diy solar

diy solar

So what would you suggest??

ghostwriter66

"Here - Hold my Beer"
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EE from LAX CA -work in SouthTX for giant evil Oil
I sort of asked this question a few days ago and got a couple of good answers ... but thought I would re-word it and see if I get anything different ...

So my company has donated (10) 445W solar panels and a battery to power a mobile aide station for one of the counties we work in. These were extra panels and batteries they had. The issue is that corporate thought we could just use one of the ALL-n-ones that they also sent (MPP 2424) that could only handle 5 panels if that ....

Along with the (10) panels they have provided a 24V 540Ah battery. ((YES its the damn 24V battery that is causing us all these issues - if it was 48 this would have taken 5 minutes)) but I digress....

Below is the specifications of those panels.
MAXIMUM POWER 445W
VMP 41.19
IMP 10.81

They need to power one 115V 8A circuit 24/7/365.

They would also like to every now and then charge a laptop or something BUT not exceed 7A.
SO worse case scenario - 5% of the time - it would have a TOTAL MAXIMUM USEAGE OF 15 AMPS but 95% (if not more) of the time it will only be 7A...

I wanted to find a simply all in one that I could just slap in a box - HOOK UP THE PANELS AND BATTERY ... high five my partner - and then head back to the shop to watch NETFLIX ...

BUT NOT SO LUCKY ...

There is NOT an ALL-n-1 that's out there that we can afford to also give away ... and I mean most of the ones that can handle that much energy starts running $$$$$ ...

My Plan B is to tell my guys just to get some EPEVER 80A MPPT SCC and connect 5 panels to the left one ... 5 panels to the right one ... run them both to the battery ... and from the battery get a good 3KW inverter AND WE ARE DONE ...

But just to make sure that I am not just being lazy ... I was just wondering if anyone had a Plan C that we could use to accomplish the above and try to keep the equipment (the SCC + INVERTER) to $1200 or below??? Or do you think the EPEVER 80A x 2 + inverter is the way to go???

Any better solutions??

One of the other girl engineers thought we could take the MPP SOLAR 2424 they sent and use that on the left 5 panels and then just get a EPEVER 80A for the right 5 panels and hook both the 2424 and the EPEVER 80A directly to the battery ... that actually sounds like a better plan unless someone can come up with better ... (the 2424 has a built in 3KW inverter)

THX ahead of time ...
 
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8A * 115V = 920W continuous load.

24hr *920W = 22.08kWh

540Ah*3.2V*8S = 13.82kWh

10X * 445W /3.4V/8S = 163A

Is the battery sufficient?

Why 3kW on Plan B. Is surge anticipated? Otherwise, 2000W would be more than enough for the 15A load, have lower idle power/self-consumption draw and be a little cheaper.

Plan C: The MPP units are notorious for high idle power/self-consumption draw, but another kWh of consumption probably isn't enough to matter.

Plan B and C are essentially a toss up in my head.
 
One of the other girl engineers thought we could take the MPP SOLAR 2424 they sent and use that on the left 5 panels and then just get a EPEVER 80A for the right 5 panels and hook both the 2424 and the EPEVER 80A directly to the battery ... that actually sounds like a better plan unless someone can come up with better ... (the 2424 has a built in 3KW inverter)
I was about to suggest that..... but there it was at the end of your post.
 
I sort of asked this question a few days ago and got a couple of good answers ... but thought I would re-word it and see if I get anything different ...

So my company has donated (10) 445W solar panels and a battery to power a mobile aide station for one of the counties we work in. These were extra panels and batteries they had. The issue is that corporate thought we could just use one of the ALL-n-ones that they also sent (MPP 2424) that could only handle 5 panels if that ....

Along with the (10) panels they have provided a 24V 540Ah battery. ((YES its the damn 24V battery that is causing us all these issues - if it was 48 this would have taken 5 minutes)) but I digress....

Below is the specifications of those panels.
MAXIMUM POWER 445W
VMP 41.19
IMP 10.81

They need to power one 115V 8A circuit 24/7/365.

They would also like to every now and then charge a laptop or something BUT not exceed 7A.
SO worse case scenario - 5% of the time - it would have a TOTAL MAXIMUM USEAGE OF 15 AMPS but 95% (if not more) of the time it will only be 7A...

I wanted to find a simply all in one that I could just slap in a box - HOOK UP THE PANELS AND BATTERY ... high five my partner - and then head back to the shop to watch NETFLIX ...

BUT NOT SO LUCKY ...

There is NOT an ALL-n-1 that's out there that we can afford to also give away ... and I mean most of the ones that can handle that much energy starts running $$$$$ ...

My Plan B is to tell my guys just to get some EPEVER 80A MPPT SCC and connect 5 panels to the left one ... 5 panels to the right one ... run them both to the battery ... and from the battery get a good 3KW inverter AND WE ARE DONE ...

But just to make sure that I am not just being lazy ... I was just wondering if anyone had a Plan C that we could use to accomplish the above and try to keep the equipment (the SCC + INVERTER) to $1200 or below??? Or do you think the EPEVER 80A x 2 + inverter is the way to go???

