diy solar

diy solar

Feedback and Guidance for an Off Grid sytem and battery

Peaces

New Member
Joined
Apr 26, 2023
Messages
22
Location
France
Hi guys

Before asking anything I'd like to thank everyone for all the help and information that is provided on this forum, I learned so much thanks to you all it's invaluable.


I'm building my first battery and electric system therefore I would love some guidance on my choices of equipment. I already have an idea of what to get and where but maybe there are other more fitting equipment / sellers(or manufacturers) I should go to so if you'd recommend anything else please let me know.
This is all to be built in an RV, and I'm in France which is why the inverter is 230vac.
Here's what I'd go with right now :

BATTERY

24V system ( 48V seemed too much for the size I'm going but I could get lower amperage cells instead, dunnot if it would change much ).

CELLS
LiFePo4 230/280/302ah Grade A 230ah is the minimum, I can go for more if the value is there ( should avoid EVE's 280ah I believe )
EVE - CATL - CALB I don't think any of the manufacturer is better / more reliable then the others, comes down to the reseller I assume.
I'd go with Shenzhen Luyuan Technologie with the reviews I've read.
https://szluyuan.en.alibaba.com/productgrouplist-915816602/Grade_A_lifepo4_battery.html

BMS
Jiabaida seems to be a good manufacturer, I believe having a 200a BMS won't be a problem if I don't pull more than 200ah and scale the system accordingly.
Their AP21S001 200a LiFePo4 seems to fit my needs.
https://jiabaidabms.com/products/jb...ve-balance-temp-sensor?variant=42185731080354

CABLING
Sizing for 200a being the max current out the battery to inverter, the cables should be rated for 250a minimum, so going with 95mm² or 3/0AWG right ?

FUSES
A good class T ( 200/225A would do I believe ) just after the battery before the inverter, haven't looked from where I should get it yet. CNN or ANL ( they seem very similar ) for the rest of the DC circuit.
Should I go lower on the T class since the inverter won't ever be able to draw that much ?
For my DC appliances, are fuse block like ones from blue sea better than individually fusing every appliance?

INVERTER
My primary need from AC is a computer and that's it, I really don't need a powerful inverter so I looked for the least powerful ( and expensive ) and found this 3000w 24v Inverter/Charger/MPPT from MPP. Couldn't find any review about it, but they seem to have improved in quality over the years so I think it will be good.
https://maximumsolar.online/product/pip-3024gew/

SOLAR PANELS
Haven't looked into it but I should be able to put 800W on my roof, so getting the 70v requirement of the mppt should be ok.


Other Component

BATTERY CASE Not sure where to buy those, LUYUAN are selling some so maybe from them ?
INSULATION between the cells, what material should I use ?
FUSES for the ac circuit, I can't find much information for these. Circuit breakers seem to be the way to go.
SWITCH Should I use any ? The loss in resistance makes them unappealing.


That's about it I think, I tried to keep it short but ehhh.

Thanks alot for your time and knowledge, and if you care to guide me I'd be very grateful :).
 
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Couple of issues. These panels will be laying flat on the roof? If yes, they will need substantial derating to account for the less-than-optimal angle to the sun. You might derate to 60%. That means your 800W of panels might never put out more then ~480W.

The MPP is well know for it high idle consumption. Just being left on, it will consume ~100W/hr, or 2.4kWh per 24hour period. I don't think the flat array on the roof is going to keep that inverter on, except maybe in June. Since idle consumption is one of the indicators for design quality (less=better), you might want to look into other units.

You might get better performance from going straight DC? In a RV you won't be running a well-pump.
 
Couple of issues. These panels will be laying flat on the roof? If yes, they will need substantial derating to account for the less-than-optimal angle to the sun. You might derate to 60%. That means your 800W of panels might never put out more then ~480W.

The MPP is well know for it high idle consumption. Just being left on, it will consume ~100W/hr, or 2.4kWh per 24hour period. I don't think the flat array on the roof is going to keep that inverter on, except maybe in June. Since idle consumption is one of the indicators for design quality (less=better), you might want to look into other units.

You might get better performance from going straight DC? In a RV you won't be running a well-pump.
I feel kinda dumb not thinking before to power my pc with DC current directly, so I'll look in more depth into this right now.

I plan on fixing my panels on a frame that I'll be able to lift to get a better angle, but yeah it won't be the best. I was mostly thinking about having a sufficient voltage for the mppt.

As for the inverter, I didn't find much information and was expecting a 50w/h consumption at most, and turning it off when not in use was something I'd expect to do. If it's 100w/h then it would be a guarantee. I will also look back for alternatives there.

