Here's a follow on question:  What should a buyer not skimp on, in case I decide later that I need more power than I expected?  For example, is a 10K inverter twice as expensive as a 5K, or would it be a good idea to pony up for the 10K inverter up front on the chance that I may be adding more solar panels later?  Similar question with the DIN (breaker) box...

 

(Especially if I wanted to ease into solar on a constrained budget and add on as money rolls in...  And I may add an EV charger and a swimming pool and... and...)

 

 

 

8 minutes ago, KhunLA said:

That's some silly prices, and from what I read Huawei is proprietary (inverter & battery)

 

I think the 2 ACs will easily take you pass 10kWh overnight.

 

Ours ESS cost 90k for first 10kWh, with original install, & 95k for the second.  Now we can get 15kWh for 65k, same brand.

 

https://aseannow.com/topic/1268214-solar-8kw-hybrid-inverter-w10kwh-upgraded-to-20kwh-in-sept-2022-essbattery-not-diy/

 

Just checking, my wife said we used a total of 535 units last month so estimate 600 at max. What do we need? Sometimes we run 3 aircons at night if we have visitors. 

27 minutes ago, Hummin said:

Just checking, my wife said we used a total of 535 units last month so estimate 600 at max. What do we need? Sometimes we run 3 aircons at night if we have visitors. 

 

 June is terrible to base it, even May.  March & April  will be your heavy use months.  If still having the bill, should have 6 month history on the bottom of it.

 

2025:

Mar / 757

Apr / 700

May / 577 (out of town 5 nights)

June / 493 (out of town 5 nights)

 

Last year/2024 Apr & May high months, June was lowest.

 

 

2023

 

 

31 minutes ago, impulse said:

Here's a follow on question:  What should a buyer not skimp on, in case I decide later that I need more power than I expected?  For example, is a 10K inverter twice as expensive as a 5K, or would it be a good idea to pony up for the 10K inverter up front on the chance that I may be adding more solar panels later?  Similar question with the DIN (breaker) box...

 

(Especially if I wanted to ease into solar on a constrained budget and add on as money rolls in...  And I may add an EV charger and a swimming pool and... and...)

 

Would prioritize inverter and panels, as that's doing the production.  Easy to add batteries if you find out you need more.

From what I can see, 20kwh a day is reasonable to build a system with back up, and to me it seems 10kw system and 10w battery back up will be enough, or I'm wrong? 

 

I will sit down and study it more properly I just need to get hold of the basics first.

 

 

13 minutes ago, Hummin said:

From what I can see, 20kwh a day is reasonable to build a system with back up, and to me it seems 10kw system and 10w battery back up will be enough, or I'm wrong? 

 

I will sit down and study it more properly I just need to get hold of the basics first

You really need to know your usage, Feb, Mar, Apr & May.

 

I edit my above post with what we used 2023 / 24 / 25

 

Our 8kW inverter will produce 50kwh a day, if sun cooperating.  As did that one day, and it was even partly cloudy (not overcast), then there are days, just topping up battery before sunset.  At least one day, failed to top up.

 

Our lowest production day when home, was 8.2kWh, and didn't topped up battery before sunset.

 

https://aseannow.com/topic/1268214-solar-8kw-hybrid-inverter-w10kwh-upgraded-to-20kwh-in-sept-2022-essbattery-not-diy/page/4/#findComment-17734118

 

 

12 minutes ago, Hummin said:

From what I can see, 20kwh a day is reasonable to build a system with back up, and to me it seems 10kw system and 10w battery back up will be enough, or I'm wrong? 

 

I will sit down and study it more properly I just need to get hold of the basics first.

 

 

You're wrong,

I'd want a 300ah 15unit battery minimum, about 50kbht on a 6kw inverter 10kbht for the bedroom air con unit and upstairs electricity.

And another battery, with 6kw or 10kw inverter for the downstairs air con and electricity.

I'd leave any shower heaters on the grid.

9x 580w mono type bifacial panels (20kbht) on each inverter.

 

Total around 170kbht

 

 

 

4 minutes ago, BritManToo said:

You're wrong,

I'd want a 300ah 15unit battery minimum, about 50kbht on a 6kw inverter 10kbht for the bedroom air con unit and upstairs electricity.

And another battery, with 6kw or 10kw inverter for the downstairs air con and electricity.

