Solar - General

[KhunLA]

17 minutes ago, Thaifish said:

There is an on-mass roll out of meters happening everywhere around Issan. 

Same down here/PKK, as all new meters (inclusive, 14 month on) seem to be digital.  One builder, having new houses nearby, about 15, this past year, and all have new digital meters.

[Muhendis]

21 minutes ago, Thaifish said:

but things are changing ever so slowly here.

Things are, like you say, changing ever so slowly.

This sub-lightning speed of change is one of the reasons we went solar. 

We waited 7 years to get our permanent PEA supply.

PEA weren't the people to talk to for us. We had to get approval from the local government office who would then pay for PEA to install the supply.

They wouldn't do it until 6 or more houses needed it. That took us about 3 days to arrange. For that 7 year wait, solar was the only way to go for me.

Just imagine the cost of 7 years at temporary/construction price of 8 Baht/unit.

Any advance on 256k anyone?

[The Fugitive]

13 minutes ago, Muhendis said:

Things are, like you say, changing ever so slowly.

This sub-lightning speed of change is one of the reasons we went solar. 

We waited 7 years to get our permanent PEA supply.

PEA weren't the people to talk to for us. We had to get approval from the local government office who would then pay for PEA to install the supply.

They wouldn't do it until 6 or more houses needed it. That took us about 3 days to arrange. For that 7 year wait, solar was the only way to go for me.

Just imagine the cost of 7 years at temporary/construction price of 8 Baht/unit.

Any advance on 256k anyone?

Slowly is the operative word. Took 3 years for the failed street lamp outside our house to be repaired. That a relative is the partner of a high ranking woman at our TessaBaan and also knowing several workers made no difference. We were repeatedly told we were on the list and just had to wait.

[Thaifish]

21 hours ago, MangoKorat said:

Oh and one related question - the PEA just love their overhead wires. I on the other hand hate them.   Does anyone know if they'll bring their supply on to site underground if I dig the trench and put a conduit in?

 

My power from the grid was put underground in conduit no problem.

[Crossy]

@Thaifish have you had a bill against your electronic meter yet? If not, when one comes do ensure that the export energy isn't on it as a charge!!

 

[Thaifish]

3 minutes ago, Crossy said:

@Thaifish have you had a bill against your electronic meter yet? If not, when one comes do ensure that the export energy isn't on it as a charge!!

 

 

Yes have received a bill and studied it as I do. The bill had a slightly different layout to normal as it showed both the old meter usage + the new digital usage. Could not see any export charges. Thanks for letting us know.   

 

[patman30]

23 hours ago, MangoKorat said:

doesn't that work out more expensive

when i was looking at inverters for my own setup
a 15KW inverter (i forget the brand) was 3x the cost of my 5KW growatt inverters

[TimeMachine]

3 hours ago, Thaifish said:

 

From Burriram. I got busted with an old reverse spinning disk meter about 3 years ago. PEA turned up about a week later and installed a one way meter. There was no fines or anything like that. Have just had a digital meter installed now which I have been trying to get one ever since they took the reverse spinning meter away. There is an on-mass roll out of meters happening everywhere around Issan. Scrolling through the digital meter menu it shows the export power reading is greater than the import. Long story but since my Solar installation 10Kw I have got nowhere with PEA purchasing the export power. I am now in the process of bypassing the local PEA and going through their Bangkok headquarters. I doubt I will get anywhere but things are changing ever so slowly here.

I suppose not being able to get money or credit for feed in is a bummer. I would just try and store some into a small battery backup then rather than it go to waste back into the grid for free. Just a basic car battery small inverter to run a fan and lights for when power goes out. Timered to charge only when sun is out. Good to know that you can do your own grid tied and they won't throw u in prison. Thanks for responding.

Edited November 3, 2023 by TimeMachine

[MangoKorat]

After reading Crossy's excellent guide to the different types of system in depth, I've come to the conclusion that like him, I'll be going for an On Grid Hybrid system. That type is clearly going to cost me more but I think it will be worth it in the long run.

