What is a reasonable budget for a home solar panel system - any reccomendations for installers.

[Longwood50]

I am building a new home and considering adding a solar system to supplement getting power from the grid.  During the day I will have the following running:

1. 30,000 - 36,000 btu cassette air conditioning SEER in the 18 to 20 range
2. Refridgerator 19.8  new inverter model
3. A few lights all LED
4. Water pump for well and water storage tank
5. Pool pump
6. On occasion 1 to 2 ceiling fans
7. Some electric appliances including Microwave, TV, Computer, Cook Top, vaccum  
8. Every other day dishwasher inverter
9. Clothes washer every day 1-2 hours inverter model

I am not sure of the process for how to calculate the size of the system one needs.  I know it is based on BTU's but since the home is under construction, I won't have an accurate estimate until after living in the home. 

The home is a single story, with 3 phase electric service. 

What questions should I be asking.  What would be a reasonable guess as to the cost of the system. And, does someone have a good experience with an installer that they could reccomend. 
 

[motdaeng]

as nobody has responded yet, i'll give it a try. however, i only have basic knowledge about

solar systems; other forum members are the experts.

 

various projects are well-documented in this forum, and they have been very helpful in 

my decision-making process regarding a solar system!

 

for references of an installer, please provide your location.

 

why choose a 3-phase system? are there plans for future expansions? 

3-phase systems can be more expensive for both house installation and the solar installation.

 

you listed your energy consumption only for during the day. 
have you decided a hybrid system is out of question?

 

what is your goal with the solar system? do you want to reduce electricity costs only, 

or do you aim to become more or less self-sufficient?

 

how many hours do your air conditioners run per day?

only in the summer or throughout the whole year the same?

 

do you own an electric vehicle, or are you planning to buy one? 

 

how is the roof's orientation, slope, surface area?

 

since it's not a DIY project, you should also expect costs in the range of few hundred thousand thb,

even for a medium-sized system.

 

 

[KhunLA]

Are you living in a comparable size house now with the extras; pool, etc.

 

If so, simply go by your present bill and units used every month.  That's what we did, along with taking our largest bills from  previous house.

 

Our inefficient rental was running 600-700kWh a month, and our much larger previous house topped up about 1200kWh  month.  So we sized a system that would handle that.  Without the need for PEA/MEA.  Connect to, but basically off Grid.

 

New house, better build, materials & components (inverter ACs), and our usage, with abusive AC use, fits that range, 600-1000kWh a month, depending on time of year.   That's with having EVs.

Our Solar System

[Muhendis]

On 8/5/2023 at 4:46 PM, Longwood50 said:

I am not sure of the process for how to calculate the size of the system one needs.  I know it is based on BTU's but since the home is under construction, I won't have an accurate estimate until after living in the home. 

On each piece of electrical equipment there is a rating plate which tells how many watts (not BTu's which is for thermal cooling requirements) that equipment uses. This rating plate is generally out of obvious site on the side or the rear of equipment. To calculate your power consumption you need to add these wattages together but only for the equipments which are likely to be running at the same time. This will give a maximun power rewquirement.

Add 20% to this for a reasonable margine and for furure expansion. That is the output power you will need from your inverter. Solar panel power is usually limited to the maximum power input of the inverter (plus a derating factor of up to 20%).

Since you are looking to "supplement" grid power with solar, you could split your electrical instalation into grid fed and grid/solar fed.

If you want to consider battery backup, then size of the battery depends on how long you want to run for without grid power. Batteries are expensive.

 

Repeat of Motdaen's question:- Why do you want three phase power supply?

[Longwood50]

8 hours ago, Muhendis said:

Repeat of Motdaen's question:- Why do you want three phase power supply?

I am just aware that the development that I am building in provides it.  I certainly am not going to be putting in a ev charger that requires it.  

Please excuse my ignorance, if the development is providing 3 phase do I have an option to go with only single phase? 

 

[Muhendis]

1 hour ago, Longwood50 said:

I am just aware that the development that I am building in provides it.  I certainly am not going to be putting in a ev charger that requires it.  

Please excuse my ignorance, if the development is providing 3 phase do I have an option to go with only single phase? 

 

Single phase is normal. The three phase brought to the development will be a high voltage and will be fed into a transformer for low voltage (220v) single phase for distribution to the houses. 

 

You can have three phase at a price if you really want it but it will be expensive and a three phase solar instalation also very pricey. 

