Solar power, can it be done DIY?

[Sophon]

Apologies in advance for a long post, but I want to give as much information as possible.

I have read some of the topics in the Renewable energy forum, and as some of you have already done it yourself, obviously the answer would be yes. So what I really mean is; can it be done by someone starting out from scratch with little previous knowledge of electrics/electronics? I did all the electrical wiring when we build our house (with a lot of help from this forum, special thanks going to Crossy), and have had not had a single problem over the subsequent eight years, but that is as far as my knowledge of electrics go. 

Our electrical consumption is fairly limited, so having a professional company install solar at our house would not make any financial sense. Even if saving on costs by installing it myself, the purely financial argument for solar is probably not very convincing in our case. However, my decision on whether to go for solar or not, will not be solely financially based. We have the occasional power cut during thunder storms maybe once or twice per month on average. It’s really not that bad, but if we decide to have solar power, I want to kill two birds with one stone by going for a hybrid, on-grid system. I would like us to be largely self-sufficient, but don’t mind having to draw on the grid from time to time when there is no sun, or our consumption is at its maximum. If it turns out that we draw more energy from the grid than expected, I wouldn’t mind the option to export (unofficially) to the grid to minimize our costs. We still have the old type spinning meters. 

First a little information about our circumstances.
As mentioned our power consumption is relatively modest and doesn’t fluctuate that much between the different months. Our “base consumption” is around 300-500 W, and we only go above 1,000 W if the water pump or one of the kitchen appliances (rice cooker, electric kettle) is on. The only time we exceed 2,000 W if the shower heater (and pump) is on, and I have never seen us go above 4 kW. 

Over the last few years the consumption numbers have been as follows:

 

2018: 
Total cost for the year THB 16,827 for 4,189 kWh.
Averages 349 kWh per month or 11.5 kWh per day.
Monthly high 394 kWh, low 312 kWh.

 

2019: 
Total cost for the year THB 18,427 for 4,504 kWh.
Averages 375 kWh per month or 12.3 kWh per day.
Monthly high 470 kWh, low 300 kWh.

 

2020: 
Total cost for the year THB 16,649 for 4,209 kWh.
Averages 351 kWh per month or 11.5 kWh per day.
Monthly high 375 kWh, low 321 kWh.

 

2021: 
Total cost for the year THB 15,694 for 4,048 kWh.
Averages 337 kWh per month or 11.1 kWh per day.
Monthly high 372 kWh, low 299 kWh.

 

2022 (seven months): 
Total cost for the year THB 10,529 for 2,440 kWh.
Averages 349 kWh per month or 11.5 kWh per day.
Monthly high 381 kWh, low 295 kWh.

 

The cost for 2020/21 is slightly effected by the Covid discounts, but not the consumption figures.

We have ordered a new EV, which will probably arrive sometime at the end of this year or the beginning of next. This will obviously add to our consumption, but as we really don’t drive that much a shot in the dark is that we will consume an additional 1,000 kWh per year for the EV. I plan to almost exclusively charge the EV using a “granny charger” during mid-day on sunny days so as to avoid drawing power from the grid. As our normal drives are only around 50-60 km, a few hours charging at 2.3 kW will be enough to top up the battery again. With the EV added, and figuring in the rising cost of electricity, my costs for electricity for 2023 will probably be somewhere in the THB 20k – 25k range. 

To get an idea of what kind of battery storage I will need, I logged our consumption for a month from 8.00 - 16.00 and from 16.00 – 8.00 with the following result:
39% of our consumption fell from 8.00 – 16.00 when the solar panels produce power.
61% of our consumption fell from 16.00 – 8.00 there will be little output from the panels, so will largely need to be covered by battery storage.

 

During that month we on average consumed 10.8 kWh per day, so slightly less than a normal month (this was February). This was split with 4.2 kWh during daytime and 6.6 kWh during the “night”.
8.00 – 16.00: Average 4.2 kWh, high 9 kWh, low 2 kWh.
16.00 – 8.00: Average 6.6 kWh, high 9 kWh, low 5 kWh.

 

Only on four days did we use more than 7 kWh between 16.00 and 8.00, so as battery storage is expensive it probably makes more financial sense to only plan for batteries to cover 7 kWh, and draw from the grid to cover any excess.

 

From what I have learned reading other people’s topics, I will need the following equipment:
10-12 solar panels approx. 340 W.
5 kW hybrid on-grid inverter.
10 kWh of battery storage, more would be better but would come at a cost.

 

I believe it should be possible to buy these items for a ball park figure of THB 150k, and they should make it possible for me to save at least 75% on my cost of electricity. So that would mean annual savings of THB 15k+ or about 10% of the investment.

 

My initial impression is that a solar installation is somewhat more complicated than wiring up a new house. But then again, when I first started planning how to wire the house, it seemed fairly complicated too. In the end it wasn’t too bad. 

So what’s the verdict, do you think I would be able to do this myself (“with a little help from my friends”)? I don’t plan on building my own battery storage as others have done or anything like that. I will be buying ready to go equipment and just put it all together myself. And am I completely off with what I have quoted about costs, savings and necessary equipment to achieve my goal?