Thanks alot for your message.
Can all-in-one units with MPPT + Inverter usually turn off the inverter but still have the MPPT on ?
I'm pretty sure it's yes but just to be sure.
 
A lot of RV'ers use Victron gear which states right on the spec sheet the no-load current draw so you know exactly how much you would use. The MPP's are also notoriously loud which might drive you crazy and something people typically don't even think to check on before purchasing. Since you use 230VAC you might look at https://www.victronenergy.com/uploa...V-48V-3kVA-48V-5kVA-MPPT-250-70-100-GX-EN.pdf
I did think about it, could have tried to change the fan for a quieter one but the off button seems more appealing.
Victron really feels expensive though I can't say it's not backed up by good performances.

I think I'm gonna look for an efficient MPPT and a low power Inverter since my use of AC is diminishing every time I think about it.
 
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Victron really feels expensive though I can't say it's not backed up by good performances.

I think I'm gonna look for an efficient MPPT and a low power Inverter since my use of AC is diminishing every time I think about them.
Take a look at Samlex. They make a quality 12V inverter that has low idle demand, and UL-listed. It's high-frequency, so you won't be running big power tools on it. But, a combination of several 12VDC appliances, and just a few 230VAC ones, might let you get by almost entirely on DC, but only turning on the AC inverter when you really need it.
 
After some research, I found how to power PCs with DC current directly and which MPPT and Inverter I'd like to go with.
I checked on Samlex and they're definitely building good inverters, but I plan on leaving it off most of the time so I won't need such one's.

I'm thinking of going with the MPPT Tracer AN 40A and probably the IPower-Plus 24v 1500W Inverter from Epever too.


I'd love to get some more insight about my choices of equipment, especially for the battery build as it's the most expensive and important so if anyone could provide me some more I'd be grateful.
 
IPower-Plus 24v 1500W Inverter from Epever too.


I'd love to get some more insight about my choices of equipment, especially for the battery build as it's the most expensive and important so if anyone could provide me some more I'd be grateful.
Looking at the specs of the inverter, there are two numbers that stand out to me. First, they list the surge current as good for 5 seconds. That's excellent. Other cheaper quality inverters might surge to 200% for only 16 milliseconds.

Secondly, the total harmonic distortion, or THD is listed as <3%. That is also very good. I've seen other inverters with a THD as high as 10%. That is really hard on electric motors.

So, the paper specs look good. Whether or not the real-world specs match the paper specs is something you'll just have to find out for yourself. Please get back to us with results. Especially focus attention on what power tools the inverter can run. Anything running on an electric motor under load will have a substantial starting surge.
 
Looking at the specs of the inverter, there are two numbers that stand out to me. First, they list the surge current as good for 5 seconds. That's excellent. Other cheaper quality inverters might surge to 200% for only 16 milliseconds.

Secondly, the total harmonic distortion, or THD is listed as <3%. That is also very good. I've seen other inverters with a THD as high as 10%. That is really hard on electric motors.

So, the paper specs look good. Whether or not the real-world specs match the paper specs is something you'll just have to find out for yourself. Please get back to us with results. Especially focus attention on what power tools the inverter can run. Anything running on an electric motor under load will have a substantial starting surge.
I will happily come back to this forum to share how my setup and individual components are working after testing them the best I can.

I may go with a different model since I found a reseller for them but the difference in price between this IP Plus being more than 2 ( or 3 times since one model is out of stock ) more costly really turns me down. The other model is "less" compatible with lithium as discussed in this thread but I don't think it will be an issue considering how little I will use it.

The total harmonic distortion is still of <3%, which I thought to be quite common but apparently not, just the surge power doesn't seem to be able to last 5s as the other model and can't go above 80% for more than 15 mins.
 
CELLS
LiFePo4 230/280/302ah Grade A 230ah is the minimum, I can go for more if the value is there ( should avoid EVE's 280ah I believe )
EVE - CATL - CALB I don't think any of the manufacturer is better / more reliable then the others, comes down to the reseller I assume.
I'd go with Shenzhen Luyuan Technologie with the reviews I've read.
https://szluyuan.en.alibaba.com/productgrouplist-915816602/Grade_A_lifepo4_battery.html

BMS
Jiabaida seems to be a good manufacturer, I believe having a 200a BMS won't be a problem if I don't pull more than 200ah and scale the system accordingly.
Their AP21S001 200a LiFePo4 seems to fit my needs.
https://jiabaidabms.com/products/jb...ve-balance-temp-sensor?variant=42185731080354
Hi everyone

I'm bumping this thread to get a bit more insight about what I'd use to create a 24V battery. Being Cells that I'd purchase from Luyuan and a BMS from Jaibaida as I wrote a bit more in depth higher.

Any help and guidance is greatly appreciated.
 
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