Solar power, can it be done DIY?

[Sophon]

2 hours ago, Crossy said:

 

Sort of.

 

The spec. you show says that if you run your inverter between 110% and 150% full load it will shut down after 10 seconds. Exceed 150% full load and it shuts down after 5 seconds. The idea being that it can support brief overloads such as motor stating surges.

 

What happens between 100% and 110% is indeterminate, it may or may not shut down after 10 seconds, this "gap" is to ensure that it WILL run at 100% indefinitely regardless of manufacturing tolerances.

 

Your 5.5kW unit running at 6kW is running at 109% and is in the "unknown" area, it may run ok, it may shut down after 10 seconds or 10 minutes (more likely on overheat).

 

It is generally accepted as "unwise" to design your system to run the inverter at maximum power regularly or for extended periods anyway.

 

If you actually have the above loading pattern you need a bigger inverter or a gas water heater.

 

 

Our load going over 5.5kW is an unlikely event, but it could theoretically happen in the winter when the water is cold (we live in the north), and if other major loads like a rice cooker is on at the same as we crank up the temperature on the shower heater. At the moment our total load, including all the normal background loads, is around 3.5kW when the shower heater is on. But it will go up somewhat when the water gets colder..

 

It's definitely not something that would be worth upgrading the system over, if it turns out to be a problem, we will just make sure that we don't take warm showers when other big loads are running. I am just trying to understand, what will happen if we do go over the rated power.

 

The inverter in question has this setting:

 

 

If I change that to "Bypass enable", would that mean that the inverter would automatically change to PEA power if overloaded, and would it automatically return to normal mode when the load falls below the rated limit?

[Crossy]

6 minutes ago, Sophon said:

If I change that to "Bypass enable", would that mean that the inverter would automatically change to PEA power if overloaded, and would it automatically return to normal mode when the load falls below the rated limit?

 

That is how I would interpret the description in the manual.

 

They only way to find out if it really does work like that would be to test it.

 

[Sophon]

So I have decided against going for the Powland hybrid On/Off-grid inverter I posted about on the 12th of August. It turned out, that the second manual the seller sent me was for another inverter, and the manual for the Powland inverter is just lacking in details. There is nothing about the different settings, and being new to solar inverters, I don't want to have to guess what the different options in the settings do.

 

The two Inverters I have narrowed it down to (at least for now), are both cheap Chinese hybrid  off-grid inverters.

 

Inverter number one:

 

Inverter number two:

 

The two inverters are basically 95% identical, just different model years with minor updates. The first one (which I believe is the one BritManToo has) is the 2019 model and the second one is the 2022 model.

 

It seems like they have tried to simplify things in the 2022 model, so they have removed settings and information screens, that doesn't necessarily make sense. They have also tried to optimize battery charging (at least that my interpretation of the changes), maybe to make it more compatible with Lithium batteries. Neither model has an option to select Lithium in battery type, but where the older model never mentions Lithium batteries the newer one at least states that it will work with that battery type.

 

In the following I will go through the differences between the two models. The older model is on the left and the newer on the right:

The only difference is under the "Output Short Circuit Protection:

 

 

The new inverter is slightly more efficient.

 

There are also changes to the DC warning and cut-off voltages. I have no way near enough knowledge to determine if these changes are an improvement or not, but one would like to think, that when they make the effort to change things it's for the better. 

 

They have added some additional information for the new model, but the only real change is that max. PV charging current has gone up from 100A to 110A.

 

 

The newer model is a little bigger and heavier, and can apparently work under slightly hotter conditions.

 

So all in all fairly minor changes in the spec. sheets between the two models.

 

Beyond what is mentioned in the specs. there are a few other noteworthy physical changes and quite a few software changes between the two models. But as this post is already quite long, I think I will split those into a separate post.

 

Ignore the below pics. I am unable to delete them.

 

 

 

 

[Sophon]

So, on to the other changes mainly in the settings and information display software. As I mentioned, the overall impression is that the manufacturer has tried to simplify things by removing settings/options that you would not want to use anyway.