No need for now to post links to Shopee/Lazada/AliExpress with equipment I can buy. If I satisfy myself that I will be able to do this, I will make follow-up posts to fine-tune the details. If it's a go, I plan to install the system during the dry season, the time between now and then is for planning.

Thank you in advance for any input you may have to give (even negative one).

[KhunLA]

If you got the crew, tools & knowledge, any thing can be DIY.

Will Prowse can hold your hand along the way: 

https://www.youtube.com/c/WillProwse

 

Besides a couple on the forum.  Price your system, components, then compare to same installed for you.   I did just that, and for me, the installed price came in close enough for me to not bother, since not having the crew, tools or experience.

[Tubulat]

To give you a hint, with that consumption per month I would think twice before making a big investment.

Yes I have solar cells including batteries and meets my needs for 95%, my month average was about 2500 thb.

It is working now for about 15 months.

But I've got problems with one of the 2 inverters I use and in this country, they like to sell to you but if you have problems, they can't help you.

It's a lot of investment and, I think about 350-400 thousand bath did it cost me, (12 solar cell panels aver. 500W, 2 inverters, and 2 lithium battery packs, each 260Ah) so when everything is correct working it will takes 12.5 years before you even broke.

Anyway, that's my experience.

Oh, yes I forgot to mention, I did everything by myself.

Edited August 1, 2022 by Tubulat

[Bandersnatch]

Lots to unpack @Sophon but a few points to start with:

 

I purchased the panels locally and imported the inverters and batteries so I wasn't gouged with a big mark up. I then got a local team I had used before to do the install. 

 

I have a friend who wanted to do all the install except fitting the panels and my guy gave him a reasonable price for that.

 

Regarding the EV I would recommend going for the free wall box that comes with most EVs in Thailand as that will give you a 7kW charging speed. It will mean a 10kW or 2x5kW inverters but it does mean that you will be able to dump your maximum solar production into the car in the middle of the day and avoid curtailment.

 

 

 

 

 

[sidgy]

Did my own after following a couple of threads on here with no electrical background/knowledge. I certainly wouldn't attempt a house rewire like yourself.

Mine was a simple configuration using a grid tie inverter that simply plugs into an existing socket, as i saw others doing on this forum and guessed it was something i could manage (shout outs to @Crossy and @BritManToo )

I too have old style spinning meter and export "unofficially" to the grid during the day. This is also why i only went to cover 50-60% of usage to avoid getting switched to new style meter, and maybe increase capacity after this set up has paid for itself.

Set up is coming up to two years and still on course to have paid for itself within my three year target, even with having changed one grid tie inverter.  

Obviously when the grid goes down, so does our power so your second bird wont be killed but whilst you still have old spinning meter, it will certainly help bring your bills down and after R.O.I you will already have some infrastructure for your proposed set up bought and paid for before the more costly expense of a hybrid system

 

[Sophon]

3 hours ago, KhunLA said:

If you got the crew, tools & knowledge, any thing can be DIY.

Will Prowse can hold your hand along the way: 

https://www.youtube.com/c/WillProwse

 

Besides a couple on the forum.  Price your system, components, then compare to same installed for you.   I did just that, and for me, the installed price came in close enough for me to not bother, since not having the crew, tools or experience.

We live in a small village out in the countryside, so even if I could find someone to install a system at a reasonable mark-up, I suspect it would be next to impossible to get them to come out if sometime in the future I started having problems. The good thing about having done something yourself is, that you know exactly how everything is set up and get an understanding of how the system works. So if you later have problems or want to make changes, you have a better chance of knowing what to do.

[Sophon]

3 hours ago, Tubulat said:

To give you a hint, with that consumption per month I would think twice before making a big investment.

Yes I have solar cells including batteries and meets my needs for 95%, my month average was about 2500 thb.

It is working now for about 15 months.

But I've got problems with one of the 2 inverters I use and in this country, they like to sell to you but if you have problems, they can't help you.

It's a lot of investment and, I think about 350-400 thousand bath did it cost me, (12 solar cell panels aver. 500W, 2 inverters, and 2 lithium battery packs, each 260Ah) so when everything is correct working it will takes 12.5 years before you even broke.

Anyway, that's my experience.

Oh, yes I forgot to mention, I did everything by myself.

As I mentioned, I understand that from a purely financial viewpoint it isn't a slam dunk. however, I like the idea of producing my own energy and not having to worry about future energy price increases. I have the funds available in the bank doing little, so yearly savings of 10% of the invested amount (unless my estimates are off), doesn't sound too bad. I understand that my pay-back time probably won't be 10 years, as there is a good chance that the batteries and/or the inverter might not last that long.

 

My estimated consumption is only 20% lower than yours, and my planned investment only half of what you spent, so perhaps my estimates are off (or maybe you oversized your system?).

 

Thank you for the diagramme.

