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feedback: this forum has convinced me not to build a solar system.

thomBangor said:
After lots of feedback, I've designed this and am looking for holes in the design. Would like to pull the trigger soon and purchase parts since they have 1-20 month lead times and winter is coming.

diysolarforum.com

Schematic for EG4 off-grid system. I think I'm going to pull the trigger soon and buy parts.

After lots of feedback from this forum, I think I'm going to go with this design. If you find any holes in it please let me know.
diysolarforum.com diysolarforum.com

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Nothing about specifications just wanted to tell you how my wife's attitude changed.

I started with a tiny 1.6kw system just runs the fridge, my home server, lights and fans my battery is just a small deep cycle FLD that can run 2 fans some lights and the fridge/Server during a power cut I didn't want to cycle the battery so we power from the grid at night. During the day when power is free we run 10 or so fans flowing air throughout the house every day I would tell my wife we saved 70¢ today/saved 40¢today(she looked at me like I'm an idiot,TBF I am).

First monthly bill came in we saved like $14 boss was slightly impressed.

First power cut and her attitude changed to "do you think we should power the whole house with solar"

Guess I should say many wives have bad expectations for our projects but once our toys exceed expectations to their benefit they generally support us whole heartedly, atleast that's my experience.
 
Hedges said:
8000W of panels because that's the recommended amount for inverter?
4000W per MPPT it says, I'd go for at least 6000W each, in the form of 2x 3000W arrays/strings of different orientations wired in parallel. That should put out 4000W for several hours rather than just peak.
STC ratings are only achieved under bright cool conditions. Otherwise maybe 70% to 90% in direct sun.
So I'd like to put 12kW to 15kW (STC) of panels on it. More panels for times of less light.
If the MPPT circuits are weak, they may not like that. Aiming for "NOMINAL MPPT VOLTAGE 320 VDC" might reduce the stress.
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8kW of panels because that is what fits on the roof. If more fit then I would put more and pipe them in parallel groups.

One side of this roof gets a lot less sun than the other, so I predict I will get nowhere near the power limit.

With 10 panels I'm expecting the string voltage to typically be around 370 V, which seems to me not far from the 320V nominal?
 
Solar Guppy said:
The EG4 "all weather" battery has no environmental specifications, how do you know your outside winter temperatures are within it's operational range? And while it says something about a heater, what is the power draw on that??.

I would never install battery's outdoors, best case is huge reduction of capacity and large tar loads to keep it from freezing.
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1720711969783.png

The 32 deg charging lower limit might be a problem, but I know of nothing else in the ballpark. I'll insulate/paint black/design an arduino heater if need be. Cross that bridge when I come to it.

Whatever energy it needs to use for heat, I'm in favor of. I can always improve that with rockwool. I cannot justify putting batteries inside my home until I'm dead certain they are fireproof.
 
Brucey said:
Do you have the crimping tools to terminate your PV cables with mc4 connectors? I think that's bare wire? Any reason you aren't getting the battery from Current Connected as well? Higher shipping? Personally I'd go with cc for all of it except the panels.
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Yes higher shipping. Also signature has a $3000 minimum for free shipping, and I doubt I will need as much technical help with the battery as I will with the inverter.

Although there is something on the CC website about matching prices and free shipping w/ code SUMMER during the 4th holiday. I'll ask them about it.
 
thomBangor said:
View attachment 227986

The 32 deg charging lower limit might be a problem, but I know of nothing else in the ballpark. I'll insulate/paint black/design an arduino heater if need be. Cross that bridge when I come to it.

Whatever energy it needs to use for heat, I'm in favor of. I can always improve that with rockwool. I cannot justify putting batteries inside my home until I'm dead certain they are fireproof.
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Myself and many others agree with you on the battery&home front I'll be starting construction of a fireproof power shed in the coming weeks obviously I don't have to deal with the cold it's the heat here but my advice to you, unsure if others agree is don't insulate the batteries better you look at some form of insulated shed. Wrapping the batteries with any form of insulation is likely to compound any heat generated through charge/discharge better it be allowed to dissipate into its surroundings likely the batteries have some requirements about space around them in their datasheet.
 
The outdoor PP are double skinned steel and have fire suppressors, I'm thinking the indoor version is the same too.
I am more worried about parking a gas car/mower etc in the garage than my solar system.
Small note on your diagram, the ATS is not between your solar system and the grid.
Remind us again, plans/permits/inspections required or not ?
 
Looks like you interdigitated the MPPT to the panels. Recommend you not do that and instead group panels on one MPPT together. If you have any shading, i tis better to have the shade in one MPPT and not the other as much as possible. Also, makes it nicer to service panels if the two MPPT sections are not intertwined. This should also reduce wiring length and losses.

For my parent's house with 3 string of 10 panels each, in a 2x 15 array, they are going to be grouped as three side by side 2x5 groups. Trying to keep all panels on the MPPT as close to each other as possible keeps them all performing similarly.

Mike C.
 
ThaiTaffy said:
Nothing about specifications just wanted to tell you how my wife's attitude changed.

I started with a tiny 1.6kw system just runs the fridge, my home server, lights and fans my battery is just a small deep cycle FLD that can run 2 fans some lights and the fridge/Server during a power cut I didn't want to cycle the battery so we power from the grid at night. During the day when power is free we run 10 or so fans flowing air throughout the house every day I would tell my wife we saved 70¢ today/saved 40¢today(she looked at me like I'm an idiot,TBF I am).

First monthly bill came in we saved like $14 boss was slightly impressed.