 

It is very difficult for me to do an energy audit as quite rightly, many have suggested as when I build the house I'm planning, my circumstances will change quite a lot.  I can't even consider that with any accuracy at my current Thai home as I don't live in Thailand full time yet and my useage varies greatly.  Keeping in mind that one of my main considerations was that I would like to have my aircon on whenever I wish, I can only guess that a 10kw system will take care of my requirements. 

 

However, it seems there is more to it than just guessing how many kw I need - I need to decide on how panels and batteries will be required and that's where I am stuck and my lack of knowledge comes to the forefront.

 

I'm aware that I will need a minimum number of panels to achieve the output that I require but if I understand correctly, I can have as many panels as I wish/have space for?  I also guess that having more panels than the bare minimum will assist in providing the power I am hoping for when the sun is not at its best?

 

One website I looked at states that 24 panels rated at 415w will produce 9.96kw - an easy enough calculation.  Real world there will be some loss and those figures are optimal right?

 

Crossy has advised that I locate the panels on the ground or on a low building.  That would require a complete change of the building/layout design which is problematic. As its a new build, I'm pretty sure that I can 'design in' access to the roof without too much trouble.  Allowing for space for access/maintenance, I should have around 50 sq m available for panels. If that's not enough, I could locate additional panels over my septic tank area. Are there any problems with having panels in 2 locations?

 

Regarding batteries, again there must surely be a minimum amount but if I have more than the minimum, I have more storage so will be able to have more power for longer.....correct?

 

Is there a maximum amount of batteries or an amount where charging them all takes so long that it is not viable?

 

I may not be able to provide a proper 'energy audit' but I can have a 'best guess' at the amount of power I will need and when I'm likely to need it - if I do that would somebody be prepared to advise me on the amount of panels/batteries that would be best suited to my needs?

 

It would be nice to think I could run all the time using only solar but as I will have a grid connection, its a goal not a necessity.

 

Of course, the over-riding factor is, how much I'm prepared to spend on this system. I had originally thought I could do it for 300k but I get the feeling 500k may be closer to the mark. I don't think I'd be prepared to go over that figure - given that my original reason for going solar was being able to have aircon on whenever I want without worrying about high electric bills and the additional environmental impact.

Edited November 6, 2023 by MangoKorat

[MangoKorat]

Amendment/correction to the above - with a little tweaking + I had not allowed for the fact that the roof will oversail the building's dimensions, I can probably make 70sq m available on a single south facing pitch of the roof whilst still allowing walkways for maintenance.

[Crossy]

Have a look at the newer hybrids that offer "grid-assist" modes rather than the on-grid hybrid we have. These don't have a separate "essential power" output as basically, the whole output is "essential". GroWatt are a popular budget brand which lend themselves to DIY.

 

70m² of roof is going to house about 30-35 340W panels (or fewer bigger ones) so 10 - 12kW of solar. Our 12x6m car port has 32 panels with space for 6 more.

 

That will generate, on average, about 35kWh per day.

 

How much storage you need will depend upon your usage patterns, luckily storage is easily expanded so start smallish.

Your inverter size will depend upon your maximum load, you can estimate this reasonably well from your house design since your major loads are likely to be A/C, cooking and water heating. Plus whatever your man-cave uses of course.

 

 

 

[MangoKorat]

Thanks for that Crossy, I've been mulling over your suggestion regarding ground mounted panels or mounting them on low roofs. I had as I said previously, dismissed it as my outbuildings will be at the rear of the house - North.  However, what we are essentially building is a farmhouse and although I really don't want to create a farmyard, madam keeps banging on about her 'tractor house'.  I'm thinking I could accommodate that with a car port type, open fronted single pitch roofed building in line with the house to the west of it - roof South facing. I guess its only fair to let her have a little win and if that solves the solar location problem, so be it. I can easily screen it 😁.  This would probably be either very close to the house or joined to it so there shouldn't be too much of a problem with voltage drop, if that's a problem?

 

From my days in project management I always started with a set of qoutes, presented them to the client and then worked on shaving 10 to 15% off them if possible without compromising on quality.  There's nothing better than earning 'brownie points' towards your bonus from a client who sees you've just reduced his costs significantly.  However, in this case I'm both project manager and client and I have no experience and therefore no idea on what this system will cost.