 

[Sophon]

1 hour ago, Bandersnatch said:

Lots to unpack @Sophon but a few points to start with:

 

I purchased the panels locally and imported the inverters and batteries so I wasn't gouged with a big mark up. I then got a local team I had used before to do the install. 

 

I have a friend who wanted to do all the install except fitting the panels and my guy gave him a reasonable price for that.

 

Regarding the EV I would recommend going for the free wall box that comes with most EVs in Thailand as that will give you a 7kW charging speed. It will mean a 10kW or 2x5kW inverters but it does mean that you will be able to dump your maximum solar production into the car in the middle of the day and avoid curtailment.

 

 

 

 

 

I will definitely take the free wall box that comes with my EV, but I have read your posts (and seen the MG podcast) so suspect that the installer will refuse to install it. We only have a 15/45A meter, and our 16 sq.mm. copper cables won't support an upgrade to a 30/100A meter. And I definitely do not want to change the existing 50 m of buried cable, or get a second meter which would then require a second set of cables to be buried. In reality my existing meter should be able to cope with the wall box, but the installer won't see it that way. I will insist on getting the wall box for future install, or to sell with the car if I decide to change it in the future.

[Sophon]

19 minutes ago, sidgy said:

Did my own after following a couple of threads on here with no electrical background/knowledge. I certainly wouldn't attempt a house rewire like yourself.

Mine was a simple configuration using a grid tie inverter that simply plugs into an existing socket, as i saw others doing on this forum and guessed it was something i could manage (shout outs to @Crossy and @BritManToo )

I too have old style spinning meter and export "unofficially" to the grid during the day. This is also why i only went to cover 50-60% of usage to avoid getting switched to new style meter, and maybe increase capacity after this set up has paid for itself.

Set up is coming up to two years and still on course to have paid for itself within my three year target, even with having changed one grid tie inverter.  

Obviously when the grid goes down, so does our power so your second bird wont be killed but whilst you still have old spinning meter, it will certainly help bring your bills down and after R.O.I you will already have some infrastructure for your proposed set up bought and paid for before the more costly expense of a hybrid system

 

Yes, starting with a hybrid on grid system but without (at least initially) investing in the batteries, and instead using the grid as storage would certainly bring the cost down and increase return on investment. But it would still leave us in the dark when the grid goes down, which does get annoying over time. I have previously thought about getting a generator for such times, but I think a solar system is a better solution.

 

Saving on the electricity bill is not my only consideration, it might not even be the biggest one. I just like the idea of "help saving the world" by generating our own power, and not be concerned with the future cost of electricity or the status of the grid.

 

 

[KannikaP]

4 hours ago, Sophon said:

and we only go above 1,000 W if the water pump or one of the kitchen appliances (rice cooker, electric kettle) is on.

How often is that?

[Sophon]

14 minutes ago, KannikaP said:

How often is that?

The water pump goes on whenever we use water, so many times a day but only for a short while. Rice cooker is on twice a day for half an hour or so, and the kettle once or twice for 5 minutes.

[007 RED]

Hi @Sophon.  To answer your initial question, yes it is possible for someone with little or no previous experience of solar systems to undertake a DIY installation.

 

A couple of years ago at the beginning of the pandemic ‘lockdown’ I was reading @Crossy post “How about a solar car port on a budget” and this inspired me to consider doing something similar.

 

I openly confess to having no previous experience of solar systems and a fairly basic knowledge of electrical/electronic systems dating back to my days at Coventry Polytechnic some 50 plus years ago.  In fact, I would happily describe myself as a total nerd when it comes to solar systems.  That said, DIY seems to be in my DNA.

 

I have to admit, learning and researching about solar systems was a great experience which helped alleviate the boredom created by ‘self-hibernation’ under the Covid19 restrictions in force at the time.

 

We (my wife and I) had a car port constructed in 2018 on land that we purchased adjacent to our house and this was ideally positioned in so far that one side of the roof was South facing and inclined at about 15^o.  Most importantly it was not shaded during the day, therefore, any solar panels mounted on the roof should (in theory) capture maximum sunlight during the day and would not be seen from the road.

 

From the information obtained from our local PEA, I discovered that our average usage was 275 units per month (approximately 9 units per day).  This info can be obtained by entering a couple of basic details into the PEA ‘s web page https://www.pea.co.th/en/e-Service/Meter-Reading-History .   So based upon this info, I decided to go for a simple grid tied solar system with the intention of reducing our monthly subscription to the local PEA by about 75%, (e.g. from 9 to approximately 7 units/day).

 

As a result, I've put together a small scale solar system comprising 4 x 415W half cut mono solar panels plus a 2kW GTI inverter.  Total cost was 28K THB including stainless steel mounting brackets, cables/connectors and isolator switches.

 

 

 

Note:  4 x415W panels should be capable of producing approximately 1660W under ideal (laboratory) conditions, but in reality such a configuration is more likely to only produce 75% of that due to heat and shading etc.  Therefore, with a 6 hour ‘window’ of decent sunlight a day the panels are more likely to produce about 1245W .  Hence the panels should produce around 7 units per day which meets my original intention of reducing my monthly bill by 75%.