It all depends on power usage and in particular the horsepower ratings of any motors you may want running. Above a certain size, three phase motors are smaller and more efficient than single phase.

 

Normal domestic power is well served with single phase.

[TimeMachine]

Unless you are setting up as an electronic enthusiast yourself or its a must because house has no power from the street its not worth it.  The payoff period is around the 20 year period. 

Reliability of electronics, cost of panels and inverter and batteries.

There is no government support like in other countries. Put your money elsewhere such as high efficiency appliances and  insulation. Solar is just a gimmick here in Thailand. 

 

 

[mistral53]

The elephant in the room is the installer, or the lack of service they will provide should you have a problem during the warranty period, or even more so 10 or more years after installation........... ask me how I know.....lol

 

With that said, find an installer that has plenty of experience installing solar systems - its a very very simple job for installers with plenty of system installs under their belly. Ask for referrals of prior installations in your neck of the woods.

 

Once you found a handful of installers, specify tier-1 equipment (Huawei inverter, Longi, Jinko or equivalent panels etc) then squeeze them for the lowest price, take the lowest bidder.

 

A mid-sized system should have a payback of less than 4 years - thanks to high electricity prices.

Don't install a hybrid battery system, they will never pay back the investment - but there might be other reasons why batteries make sense.

 

One more comment about installers: I have yet to meet one that knows anything about maximizing efficiency of the solar array, that's why they are called installers.

[TimeMachine]

1 hour ago, mistral53 said:

The elephant in the room is the installer, or the lack of service they will provide should you have a problem during the warranty period, or even more so 10 or more years after installation........... ask me how I know.....lol

 

With that said, find an installer that has plenty of experience installing solar systems - its a very very simple job for installers with plenty of system installs under their belly. Ask for referrals of prior installations in your neck of the woods.

 

Once you found a handful of installers, specify tier-1 equipment (Huawei inverter, Longi, Jinko or equivalent panels etc) then squeeze them for the lowest price, take the lowest bidder.

 

A mid-sized system should have a payback of less than 4 years - thanks to high electricity prices.

Don't install a hybrid battery system, they will never pay back the investment - but there might be other reasons why batteries make sense.

 

One more comment about installers: I have yet to meet one that knows anything about maximizing efficiency of the solar array, that's why they are called installers.

Payback 4 years.  Can you show the math on that setup? Dont mean to be rude but that seems way off. 

[liddelljohn]

I had a full 4kw system in UK with batteries and FIT {feed in Tariff}

total cost £11600  paid for itself in 7 years , also ran 2 Bosch  aircon/heater airpumps with the system , saved a bundle on gas in winter they cost £4k

[TimeMachine]

53 minutes ago, liddelljohn said:

I had a full 4kw system in UK with batteries and FIT {feed in Tariff}

total cost £11600  paid for itself in 7 years , also ran 2 Bosch  aircon/heater airpumps with the system , saved a bundle on gas in winter they cost £4k

Allow me to show some rudimentary figures. 

Example. Excuse me for any mistakes. 

Cost of electricity in london 34p = 0.34£
4kw inverter during sunny period 5 hrs per day with 4kw panels. 
20kwh per day x 0.34 = 6.8 £ per day. 
1 year electricity making value =  365 days x 6.8 £ = 2,482.£

11,600 spent on system/ 2,482 = 4.68 years. Sounds great BUT... 

 

In reality,  inverters may not work up to exact 4kw.

Sunshine may be less than 5hr a day on average throughout the year. 

Feed in Tarrif may be a lot less than 1 for 1. In Auatralia its about 7 times less 

Battery degradation and replacements. 

Faulty equipment replacements if warranty not honoured. 

The above could dramatically change the pay off period to be many years more. Anyway,  If you have made precise calculations over the period using actual invoices then 7 years is good. 

 

 

[BritManToo]

I paid around 100k for 9 x340w panels, 5k5w inverter and 6kwhr battery.

This provides 80% of the electricity for my 3 bed house.

 

Air-con, shower heaters and cooker are connected to the grid.

Everything else runs on the inverter.

 

You don't need to plan for high wattage low use devices to run off the solar. 

My monthly PEA bills are under 200bht.

[TimeMachine]

11 minutes ago, BritManToo said:

I paid around 100k for 9 x340w panels, 5k5w inverter and 6kwhr battery.

This provides 80% of the electricity for my 3 bed house.

 

Air-con, shower heaters and cooker are connected to the grid.

Everything else runs on the inverter.

 

You don't need to plan for high wattage low use devices to run off the solar. 