I'd leave any shower heaters on the grid.

9x 580w mono type bifacial panels (20kbht) on each inverter.

 

Total around 170kbht

 

 

 

Thanks,

5 hours ago, UWEB said:

Yes I have read the OP comment, but if he is using the AC's at night time only a Solar System will not reduce his Power Bill significantly.

What? Systems reverse your meter during generation and draw during the evening… it’s a credit / debit system! 

 

5 hours ago, KhunLA said:

What's your highest use (kWh) bill, and will probably be April.   Should be on the bottom of your current bill. and size the system to produce at least that a much.  March April,  most use of kWh.   

 

370k for on grid, is way too much.  Especially since it probably doesn't have a battery.  How's your grid, do you have brown out, or cut offs.  Half decent steady current.  You may want an ESS.

 

Are you home all day, and how much use at night ?  As ESS (battery) is a big part of the cost, and some folks may not even need.   Which ever, get a hybrid inverter, and you can add one later if wanting.

 

If you decide on 10kW inverter, then consider two 5kW inverter, for redundancy.   Something I wish we did, instead of our 8kW inverter.   

 

Where are you located ?   Electric use over night, is minimal for us.  About 7kWh (w/ 1 AC on), so all of ~325 baht X 30 days = 10k baht against the cost of battery and ROI.   You can always add one later.

 

If in N or NE with cooler nights, you don't need AC for a few months at night or some days, if cost is an issue.

Don’t you get generation credit during the daytime and debit use in the evening? If your system is sized for your peak season then it’s generating credit the other 9 months. It trues up…. Correct? Is Thailand different than other places? 

8 minutes ago, Mo Sawadee said:

What? Systems reverse your meter during generation and draw during the evening… it’s a credit / debit system! 

 

Don’t you get generation credit during the daytime and debit use in the evening? If your system is sized for your peak season then it’s generating credit the other 9 months. It trues up…. Correct? Is Thailand different than other places? 

You're betting the PEA won't notice, if they do, they'll fit a digital meter and might even add your generated electricity to your bill.

Sure, you can get away with winding a meter back for a while, but best not to bet on it.

2 hours ago, Yellowtail said:

I don't think it's critical this close to the equator, I think it's only a couple degree variation through the year. 

 

 

 

It varies way more than that from summer to winter.

 

I believe the difference in sun angle (altitude) during one year is the same no matter where in the world you are at +/- 23.45 degrees from the equinox elevation at that location. The difference in sun angle during one year is due to the tilt of the Earth, and we all live on the same earth. 

38 minutes ago, Mo Sawadee said:

What? Systems reverse your meter during generation and draw during the evening… it’s a credit / debit system! 

 

Don’t you get generation credit during the daytime and debit use in the evening? If your system is sized for your peak season then it’s generating credit the other 9 months. It trues up…. Correct? Is Thailand different than other places? 

Reversing your Meter is illegal, if PEA becomes aware you will have your Meter changed to a digital one next day.

31 minutes ago, BritManToo said:

You're betting the PEA won't notice, if they do, they'll fit a digital meter and might even add your generated electricity to your bill.

Sure, you can get away with winding a meter back for a while, but best not to bet on it.

Do you have a diverter where connected to the grid, your system is isolated and when connected to the solar system, grid is off? 

 

What kind of official bureaucracy is necessary to get it approved in Thailand, and is it the same everywhere 

16 minutes ago, Sophon said:

 

It varies way more than that from summer to winter.

 

I believe the difference in sun angle (altitude) during one year is the same no matter where in the world you are at +/- 23.45 degrees from the equinox elevation at that location. The difference in sun angle during one year is due to the tilt of the Earth, and we all live on the same earth. 

So, what is the equinox elevation of Bangkok?

Ok, your current yearly electric bill is 36k a year

Example: Solar install with battery approx 200k

How much would your yearly electric bill be after solar install? 

 

 

3 hours ago, Hummin said:

Do you have a diverter where connected to the grid, your system is isolated and when connected to the solar system, grid is off? 

 

What kind of official bureaucracy is necessary to get it approved in Thailand, and is it the same everywhere 

 

Your hybrid inverter will decide (per your settings), where you use from, and where your solar goes.

 

Ours is set ...

