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Old 05-03-2020, 09:52 PM   #1
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Efficient/Effective Solar Setup

I am currently planning my solar/power system and want to take advantage of the Renogy sale that is about to end. I am already planning on buying mostly Renogy components considering the quality/price for a solar system.

I plan on having 300 watts of monocrystalline solar panels on the roof - these will be purchased later on.

The panels will run into a Renogy 40 amp MPPT Charge Controller
https://www.renogy.com/rover-li-40-a...ge-controller/

This will charge 2 200 Ah Renogy Deep Cycle AGM Batteries (Best way to get 400 Ah out of good batteries for the cost?).
https://www.renogy.com/deep-cycle-ag...12-volt-200ah/

I plan on also using the 500 amp Renogy Battery monitor as well.

For 110V, I want to use the 700 watt Renogy Pure Sine Wave Inverter.
(Is there a similar wattage of another brand as good for less $$?)
https://www.renogy.com/700w-12v-pure...wave-inverter/

And finally for shore power the most cost effective method I see thus far is the Samlex 30 amps battery charger.
(I like the idea of an inverter charger but sure if the Rengoy 1000W one for $400+ is worth the convenience.
https://www.amazon.com/gp/product/B0...TW0ZXVPR&psc=1

I would like to remove any possible bottle necks and have a sub $2000 (including hardware) solar system of between 300-400 Ah. These items add to about $1200 on Renogy's website and would be $100 with the sale.

Thanks!
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Old 05-05-2020, 08:27 AM   #2
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If money were no issue, I'd do exactly what you're doing with Renogy. I wish they had 24V batteries, however, as I believe their 12V can't be hooked up in series due to the internal BMS. In any case, if you can afford it, I'd absolutely do it.


I'd also add their DC to DC battery charger, and I'd get the combined inverter/charger combo for shore power, but that's just because my bus has a severe lack of space.


And I just went to their website to see what sale was going on, and just picked up a few of their curved brackets to mount my panels with (I have three of their 300W panels)
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Old 05-05-2020, 08:43 AM   #3
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What all are you planning for electrical components? How much are you going to be drawing? What do you think will be your primary charging source while out and about? I reread your post and while I would still go with all Renogy products, I'm curious what you're planning with the end result.
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Old 05-05-2020, 10:56 AM   #4
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This will charge 2 200 Ah Renogy Deep Cycle AGM Batteries (Best way to get 400 Ah out of good batteries for the cost?).
https://www.renogy.com/deep-cycle-ag...12-volt-200ah/

400*.80=320
Best way to get 320 Ah out of good batteries for the cost? For sure.
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Old 05-13-2020, 08:30 PM   #5
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Quote:
Originally Posted by Shrek (russel) View Post
This will charge 2 200 Ah Renogy Deep Cycle AGM Batteries (Best way to get 400 Ah out of good batteries for the cost?).
https://www.renogy.com/deep-cycle-ag...12-volt-200ah/

400*.80=320
Best way to get 320 Ah out of good batteries for the cost? For sure.
Can you explain the 0.8 multiplier? If that is depth of discharge 80% is not realistic for any lead acid battery I am aware of. 50% is standard, and 30% is conservative (optimized for battery life/health) for deep cycle lead acid.


If cost is your number one priority I would look into these two options:

1. Lowest Upfront cost, flooded lead acid deep cycle golf cart batteries. 6 of these Duracell GC2's would give you 645Ah Nominal / 325Ah Usable at 12V and cost $540 total / $130 cost per usable kilowatt moderately good cycle life (a bit better than AGM, substantially worse than lithium)

2 Cost over time, lithium batteries have a high upfront cost, but will last substantially longer than lead acid batteries if properly cared for, and have greater depth of discharge (80% is standard) so you get more usable capacity out of a given battery size. There is a steeper learning curve with lithium, and the best value comes from building your own battery bank out of raw cells. Currently some of the best value on raw cells hover in the $220-250 range per usable kilowatt including the cost of an entry level BMS. But I want to be clear, building with raw cells, requires learning, and research, and work, and confidence on your part. The cost of 'drop in' lithium batteries is much higher.

