Educated guess for off-grid system

[Excel]

Planning my final project and this time, apart from being extremely efficiently insulated I am considering a totally off grid solar power supply. We have the land at the back for the panels so no issue with space.  To run the a/c 24/7 together with all the other electrical loads my current estimate is a usage of around 6500 - 9000 units per month.  So ladies and gentlemen what would be your best guesstimates for a reliable, high quality totally automated off-grid installation for that power requirement ? Number of panels, batteries and battery types would be of interest to know the best available in terms of longevity and minimal maintenance. Is it unreasonable to anticipate a battery life of 10 years ?  I have done some elementary sums and system doodling and it gets me to around 2.8 million baht - How far out am I do you think ? Hopefully by the time this project gets underway next year panel prices will have reduced.

[Crossy]

Do you have an idea of your peak loading, that will determine your inverter sizing.

 

9,000 units a month is about 300 a day (that's nearly 10 times what we use), you are looking at something like 600m² of panels, say about 100kWP!!! 

 

How much autonomy will be needed (for low sun days), backup power supply (genset or is there grid nearby which could be used as backup)?

 

Definitelely LifePO4 battery technology, much safer than Li-ion.

 

With a system that size going directly to the manufacturers becomes viable.

 

 

[Excel]

1 hour ago, Crossy said:

Do you have an idea of your peak loading, that will determine your inverter sizing.

 

9,000 units a month is about 300 a day (that's nearly 10 times what we use), you are looking at something like 600m² of panels, say about 100kWP!!! 

 

How much autonomy will be needed (for low sun days), backup power supply (genset or is there grid nearby which could be used as backup)?

 

Definitelely LifePO4 battery technology, much safer than Li-ion.

 

With a system that size going directly to the manufacturers becomes viable.

 

 

Well guess peak loading will be when all a/c is running together on start-up with ovens etc. So as I anticipate the combined total of the a/c units ( max ) will be around 30 - 40 Kw at start-up then with the rest guess it could be in the region of 45 kw peak load. As for autonomy that is needed to be 100%. I want a totally independent system although a genset will be installed for emergency use during routine maintenance etc. My original guestimate considered panels with an average efficiency of 25% of quoted output. The reason for this was to consider for times with less than bright sunshine, times prior to panel cleaning when they are dusty and general de-rating over time. Panel cleaning will not be an issue as I intend to install at ground level on our land, well on a raised structure naturally. This will also allow ambient cooling airflow over the panels.

Now with respect to the  LifePO4 batteries you mentioned what is the generally considered lifespan of them ? Also I shall want sufficient battery capacity for 72 hours of non charging for periods where there are days of no sun etc. or other considerations.

What I haven't considered until this reply is what the hell happens when the loading requirement is lower bound for the property and it is a bright sunny day and producing oodles of electricity !!!  Now, there will be no connection to the grid so how is that controlled ?

[Crossy]

Don't worry about excess production when there's low load, once the batteries are full the charge control system will simply shut down, the panel output just goes to zero (lots of volts but no amps), they are quite happy in this state.

 

72 hours autonomy @ 300kWh per day is 900kWh of battery! That's about 66 x 13kWh Tesla PowerWalls.

 

Just the batteries will blow your 2.5MBaht budget ???? 

 

100kWP of panels at current prices would be say 500kBhat.

 

45kW worth of off-grid inverters say 200kBaht (you are going to need a bunch of additional charge controllers too).

 

Say another 400kBaht for mounting hardware, cable, surge suppressors etc etc.

 

Then double the number for a contractor install, say 2.5MB WITHOUT the batteries.

 

You probably need to talk to an industrial installer.

 

I'm assuming this isn't a home, maybe a resort?

[Excel]

1 hour ago, Crossy said:

Don't worry about excess production when there's low load, once the batteries are full the charge control system will simply shut down, the panel output just goes to zero (lots of volts but no amps), they are quite happy in this state.

 

72 hours autonomy @ 300kWh per day is 900kWh of battery! That's about 66 x 13kWh Tesla PowerWalls.

 

Just the batteries will blow your 2.5MBaht budget ???? 

 

100kWP of panels at current prices would be say 500kBhat.

 

45kW worth of off-grid inverters say 200kBaht (you are going to need a bunch of additional charge controllers too).

 

Say another 400kBaht for mounting hardware, cable, surge suppressors etc etc.

 

Then double the number for a contractor install, say 2.5MB WITHOUT the batteries.

 

You probably need to talk to an industrial installer.

 

I'm assuming this isn't a home, maybe a resort?

Many thanks for that Crossy.Actually the budget is not an issue, the 2.8 million was only my initial estimate. Good info. I googled for solar installers but to me they hardly seem industrially minded !! In fact I hope their installations are better than their websites.  Are you aware of any good industrial installers here or could give   me an insight as to where to look ?

Edited March 20, 2022 by Excel

[cantdrive55]

On 3/20/2022 at 12:32 PM, Excel said:

Many thanks for that Crossy.Actually the budget is not an issue, the 2.8 million was only my initial estimate. Good info. I googled for solar installers but to me they hardly seem industrially minded !! In fact I hope their installations are better than their websites.  Are you aware of any good industrial installers here or could give   me an insight as to where to look ?

