What kind of Solar system do I need for this? (off grid)

[MJCM]

Need your help once again

 

We are thinking of building a small 5x5 living/bed room and 3x3 bathroom "cottage / man cave" in the back of the property.

 

As it's 200 Meters away from the road and approx 140 Meters from the house we want to entirely power it with Solar! (instead of dragging 25mm2 NYY all the way there ???? )

 

It has to power the following

 

- Aircon Daikin 18k BTU Inverter (sometimes running 24/7)

- Water Pump 250 Watt inverter (only used for Shower and Toilet)

- Water heater (4.5 kw) not used much as mostly will shower in the house when it's cold

- 55" LED TV with a Media Player (NUC)

- 2 or 3 standing fans

- LED Lighting

 

I think the main question is how much battery do we need.

How many panels would that need? Need to make stands for it ????

 

TiA

[KhunLA]

Tough call, but would start with 10kws w/10kws ESS.  Probably cost about the same price as the man cave, if not more.  Tough call, as if not enough, expanding may be an issue if inverter not large enough.  Need a quality build, with 'super/Q/K' block, insulated rolled steel roof, and ceiling (37) insulation, and extended roof for some wall shading E/S/W.  Along with about 50 sqm for panels.

22 x .455w panels will get your 10kws.  May need to add another 10kws ESS if not enough.

 

AC is probably going to use 300 an hr, so 4kw overnight (12 hrs) and if a stretch of cloudy / rainy days, will be an issue, even though won't need as much, but 2 days, and you'll be empty.  If not sooner, as you don't won't to go below 20-30% of battery.

 

Will eventually pay for itself, but you may want to run a line from main house, from PEA, JIC, as back up, as you'll probably need it on long stretch of rainy season.

 

I think anyway, with quick off my head guess.

[MJCM]

Thanks @KhunLA

 

Blocks that will be used is 10CM AAC Block. Insulated (on top of the building as much as possible)

 

Place for Panels is abundant (outside of the Property) that is why my question for how many panels. Will have my BIL and his son make the stands for it! (they are good at welding)

 

What does ESS mean???

[KhunLA]

9 minutes ago, MJCM said:

What does ESS mean???

Energy storage systems (ESS) ... Battery rack back up.

They've gotten better & cheaper the past year or so.   Competition is a beautiful thing.

[BritManToo]

The battery will cost you ........ 5KWhr lipo = 25-40Kbht.

That will power your media and lighting for 8hrs.

Forget the air-con/shower heater/pump and it should work.

 

At least 6 340w Solar panels, another 20kbht.

And an off grid hybrid solar inverter another 20kbht.

 

If you want aircon, everything x3 or x4.

Edited December 14, 2021 by BritManToo

[Crossy]

All good stuff ^^^.

 

Your inverter is going to be your single biggest investment so size it correctly. Work out your maximum load and double it!

 

Panels and storage are easy to expand, your inverter less so. Even if you get a unit that can run in parallel you might not be able to get a second compatible inverter in future when you need it.

 

From the OP I'd be looking at a 10kW inverter. Go for an off-grid hybrid (see my pinned thread) so if you do have a bad run of solar you can run a looong extension lead from the house or hook up a portable generator.

 

A 330W panel will produce, on average, about 1.1 kWh of energy per day, so tot up your daily usage and add 20% for your panels.

 

Similarly for your storage, match storage to daily usage. 

 

EDIT And go and buy a propane water heater, your solar energy budget will love you for it!

[MJCM]

To run Aircon would be mandatory!!

 

So what @KhunLA is saying same cost for building the "man cave" for solar isn't that far off!!

 

So I would be in the 400k+THB x 2 range just for this? (1x 400k for building and then another 400k+ just for the solar)

 

Ps: Water heater isn't an issue as the main house has a 6kW water heater so always can take a hot water shower there, but a propane (Matsumo??) water heater will be considered!

[Crossy]

@MJCM will this be a DIY or Contractor solar system?

 

DIY will be a LOT cheaper and a zillion times more fun (if that's what floats your boat of course).

 

[MJCM]

4 minutes ago, Crossy said:

@MJCM will this be a DIY or Contractor solar system?

 

DIY will be a LOT cheaper and a zillion times more fun (if that's what floats your boat of course).

 

@Crossy

 

a 100% contractor Solar System!