 

As I said, I had a wild guess on 300k initially and without looking back, I believe one member put together a 10kw system for that amount.  Time has moved on and I believe what I'm planning could well be more expensive than that but I would like to put a cap on the spend in order that I can budget for the other major spends - the uPVC doors and windows and kitchen cost me close to 500k at my current house and that was in 2018. One thing I learned when re-fitting/altering my current house is that Western style fittings are far more expensive in Thailand than they are in the West. The kitchen for example would have been at least 50k less in the UK.

 

However, it appears that the opposite may be true when it comes to solar systems - Growatt Inverters are around 25% cheaper in Thailand than they are in the UK. Is it realistic to be able to put a decent quality system together with LFP batteries for 500k or less?

 

 

 

 

[MangoKorat]

On the subject of power usage

 

At my current Thai property I use an Air Source Heat Pump to provide hot water - I insist on hot water. I was very happy with its performance but soon after installing it I realised that it was not as economical as I'd thought because the system was heating up a tank containing 200L of water - a shower uses what? 40 to 50L??  However, I can see a situation at the new house where several showers will be taken in the morning at similar times and before the sun does its job.  I've had some of the smaller electric showers in the past and as soon as you increase the flow, the water is barely luke warm. If I was to install them now I would go for a minimum of 7.5kw.

 

So it could be that an Air Source Heat Pump would reduce demand at particular times.  They're not cheap but they are nowhere near as expensive in Thailand as they are in the UK.  I bought mine from a mate who owned a factory in Chonburi that put them together and it cost 50,000. He's retired now but I think he can still obatin them.  Is that worth considering or is it better to let the grid top up at high demand times when the batteries are low? Or then again, would it be better to spend the cash on more storage?

Edited November 6, 2023 by MangoKorat

[Muhendis]

27 minutes ago, MangoKorat said:

On the subject of power usage

 

At my current Thai property I use an Air Source Heat Pump to provide hot water - I insist on hot water. I was very happy with its performance but soon after installing it I realised that it was not as economical as I'd thought because the system was heating up a tank containing 200L of water - a shower uses what? 40 to 50L??  However, I can see a situation at the new house where several showers will be taken in the morning at similar times and before the sun does its job.  I've had some of the smaller electric showers in the past and as soon as you increase the flow, the water is barely luke warm. If I was to install them now I would go for a minimum of 7.5kw.

 

So it could be that an Air Source Heat Pump would reduce demand at particular times.  They're not cheap but they are nowhere near as expensive in Thailand as they are in the UK.  I bought mine from a mate who owned a factory in Chonburi that put them together and it cost 50,000. He's retired now but I think he can still obatin them.  Is that worth considering or is it better to let the grid top up at high demand times when the batteries are low? Or then again, would it be better to spend the cash on more storage?

I don't know about Air Source Heat Pumps, but what I use is a flat panel heat exchanger which cost about 400 Baht to put together.

Like you, I have a 200L storage tank which is insulated, and a water circulation pump powered from a small 65W solar panel. The whole lot came to about 1,500 baht.

So, with zero running costs and no maintainance costs (yet) I get 200L of hot water daily. Been like that for ten years or more now.

 

Your post suddenly switches to topping up batteries from the grid. Why are you considering that?

Edited November 7, 2023 by Muhendis

[MangoKorat]

52 minutes ago, Muhendis said:

So, with zero running costs and no maintainance costs (yet) I get 200L of hot water daily. Been like that for ten years or more now.

Yes, someone posted on those but would it provide 3 showers at 6am without running cold? If so its a far better option than my Heat Pump.

[MangoKorat]

54 minutes ago, Muhendis said:

Your post suddenly switches to topping up batteries from the grid. Why are you considering that?

I'm not, I'm trying to decide on the best system and I'm a total novice.

[Muhendis]

7 minutes ago, MangoKorat said:

Yes, someone posted on those but would it provide 3 showers at 6am without running cold? If so its a far better option than my Heat Pump.

 

6 minutes ago, MangoKorat said:

I'm not, I'm trying to decide on the best system and I'm a total novice.

OK I think I know what you're saying.

A fuller description of my system might help.

I have two showers one which uses only solar hot water and the other which uses an instant 4kW electric heater (4kW is plenty hot enough at 80% of max.).