 

It was a real DIY job from beginning to end. 

 

The only physical assistance I had was lifting the panels onto the car port roof. (Don't ask).

 

The system has now been running for 10 months and I’m well on target to recover my initial investment in about 2.5 years.  One forum member suggested that saving just a few Baht a month was ‘penny pinching’.  Well, if you consider the pathetic interest rate that you get from most bank savings accounts, compared to the potential cost saving per year generated by a solar system, solar way out performs the interest rate by far, so I think it’s fair to say solar is in fact a shrewd long term investment.

 

I think that the real motivation for me was that at the age of 74, designing, installing and commissioning a grid tied solar system, albeit a small one, was a great challenge.  Throughout my life, I have always enjoyed the challenges which have been ‘thrown’ at me.  Any long term financial payback, or contribution towards assisting the world to become carbon neutral would just be an incidental bonus so far as I was concerned.

 

A few words of caution

 

Firstly, it should be noted that the electric authorities (MEA or PEA) will not approve a DIY grid tied installation.  According to their policies, all solar system installations which are connected to the grid must be undertaken by one of their approved installers and it must have an electronic meter fitted.  The system must be subsequently certified by one of their engineers.

 

The cost of having a system installed and approved is very overpriced expensive, and the payback for any power which the system might feedback into the grid is very low (approximately half that of the normal purchasing price).

 

Secondly, if you DIY install a grid tied solar system and have a spinning disc type meter any excess power produced by the system can potentially be fed back into the grid and make the disc spin backwards thus reducing the number of units used.  This practice is frowned upon by the electric authorities and if discovered (usually by the meter reader) they (MEA/PEA) will at best replace the meter with an electronic one which prevents ‘spin back’ or at worse they may disconnect the supply and demand that the solar system’ be removed and/or impose a fine.

 

FYI... We know from past records that our meter reader visits on, or about the 15th of each month.  So I've installed a Crossy 'patented'  NO Export Device which is activated prior to the meter reader's visit.  This stops the system exporting any surplus power back into the grid and the meter spinning backwards.  Once the meter reader has been its switched back into Export mode again.

 

The physical switch shown above has now be complemented with an electronic controlled relay device which can be activated by an application on my phone via the internet as seen below.

 

Best of luck with your proposed venture.

Edited August 2, 2022 by 007 RED
Solar Export Control photo added

[Sophon]

4 hours ago, 007 RED said:

Hi @Sophon.  To answer your initial question, yes it is possible for someone with little or no previous experience of solar systems to undertake a DIY installation.

 

A couple of years ago at the beginning of the pandemic ‘lockdown’ I was reading @Crossy post “How about a solar car port on a budget” and this inspired me to consider doing something similar.

 

I openly confess to having no previous experience of solar systems and a fairly basic knowledge of electrical/electronic systems dating back to my days at Coventry Polytechnic some 50 plus years ago.  In fact, I would happily describe myself as a total nerd when it comes to solar systems.  That said, DIY seems to be in my DNA.

 

I have to admit, learning and researching about solar systems was a great experience which helped alleviate the boredom created by ‘self-hibernation’ under the Covid19 restrictions in force at the time.

 

We (my wife and I) had a car port constructed in 2018 on land that we purchased adjacent to our house and this was ideally positioned in so far that one side of the roof was South facing and inclined at about 15^o.  Most importantly it was not shaded during the day, therefore, any solar panels mounted on the roof should (in theory) capture maximum sunlight during the day and would not be seen from the road.

 

From the information obtained from our local PEA, I discovered that our average usage was 275 units per month (approximately 9 units per day).  This info can be obtained by entering a couple of basic details into the PEA ‘s web page https://www.pea.co.th/en/e-Service/Meter-Reading-History .   So based upon this info, I decided to go for a simple grid tied solar system with the intention of reducing our monthly subscription to the local PEA by about 75%, (e.g. from 9 to approximately 7 units/day).

 

As a result, I've put together a small scale solar system comprising 4 x 415W half cut mono solar panels plus a 2kW GTI inverter.  Total cost was 28K THB including stainless steel mounting brackets, cables/connectors and isolator switches.

 

 

 

Note:  4 x415W panels should be capable of producing approximately 1660W under ideal (laboratory) conditions, but in reality such a configuration is more likely to only produce 75% of that due to heat and shading etc.  Therefore, with a 6 hour ‘window’ of decent sunlight a day the panels are more likely to produce about 1245W .  Hence the panels should produce around 7 units per day which meets my original intention of reducing my monthly bill by 75%.

 

It was a real DIY job from beginning to end. 

 

The only physical assistance I had was lifting the panels onto the car port roof. (Don't ask).

 

The system has now been running for 10 months and I’m well on target to recover my initial investment in about 2.5 years.  One forum member suggested that saving just a few Baht a month was ‘penny pinching’.  Well, if you consider the pathetic interest rate that you get from most bank savings accounts, compared to the potential cost saving per year generated by a solar system, solar way out performs the interest rate by far, so I think it’s fair to say solar is in fact a shrewd long term investment.

