Grid tie solar in a generator-based environment? (split from the Solar Car Port thread)

[ExpatOilWorker]

<Note this is a branch from the Solar Car Port thread which I think deserves its own dedicated thread>

 

Just met the owner of the below system and the cost are as follow:

Panels 10x470W = 40,000 baht

Inverter = 16,000 baht

Battery (used) 48V x 200 Ah = 30,000 baht

Breaker, wire, box, etc, = 10,000 baht

Labor = Self installation 

 

In total, just shy of 100,000 baht for nearly a 10 kWh hybrid system 

 

How does that compare in price to your system Crossy?

 

[Crossy]

1 hour ago, ExpatOilWorker said:

How does that compare in price to your system Crossy?

 

It's cheaper by a fair bit, but the hybrid inverter doesn't appear to be grid tie so your load must remain below the inverter maximum output. Our 5kW grid-tie hybrid was 45k Baht.

 

We are at about 180k for roughly 20kWh (gets to 30kWh on a decent day) grid-tie (zero export available if needed), but the inverters are both running at about 50% solar input coz I've not bought any more panels yet. I need one of those "round tuit" devices methinks.

 

Similar battery pack (used golf-cart cells), our 200Ah (tested as 165Ah) 48V pack was 24k but the BMS and balancer pokes it towards 30k. 

 

Good to see he's using a decent "flying capacitor" active balancer on the battery pack (the bare circuit board), I have the same (or very similar unit).

[Muhendis]

For you Crossy.    Enjoy.

[Crossy]

33 minutes ago, Muhendis said:

For you Crossy.    Enjoy.

 

The guy on Ringwood market who used to sell those also sold "left-handed" mugs, they were actually a production error and had the picture on the wrong side. They were so popular he had to actually order more from the factory.

 

[Muhendis]

8 minutes ago, Crossy said:

 

The guy on Ringwood market who used to sell those also sold "left-handed" mugs, they were actually a production error and had the picture on the wrong side. They were so popular he had to actually order more from the factory.

 

Is that the place you drive past on the way to Southampton?

[Crossy]

1 minute ago, Muhendis said:

Is that the place you drive past on the way to Southampton?

 

If coming from the west on the A31 yup, just before you get to the New Forest.

 

Superb (and lethal) real-ales from Ringwood Brewery too.

 

[Muhendis]

21 minutes ago, Crossy said:

 

If coming from the west on the A31 yup, just before you get to the New Forest.

 

Superb (and lethal) real-ales from Ringwood Brewery too.

 

Well remembered happy days looking at boats I couldn't afford. Way before solar .

[ExpatOilWorker]

1 hour ago, Crossy said:

 

It's cheaper by a fair bit, but the hybrid inverter doesn't appear to be grid tie so your load must remain below the inverter maximum output. Our 5kW grid-tie hybrid was 45k Baht.

 

We are at about 180k for roughly 20kWh (gets to 30kWh on a decent day) grid-tie (zero export available if needed), but the inverters are both running at about 50% solar input coz I've not bought any more panels yet. I need one of those "round tuit" devices methinks.

 

Similar battery pack (used golf-cart cells), our 200Ah (tested as 165Ah) 48V pack was 24k but the BMS and balancer pokes it towards 30k. 

 

Good to see he's using a decent "flying capacitor" active balancer on the battery pack (the bare circuit board), I have the same (or very similar unit).

Another interesting thing about his setup is that he is running all panels in serie, but since the inverter is rated to 500V he had to remove one panel and is currently only using 9 panels.

[Crossy]

5 minutes ago, ExpatOilWorker said:

Another interesting thing about his setup is that he is running all panels in serie, but since the inverter is rated to 500V he had to remove one panel and is currently only using 9 panels.

 

Two 5 panel strings in parallel should work for him ???? 

[ExpatOilWorker]

6 hours ago, Crossy said:

the hybrid inverter doesn't appear to be grid tie so your load must remain below the inverter maximum output.

That might actually be perfect for me, as in no way shape or form can I push any juice back into our community genset grid. Apparently, it can fry the control boards on the gensets.

