ExpatOilWorker

That is absolutely brilliant. I see you have different settings during the day, so during cloudy days, you will always start the night with 50% batteries. Just one question, shouldn't your grid charge settings be ON? What brand of inverter are you using?

Just normal variations.

😁 😂 😀 🤣 😁 😂

Turning right or the red car 🚘 has the rightaway. It is a question on the driver license test.

@Crossy, sorry to keep asking questions. You earlier indicated that the Deye inverter could work as a UPS, but I don't see such an option in the manual. There is an option for the inverter to shutdown at a certain SOC and by shutdown, I assume this is Chinese-manual for switching from battery to grid, right? The UPS scenario I am looking for is that the inverter will use battery down to say 30%, then switch to grid. If the grid then goes down, the inverter will go back to battery until a lower, say 10%, battery protecting SOC. Is there an option for that?

@Crossy, just out of curiosity, how does it actually work when the inverter priorities solar power to the "home load" over grid power? I assume the CT play a role here. Does it measure the current and then the inverter increase the voltage a fraction above grid voltage? Must be a fine balance in order just to match home usage and not push power into the grid.

Awesome! I prefer bingo now, rather than blue smoke later. Water heater and stove is all gas. The 1,800 W vacuum cleaner is my only odd "heavy" load. It is a cabin in the woods after all.

It is all starting to make sense now, thanks. If I understand correctly, the load was on the wrong output in the solar sparky's sketch. It should look like this with "zero export to grid" activated in the inverter settings, right?

The plan is never to export, as others have tried and it damaged control boards at the generator. Thai Solar System will quote a 10 kW Deye inverter. Are you saying the inverter can only support a small load when the grid is down? That is bad news, as we have frequent power outages and I was planning to run the whole house, around 3,000 W, from the batteries. Is that really not possible?

Take away the generator and home load, which is unique to your setup, and with the AVR in the B position isn't that exactly the same at the solar sparky's hand drawing? You both have the CT in the same position.

Nope, that is absolutely not the idea. Isn't the battery connected as per the red circle and the CT just preventing feed back on the export side of the inverter?

The sparky is now suggesting to have a CT (current transformer) installed on the export side of the inverter to avoid power feed back. That sounds like a sensible solution.

Just came back from Thai Solar System and should get a quotation in a few days. They outsource the installation to local teams around the country, so it was not possible to iron out the finer details with the actual installation team, but the AVR can stay on the grid side. @Crossy, does this look like professional work or are there some Somchai red flags? Ignore the lead-acid batteries, it must be one of their more low budget installations.

https://youtu.be/cmTeg0B9tH8?si=1YOvyOJoHMKiBJWW

It was a top 7 event.

You already had the diesel generator and wiring up comes as second nature to you, but isn't the generator pretty much redundant? It will have to be a long night, with ur 95 kWh totally drained and the grid down before you really need it. DEFCON 1 or you have a box of candles for the very end?

They burn through 6.5 million baht/month, but at least we have a 30,000 litre diesel carbon footprint 👣 every day.

Good suggestions, but no and it is complicated. The generators work great and have good voltage, most of the time, but they each have about 50,000 running hours and we have had a few unscheduled shutdowns. PEA is the only alternative, but they are not interested is selling more power. PEA run their own generators, but since they by law has to sell at the government rate, they are making a loss on every kWh they produce. On top of that, my impedance is 1.25 ohms, which shave off another 5-10 V depending on load. Solar 🌞 it is.

Currently 167 V, but can at times drop below 160 V. I already have the AVR, so my only worry is if there is any possibility the AVR and inverter will "fight" each other, possibly cause damage to either unit. It is reassuring that the inverter simply just disconnect below 180 V and jumps to battery, but that creates a new problem. If the battery runs out, the inverter will switch to grid, potentially damaging pumps and other household equipment with low voltage.

There is an alternative solution, but it involves Putin in a grave.

@Crossy, should a AVR be installed before a hybrid inverter if grid voltage is somewhat on the low side? If yes, does it make a difference if the AVR is of the relay, servo or thyristor type?

Nah, I will let Somchai do all the mistakes. I hope to sit down with the vendor later this week. Target for installation is July this year. It will be a system very similar in size to yours. What brand do you have for inverter and panels?

Solar was in its infancy and prohibitively expensive when the generators were installed 15 years ago. They have done well and been a reliable source of power, but lately time, weather and geckos are starting to play tricks on various control boards. Thanks to the price drop in solar, it is time to move on. By the way, PEA is still running the rest of the island on 8 huge generators and are bringing in tons of diesel ⛽️ every second night.

From a reliability point of view would it make sense to have 2 x 5 kW inverters rather than a single 10 kW inverter? I am remote, so help is far away.

Thanks for the offer, much appreciated, but I am on one of the islands far from Isaan. I will visit thaisolarsystems shop in Bangkok and see what they suggest.