Home Data Center Build - Solar Guru Guidance Needed

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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby Gordon-Loomberah » Mon Apr 09, 2018 10:27 am

If you are in the south of the country, with only 1.2kW of PV, you will only be able to use this system as your source of energy in sunny weather in winter.
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby Warpspeed » Mon Apr 09, 2018 12:10 pm

GregoInc wrote:That aligns will my calculations which is fantastic. I used a power monitor over a 24 hour period and it came in at around 2.4 kWh

Next thing would be to determine how much of that is daytime load, and how much is night time load.
Right now, daytime load would be from about 7Am to 5Pm (Melbourne daylight saving time)

Battery will obviously need to source all of your night time load, which right now will be about 14 hours. What you are proposing sounds about right.
Solar will need to cover everything day + night with something to spare even on pretty poor cloudy days.
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby Gordon-Loomberah » Mon Apr 09, 2018 12:18 pm

Warpspeed wrote:... (Melbourne daylight saving time)


eh? I thought the whole country ended daylight saving time on 1st April.
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby Warpspeed » Mon Apr 09, 2018 12:38 pm

Haha yes, you are quite right, but the times given are correct.
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby davidg » Mon Apr 09, 2018 3:00 pm

GregoInc wrote:So it's likely starting with a 48v 100Ah battery pack may be good, and I can add an additional pack later if I increase the PV capacity.


The next part is to workout is how much Solar you will really need ideally for winter in June, that determines how much PV you will ideally need to not only supply power during the day but to also recharge the batteries in the available sun time, that will cover most of the time it's actually required and how much might be enough, I think you will find you will need more PV than you have currently have a quick estimate without any calcs would be double what you have at the moment typically I' suggest you go for 3 panels in a string which would be about 9 panels or more, as an example a Midnite should cope with that config depending on the VOC of the panels, the advantage is typically the array will start supplying power earlier in the AM with this and at the end of the day as well.

It's a waste of time using an annual average for standalone because you the power is not used that way in real life with standalone systems.

For instance on occasion even with 8.2kW's I have had days where the sun has been so bad it's been less than 1kWh for the daylight period production.

With "off-grid/standalone" you must either cater for these really poor days in some way, generator or in your case buy power from the grid or increase the AH of the batteries to allow for the bad day or both and also increase the size of the array to deal with reduced long periods of production, such as clouds which are the norm rather than the exception, it's pretty common for an array to produce about 50% of it's peak output most of the time, the reason why over sizing is a popular option.
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby GregoInc » Thu Apr 12, 2018 3:16 pm

Hi David,

Thanks again for your advice/knowledge, really appreciate your experience. Right now my fallback position will be an automatic transfer over to grid power. But over time I aim to build the system to be self sufficient.

Just took a big gamble and purchased a Mitsubishi Outlander PHEV battery pack from overseas. Yep, overseas... sight unseen and untested. So I am waiting for delivery.

The pack contains 80 YUASA LEV40 cells... which I hope to integrate into my offgrid system. Basically each cell is 40Ah at 3.75 volts. So it will be 15 cells in series to make my 48 volt system.

sim.jpeg
Mitsubishi phev battery
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My wife is totally going to kick my ass if the batteries are no good :(
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby davidg » Fri Apr 13, 2018 2:30 pm

GregoInc wrote:The pack contains 80 YUASA LEV40 cells... which I hope to integrate into my offgrid system. Basically each cell is 40Ah at 3.75 volts. So it will be 15 cells in series to make my 48 volt system.


Parallel Pairs and then series them you will use 32 of them then. assume that they only have 80% of their original capacity for capacity estimates (assuming there working OK).

you will need a decent management system/s to ensure you treat them properly, although for short term testing it should be fine, about a month maybe but after that.
Last edited by davidg on Fri Apr 13, 2018 3:22 pm, edited 1 time in total.
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An OTT Genset for a house.
PVOutput Stats

Sparkys light up your life :)
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby GregoInc » Fri Apr 13, 2018 3:09 pm

davidg wrote:Parallel Pairs and then series them you will use 32 of them then.


Assume I am a complete newbie... any chance you could point me to a diagram?
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby GregoInc » Tue Apr 17, 2018 8:25 pm

I am currently looking at purchasing a Goodwe NS series PV inverter. Have done loads of research and am pretty comfortable with my choice of manufacturer.

I have a question around hooking up the solar panels to the PV inverter. From what I understand the inverter has a single pair of MC4 connectors. Therefore I assume the solar panels need to be connected in series to the inverter?

I have 4 x 300 watt panels, so I figure I connect the panels togather in series, with a single positive and negative cable running down to the PV inverter. Is that a fair assumption?

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PV Series
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Look forward to your advice.
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Re: Home Data Center Build - Solar Guru Guidance Needed

Postby Gordon-Loomberah » Tue Apr 17, 2018 8:49 pm

It wont work if this is meant to be an off-grid system, that's a grid-connect series of inverter.
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