We get plenty of hot water for a couple of showers from the solar heated water in the evening and there's still some left for a warm shower in the morning. That can be hotter if the previous day was particularly hot and sunny.

The instant hot water shower I prefer in the mornings runs off the solar charged batteries which are then down to 70% of full which is what was intended by design.

The inverter which powers the shower et.al. is a simple 8kW job

[007 RED]

11 hours ago, MangoKorat said:

One website I looked at states that 24 panels rated at 415w will produce 9.96kw - an easy enough calculation.  Real world there will be some loss and those figures are optimal right?

 

Your assumption that in the real world there will be some loss is correct.  In fact, the losses can be as high as 25%.  So this is something that you need to bear in mind when doing your calculation with respect to the number of panels that you need.

 

My system is small compared to what you are considering, but it can illustrate real world loss. 

 

My system comprises 4 x 415W monocrystalline half cut panels mounted on my carport roof, which is inclined at approximately 15^o and facing due South, which in theory is an ideal installation that should be capable of producing 1.66kW.

 

Below is a graph taken from my solar system monitoring facility yesterday.

 

As you will see at 12:20pm the system was producing a max of 1.33kW.  At that point in time, it was reasonably sunny, so the sunlight should hitting the panels almost perpendicular.  That said 1.33kW which is approximately 20% below what the panels in theory should be capable of producing.

 

FYI… The sudden drop in output was cause by horrible grey fluffy stuff floating by.  The big drop in output around 3pm was caused by heavy rain/thunderstorm which continued to around 6pm.

 

So what causes this loss?

 

All solar panels are rated under laboratory conditions.  Basically, this is with a constant known light source which is directed perpendicular to the photovoltaic cell, at a constant ambient temperature of 25^o C.

 

Firstly, this means that if the sunlight is at an angle less/more than perpendicular to the solar panel there is going to be loss in output.  This can be seen from my graph above as the sun rises to its highest point around noon.

 

Secondly, the biggest culprit is going to be heat.  As you are aware the average ambient daytime temperature here in Thailand is around 32^o C.  Hence for every degree above the laboratory test temperature of 25^o C the panel will lose a given percentage of its efficiency.  The panel spec provided by the manufacturer/supplier will indicate % efficiency loss per degree above 25^o C.

 

Although the average daytime ambient temperature is around 32^o C, the panels will in fact get considerably hotter due to heat radiation from the sun.  I appreciate its not the most scientific illustration, but the photo below shows the temperature of my panels at noon on a good sunny day.  They were hot to say the least.

 

 

Hence, from the above photo it will be seen that the panels at that point in time were 38^o C above the laboratory test condition, which would results in 38 x % decrease in the panel’s efficiency, which would not be insignificant.

 

Thirdly, albeit a minor one, dust, dirt, bird droppings, leaves  and clouds etc will also contribute to a loss in the panel’s efficiency.  Below is a photo of the dust/dirt on my panels.  In fairness, I live in an area where there are a number of factories who tend to emit pollution, so cleaning on a regular basis helps maintain best possible performance.

 

 

So, I would suggest that using the illustration which you used, e.g., 24 panels at 415W = 9.96kW is more than likely to only produce around 7.47kW on a good sunny day at noon and you may need to consider increasing the number of panels or going for large output panels e.g. 450W.  Hence, 24 panels at 450W will give a theoretical output of almost 13kW, which assuming a 25% loss will give you a more realistic output of 9.7kW.

 

I hope this helps, and good luck with your proposed project

[MangoKorat]

11 hours ago, Muhendis said:

 

OK I think I know what you're saying.

A fuller description of my system might help.

I have two showers one which uses only solar hot water and the other which uses an instant 4kW electric heater (4kW is plenty hot enough at 80% of max.).

We get plenty of hot water for a couple of showers from the solar heated water in the evening and there's still some left for a warm shower in the morning. That can be hotter if the previous day was particularly hot and sunny.

The instant hot water shower I prefer in the mornings runs off the solar charged batteries which are then down to 70% of full which is what was intended by design.