 

I think that the real motivation for me was that at the age of 74, designing, installing and commissioning a grid tied solar system, albeit a small one, was a great challenge.  Throughout my life, I have always enjoyed the challenges which have been ‘thrown’ at me.  Any long term financial payback, or contribution towards assisting the world to become carbon neutral would just be an incidental bonus so far as I was concerned.

 

A few words of caution

 

Firstly, it should be noted that the electric authorities (MEA or PEA) will not approve a DIY grid tied installation.  According to their policies, all solar system installations which are connected to the grid must be undertaken by one of their approved installers and it must have an electronic meter fitted.  The system must be subsequently certified by one of their engineers.

 

The cost of having a system installed and approved is very overpriced expensive, and the payback for any power which the system might feedback into the grid is very low (approximately half that of the normal purchasing price).

 

Secondly, if you DIY install a grid tied solar system and have a spinning disc type meter any excess power produced by the system can potentially be fed back into the grid and make the disc spin backwards thus reducing the number of units used.  This practice is frowned upon by the electric authorities and if discovered (usually by the meter reader) they (MEA/PEA) will at best replace the meter with an electronic one which prevents ‘spin back’ or at worse they may disconnect the supply and demand that the solar system’ be removed and/or impose a fine.

 

FYI... We know from past records that our meter reader visits on, or about the 15th of each month.  So I've installed a Crossy 'patented'  NO Export Device which is activated prior to the meter reader's visit.  This stops the system exporting any surplus power back into the grid and the meter spinning backwards.  Once the meter reader has been its switched back into Export mode again.

 

The physical switch shown above has now be complemented with an electronic controlled relay device which can be activated by an application on my phone via the internet as seen below.

 

Best of luck with your proposed venture.

Thank you for your encouragement. 

 

If I decide to do this, and at the moment I am strongly leaning towards giving it a try, I will at least initially not export to the grid. I will start out seeing how much I end up relying on the grid, and then decide if I should do some unauthorized export or not. Sooner or later we will lose that option anyway when the PEA changes our meter to a smart meter. I don't think that will be soon though, as our PEA people don't move quickly. I have for more than five years unsuccessfully tried to get them to come out and put a cover on our meter to prevent people from getting electrocuted.

 

I read your story about "commandeering" the crane to have your solar panels lifted onto your roof.  I will not put ours on the roof, primarily because I don't really want to have them up there but also because our house have a roof construction with very limited roof space pointing in the right direction (south).

 

Putting the solar panels would also make installation, cabling and later cleaning and maintenance much more difficult.

 

In our case the best place for the panels is about 50 m from our house where the PEA supply goes to a pole on our land before going underground to the house. At this point the cables from PEA is spliced onto the NYY cable going to the house, so "unsplicing" the cables and connecting the inverter would be easy. It's also one of the least shaded part of our land with no shade at all between approximately 7 in the morning and 5 in the afternoon. I plan to put the panels on something like this (only smaller):

 

I have taken the photo near our house down by Tha river, where they have just (after I took the picture) put up 84 solar panels. Not completely sure what the project is, but I suspect power for some kind of pumping station.

 

Thank you again for your info.

[007 RED]

12 hours ago, Sophon said:

Thank you for your encouragement. 

 

If I decide to do this, and at the moment I am strongly leaning towards giving it a try, I will at least initially not export to the grid. I will start out seeing how much I end up relying on the grid, and then decide if I should do some unauthorized export or not. Sooner or later we will lose that option anyway when the PEA changes our meter to a smart meter. I don't think that will be soon though, as our PEA people don't move quickly. I have for more than five years unsuccessfully tried to get them to come out and put a cover on our meter to prevent people from getting electrocuted.

 

I read your story about "commandeering" the crane to have your solar panels lifted onto your roof.  I will not put ours on the roof, primarily because I don't really want to have them up there but also because our house have a roof construction with very limited roof space pointing in the right direction (south).

 

Putting the solar panels would also make installation, cabling and later cleaning and maintenance much more difficult.

 

In our case the best place for the panels is about 50 m from our house where the PEA supply goes to a pole on our land before going underground to the house. At this point the cables from PEA is spliced onto the NYY cable going to the house, so "unsplicing" the cables and connecting the inverter would be easy. It's also one of the least shaded part of our land with no shade at all between approximately 7 in the morning and 5 in the afternoon. I plan to put the panels on something like this (only smaller):

 

I have taken the photo near our house down by Tha river, where they have just (after I took the picture) put up 84 solar panels. Not completely sure what the project is, but I suspect power for some kind of pumping station.

 

Thank you again for your info.

I totally agree with your comment about not wanting panels on your roof and that you're considering ground mounting them as per the photo.

 

Once installed they shouldn't need any serious maintenance other than periodic cleaning, but in my case that presents a 'slight' problem in so far as having to climb up onto the car port roof which is constructed with cement sheet tiles and the potential risk of one breaking when l'm standing on it and dropping 4 meters onto the concrete floor.   At 75 that's not going to have a 'happy ending'.