Do I need to replace my old aircon units and the water pump with inverter type units, to avoid the x7 startup consumption or will the 6000 W solar inverter be able to handle the older 13k BTU units?

[Crossy]

You might get away with inverter A/Cs, they do tend to soft start. Our 6kVA genset won't reliably start our conventional 12kBTU bedroom A/C but the 23kBTU inverter unit in the lounge starts every time.

 

Personally I'd go with a proper grid-tie hybrid if you want to store energy for night use but leave the unit set to zero export, no power back to the grid, ever, but if you suddenly need 10kW then it's available without any messing about. Of course there's also the handy-dandy UPS functionality too.

 

It really depends what you want to achieve.

[Muhendis]

9 minutes ago, ExpatOilWorker said:

That might actually be perfect for me, as in no way shape or form can I push any juice back into our community genset grid. Apparently, it can fry the control boards on the gensets.

Do I need to replace my old aircon units and the water pump with inverter type units, to avoid the x7 startup consumption or will the 6000 W solar inverter be able to handle the older 13k BTU units?

You would need to check the specs of the ac output from the inverter. They normally indicate what the short duration peak power is. It seems to normally be about double for ½ second or maybe 1 second.

[ExpatOilWorker]

1 hour ago, Crossy said:

You might get away with inverter A/Cs, they do tend to soft start. Our 6kVA genset won't reliably start our conventional 12kBTU bedroom A/C but the 23kBTU inverter unit in the lounge starts every time.

 

Personally I'd go with a proper grid-tie hybrid if you want to store energy for night use but leave the unit set to zero export, no power back to the grid, ever, but if you suddenly need 10kW then it's available without any messing about. Of course there's also the handy-dandy UPS functionality too.

 

It really depends what you want to achieve.

Apparently grid-tie hybrid and gensets are not the best of friends.

From the Internet:

"However, the standard grid-tie inverter’s sensing circuit is very sensitive, especially to hz, and it will require a good quality generator for this to work. Some inverters, that are designed to work in mixed source environments, like the Outback Inverters, are capable of even working with poorly regulated generators."

 

Even of zero export is selected, the inverter is still synchronized with the genset grid and I guess floating a few mA back and forth. That is all good, until a genset trips and the backup genset kicks in. At the moment we just experience flickering lights during this 1-2 seconds switch, but the inverter might think all hell have broken lose with such a dramatic switch.

Please correct me if I am wrong, I am on very thin ice with all this solar electronics. 

[Crossy]

How big are the gensets? I'm assuming they're not the wimpy little things we use for domestic backup power.

 

Big units will be much more stable frequency wise (more rotating mass).

 

Power dips during switch-over shouldn't cause your inverter headaches, if it's long enough the UPS function will cut in to keep you alive.

[sezze]

What exactly does the 2nd pic do ? Since the 1st is a hybrid inverter , with breaker box , all in one , charger inverter . 3th pic are the batts , but i do not get 2nd pic . I see a 12V inverter 3000W it states , and a charge controller . The batteries are not wired on the fuses also , so it must have been the old system , replaced by the new .

[ExpatOilWorker]

22 hours ago, Crossy said:

the hybrid inverter doesn't appear to be grid tie so your load must remain below the inverter maximum output.

As it turns out, the inverter is tied to the grid but not grid tie!

The inverter is connected to the grid, so if the battery runs low at 4 am the grid will simply take over the load and you can stay in bed with the AC running.

I am not sure if the inverter will charge the batteries with grid power during prolonged cloudy periods or the batteries will simply stay low and hope for sunnier days tomorrow. Anyone knows or God forbid, time to pull out the user manual?

What Crossy is raising the non-grid-tie red flag about, it that you can't combine grid and solar power, meaning the entire household is limited to 5,500 W.

 

Next step is to make a list of start up power (Amps) for aircons,  water pump, vacuum cleaner, hair dryer, ceiling fan, floor fan, blender, drill, etc.

Never an easy day in solar world.