My monthly PEA bills are under 200bht.

Are you using your AC at all? 200 baht bill on street power suggests you are only using your water heater and cooker. 

[BritManToo]

25 minutes ago, TimeMachine said:

Are you using your AC at all? 200 baht bill on street power suggests you are only using your water heater and cooker. 

Only use air-con when it's over 30c at night.

We normally sleep with all windows open and a fan blowing to keep mozzies from landing.

This year has been unusually cold, so maybe 4 nights in total.

[Muhendis]

8 hours ago, TimeMachine said:

Unless you are setting up as an electronic enthusiast yourself or its a must because house has no power from the street its not worth it.  The payoff period is around the 20 year period. 

Reliability of electronics, cost of panels and inverter and batteries.

There is no government support like in other countries. Put your money elsewhere such as high efficiency appliances and  insulation. Solar is just a gimmick here in Thailand. 

 

 

This is a strange viewpoint.

Please provide figures for your 20 year "payoff" (payback) time.

I have an 8 kw system with batteries which recovered it's costs in five years.

Also I am content in the knowledge that I am not contributing to climate change.

For me, cost of instalation was almost zero. I have the skills and knowledge to do that myself.

The Thai government will pay for any spare electricity you have but it's not much and can take a long time to organise.

[TimeMachine]

13 minutes ago, Muhendis said:

This is a strange viewpoint.

Please provide figures for your 20 year "payoff" (payback) time.

I have an 8 kw system with batteries which recovered it's costs in five years.

Also I am content in the knowledge that I am not contributing to climate change.

For me, cost of instalation was almost zero. I have the skills and knowledge to do that myself.

The Thai government will pay for any spare electricity you have but it's not much and can take a long time to organise.

If you give me the specs ill run the numbers. One example is in above post that shows a short period to promote solar.  But thats best case dreamland scenario.  Modify the numbers to the other end of the spectrum and you will get 20 years. 

Tell me inverter size and spec. 

Panel numbers and spec. 

Battery cost and spec. 

Tell me the appliances and frequency of usage

Theres not one correct answer.

 

If you install yourself and have no failures, and are not cheated on specs then it can work out a lot less than twenty years. If you put blind trust in a company to install a system and are overcharged for bad spec equipment and have to pay for failures then it could easily be 20. 

 

In short if you dont have the knowledge already you are taking big risk in trusting others.  A lot of money and wasted time when you could just pay a small bill every month.

I've installed one small system myself and estimated 10 years payoff.  I dont regret doing it but wouldnt do it again or recommend it. 

[BritManToo]

10 minutes ago, TimeMachine said:

If you give me the specs ill run the numbers. One example is in above post that shows a short period to promote solar.  But thats best case dreamland scenario.  Modify the numbers to the other end of the spectrum and you will get 20 years. 

Tell me inverter size and spec. 

Panel numbers and spec. 

Battery cost and spec. 

Tell me the appliances and frequency of usage

Theres not one correct answer.

 

If you install yourself and have no failures, and are not cheated on specs then it can work out a lot less than twenty years. If you put blind trust in a company to install a system and are overcharged for bad spec equipment and have to pay for failures then it could easily be 20. 

 

In short if you dont have the knowledge already you are taking big risk in trusting others.  A lot of money and wasted time when you could just pay a small bill every month.

I've installed one small system myself and estimated 10 years payoff.  I dont regret doing it but wouldnt do it again or recommend it. 

We're living in Thailand, my 5.5kw system cost 100kbht (2,300GBP).

You're living in the UK, your 4kw system cost 11,600GBP.

 

I'm not surprised Solar isn't worthwhile in the UK, it rains all the time, and equipment is expensive.

In Thailand it's sunny all the time, and equipment is cheap, so far this year only last week was wet and overcast.

[TimeMachine]

14 minutes ago, BritManToo said:

We're living in Thailand, my 5.5kw system cost 100kbht (2,300GBP).

You're living in the UK, your 4kw system cost 11,600GBP.

 

I'm not surprised Solar isn't worthwhile in the UK, it rains all the time, and equipment is expensive.

In Thailand it's sunny all the time, and equipment is cheap, so far this year only last week was wet and overcast.

I do agree,  thailand should have solar everywhere.  If you checkout google terrain view there is hardly any. The government is not supporting it. I disgree regarding cost of equipment.

Panels,  inverters,  and especially batteries are too much and need government subsidy and regulation to stop dodgy equipment for it to be worthwhile to promote the solar industry. 

