The Alternative Energy Thread - Generators, Solar, UPS, Wind

[mgalaxy3]

Looks nice!
Do try to keep the batteries cool.. life of lithium batteries reduced by half at around 35-40C temps.

[mrdeejay]

Consulted a few friends with electrical engineering backgrounds. Decided to stick to LV batteries for this project.

Why?

[AkbarGr8]

Yup. Will have exhaust fans in the custom case + exhaust / ventilation in the room.

[AkbarGr8]

Overall reliability of the system, having 3 LV batteries instead of 1 or 2 HV, battery replacement cost if needed are a few points that come to mind.

[mrdeejay]

I was thinking more along the line of safety. But we all have solar panels that also operates at 500VDC, so I guess that risk is always there. With HV batteries if you use proper conduit so that all wires are securely covered, and equipment is properly grounded, then that should make it safe enough. As to the cost of batteries, HV are a little more expensive than LV ones.

With your LV setup, have you tried running house/load on battery alone? I'm curious how much fan noise does inverter make when battery is charging or discharging at 3+ KW? I've heard that HV inverter makes less noise because its working with lower currents vs LV inverter which has to push more current.

[mgalaxy3]

It makes little sense to get an HV system for small to medium systems. Safety risk is one factor (which is not followed in Pak at all), there are major issues with high cost as well as extremely limited support and equipment choice in terms of inverters as well as batteries.

Not only in Pakistan but globally too, most residential systems are low voltage (48v-51.12v) . HV are not that common.

If I was installing a 50kw+ hybrid/off grid setup I might consider getting an HV inverter and batteries . At that size it would probably benefit from less wire thickness requirement specially for batteries.

[mgalaxy3]

@AkbarGr8 all good, but ventilation alone will not bring down ambient or battery temperature..
Remember all lithium batteries are rated for their lifecycles at 25C and 0.2c to 0.5c rates depending on claimed spec.

At 35c it starts getting to significantly reduce life and at 40C or above life is reduced to almost half.

6000 cycles battery will not give 6k cycles if kept at 35-40c is what I mean.. somewhere around 3000-3500 cycles. If the aim is to keep them for a long time beyond 8 years.

[AkbarGr8]

I have an Inverex 8kw at home. The fan runs due to the hot weather / load when above 3kw. Inverter itself doesn't have any sound.

Entire house load runs fine. Just have to make sure your load is within battery discharge limits if completely on battery / dc wiring used for battery to inverter needs to be capable of handling the load.

[AkbarGr8]

This is correct. 8 years life is totally fine. Probably the inverter will require replacement by then as well.

Having exhaust / ventilation are the least possible steps that one can take to increase battery life, albeit how much this helps is totally debatable.

[mrdeejay]

The fan runs due to the hot weather / load when above 3kw. Inverter itself doesn't have any sound.

You said inverter itself doesn't have any sound so then which fan comes on? did you mean that inverter fan comes on but its very quiet? If yes, can you please install dB app on your phone and share a screenshot when fan is running. I want to get an idea of sound levels as I'm planning on getting nitrox 12kw.

With my current/really old InfiniSolar I've noticed that its fans get really loud when its producing around 10kw from PV, or when its discharging battery at over 3kw.

[AkbarGr8]

I mean the fans can get loud when running, the inverter itself has no noise when the fans are off.

I'm personally going to get an inverex 20kw LV next year but will be mounting it outside in a shaded area with ventilation. Batteries will most likely be inside or some other suitable location.

[mgalaxy3]

Yep try to place them in an air conditioned space if possible

[AkbarGr8]

Here's a final view of the battery case. MashaAllah project was a huge success and everything is running great.

[mgalaxy3]

Looking good.
What materials you used to build it? And what metal

[AkbarGr8]

I got it fabricated from a guy who specialises in building dbs for homes who has recently ventured into battery case shell manufacturing.

Gave dimensions and expected weight bearing capacity along with a sample photo of my vision.

Turned out better than I expected. Just this case with transport was 65K.

[mrdeejay]

I mean the fans can get loud when running,

When the fans are loud, can you please record noise level using decibel app and share the screenshot?

[AkbarGr8]

(post withdrawn by author, will be automatically deleted in 24 hours unless flagged)

[mrdeejay]

Thank you!! That doesn't sound too loud though, maybe its just the video.

[AkbarGr8]

Possibly! It is louder than the video for sure. Lol

[mrdeejay]

That's why I was asking to do a download "Decibel X" app and use that to record sound level - 6-10" away from the inverter. It also has the option to record frequency chart, so you can tell what's the loudest frequency.