Here's one for you lads

[malcolmsanford]

[TABLE="width: 598"]
[TR]
[TD]1. 24k BTU Split type Aircon – 12.2Amp, 2,730Watts
[/TD]
[TD]Watt[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]2. UPS 10KVA 3Phase 230V[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]3. Motion Sensor and Access Control[/TD]
[TD]20[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]4. Fire Alarm/Siren[/TD]
[TD]30[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]5. Lights (8pcs)[/TD]
[TD]144[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]6. Emergency lights[/TD]
[TD]500[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]7. Client Equipment[/TD]
[TD]300[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]8. Electrical Outlet – 6 pcs[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]TOTAL LOAD[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[/TABLE]

We have been tasked by a client over here to design a PV system for several remote sights over here that will be used for Antenna Masts. So I'm dealing with Americans which is always bad news.

So I have been sent the above specs from them and going over it seems quite straight forward. I have recommended that instead of the 24,000 BTU unit for a cubicle the size of which is Approximate dimension: 5.5m x 2.5m x 2.5m, so a little excessive, that we utilize Evaporation cooling. As the sites are visited weekly water should not be a problem

Now the PV side on that load should be about 1.5KW so not too bad and I have sourced something like this website but it's from the States. Does any of our PV lads know an equivalent from the UK we must do one and can link me to it please


Off-Grid Photovoltaic Systems


But what is getting me is the UPS 3 phase 10KVA for what would be a single phase 1.5KW supply if they use evaporated cooling. They have accepted the cooling option but still insist on the 10kVA UPS .................no talking to some

What I would like to throw out here again to the PV lads, Because the cubicle is 24/7 obviously we will need batteries for the night/early morning. So every day for a few milli-seconds we will get a situation where there is power interruption from PV-Baterry_PV and I would imagine the UPS would want to kick in. Can you see any conflict with the inverter/charger on the PV and the inverter on the UPS. I can see some sort of conflict but can't prove it as such

 

[maffa ent]

not many replies eh!

possibly because most of us have not got a clue what you're on about with most of that! haha!

obviously quite specialized installations? if i got asked to get involved in a contract like that, i think my laptop - or my brain - would go into meltdown!

still, you've gotta learn eveything the first time you do it eh?

good luck with it mate, it sounds like it could be a good earner!

 

[Gavin A]

sorry, I didn't see this before.

tbh, I've never come across a 3 phase off grid system. After a quick web search I see they do actually exist, but I'd expect they'd be prohibitively expensive.

I'm not clear what the peak and weekly loads actaully are on the system - you need to know this before you can do anything else.

UPS - the entire system is already one giant UPS system, but presumably there's a part of it that requires back up in the case that the inverter dies. tbh, I'd seriously consider a back up generator as an option, as otherwise you're basically replicating the existing battery / inverter set up, which ain't going to be cheap, and would still need to be charged from the solar.

basically though I think this really boils down to the size of the battery bank, and inverters required to supply the peak load consituously for as long as it might be needed, as well as the maximum weekly load. The PV system then needs sizing to be able to also suppy that level of power on average across the week / month, and you need to size both with enough contingency to allow for the worst likely periods of reduced generation in winter (or potentially sand storm periods?). If you're using a generator for back up anyway, then you can then factor that in, and automate the process of the generator kicking in to recharge the batteries when the batteries fall below a certain level of charge... but then also set some sort of alarm function to ensure the generator gets topped up on the weekly visit.

that's your starter for 10, hope it helps.

 

[solarfred]

Funny I am working on solar power for a biofilter system and this is exactly the same scenario in as far as you cannot possibly afford to run out of power as the system will crash/die. A generator is a no, no for budget and aesthetic reasons so it has to be 100% solar and it has to get through the winter. Lateral thinking is a requirement and a garden full of experimental configurations is mandatory. The theory is great but I need to see it works in practice. Great thing about off grid UPS is that you can tell what capacity is available under worst likely conditions but you cannot guarantee it will work 100% (without a generator). Of course I will not get a US$ breach of contract writ but may have to restart the filter and add another panel. Good luck with that one.

 

[malcolmsanford]

Hi guys Thank you for feed back

Generator is a no go .............within a week they reckon someone will have "out-sourced" it,as you can imagine generators in remote areas are pretty handy bits of kit to have.

I have definitely got them over to evaporating cooling but there are issues with water, it's a desert after all so we are still investigating this

I'm used exactly the same argument as Gav, the PV/Batteries are in all intent and purposes a UPS system, so why spend money on another. I think the mentality is IT equipment, data equipment, must never fail = UPS. I'm slowly winning this one, as though they have not as now going to be doing away with it, the 3 phase 10kVa is going to be a single phase 2000va-3000va one. I'll win in the end and do away with it ....I hope

I've also recommended that the system have a telemetry alarm system on it, though remote it could be reached in 4-5 hours easily so we will design a system that once the battery power drops below a pre defined level, say 8 hours it will set indicate at the HQ

Thanks for all the responses lads, it is as you all say a suck it and see situation. Remarkably the link I posted, I contacted these guys and they don't do a one size fits all situation but actually do bespoke systems, so the chances are we will use them. I though just love trying to do something like this myself, better than slinging a bit of T+E in

Thanks the response lads, Once it is up and running, if I can I'll post some pictures, but it's quite sensitive and well ..........if I post them, and then go quiet send in the cavalry to rescue me

 

[maffa ent]

Hi again malcolmsandford, just read the updates to this post.

when i saw the 'thanks', i thought you were being sarky, but when i read my reply, i sort of understood why!

but honestly, when i posted the reply i was just trying to morally support you in your thought processes, and info finding. I don't mind admitting i'd be out of my depth with your job, but i will be keeping an interested eye on progress, and hope you get it all sorted.

i'll look out for the updates, and hopefully not in the obituaries! :wink_smile:

 

[malcolmsanford]

maffa ent no I hope you didn't think that I was being sarky mate, far from it, it was nice that you wished me luck and offered a reply.

It's like everything really once you have done one hopefully the 2nd on wards becomes a little easy.

So thanks again Maffa, it's a genuine one honestly mate

 

[grantr37]

I hope they have an open chequebook , I imagine they do with what its for.......you will need about $120,000USD just for the 3 phase off grid that they are demanding, and it will need maintenance at least once every 4 weeks, which makes it pointless....why not just spend $60,000 on a good generator system and put a big tank of diesel in....maintenance moves to 3 months then if using to charge Batteries...

 

[malcolmsanford]

Well as I said in my 2nd post mate diesel genny will last about a week, before it becomes a reassigned asset so they are really not going to go down that road.

The site will be visited I reckon if not weekly then at least 3 times a month. It is pretty sensitive and so it will be well looked after.

Thankfully the 3 phase UPS I have managed to get them down to a 2kva single phase unit so there is no need for any 3 phase supplies. Without the silly split A/C unit total load will be about 1200-1400 watts.

The panels I think are going to be erected half way up the mast, I'll look forward to seeing that design, as again they are worried if it was ground mounted it may walk away, but I personally doubt it.

It is a first over here and I'l sure changes will be made before it is eventually scoped. Cheers for the input.

 

[Energetic]

This might be worth a look...

Solar Battery PR | the PowerRouter

nice bit of kit that will be useful in the UK when the grid starts to die from investment starvation... They do on and off grid versions but only up to a 5kw pv array so not sure if it will be enough for you...

Sounds an interesting job, good luck with it...