... use solar first

... then battery

... if battery @ 30%, then use grid

... DO NOT EXPORT TO GRID

 

3 hours ago, Furioso said:

Ok, your current yearly electric bill is 36k a year

Example: Solar install with battery approx 200k

How much would your yearly electric bill be after solar install? 

All things being equal, that would be ~648kWh a month,

for a ฿3k monthly bill (฿3003.42), or 7.776MWh

 

Coincidentally, is about what we produced / consumed in 2023

To do that, we needed a 8kW inverter & 10kWh ESS, and you'll be basically off grid, with almost NO electric bill.   You could probably easily DIY for 200k, though good luck getting it installed for 200k.

 

1 minute ago, KhunLA said:

 

All things being equal, that would be ~648kWh a month,

for a ฿3k monthly bill (฿3003.42), or 7.776MWh

 

Coincidentally, is about what we produced / consumed in 2023

To do that, we needed a 8kW inverter & 10kWh ESS, and you'll be basically off grid, with almost NO electric bill.   You could probably easily DIY for 200k, though good luck getting it installed for 200k.

Thank you.

 

 

1 minute ago, Hummin said:

Thank you.

I edited that post, as forgot to answer your query, now answered, I hope.

18 hours ago, KhunLA said:

700 kWh in May, did rainy season start late up there. 

Nope, the rains actually seemed to start earlier than normal this year, but it was hot.  We were getting thundershowers moving through on otherwise sunny days.  Now we have that sort of all-day overcast which is typical of rainy season and its cooled perceptibly since June.

18 hours ago, KhunLA said:

700 kWh in May, did rainy season start late up there.   We used ~650 and we have BEV.  Actually used 577, but out of town for 5 days, so added 15%.   Out of town, also means car came back at 20%.  So that's 35kWh to the car.

 

Unless not in the budget, I'd go 10kW of inverter & 10kWh of ESS, and that should put you 'off grid', as we are, and we use more than you.  If home, March & April can be 1000 kWh months.  We do abuse the AC during the day, and have the BEVs.

 

At least 10kWh of inverter, 5kWh of battery.  Can always add another battery later.   We did, but just for longevity of life, not because we needed over night.  Hindsight, we shouldn't have, as 2 yrs later and the prices dropped quite a bit.  We could have added 15kWh of ESS instead of 10kWh, for much less.

 

I would go heavy on inverter (10 or two 5s) & max out the panels, and worry about how much battery later.   5 might be enough, or you might want 10kWh, after a while.  But definitely a hybrid inverter (s).

 

Our house is well built, insulated block, insulated roof & ceiling, minimal wall exposure to sun.

Question:

I assume your system is still hooked to the grid so that if you have maxed out your power (think on a Hot Season day running both A/Cs all day) and you need to draw off the grid.  Is the the way to go and doable?  And yeah, I'm looking to do this on a budget.  My goal is to 1) offset my electricity bill, and during the rainy season when we have most of our PEA outages to have full electric to the house when the PEA power goes out.

Acronyms?  I don't know what BEV and ESS are.  Could you explain.  Thanks!  

18 hours ago, KhunLA said:

Our house is well built, insulated block, insulated roof & ceiling, minimal wall exposure to sun.

Ours is too.  We rewired the house about 6 years ago. Put insulation into the roofs, we have external sunscreen blocking the sun from hitting the south facing walls.  I renovated an existing home so the insulated block would have been a grand idea had I built new. Replaced all the windows with high quality double glass sliding windows and we keep the two kitchens (Yep! we have two kitchens, main kitchen and dining areas with another sink. Wife likes to cook, so do I for that matter) separated from the main house using sliding glass doors which traps any kitchen heat.  The house much cooler during the Hot Season and warmer during the Cool Season (it gets downright cold here in January at which time I'll run a free standing heater in the bedroom/study). 

20 minutes ago, connda said:

Question:

I assume your system is still hooked to the grid so that if you have maxed out your power (think on a Hot Season day running both A/Cs all day) and you need to draw off the grid.  Is the the way to go and doable?  And yeah, I'm looking to do this on a budget.  My goal is to 1) offset my electricity bill, and during the rainy season when we have most of our PEA outages to have full electric to the house when the PEA power goes out.

Acronyms?  I don't know what BEV and ESS are.  Could you explain.  Thanks!  