Any better solutions??

One of the other girl engineers thought we could take the MPP SOLAR 2424 they sent and use that on the left 5 panels and then just get a EPEVER 80A for the right 5 panels and hook both the 2424 and the EPEVER 80A directly to the battery ... that actually sounds like a better plan unless someone can come up with better ... (the 2424 has a built in 3KW inverter)

THX ahead of time ...
I’m missing a couple things:

1/ why are you looking for a 3kW inverter when average load is under 1kW and peak load is less than 2kW? I suppose a 3kW inverter won’t cost that much more but I don’t see that it buys you much…

2/ how are cloudy days going to be handled? Are you assuming every day is a sunny day or is there a backup generator (or whatever)? Or does an occasional day or week of down time due to poor weather not pose a problem?

Depending on how many panels you use, you can have plenty of PV power to deliver 1kW during daylight hours while also charging a battery, so the battery only needs to be big enough to cover 16-18 hours worst-case overnight in the winter.

1kW / 90% efficiency x 16-18 hours means a battery with usable capacity of 20kWh should suffice (and your 13.44kWh battery should be plenty even using at 80%).

So again, assuming no need for additional capacity to cover overcast days, your 13.4kWh battery charged by 2 or 3 Epever SCCs and feeding a 3kW WZRELB inverter should get the job done for well under $1000.

Your 4.45kW of panels will probably drive peak charge current of over 150A but and you need 1kW / 90% x 24h = 26.7kWh generated per day, meaning you probably need to capture all of the available energy coming off of those panels.

The 80A Epever SCC will take a maximum of 200V, so 3S max, but 3S2P will drive 2.7kW or ~95A at peak, so an 80A fed by a 1S5P string will just manage the 76A peak current you’ll get from 5 panels.

$396 for the 100A Epever Tracer1015AN currently on Amazon and $299 for the 2kW 24V WZRELB inverter, so you are $109 under budget (or you can splurge and spend another $22 for the 3kW 24V PSW and give yourself a bit more breathing room…).
 
I’m missing a couple things:

1/ why are you looking for a 3kW inverter when average load is under 1kW and peak load is less than 2kW? I suppose a 3kW inverter won’t cost that much more but I don’t see that it buys you much…

2/ how are cloudy days going to be handled? Are you assuming every day is a sunny day or is there a backup generator (or whatever)? Or does an occasional day or week of down time due to poor weather not pose a problem?

Depending on how many panels you use, you can have plenty of PV power to deliver 1kW during daylight hours while also charging a battery, so the battery only needs to be big enough to cover 16-18 hours worst-case overnight in the winter.

1kW / 90% efficiency x 16-18 hours means a battery with usable capacity of 20kWh should suffice (and your 13.44kWh battery should be plenty even using at 80%).

So again, assuming no need for additional capacity to cover overcast days, your 13.4kWh battery charged by 2 or 3 Epever SCCs and feeding a 3kW WZRELB inverter should get the job done for well under $1000.

Your 4.45kW of panels will probably drive peak charge current of over 150A but and you need 1kW / 90% x 24h = 26.7kWh generated per day, meaning you probably need to capture all of the available energy coming off of those panels.

The 80A Epever SCC will take a maximum of 200V, so 3S max, but 3S2P will drive 2.7kW or ~95A at peak, so an 80A fed by a 1S5P string will just manage the 76A peak current you’ll get from 5 panels.

$396 for the 100A Epever Tracer1015AN currently on Amazon and $299 for the 2kW 24V WZRELB inverter, so you are $109 under budget (or you can splurge and spend another $22 for the 3kW 24V PSW and give yourself a bit more breathing room…).

YEP we are on the same sheet of paper ... I guess I will drop down to a 2KW simply because it is about $50 cheaper BUT mainly because it will have less wasted amps during use ... Thx for your help ...
 
YEP we are on the same sheet of paper ... I guess I will drop down to a 2KW simply because it is about $50 cheaper BUT mainly because it will have less wasted amps during use ... Thx for your help ...
Good luck!

And by the way, parallel string to Epever SCC charging 560Ah 24V LiFePO4 feeding Reliable 3kW inverter is exactly the architecture of my DC-coupled backup power rig (battery feeds a pair of 1kW GTIL inverters for time-shifting / load-shaving 99.99% of the time).

So please let me know how your ‘clone’ of my system works out ;).

And can I ask what 450W panels you are using? I’m eyeing a few of the new 450-500W panels for an additional 1kW of power next year and looking for recommendations.
 
The Midnight DIY 24V inverter looks interesting, but of course can't process that much PV.
I don't see mention of stackable.
One of their inverters + one charge controller might do it.
Buying 19 units, you should have some negotiating power.


 
MPP LV 2424, 3 panels true east, three panels true south, three panels true west. My guess is you never exceed 145v, 80a, or 2000w input and you will get a maximum solar day worth of power...

Of course if this is mission critical (and it sounds like it is), maybe not...
 
I assume this is just back up power and there is grid available? If that is the case, then I think the MPP LV2424 would work fine with grid assist.
 
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