Compared to the Renogy batteries, 3 x 200Ah Renogy AGM would give you 600Ah Nominal / 300Ah Usable at 12V and cost $1200 total / $312 per usable kilowatt. One advantage of the AGM is they are 'maintenance free,' with really no learning curve or hassle but they are more costly and have a shorter cycle life than the other two options (much shorter than lithium, marginally shorter than flooded lead acid)
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Old 05-13-2020, 08:52 PM   #6
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Quote:
Originally Posted by bigbeanbus View Post
I am currently planning my solar/power system and want to take advantage of the Renogy sale that is about to end. I am already planning on buying mostly Renogy components considering the quality/price for a solar system.

I plan on having 300 watts of monocrystalline solar panels on the roof - these will be purchased later on.

The panels will run into a Renogy 40 amp MPPT Charge Controller
https://www.renogy.com/rover-li-40-a...ge-controller/

This will charge 2 200 Ah Renogy Deep Cycle AGM Batteries (Best way to get 400 Ah out of good batteries for the cost?).
https://www.renogy.com/deep-cycle-ag...12-volt-200ah/

I plan on also using the 500 amp Renogy Battery monitor as well.

For 110V, I want to use the 700 watt Renogy Pure Sine Wave Inverter.
(Is there a similar wattage of another brand as good for less $$?)
https://www.renogy.com/700w-12v-pure...wave-inverter/

And finally for shore power the most cost effective method I see thus far is the Samlex 30 amps battery charger.
(I like the idea of an inverter charger but sure if the Rengoy 1000W one for $400+ is worth the convenience.
https://www.amazon.com/gp/product/B0...TW0ZXVPR&psc=1

I would like to remove any possible bottle necks and have a sub $2000 (including hardware) solar system of between 300-400 Ah. These items add to about $1200 on Renogy's website and would be $100 with the sale.

Thanks!
This is the setup I have except 6 100 w panels. All Renogy gear. I’m not hooked up yet.
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Old 05-14-2020, 04:06 PM   #7
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Originally Posted by dzl_ View Post
Currently some of the best value on raw cells hover in the $220-250 range per usable kilowatt including the cost of an entry level BMS.

That's an insanely good deal that I wish I would've seen before buying my pouches. You could make a 12V 3kWh lithium pack for $500... For the next bus!
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Old 05-14-2020, 06:59 PM   #8
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[QUOTE=dzl_;386508]Can you explain the 0.8 multiplier? If that is depth of discharge 80% is not realistic for any lead acid battery I am aware of. 50% is standard, and 30% is conservative (optimized for battery life/health) for deep cycle

https://batteryuniversity.com/learn/article/absorbent_glass_mat_agm

80 is normal life cycle for amg. 50 and lower just makes them last longer.

We use amg is all our back up systems for cell sites and pull them down to 80 before cut off and will come back.
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Old 05-15-2020, 10:24 PM   #9
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[QUOTE=Shrek (russel);386665]
Quote:
Originally Posted by dzl_ View Post
Can you explain the 0.8 multiplier? If that is depth of discharge 80% is not realistic for any lead acid battery I am aware of. 50% is standard, and 30% is conservative (optimized for battery life/health) for deep cycle

https://batteryuniversity.com/learn/..._glass_mat_agm

80 is normal life cycle for amg. 50 and lower just makes them last longer.

We use amg is all our back up systems for cell sites and pull them down to 80 before cut off and will come back.
Interesting, I learned something new. Never heard of anyone recommending 80% DoD with any type of lead acid, but I suppose for this type of application (backup power) shortening the cycle life probably isn't a big consideration.

Looking at a few datasheets, there is a bigger loss of cycle life from 25% DoD to 50% DoD than there is from 50% to 80% so I can see why in some situations this would be an acceptable loss. I had assumed there was a bigger cliff around 50% DoD. Though it looks like even 80% isn't a magic number, 100% DoD is worse than 80% but not exponentially worse.

How many cycles do you plan for, and what batteries do you use?

Regardless, I don't think we should be discussing 80% or 100% DoD for skoolie applications where cycle life is a much more important factor. For use cases where the batteries will be discharged often, <50% or ideally <30% seems smart.

Based on the Vmax AGM chart:
100% DoD = ~300 cycles until 80% capacity remains

80% DoD = ~450 cycles until 80% capacity remains
50% DoD = ~700 cycles until 80% capacity remains
25% DoD = ~1150 cycles until 80% capacity remains

Renogy's datasheet for the Battery in question seems to show:
100% DoD = ~275 cycles until 80% capacity
50% DoD = ~550 cycles until 80% capacity
30% DoD = ~1300 cycles until 80% capacity
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