The inverter which powers the shower et.al. is a simple 8kW job

Thanks, I think there's a good argument for including a solar water heater in my system and I fully understand that there will be losses in the solar energy system.  I'd take a stab that trying to calculate such losses is very difficult because they are not just limited to parts of the system itself but also down to other factors like cloud etc. as you clearly illustrate.

 

One thing I wonder, and I'd probably have to talk to the supplier, is if I can find a way of incorporating a solar water heater with a heat pump so that it heats water in the same tank.  Not sure that's possible as its a pressurised system in part.  The heat pump is supplied directly from the cold water system via a one way valve, it could be possible to use the solar heater as the supply instead - I don't see why not but it may require a second water pump.

 

I'm going to have to have an alternative for hot water in any case and whilst 50,000 for a heat pump might sound a lot, the alternative is 3 x electric showers + 1 under sink heater (they have to be very high powered to be of any use) and that would still leave the hand basins with only cold water.  My current heat pump supplies the entire hot water system - 3 showers, 3 basins + the kitchen sink. I have the overall temperature set fairly high but the showers are thermostatic valve types. The pump itself has a built in expansion tank and copes well without an additonal one.

[Muhendis]

25 minutes ago, MangoKorat said:

Thanks, I think there's a good argument for including a solar water heater in my system and I fully understand that there will be losses in the solar energy system.  I'd take a stab that trying to calculate such losses is very difficult because they are not just limited to parts of the system itself but also down to other factors like cloud etc. as you clearly illustrate.

 

One thing I wonder, and I'd probably have to talk to the supplier, is if I can find a way of incorporating a solar water heater with a heat pump so that it heats water in the same tank.  Not sure that's possible as its a pressurised system in part.  The heat pump is supplied directly from the cold water system via a one way valve, it could be possible to use the solar heater as the supply instead - I don't see why not but it may require a second water pump.

 

I'm going to have to have an alternative for hot water in any case and whilst 50,000 for a heat pump might sound a lot, the alternative is 3 x electric showers + 1 under sink heater (they have to be very high powered to be of any use) and that would still leave the hand basins with only cold water.  My current heat pump supplies the entire hot water system - 3 showers, 3 basins + the kitchen sink. I have the overall temperature set fairly high but the showers are thermostatic valve types. The pump itself has a built in expansion tank and copes well without an additonal one.

My solar hot water is a direct system pressurised at around 3 bar. I don't know if such as mine is available commercially 'cause I built my own with copper pipe and ali. sheet for heat collection all enclosed in a polycarbonate/wood box. 

Fun project. 

Temperature of water gets up to over 50 C.

I think there is no reason not to incorporate a solar water heat exchanger into your existing heat pump.

[MangoKorat]

1 minute ago, Muhendis said:

I think there is no reason not to incorporate a solar water heat exchanger into your existing heat pump.

Yes, I can't see why not but on the supply side.

[Muhendis]

35 minutes ago, MangoKorat said:

Yes, I can't see why not but on the supply side.

Putting such a heat exchanger on the primary or supply side would have minimal effect. 

Water would receive a little heat coming in but would be replaced by new cold water. The amount of heat gained in this way would not be worth the effort.

To take advantage of solar water heating you would need to recirculate the water between the exchanger and a storage vessel. I this way, water warmed by the panel would be stored in the tank and then recirculated through the heat exchanger adding more heat as it goes round the system.

So it would need to be on the secondary side.

[MangoKorat]

16 hours ago, Crossy said:

Your inverter size will depend upon your maximum load, you can estimate this reasonably well from your house design since your major loads are likely to be A/C, cooking and water heating. Plus whatever your man-cave uses of course.

Right well that may take some time as the design has to be finalised before the size of the aircon units can be calculated etc.

 

In the meantime, can I ask if any part of the system is liable to damage from usage?  I will have a  small MIG welder in my workshop - around 180amp.  Just wondering if my workshop would be better running off the grid?

[MangoKorat]

5 minutes ago, Muhendis said:

Putting such a heat exchanger on the primary or supply side would have minimal effect. 

Water would receive a little heat coming in but would be replaced by new cold water. The amount of heat gained in this way would not be worth the effort.

To take advantage of solar water heating you would need to recirculate the water between the exchanger and a storage vessel. I this way, water warmed by the panel would be stored in the tank and then recirculated through the heat exchanger adding more heat as it goes round the system.