 

 

 

 

[Crossy]

Assuming these beasts are parallel capable you could use several to meet your peak load requirements.

Alternatively keep the really big loads (water heaters perhaps) on the grid and use the solar energy for everything else.

 

Lot's of ways to skin this particular cat ????

 

[Muhendis]

35 minutes ago, ExpatOilWorker said:

Next step is to make a list of start up power (Amps) for aircons,  water pump, vacuum cleaner, hair dryer, ceiling fan, floor fan, blender, drill, etc.

This is a lot simpler than you might think. You only need to worry about the biggest loads. If you work it backwards from the maximum power capability of the inverter which is 5.5 kw. First there is the short duration peak power capability which is 11 kw Divide that by 9 = 1.22kw (I use nine times for startup current under load). Look for any of your motors which get anywhere near that. Have a think about what else may be already running at that time (fridge for example). If you're still less than the short duration peak then there is nothing to worry about. Worst case scenario is, of course, all motors switched on at precisely the same time. That's never going to happen.

[driver52]

On 8/16/2021 at 6:32 AM, ExpatOilWorker said:

just shy of 100,000 baht for nearly a 10 kWh hybrid system

that sounds a bit of a bizarre statement to me! ????

ie you've actually quoted 4700watts worth of panels BUT the total kWh depends on the amount of sunshine during the day, shirley?

[j.a.farang001]

23 hours ago, Crossy said:

Personally I'd go with a proper grid-tie hybrid if you want to store energy for night use but leave the unit set to zero export, no power back to the grid, ever, but if you suddenly need 10kW then it's available without any messing about. Of course there's also the handy-dandy UPS functionality too.

This is exactly what we want for the house we're building in Chiang Rai. Do you have any points of contact in that neck of the woods?

[Crossy]

2 minutes ago, j.a.farang001 said:

This is exactly what we want for the house we're building in Chiang Rai. Do you have any points of contact in that neck of the woods?

 

Me no, we are to far away, @Thaifish seems to have had a decent contractor, have a look at his thread or he will likely be along shortly anyway.

 

[ExpatOilWorker]

1 hour ago, driver52 said:

that sounds a bit of a bizarre statement to me! ????

ie you've actually quoted 4700watts worth of panels BUT the total kWh depends on the amount of sunshine during the day, shirley?

That is correct, but with a hybrid the fun and action happen at night. You just toss a few extra panels on top of the roof and forget they are even there. It is all about batteries baby, both in terms of cost and capacity if you can survive from sunset to sunrise and here kWh play a critical part.

[driver52]

2 hours ago, ExpatOilWorker said:

That is correct, but with a hybrid the fun and action happen at night. You just toss a few extra panels on top of the roof and forget they are even there. It is all about batteries baby, both in terms of cost and capacity if you can survive from sunset to sunrise and here kWh play a critical part.

ah so it's your batteries that are 10kWh? those batteries are tiny compared to 'old fashioned ones' lol

where's the battery pic from? those bits on the top look interesting!

[Thaifish]

16 hours ago, Crossy said:

Do you have any points of contact in that neck of the woods?

 

16 hours ago, Crossy said:

@Thaifish seems to have had a decent contractor, have a look at his thread or he will likely be along shortly anyway.

My contractor Bangkok based. Dragon energy.

https://www.dragonenergysolar.com/en/

 

I have not updated my post recently but I am going down the path of installing a 15kwh Huawei battery bank..$$$$$...probably install myself

 

[ExpatOilWorker]

49 minutes ago, driver52 said:

ah so it's your batteries that are 10kWh? those batteries are tiny compared to 'old fashioned ones' lol

where's the battery pic from? those bits on the top look interesting!

On 8/16/2021 at 11:45 AM, Crossy said:

Good to see he's using a decent "flying capacitor" active balancer on the battery pack (the bare circuit board), I have the same (or very similar unit).

It is some sort of BMS (Battery Management System), but only sparkies know what they are actually doing.

 

Battery (used) 48V x 200 Ah or 9.6 kWh, so nearly 10 kWh.