I just happened to be looking for something similiar as yourself, but on a bit of a smaller scale.  When checking various links from other threads, I came across MPP Solar and one of their projects was in Thailand.  They said they worked with this company.  https://www.aero-engineering.net/solar-pv  Looking at their website, they might be a good option to contact.

[Excel]

38 minutes ago, cantdrive55 said:

I just happened to be looking for something similiar as yourself, but on a bit of a smaller scale.  When checking various links from other threads, I came across MPP Solar and one of their projects was in Thailand.  They said they worked with this company.  https://www.aero-engineering.net/solar-pv  Looking at their website, they might be a good option to contact.

Many thanks for that. Looking at their site it does appear that they are capable. I shall contact them soon. Thanks again

[cantdrive55]

On 3/22/2022 at 2:22 PM, Excel said:

Many thanks for that. Looking at their site it does appear that they are capable. I shall contact them soon. Thanks again

As a follow up, I contact MPP in Taiwan and they said that Aero is their distributor here, so they informed me that Aero would get back to me with a quote.

 

[sezze]

I continuous ask myself why people with industrial plans are asking "us noobs" . A 300kW per day use ... thats 15kW/h 24/7 ... that ain't just a project , that is something needing serious supervision , planning , industrial scale . Even just a generator generating that amount will cost you some serious money . If you are talking a multi million Baht investment , do not ask us , who order from Lazada/Shopee/Ali . The dealers there cannot follow up on these kind of orders , it simply is a different scale . I do not mean to be bad , but ask yourself what are you planning to do . We are talking about powering homes , with less then 30kWh daily , often 10-20 . This is a different scale , requiring much more funds , parts , planning ... just different .

[Excel]

2 minutes ago, sezze said:

I continuous ask myself why people with industrial plans are asking "us noobs" . A 300kW per day use ... thats 15kW/h 24/7 ... that ain't just a project , that is something needing serious supervision , planning , industrial scale . Even just a generator generating that amount will cost you some serious money . If you are talking a multi million Baht investment , do not ask us , who order from Lazada/Shopee/Ali . The dealers there cannot follow up on these kind of orders , it simply is a different scale . I do not mean to be bad , but ask yourself what are you planning to do . We are talking about powering homes , with less then 30kWh daily , often 10-20 . This is a different scale , requiring much more funds , parts , planning ... just different .

I posed the question for those with knowledge and certainly there are one or two professional engineers on here with exactly that. If you have no interest in the subject then please don't spoil the thread with your pointless and irrelevant comments as you have no idea of the project I am planning.

[sezze]

6 minutes ago, Excel said:

I posed the question for those with knowledge and certainly there are one or two professional engineers on here with exactly that. If you have no interest in the subject then please don't spoil the thread with your pointless and irrelevant comments as you have no idea of the project I am planning.

OK then , a quick quote ...

300kWh per day :

75kWp of solar minimum @ 10 baht/W , at least 750k

inverters ... tricky since idk how you want it , but lets just say low budget 5000W inverters ( and they are not the ones you need but ok ...) @20k per piece :

10 of them might do it ... but like i said , unknown how and what ... so

200k

Batteries ... imagining lot of power to be used at night , 3/4th out of it , since aircons .... meaning 220kWh used at night . 250kWh of batteries might do it ... euhhmmm let me think . 10kW for 50k so ...

1.25 million .

no installation , no planning , no mounting things , no fuseboxes or anything like that ...

2.2million . I'd rather say at least 3 million needed and since the batteries are the big cost , i would count in a 10% change per year , so another 125k per year of replacing batteries .

[Excel]

1 hour ago, sezze said:

OK then , a quick quote ...

300kWh per day :

75kWp of solar minimum @ 10 baht/W , at least 750k

inverters ... tricky since idk how you want it , but lets just say low budget 5000W inverters ( and they are not the ones you need but ok ...) @20k per piece :

10 of them might do it ... but like i said , unknown how and what ... so

200k

Batteries ... imagining lot of power to be used at night , 3/4th out of it , since aircons .... meaning 220kWh used at night . 250kWh of batteries might do it ... euhhmmm let me think . 10kW for 50k so ...

1.25 million .

no installation , no planning , no mounting things , no fuseboxes or anything like that ...

2.2million . I'd rather say at least 3 million needed and since the batteries are the big cost , i would count in a 10% change per year , so another 125k per year of replacing batteries .

On a 70 - 100 million baht project I can assure you the aim is for a professional installation, not an amateurish cheap Charlie affair.  Anyway installation leads have already been pm'd to me so thanks to all others who contributed positively.

[tjo o tjim]

One thing you need to establish for yourself is the cost of downtime or level of acceptable downtime.  You likely want to size the system to accommodate 95-99% of your annual consumption days-- you will have days and weeks that being off-grid is not going to be cost effective with batteries and solar alone.  A backup generator is the easiest approach, along with some provisions for load shedding.