 

I learn a lot from you guys here, but it's enough to ask the "difficult" questions to the contractors so they get the good equipment in, but it's not enough to judge their work.

 

Unfortunately I am not up to par to judge their work (I think i have proven that with my Solar Pump topic)

 

[Crossy]

1 minute ago, MJCM said:

a 100% contractor Solar System!

 

It really isn't rocket science. Red to red. Black to black. ???? 

 

If smoke comes out you got is less than correct!

 

[MJCM]

1 minute ago, Crossy said:

 

It really isn't rocket science. Red to red. Black to black. ???? 

 

If smoke comes out you got is less than correct!

 

DC,

 

I had my interactions with electric (electric fence (low voltage) ) and it wasn't nice so I don't want to try it with Solar!  ????

[Crossy]

Just now, MJCM said:

I had my interactions with electric (electric fence (low voltage) ) and it wasn't nice so I don't want to try it with Solar!  ????

 

Long ago I was making my way back from the Astronaut Club on RAF Rudloe Manor via the sergeant's mess at SPE Corsham when I got "caught short". I can assure you that, despite what the Mythbusters say:-

a. Electric fences are not Low Voltage and

b. A stream of urine is, most definitely, conductive.

 

I suspect that the HV energising of the tadpoles led to the creation of my eldest son, who due to a friend joking about a name to go with "Anthony" (my middle name), is now stuck with Mark Anthony!

 

[BritManToo]

6 minutes ago, MJCM said:

DC,

 

I had my interactions with electric (electric fence (low voltage) ) and it wasn't nice so I don't want to try it with Solar!  ????

Don't touch the wires and nothing can go wrong.

Replaced a 2-way light switch yesterday, too lazy to turn the fuse box off, didn't touch the hot wire.

[blackprince]

24 minutes ago, Crossy said:

@MJCM will this be a DIY or Contractor solar system?

 

DIY will be a LOT cheaper and a zillion times more fun (if that's what floats your boat of course).

 

In our case we were required to use an approved / licensed installation company.

Possibly because of the size of the system, or because of the grid-tie, or perhaps both.

 

3 minutes ago, MJCM said:

It really isn't rocket science. Red to red. Black to black. ???? 

 

If smoke comes out you got is less than correct!

 

555 I'm not an expert or even a beginner in electricity, but I do know it can kill!!

I'm ok for changing a plug, but that's about it.

[MJCM]

3 minutes ago, BritManToo said:

Don't touch the wires and nothing can go wrong.

Replaced a 2-way light switch yesterday, too lazy to turn the fuse box off, didn't touch the hot wire.

I did it many times (unintentionally) when cleaning the wires and I regretted it ever since!!

Edited December 14, 2021 by MJCM

[nobodysfriend]

Just figure out how many watts you will consume ever day .

Buy and install solar panels for at least double that amount . 12, 24 , or 48V , up to you ... Why not make a double roof with the panels on it ? You might not need aircon then . Design the place that there is a possibility of natural air circulation . Use gas for cooking or hot water . For energy storage , you can use the big truck batteries , ( 200Ah = 6500 baht , if you have an old one to exchange , the price lowers to about 4500 baht ) .

You will need tom have at least 3 of them , they last about 5 years , ( at least , mine did ) . Choose the inverter that suits your system , plenty available on Lazada ...

Edited December 15, 2021 by nobodysfriend

[MJCM]

14 minutes ago, nobodysfriend said:

Just figure out how many watts you will consume ever day .

Buy and install solar panels for at least double that amount . 12, 24 , or 48V , up to you ... Why not make a double roof with the panels on it ? You might not need aircon then . Design the place that there is a possibility of natural air circulation . Use gas for cooking or hot water . For energy storage , you can use the big truck batteries , ( 200Ah = 6500 baht , if you have an old one to exchange , the price lowers to about 4500 baht ) .

You will need tom have at least 3 of them , they last about 5 years , ( at least , mine did ) . Choose the inverter that suits your system , plenty available on Lazada ...

Thx, but using Truck Batteries for Solar Storage, what about the Depth of Discharge with those??? I believe it's not good for them to go under a certain minimum charge.

 

What I understand is that you either need to have Gel or even better LifePo4 batteries so you can discharge them a lot more (up to 80% I believe)

 

Water heater is not an issue (can do without it) but AIrcon is a Must!! I believe the 18k BTU Daikin Inverter draws maxi 2000+/- Watts! (Correct????)