[Crossy]

9 hours ago, driver52 said:

ah so it's your batteries that are 10kWh? those batteries are tiny compared to 'old fashioned ones' lol

where's the battery pic from? those bits on the top look interesting!

 

The golf-cart cells are about 280 x 182 x 71 mm and weigh in at 4.2kg each. You need 16 of them for a 48V pack like that. The used 200Ah ones come in at about 1,600 Baht a pop.

 

The black bit top right is the BMS (Battery Management System). This monitors the voltage of the individual cells and cuts off charge / discharge should any one cell approach a dangerous (to the cell) level. Lithium cells are very easy to kill with over charge/discharge. Many have BlueTooth or WiFi so you can monitor your cells if that's what floats your boat.

 

The naked pcb to the left is a "flying capacitor" active cell balancer. This takes energy from cells with high voltage and gives it to cells with lower voltage keeping all the cells within a specific range of voltages. Our (very similar pack) has all 16 cells within 0.014V after 12.5 hours of night-time discharge @500W. 

 

Note:- Most BMS's do have cell balancing but it's usually "passive" and can only transfer between adjacent cells with very limited current. The active balancer can transfer at up to 5A between any pair of cells. Dead clever (and cost 2k Baht).

[ExpatOilWorker]

5 minutes ago, Crossy said:

 

The black bit top right is the BMS (Battery Management System). This monitors the voltage of the individual cells and cuts off charge / discharge should any one cell approach a dangerous (to the cell) level. Lithium cells are very easy to kill with over charge/discharge. Many have BlueTooth or WiFi so you can monitor your cells if that's what floats your boat.

 

The naked pcb to the left is a "flying capacitor" active cell balancer. This takes energy from cells with high voltage and gives it to cells with lower voltage keeping all the cells within a specific range of voltages. Our (very similar pack) has all 16 cells within 0.014V after 12.5hours of night-time discharge @500W. 

 

Note:- Most BMS's do have cell balancing but it's usually "passive" and can only transfer between adjacent cells with very limited current. The active balancer can transfer at up to 5A between any pair of cells. Dead clever (and cost 2k Baht).

Important information.  Active balance is the way to go.

While we are at the subject can you also explain what is meant by 3S, 4S, 7S, etc.? Is it number of batteries in series?

 

Are the below models active or passive? 

THB 1,450.93  8%OFF | DALY Smart BMS 12V 36V 48V 30A 60A 80A 100A 120A 150A 200A LiFePo4 Li-Ion Battery 3S 4S 7S 8S 10S 12S 13S 16S 20S 24S Balance
https://a.aliexpress.com/_mM8bufh

[Crossy]

The 3S, 4S etc. designation is indeed the number of cells in series, for 48V LiFePO4 it's 16S.

 

You sometimes see see designations like 2P16S which is 16 pairs of parallel cells making up a pack (one BMS could manange them all) or 16S2P which is two 16 cell packs in parallel (which would need a separate BMS for each 16S set).

 

The Daly Smart BMS's are passive balance and at a miniscule 30mA current (we have the 100A 16S one with BlueTooth).

 

The active balancer is definitely the way to go, particularly if you have a random collection of used cells.

 

I got the balancer and BMS from Lazada local stock sellers being an instant-gratification junkie.

[ExpatOilWorker]

On 8/17/2021 at 5:58 AM, Crossy said:

How big are the gensets?

85 KVA Cummins, but as you can see bearly idling at 3 kW.

Even a small solar system could easily overwhelm the grid at high noon.

I could go down and take a reading late at night, when everyone are using aircons, but I might never return from such a risky endeavor if I encounter the local wildlife. The night belong to the jungle.

 

[Crossy]

2 minutes ago, ExpatOilWorker said:

85 KVA Cummins, but as you can see bearly idling at 3 kW.

Even a small solar system could easily overwhelm the grid at high noon.

I could go down and take a reading late at night, when everyone are using aircons, but I might never return from such a risky endeavor if I encounter the local wildlife. The night belong to the jungle.

 

Yeah, I wouldn't be exporting to those, but they should be stable enough to support grid-tie with no-export.