[Muhendis]

20 minutes ago, BritManToo said:

so far this year only last week was wet and overcast.

Yeah, and it rained too but solar still filled up 750 Ah battery.

[BritManToo]

7 minutes ago, Muhendis said:

Yeah, and it rained too but solar still filled up 750 Ah battery.

Not me, I've been using PEA overnight for the past week.

Enough solar to power the day, but not enough to fill the 6kwhr batteries past about 3am.

[Muhendis]

3 minutes ago, BritManToo said:

Not me, I've been using PEA overnight for the past week.

Enough solar to power the day, but not enough to fill the 6kwhr batteries past about 3am.

I guess you don't have sunny mornings at 3 a.m.

Maybe a few more panels? ????

[BritManToo]

3 minutes ago, Muhendis said:

I guess you don't have sunny mornings at 3 a.m.

Maybe a few more panels? ????

Not cost effective ..............

10 days overcast a year costs me about 10 units of electricity from the PEA ....... 40bht.

[Muhendis]

5 minutes ago, BritManToo said:

Not cost effective ..............

True. Especially expecting any solar activity at 3 a.m.

Did you really mean 3 p.m.?

[KhunLA]

7 hours ago, TimeMachine said:

Payback 4 years.  Can you show the math on that setup? Dont mean to be rude but that seems way off. 

Our ROI should be between 5.32 yrs +/-, depending how much we drive.  And yes, I include the EVs as part of that savings.

 

Our cost, a wee bit more than most w/20kWh of ESS so an extra ฿195k to be off grid.  43% of the system price, to save 25-33% of usage overnight.   So ROI would be shorter with just a tie in system.

 

Unless not at home or overpaying, solar system in TH will definitely give you a nice ROI ... IF  you live that long.   Wife should enjoy decades of savings.

 

IF PEA bought excess, then we could easy export 10-20kWh a day.

[Muhendis]

29 minutes ago, Muhendis said:

Yeah, and it rained too but solar still filled up 750 Ah battery.

Perhaps I should point out that I limit my night time battery consumption to 30% DoD and my batteries are lead carbon which have a very high charge acceptance and are anticipated to have a life expectancy of 11½ years.

If I were to go to 80% DoD they would still be good for 2k cycles.

[McTavish]

As @KhunLA has done, we purchased a Deye inverter.  The SUN-10kSG04LP3-EU model is a 3-phase 10kw hybrid inverter although I chose not to install ESS/battery storage immediately as I foresee major advances in this technology, hopefully within 12 months.  We are spending approx 1,000bt per month PEA, a saving of ~3,500bt. 

 

Expected payback = 5.5 years.   [Battery cost would extend payback period to ~7 years]  

 

Our home comprises a pool, spa, irrigation pump and split system a/c's, 2 fridges and the usual appliances.  3-phase allows heavy equipment such as pumps to run concurrently without compromise.  A future well/pump/treatment system can also be accommodated.

 

I have a large UPS for security system, E-lighting, computer/router etc.  Have also run one fridge off it also during an extended night outage.  

 

Longi 550w tier one panels cost 5,750 ea., highly recommended.

Deye inverters can handle unbalanced (3) phase loads which was a concern with Huawei, also an early contender.  The other limitation with Huawei being bound to using their battery/charging system compared with Deye having all built-in and ready for plug'n play battery of any make or type.

[mistral53]

7 hours ago, TimeMachine said:

Payback 4 years.  Can you show the math on that setup? Dont mean to be rude but that seems way off. 

There is a twist to achieve this that I rather not discuss on a public forum. Suffice to say, it is one of the things that make Thailand a great place! ????

 

[jvs]

Consider to install a DC pool pump,it will save you around 3500 baht

per month and it is easy to install by yourself and no hassle with converters

or regulators.

Panels hook up straight to the pump.

I think the cost will be under 50 000 baht.

 

[Sophon]

1 hour ago, Muhendis said:

True. Especially expecting any solar activity at 3 a.m.

Did you really mean 3 p.m.?

I think he meant that his batteries run out at 3 a.m.

[TimeMachine]

1 hour ago, mistral53 said:

There is a twist to achieve this that I rather not discuss on a public forum. Suffice to say, it is one of the things that make Thailand a great place! ????

 

I guess,  feeding back in a non smart meter means you get 1 for 1.

Yes. Great advantage. 

If you want to take it a step further,  placing a large magnet in front of spinning disc will make it stop.  Oops. Sorry i dont know how that got there.