Only hooked up to the grid for, JIC, inverter craps out.  Mere 30 ish baht a month, would be silly not to.  If we had two 5kW inverters instead of an 8kW inverter, then I might cancel PEA.  Redundancy is nice, as pointed out, as our one ESS needed repair, and at the shop now, under warranty.  Or we'd be using the grid at night.   So two ESS, along with 2 inverters, in parallel is better than one of either.

 

Also re-enforced the idea that 2nd ESS wasn't needed, as we got just for longevity purposes.   Wife being 22 yrs younger, didn't want her to deal with anything in the future.  Hindsight, wasn't the best economical decision.

 

Only thing on the grid, is the MG wall charging cable, @ 7.4kWh, would be too much for solar.  Has it's own dedicated line, and bypasses the inverter.  We rarely use it though.

 

ESS .. battery for solar (energy storage system)

BEV .. full electric (Battery) EV, non hybrid

17 hours ago, KhunLA said:

You really need to know your usage, Feb, Mar, Apr & May.

Here we go:

Jan:  372
Feb:  385
Mar:  512
Apr:  585
May: 704
Jun: 621

Interesting.  I wonder why we are drawing so much in the last two months?  I let the wife take care of the bill so I've never noticed that?  Hummm?

1 hour ago, connda said:

Here we go:

Jan:  372
Feb:  385
Mar:  512
Apr:  585
May: 704
Jun: 621

Interesting.  I wonder why we are drawing so much in the last two months?  I let the wife take care of the bill so I've never noticed that?  Hummm?

That's definitely different from us.  As we peak  April & May, except this year, as rains came before Songhkram and stayed steady.

15 minutes ago, KhunLA said:

That's definitely different from us.  As we peak  April & May, except this year, as rains came before Songhkram and stayed steady.

It's almost like the weather is different up north. 

50 minutes ago, Yellowtail said:

It's almost like the weather is different up north. 

Imagine that.   I remember me posting, April, happy the rained knocked down the remaining smog, but a couple CM folks were still complaining, waiting and commenting, 'we could use some of that up here'.

13 minutes ago, KhunLA said:

Imagine that.   I remember me posting, April, happy the rained knocked down the remaining smog, but a couple CM folks were still complaining, waiting and commenting, 'we could use some of that up here'.

Why would they want more smog up there? 

64,000

 

6.2kw

 

Listed as saving 3,000 per month. Which is about right for modest homes that don't have pool pumps electric cars etc

 

https://www.lazada.co.th/products/on-off-grid-hybrid-inverter-6200-nm-eco-62kw-550w-10-i5184472859-s22012340021.html?

 

 

Huawei 3 phase 5kw 10 year warranty

 

121,000

 

https://www.lazada.co.th/products/huawei-5k-3phase-sun-2000-5ktl-m13p550w-10-i5261573174-s22361988282.html?

On 7/6/2025 at 5:47 PM, Hummin said:

I will sit down and study it more properly I just need to get hold of the basics first.

Read your meter twice or thrice a day. 8am, 4pm  and optionally midnight for week and you will know your energy usage during daytime and nighttime. I don't want to guesstimate what you need since I don't know how power efficient your  aircons are, nor do I know how well isolated your house is or which temperature you have set the aircons to.

 

1 hour ago, Packer said:

64,000 ... 6.2kw ... Listed as saving 3,000 per month. Which is about right for modest homes that don't have pool pumps electric cars etc

 

such ads should always be viewed with caution, as most of the numbers are not realistic or because they depend on many factors ...

 

for example, if someone is currently paying 4k for electricity mainly because the aircons run at night, a solar system without a battery will only reduce power consumption during the hours when the system is producing electricity (daytime sun hours) ... so the promised 3k savings per month would likely turn out to be a disappointment ... 

 

to get the promised saving of 3k per month, you would have to use every kwh exactly at the same time it is produced ...
which is only possible if the solar system is heavily undersized ... but that wouldn’t make any sense!

4 minutes ago, motdaeng said:

for example, if someone is currently paying 4k for electricity mainly because the aircons run at night, a solar system without a battery will only reduce power consumption during the hours when the system is producing electricity (daytime sun hours) ... so the promised 3k savings per month would likely turn out to be a disappointment ... 

 

They could run the aircons all day for free, then the house is so cool by sundown that the nighttime aircons only use 1,000 per month, saving the 3,000. 🙂