So it would need to be on the secondary side.

Maybe I'm not being clear.  What I'm suggesting is - supply the heat pump with water that has already been heated by the solar heating thereby using the pump's tank for storage. The pump would then only kick in when the temperature dropped.

 

I'm not sure that I want to interfere with the internals of the heat pump beyond the tankand I'm also pretty sure there won't be any spare connections inside. The secondary side is full of valves and sensors + a secondary water pump - I'm not at all sure its wise to mess with that.

 

By the way, did you use the 'green' pipe for your hot water system?  I'm pretty sure doing the jointing for a new build will be much easier but when you're working on a ladder, inside an already constructed suspended ceiling as I was at my current house - jeez its bad.  I burned my arms many times trying to heat up the joints with the jointing tool.  Those things need 3 hands at the best of times, trying to use one as I did was hellish.

[Muhendis]

8 hours ago, MangoKorat said:

Right well that may take some time as the design has to be finalised before the size of the aircon units can be calculated etc.

 

In the meantime, can I ask if any part of the system is liable to damage from usage?  I will have a  small MIG welder in my workshop - around 180amp.  Just wondering if my workshop would be better running off the grid?

Usually inverters are limited with output protection. I say usually because I tested a cheap one some years ago and it was not spec'd correctly. After a few days it sent out some very indigenous looking smoke signals and ceased to be an inverter. All the output transistors were totally destroyed.

 

My current 8kW inverter has been in service for over 7 years and is frequently loaded with 4 or more kW by my woodworking machines. I also use an inverter type arc welder with no problems.

[Muhendis]

8 hours ago, MangoKorat said:

Maybe I'm not being clear.  What I'm suggesting is - supply the heat pump with water that has already been heated by the solar heating thereby using the pump's tank for storage. The pump would then only kick in when the temperature dropped.

 

I'm not sure that I want to interfere with the internals of the heat pump beyond the tankand I'm also pretty sure there won't be any spare connections inside. The secondary side is full of valves and sensors + a secondary water pump - I'm not at all sure its wise to mess with that.

 

By the way, did you use the 'green' pipe for your hot water system?  I'm pretty sure doing the jointing for a new build will be much easier but when you're working on a ladder, inside an already constructed suspended ceiling as I was at my current house - jeez its bad.  I burned my arms many times trying to heat up the joints with the jointing tool.  Those things need 3 hands at the best of times, trying to use one as I did was hellish.

I did not use the green ppr pipe for my hot water. I wish I had. I used insulated copper pipe or rather my builder did but to my specification. I didn't know about the ppr at that time and not too sure if it was around anyway. My house was built about 10 years ago.

[Pink7]

11 hours ago, MangoKorat said:

I'm going to have to have an alternative for hot water in any case and whilst 50,000 for a heat pump might sound a lot, the alternative is 3 x electric showers + 1 under sink heater (they have to be very high powered to be of any use) and that would still leave the hand basins with only cold water.  My current heat pump supplies the entire hot water system - 3 showers, 3 basins + the kitchen sink. I have the overall temperature set fairly high but the showers are thermostatic valve types. The pump itself has a built in expansion tank and copes well without an additonal one.

Be aware that 3 x electric showers might not be able to be used in same time from a inverter capacity of for example 10kwh. I have 2 x 4500w showers but we not use in same time and i not run them on very high power(heat) If I had redo it I had built a sun heated solution. One alternative could to connect your showers to grid and not to the inverter.

 

Pink

[Muhendis]

13 minutes ago, Pink7 said:

Be aware that 3 x electric showers might not be able to be used in same time from a inverter capacity of for example 10kwh. I have 2 x 4500w showers but we not use in same time and i not run them on very high power(heat) If I had redo it I had built a sun heated solution. One alternative could to connect your showers to grid and not to the inverter.

 

Pink

Exactly right.

It matters not how much solar energy nor the size of your ESS you have. The bottle neck is the inverter output capability

[Crossy]

If you go with the cart-port (tractor house) for the panel location then the house roof is freed up for a solar hot-water system

 

Our neighbours in our old place had a heat-pipe system, on a good day it would boil the water in the tank!!