 

If l had more land, with hindsight, l would have my panels ground mounted.

 

Good luck with your prposed project and please keep us updated on progress.

 

 

[Sophon]

When looking at illustrations such as this one of a solar installation in it's simplest form it all seems fairly simple and straight forward:

 

Everything is connected to the on-grid hydrid inverter, and the inverter then acts as the command center deciding where to take energy from (solar panels, batteries or grid), and where to route that energy (house load, batteries or back to the grid). 

 

The illustration posted above by Tubulat..

 

basically shows the same, but just adds more details.

 

But when I then see other illustrations like this one from Crossy's pinned topic about types of solar installations, I start to question if my understanding is correct or if there is something I am missing.

 

Here it seems not everything is controlled by the inverter, instead there is a MPPT charge controller, a mains charger and control electronics (in addition to the inverter) connected to the battery and it's not clear to me exactly how these elements are connected.

 

Mains charger:

What's the point of the mains charger? Is it just a fail safe addition to make sure that the battery pack is always charged, even when the solar panels do not produce enough power to both cover the house load and keeping the batteries charged? If that is the case, then I can kind of see the logic in an officially sanctioned installation, when the panels don't produce enough power the batteries are kept topped up from the mains, and when there is excess power from the panels energy is then routed back to the grid. But even so, it doesn't seem optimal given the low feed back tariffs.

 

In a non-sanctioned solar installation where you are not allowed to feed energy back to the grid, using a mains charger seems counter-intuitive. I would want to keep such feed-back to a minimum, so topping up batteries from the grid would mean, that you have nowhere to feed the energy to when your panels produces excess energy. You would either waste the energy or have to feed it (illegally) back to the grid. The one situation where I can see it making sense, is if you have a highly unreliable grid.

 

But maybe I have completely misunderstood the point of the mains charger.

 

MPPT charge controller:

As far as I understand, the charge controller regulates the charging of the batteries, which will prolong the battery life. But doesn't most solar battery packs come with some form of battery management system built in? So can the MPPT and the BMS live together, and how

much better off are you with a charge controller?

 

Control electronics:

What are the "control electronics" controlling? Are they helping out of the charge controller/mains charger?

 

House load:

The illustration shows two connections from the inverter to the house load and one directly from the grid to the house. Again, it's not clear from the illustration how you would go about connecting this, which maybe makes it seem more complicated than it really is?

 

Is the direct connection from grid to load some kind of bypass in case the solar system develops a fault? If not, then what is the purpose of this direct link?

 

One of the connections between the inverter and the house load is marked "Essential Power", so presumably this is items such as refrigerators, a few lights, fans etc. that you find essential to have on in case the grid is down and your panels are not producing enough power. The unmarked connections is then the rest, i.e. of the "non-essential" items?

 

The only way I can think of that would make this work, is if your house circuits are separated into essential and non-essential circuits. In my case that would mean a rewiring of the house, something I definitely would not want to do. Normally our power cuts only lasts about an hour, and if one occurs while there is little/no sun and the batteries almost drained I will just make sure to manually turn off everything I don't find essential. It would be helpful though, if it were possible to set up some kind of alarm system in case of power cuts, as we would no longer necessarily be aware of the power being out until the batteries run out. I guess I could ask the neighbour to call us.

 

In reality it wouldn't be a big deal, as even in the worst case scenario (grid down, no sun and batteries empty) we would still be no worse off than we are today. Most of our power cuts happen late afternoon when the thunderstorms roll in, so even on a cloudy day the batteries would typically have some power. 

 

So are Mains charger, Charge Controller and Control electronics really essential/necessary/helpful elements? I just want a simple system without unnecessary complications. Of course, if there is a strong argument for including something I am willing to do so, but it should be something that gives me real benefits.

 

I have no doubt got a lot wrong above, so please correct my misunderstandings.

 

[Sophon]

No-one has yet commented on my cost estimate and guesswork about what equipment I will need from my opening post. Does that mean that I am reasonably close, or is everyone just lost for words at my level of ignorance????

[patman30]

lots of info above
i will state the obvious
as far as calculating costs go
it is impossible to predict the cost of electricity in 5-10 years time
fiat currencies are losing value quicker than ever
it may be better to spend money now rather than later
if you buy Ni-Fe batteries
you will save even more as they last 50 years

[KhunLA]

19 minutes ago, Sophon said:

No-one has yet commented on my cost estimate and guesswork about what equipment I will need from my opening post. Does that mean that I am reasonably close, or is everyone just lost for words at my level of ignorance????

Really depends on what components, brand, version of, and from where purchased being used.  

 

China ... cheaper, should be, maybe

LAZ ... less than local, maybe

Global (chain stores) ?

From Installer ... probably a bit higher, but warranty better...maybe, if still around in 5+ yrs.

