battery and the switch)

 

[Mattb4]

So you think I should look for a charger greater than 50a? Do you have any recommendations?

What size fuse would I use between the switch and battery?

I forgot about the Panel fuses thanks.

I will replace the PV switch with a breaker.

A 50a charger should be plenty for a 200ah battery setup. That is pulling ~1500w from your 2000w generator. Indeed it might be too much

 

[SamDeleted]

To minimize generator runtime, I would look for a charger with a higher amp output. That AC-DC charger should pull a bit over 10 amps from the generator.

Are you sure a 2kw generator can power much more than 1500ws of battery charger ?

 

[SamDeleted]

Do you have any recommendations?

You might be able to source a car workshop charger in 24v

I've got this

Genuine Maypole Heavy Duty Boost Start Battery Charger 350 amps 60 Amp

Genuine Maypole Heavy Duty Start battery Charger 350 AmpsBoost & 60A Charge MP727 To suit a wide rage of vehicles including: 4x4's, vans, tractors and lorries Features 12/24V maypole start boost charger Suitable for applications including cars, commercial vehicles, vans and tractors with 12V or...

www.rotatingelectrics.co.uk

Obviously that's not suitable for you it's 240v 50hz UK power , but something similar might be available ? You'll have to double check about charging LiFePo4

 

[HRTKD]

Are you sure a 2kw generator can power much more than 1500ws of battery charger ?

It should have 15 amp outlets and the charger he listed would pull just over 10 amps. So he has a bit more wiggle room to go to a slightly bigger charger. Certainly not double the output, but maybe to 60 amps.

 

[HarryN]

You will want to wire the panels 2S 2P rather than 4P like you have now.

Just like @HRTKD mentioned.

The victron solar charge controller will not start up until the panel Vmp hits nearly 35 volts in that setup and with the the low solar intensity that time of year, in parallel like that it won't start charging until mid day in a 4 P setup.

in a 2S 2 P mode, it will start charging much earlier in the day.

No question I would go with Lifeline AGMs not LiFe in that environment. There are not many other packs that can support the charge rates and temperatures that could be experienced.

I would just buy a decent 2000 watt inverter if you plan to be relying on it.

___________

I am unsure about the charge rate question. I tend to buy chargers that can feed through a 30 amp fuse.

A lot of chargers use more power on the input side than expected.

It is an inverter generator so a lot of them tend to work better at 800 - 900 watts vs full blast.

One possible strategy in a low light environment is to run the generator for an hour in the morning and then let solar try to power / charge things the rest of the day.
________________

 

[HarryN]

If it were me I would purchase poly panels instead of mono for use that time of year, and mount them essentially vertical facing south or nearly so.

Check the solar angles for that time of year but it is going to be very different than Florida.

What are you doing for heat and refrigeration?

 

[MHouser]

If it were me I would purchase poly panels instead of mono for use that time of year, and mount them essentially vertical facing south or nearly so.

Check the solar angles for that time of year but it is going to be very different than Florida.

What are you doing for heat and refrigeration?

Everything will be in the cabin except the panels.
Wood stove for heat. I already have the lifepo4 batteries but they will stay warm. Cooler with ice blocks for refrigeration. I will rejig the plan for 2S2P.

Why poly panels?

 

[Xhumeka]

A full sized fridge would likely use less power over 24 hours than your starlink router (assuming you leave your router on 24/7 also) - you may want to consider adding a fridge instead of dealing with ice (depending how long you are out there for at a time).

 

[MHouser]

A full sized fridge would likely use less power over 24 hours than your starlink router (assuming you leave your router on 24/7 also) - you may want to consider adding a fridge instead of dealing with ice (depending how long you are out there for at a time).

I will leave Starlink on 24/7. I’ve budgeted 16 hours in use @ 75 watts and 8 hours idle @ 25 watts. I’m looking into fridges thanks.

 

[HRTKD]

I will leave Starlink on 24/7. I’ve budgeted 16 hours in use @ 75 watts and 8 hours idle @ 25 watts. I’m looking into fridges thanks.

In case you didn't know, Starlink has the ability to go to "sleep" on a schedule.

 

[MHouser]

In case you didn't know, Starlink has the ability to go to "sleep" on a schedule.

 

[HarryN]

Everything will be in the cabin except the panels.
Wood stove for heat. I already have the lifepo4 batteries but they will stay warm. Cooler with ice blocks for refrigeration. I will rejig the plan for 2S2P.

Why poly panels?

Solar panels are rated using a light source that resembles very clear skies and intense direct sunlight. The light angle to the panel is fairly direct vs off angle. The light spectrum is similar to a mid summer day.

The conditions that you will be in are nearly the opposite. This is when poly panels, especially those designed for poor lighting conditions really come through, even though they produce less power using the standard test lighting sources.

_________

If you plan to leave the batteries there, then AGMs would be a much better choice.

It is a beautiful area. The weather sometimes decides on the schedule vs our calendar.

 

[Xhumeka]

Solar panels are rated using a light source that resembles very clear skies and intense direct sunlight. The light angle to the panel is fairly direct vs off angle. The light spectrum is similar to a mid summer day.

The conditions that you will be in are nearly the opposite.

Opposite conditions? In Ontario in the Summer? I'm not sure where the OP is located exactly, but I'm at the Southern tip of Algonquin Park and with clear skies (which I get a lot of) I see 100 percent power generation from my panels - which are 10 years old at this point.

EDIT - sorry, I re-read his original post and see that he will be there for September and October... now I realize why you said "opposite conditions"... my mistake!

With that in mind, you might not need a fridge afterall