First power cut and her attitude changed to "do you think we should power the whole house with solar"

Guess I should say many wives have bad expectations for our projects but once our toys exceed expectations to their benefit they generally support us whole heartedly, atleast that's my experience.
Click to expand...
Bless wives, little children and cute furry animals - they make no sense :)
 
Another vote for the batter being indoors at a moderate temperature. Temperature cycling will age the battery faster.

While the PowerPro does have a heater, that uses energy of course, and at some point, it may be depleted and the battery freezes.

The PowerPro has double wall steel and fire suppression, plus is LFP. Highly unlikely to cause a fire. Don't transfer fear of lithium fires you see on youtube to these systems, not the same risk at all.

BTW, nobody talks about gas cars catching fire in garages yet that happens about 10 times as often as EV fires which do make the news. EVs mostly use the LiCo cells which are vastly more fire prone than LFP.

Mike C.
 
There is nothing in my mower sitting in my garage to ignite the gasoline. Heck, I had a fuel tank leak in my old weed eater and all it did was drain the tank on the floor and it evaporated (left an oily residue behind thanks to being a 2 stroke engine with the oil/gas mix).

A high voltage spark or arc is a little different. Though I'm still not really worried about that happening.
 
SparkyJJO said:
There is nothing in my mower sitting in my garage to ignite the gasoline. Heck, I had a fuel tank leak in my old weed eater and all it did was drain the tank on the floor and it evaporated (left an oily residue behind thanks to being a 2 stroke engine with the oil/gas mix).

A high voltage spark or arc is a little different. Though I'm still not really worried about that happening.
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Depending on the mower it's possible for a wiring harness to short out unless the battery is actually disconnected/shutoff installed.
 
Skip wiring of panels can reduce wire length and need for jumpers.
You can skip out, then skip back, all on a single string.

Shading, have to decide if you want one panel of each string shaded, vs. two of one. Depends on minimum MPPT voltage, etc.

If two strings in parallel, then you do prefer them shaded similarly. Although 10% to 15% difference in Vmp isn't too bad.


Not sure that LiFePO4 batteries generate much heat, charging or discharging. FET BMS to have I^2R power.
Lead-acid batteries make a lot of heat charging.
Perhaps a closely spaced insulated box, with vent fan and manual vents for season, would be the way to go. Inside weatherproof shed. Or insulated shed, which needs weatherstripping.
Just insulation panels, could simply tape shut around batteries.

The one I'm going to assemble shortly (4x 4s pre-assembled packs in series) I'm simply going to hang on a retaining wall and place corrugated roofing over/around. Mild San Jose weather, rarely freezes, so BMS low-temperature cutout could be sufficient (not sure how that will affect inverter/charger operation.)
 
We had a some neighbor kids that stored a can of gasoline in a closet that contained the natural gas water heater. One afternoon there was a small explosion, much commotion, lots of yelling, fire department on site. Luckily that house was only a block away from a fire station. I went over to help repair some of the damage a few days later.
 
Brucey said:
Depending on the mower it's possible for a wiring harness to short out unless the battery is actually disconnected/shutoff installed.
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It is a Honda push mower. The only wiring is to the spark plug, and it only is energized when the engine is running.
 
Quattrohead said:
The outdoor PP are double skinned steel and have fire suppressors, I'm thinking the indoor version is the same too.
I am more worried about parking a gas car/mower etc in the garage than my solar system.
Small note on your diagram, the ATS is not between your solar system and the grid.
Remind us again, plans/permits/inspections required or not ?
Click to expand...
Permits not required. Double-skinned steel is a great feature I didn't know about. What fire suppression system?

this forum has a bunch of fire horror stories and they all seem to start with batteries, and some lifepo fire stories are starting to make the general news, so I'm going to wait. If this battery dies in 4000 cycles instead of 8000 then I still have 10 years out of it and that is past my ROI point.

e.g. https://diysolarforum.com/threads/house-burned-down.83098/
 
mciholas said:
group panels on one MPPT together. If you have any shading, i tis better to have the shade in one MPPT and not the other as much as possible.
Click to expand...
Is this true? Maybe I'm misunderstanding. I thought it was better to have the power on MPPT1 close to the power on MPPT2?

If I put all of the shaded panels on one of the MPPTs, the power ratios will be very imbalanced?
 
Hedges said:
Shading, have to decide if you want one panel of each string shaded, vs. two of one. Depends on minimum MPPT voltage, etc.
Click to expand...
Yeah
mciholas said:
Another vote for the batter being indoors at a moderate temperature.

BTW, nobody talks about gas cars catching fire in garages yet that happens about 10 times as often as EV fires which do make the news. EVs mostly use the LiCo cells which are vastly more fire prone than LFP.
Click to expand...
I could maybe put them inside the garage, but the garage has similar temperature to the outside world. Less wind, but less sun to warm it up during the day.

Can't put them in the house right now, not even in the basement. I could build a shed and insulate/ventilate based on what season it is.

I guess we'll see what happens as far as temp goes. I don't know of a better outdoor unit, and indoor isn't an option.
 
IGBT said:
So every kwh you don't pull off the grid saves you $0.30?

At that rate, even 2kw of solar panels could save you $3 a day, $1000 a year if you can find a legit use for the power.
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That's how I ended up building my Multiplus-fastened-to-a-battery system. I realized that the stuff in my home office (internet/PCs/TV) was responsible for nearly 1/2 my power bill. Add some solar panels in the back yard and I'm now avoiding the purchase of ~120 kWh a month at 44.8 cents per kWh! No transfer switch, no wiring changes, just plug my office into the inverter. If I have too much power I can charge my plug-in hybrid car. (at 44 cents/kWh my plug-in hybrid runs cheaper on gasoline btw)
And when the power goes out, I snake an extension cord down the hall to the refrigerator. ROI? I haven't worked that out. ROI is for stuff that you don't want to buy!
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