 

Prices fluctuate greatly, with options; wifi, pure sine, microinverters on panels, programmability, UPS protection/built in vs add on

Edited August 3, 2022 by KhunLA

[Sophon]

14 minutes ago, patman30 said:

lots of info above
i will state the obvious
as far as calculating costs go
it is impossible to predict the cost of electricity in 5-10 years time
fiat currencies are losing value quicker than ever
it may be better to spend money now rather than later
if you buy Ni-Fe batteries
you will save even more as they last 50 years

 

11 minutes ago, KhunLA said:

Really depends on what components, brand, version of, and from where purchased being use.

 

Prices fluctuate greatly, with options; wifi, pure sine, microinverters on panels, programmability, UPS protection/built in vs add on

I realize that it's kind of a "how long is a piece of string" questions, but I am just looking for an idea of whether it can realistically be done for around the quoted figure THB 150k (not including building the structure for the panels). I have based my estimate on equipment other people have linked to on Shopee, Lazada:
5 kW on-grid hybrid inverter THB 25,000-50,000

10-12 solar panels 340W THB 40,000-45,000

10 kWh battery storage THB 50,000-80,000

Bits and bobs THB ?

 

I can go higher than that, but if my estimate is completely unrealistic and the minimum cost would be say THB 300k then the project would no longer make sense.

Edited August 3, 2022 by Sophon

[KhunLA]

1 minute ago, Sophon said:

 

I realize that it's kind of a "how long is a piece of string" questions, but I am just looking for an idea of whether it can realistically be done for around the quoted figure THB 150k (not including building the structure for the panels). I have based my estimate on equipment other people have linked to on Shopee, Lazada:
5 kW on-grid hybrid inverter THB 25,000-50,000

10-12 solar panels 340W THB 40,000-45,000

10 kWh battery storage THB 50,000-80,000

Bits and bobs THB ?

 

I can go higher than that, but if my estimate is completely unrealistic and the minimum cost would be say THB 300k then the project would no longer make sense.

Inverter & panels in the ballpark.

ESS/battery will be on the upper end of that

[BritManToo]

9 minutes ago, Sophon said:

 

I realize that it's kind of a "how long is a piece of string" questions, but I am just looking for an idea of whether it can realistically be done for around the quoted figure THB 150k (not including building the structure for the panels). I have based my estimate on equipment other people have linked to on Shopee, Lazada:
5 kW on-grid hybrid inverter THB 25,000-50,000

10-12 solar panels 340W THB 40,000-45,000

10 kWh battery storage THB 50,000-80,000

Bits and bobs THB ?

 

I can go higher than that, but if my estimate is completely unrealistic and the minimum cost would be say THB 300k then the project would no longer make sense.

If you've got batteries, why the on grid inverter?

 

5k5w Off grid inverter 15kbht (I have this)

https://www.lazada.co.th/products/powmr-hybrid-offgrid-off-grid-inverter-35-55kw-24v-48v-solar-system-1-i2226480952-s7453256026.html

10x 345w panels 37kbht (I have this)

https://www.lazada.co.th/products/bluetech-solar-poly-340w-345w-dsm72-345-345-polycrystalline-solar-panel-345w-5bb-30-i1904718525-s5997080624.html

 

12kwhr battery 55kbht (I should have bought this)

https://www.lazada.co.th/products/i2937766522-s10775080147.html

 

Total 110kbht

 

[patman30]

2 hours ago, Sophon said:

 

I realize that it's kind of a "how long is a piece of string" questions, but I am just looking for an idea of whether it can realistically be done for around the quoted figure THB 150k (not including building the structure for the panels). I have based my estimate on equipment other people have linked to on Shopee, Lazada:
5 kW on-grid hybrid inverter THB 25,000-50,000

10-12 solar panels 340W THB 40,000-45,000

10 kWh battery storage THB 50,000-80,000

Bits and bobs THB ?

 

I can go higher than that, but if my estimate is completely unrealistic and the minimum cost would be say THB 300k then the project would no longer make sense.

i just bought 3 x 48v Growatt inverters at 32k baht each
also paid just over $5k for 3 x 15kwh batteries (48v x 300ah) from China

the selection of batteries currently here is very limited so had to order direct from China
cost is about 2/3 of the price buying local, if you can find
finding the batteries was the headache part TBH
not bought panels yet

Ni-Fe batteries cost a bit more but save you in the long run, not sold locally afaik
your estimates are about right
although you can get 5kwh inverters from 15k baht
seeing as you are going on grid
have you considered no batteries ?
or a small battery just to tie you over till 10pm, and for morning before sun comes up
(10pm to 9am is off peak hours, half price)
all depends what time you use power the most

[Sophon]

3 hours ago, BritManToo said:

If you've got batteries, why the on grid inverter?