Edited December 15, 2021 by MJCM

[MJCM]

So would I be far off going for a quote of 10kW System and 15kW Battery with around 30 Panels. (That would be around 400K THB)

 

And this would run everything (except the Water heater (or only shower during the day when the sun is it's highest and get max yield ????)???

 

I don't think I will get approval for this from SWMBO ????

[nobodysfriend]

36 minutes ago, MJCM said:

Thx, but using Truck Batteries for Solar Storage, what about the Depth of Discharge with those??? I believe it's not good for them to go under a certain minimum charge.

It is the solar charger ( best is PWM ) , that cuts the batteries off automatically when the voltage drops under 10V or so ... Mine , normal lead acid batteries , do their job for about 5 yrs now . Recently had to replace one because it turned hot .

Aircon will make the price for everything ( charger , inverter , batteries , panels , ) go up a lot ... up to you .

Edited December 15, 2021 by nobodysfriend

[MJCM]

1 hour ago, nobodysfriend said:

It is the solar charger ( best is PWM ) , that cuts the batteries off automatically when the voltage drops under 10V or so ... Mine , normal lead acid batteries , do their job for about 5 yrs now . Recently had to replace one because it turned hot .

Aircon will make the price for everything ( charger , inverter , batteries , panels , ) go up a lot ... up to you .

Thx, but where we intend to build it there is NO Shade yet. Before the trees that we planted there provide enough shade we are 1-2 years away, so Aircon is absolutely necessary! I think I will abandon the idea about having Solar there (don't even want to discuss this with SWMBO ???? ) and just get 25mm² NYY from the house to the build.

 

We already asked the PEA for an extra power meter, but they told us (unfortunately) only 1 electric meter per house book/chanote, but we could go from our current 15/45 meter to 30/100!

[JBChiangRai]

In terms of value for money, I wouldn’t even consider solar for your requirements, bite the bullet and install that 240m cable. 

[sungod]

8 minutes ago, JBChiangRai said:

In terms of value for money, I wouldn’t even consider solar for your requirements, bite the bullet and install that 240m cable. 

Nah, its fun the give the finger from your air con man cave in the height of summer during a black out.

[MJCM]

4 hours ago, HardyM said:

You may consider consulting a professional solar PV system contracto, with their vast experience in setting up solar PV systems, they can give you a tip regarding solar panel weight per square meter and the cost. Moreover, they will help you determine solar panel weight per watt so that you can make the most out of your new solar panels.

I would have definitely used a professional Solar Installer (I even got a PM from one here if he could give me a quote). But I have already abandoned the idea, 400K THB just for the solar, it is just (at the moment) not worth it. I thought it would be around 150-200k but for that price it seems I even can't run the air con. ????

 

Room for the Panels is more then plenty. They would not be on top of the building but outside in a Field that is not even used.

[Acharn]

On 12/14/2021 at 3:16 PM, KhunLA said:

<snip> ... and extended roof for some wall shading E/S/W.  Along with about 50 sqm for panels. <snip>

Don't forget that we're south of the Tropic of Cancer, so during the summer months the sun's path through the sky is to the north. In fact, with the solstice approaching, I just noticed the other day how far to the south the sun is rising now, compared to when we moved in in May. I know in the States a lot of architectural rules of thumb are based on the rule that the sun always is to the south. Things are a little more complicated here.

[JBChiangRai]

21 hours ago, sungod said:

Nah, its fun the give the finger from your air con man cave in the height of summer during a black out.

And I agree, that can often be the best reason for installing solar power.

 

I have PEA power supplied on my own underground copper cable.  54 PV panels connected to 3 grid-tied 6Kw inverters using the grid as a gigantic battery, and also 3 hybrid 5.5Kw inverters with 28KwHr of LiFePo4 batteries configured as a whole house UPS and a 15KVA AVR.  I designed it myself, all in all about 500k THB, but we are immune from power cuts, run 13 a/c units 24/7 and charge my BEV car for free.  ROI is between 4-5 years based on our consumption which is enormous.

 

If I didn't have solar power, I would use about a quarter of the power we currently use, but it is nice to have the entire house maintained at 27C, even my garage is air conditioned to keep the car cool when charging.