 

5k5w Off grid inverter 15kbht (I have this)

https://www.lazada.co.th/products/powmr-hybrid-offgrid-off-grid-inverter-35-55kw-24v-48v-solar-system-1-i2226480952-s7453256026.html

10x 345w panels 37kbht (I have this)

https://www.lazada.co.th/products/bluetech-solar-poly-340w-345w-dsm72-345-345-polycrystalline-solar-panel-345w-5bb-30-i1904718525-s5997080624.html

 

12kwhr battery 55kbht (I should have bought this)

https://www.lazada.co.th/products/i2937766522-s10775080147.html

 

Total 110kbht

 

As i understand it, in order to have the ability to export to the grid, it has to be a hybrid on-grid inverter. I can get a no brand on-grid inverter similar to the one you bought for about THB 8k more than yours:

 

 

link

 

Occasional export after a few days of little sunlight (and therefore relying more on the grid) could quickly recoup that extra investment. Anyway, it's always nice to have the option.

 

It sounds like you say it should be possible to achieve my goal for somewhere in the THB 150k region. I assume that other bits and bobs like cabling, breakers plugs etc. will not be a major expense (i.e. less than THB 10k)? I am only talking about the DC items, I have 16 sq.mm. NYY cable left over to make the necessary changes to the main supply.

[Sophon]

40 minutes ago, patman30 said:

i just bought 3 x 48v Growatt inverters at 32k baht each
also paid just over $5k for 3 x 15kwh batteries (48v x 300ah) from China

the selection of batteries currently here is very limited so had to order direct from China
cost is about 2/3 of the price buying local, if you can find
finding the batteries was the headache part TBH
not bought panels yet

Ni-Fe batteries cost a bit more but save you in the long run, not sold locally afaik
your estimates are about right
although you can get 5kwh inverters from 15k baht
seeing as you are going on grid
have you considered no batteries ?
or a small battery just to tie you over till 10pm, and for morning before sun comes up
(10pm to 9am is off peak hours, half price)
all depends what time you use power the most

Almost two thirds of our consumption is when the solar panels would produce no or little energy, so the savings would be minimal. Sure, I could export (unauthorized) to the grid, but who knows how long that would last. Besides, if I am going to do this I want to go all in and get all the benefits and flexibility of having power even when the grid is down. Even if it from a purely financial point of view would make more sense to use the grid for energy storage.

 

Would you be willing to share the contact information for your battery supplier in China/

[Crossy]

10 minutes ago, Sophon said:

As i understand it, in order to have the ability to export to the grid, it has to be a hybrid on-grid inverter. I can get a no brand on-grid inverter similar to the one you bought for about THB 8k more than yours:

link

 

Occasional export after a few days of little sunlight (and therefore relying more on the grid) could quickly recoup that extra investment. Anyway, it's always nice to have the option.

 

It sounds like you say it should be possible to achieve my goal for somewhere in the THB 150k region. I assume that other bits and bobs like cabling, breakers plugs etc. will not be a major expense (i.e. less than THB 10k)? I am only talking about the DC items, I have 16 sq.mm. NYY cable left over to make the necessary changes to the main supply.

 

Be very careful with these low-cost hybrids, I'll pretty much guarantee that this unit does NOT do export.

 

[BritManToo]

28 minutes ago, Sophon said:

Occasional export after a few days of little sunlight (and therefore relying more on the grid) could quickly recoup that extra investment. Anyway, it's always nice to have the option.

Waste of money IMHO for the ability to illegally export. 

Edited August 3, 2022 by BritManToo

[Sophon]

28 minutes ago, Crossy said:

 

Be very careful with these low-cost hybrids, I'll pretty much guarantee that this unit does NOT do export.

 

You are probably correct, there is one negative review that suggests as much.

 

What about this Must inverter:

link

 

I am very confused by the pricing for this unit, though. The 5.5 kW with wi-fi plug is priced at THB 41.279 while the 5 kW with wi-fi is priced at THB 44.888. Seems strange. Without wi-fi the 5 kW version is cheaper than the 5.5 kW version, and it is also the exact same price as the 5.5 kW version with wi-fi. So maybe they just entered the wrong price in the system for the latter. 

 

I haven't completely decided on whether to go for the on-grid or off-grid hybrid. What matters most to me is that the inverter is able to "top up" from the net, is my consumption exceeds what it can supply from panels plus battery.

Edited August 3, 2022 by Sophon

[Crossy]

6 minutes ago, Sophon said:

What about this Must inverter:

 

MUST inverters DO do export - but IIRC there's a thread somewhere on problems with the beast, including poor export performance ???? 

 

Of course YMMV!

[BritManToo]

7 minutes ago, Sophon said:

I am very confused by the pricing for this unit, though. The 5.5 kW with wi-fi plug is priced at THB 41.279 while the 5 kW with wi-fi is priced at THB 44.888. Seems strange. Without wi-fi the 5 kW version is cheaper than the 5.5 kW version, and it is also the exact same price as the 5.5 kW version with wi-fi. So maybe they just entered the wrong price in the system for the latter. 

Very brave to buy from China, no brand, no warrenty, no previous customers according to the blurb. 

[Sophon]

20 minutes ago, BritManToo said:

Waste of money IMHO for the ability to illegally export. 

You could be right. Buying an off-brand can be a risk, maybe it works well and lasts, and maybe it doesn't. But then again, the same can probably be said about brand items.

 

Does your unit have the wifi function, and if so how well does it work.