 

Feature	2019 model	2022 model	Verdict (IMO)
Physical differences:
USB communication port	Yes	No	Advantage old model. I don’t know if this is helpful in real life or not.
Battery connection	Screw connector	Ring terminal connector	Advantage new model. I imagine a ring terminal connection is more secure.
On/Off switch	On the side	On the bottom	Advantage old model. Purely objective, but I prefer the on/off switch to be away from all the wire connections.
Inverter settings:
Output source priority	UTI (utility) mode	No UTI mode	Neutral. While it can be argued that having more options is always good, I don’t see ever wanting to use a UTI mode.
Power saving mode	N/A	If no or small load the output of the inverter will be off	Neutral. I don’t see the point and wouldn’t turn it on
Output voltage	220V/230V/240V	N/A	Neutral. I wouldn’t want to change from the default 230V
Charger source priority	CUT (utility first) mode	No CUT mode	Neutral. I would never set the inverter to charge from PEA as first priority
Record fault code	Enabled as default	Disabled as default	Neutral. I can just change the setting
Low DC cut-off voltage	Default 40V	Default 42V	No opinion. I have no idea which is better, but it can be changed.
Battery equalization	Enable/disable plus many sub-menus	N/A	Neutral. As I understand this, it’s only relevant to lead-acid batteries
Information screens:
PV current	Screen shows PV current	N/A	Advantage old model. Could be useful information.
PV power	Screen shows PV power	N/A	Advantage old model. Could be useful information.
Charging current	Screen shows charging current for utility + PVs with diagrams that show if it’s utility or PV charging.	Shows only total MPPT charging current. Only one diagram.	Neutral. I wouldn’t charge from utility anyway.
Charging power	Same as for charging current	Same as for charging current	Neutral.
Load in watt	Screen shows Load plus Battery voltage	Shows Load plus Input voltage	Neutral. The added information is available elsewhere.
Battery voltage plus output voltage	Screen shows these values	N/A	Neutral. These values are already available in (several) other screens.

 

The newer model is a little more expensive, but not enough that it would be a deciding factor.

 

I am leaning towards the newer model, mainly because I get the impression that the manufacturer has made an effort to improve battery management. But I would appreciate input from anyone that actually understands what the changes to the DC cut-off and warning values have actually achieved, and whether the changes are an improvement or not. As mentioned earlier, I would like to believe that the changes are a step in the right direction (why else would they do them), but who knows.

 

So for anyone who have actually made it through both this and my previous post, would you go for the older or the newer model?

 

Edit: I see that the formatting of the table came out a bit wonky, but at least it's readable. 

[Crossy]

I'd be more worried that I don't see any setting for lithium batteries (unless I missed it).

[Sophon]

48 minutes ago, Crossy said:

I'd be more worried that I don't see any setting for lithium batteries (unless I missed it).

There are about 30 different settings, but I have only included the ones that are different between the older and the newer model.

 

It's true that there is not a specific option to select Lithium battery, but the user manual for the newer inverter does say this under features:

 

And under the battery type setting you would then select "User-defined":

 

Since there is not specific Lithium battery setting, this might require you to adjust settings 26, 27 and 29 in order to optimize battery management, but I am hoping that maybe the changes to default settings they have made are partly to address this:

 

For those with inverters with specific Lithium battery settings, what are the values in your inverter for bulk charging voltage, floating charging voltage and low DC cut-off voltage?

[Sophon]

So if you have two strings of PV panels that you want to connect in parallel, which of these connectors would you use?:

[Crossy]

1 hour ago, Sophon said:

So if you have two strings of PV panels that you want to connect in parallel, which of these connectors would you use?:

 

That's one of those Up2U questions. The wire type would be less fussy to install.

 

[Sophon]

2 minutes ago, Crossy said:

 

That's one of those Up2U questions. The wire type would be less fussy to install.

 

I was leaning towards the Y connector. The extra 10cm of wire or so might mean that the wires from the two strings could reach without having to extend one or both of them.

[Crossy]

2 minutes ago, Sophon said:

I was leaning towards the Y connector. The extra 10cm of wire or so might mean that the wires from the two strings could reach without having to extend one or both of them.

 

Sounds like a good reason to go for the Y lead ???? 

[Sophon]

On 8/18/2022 at 10:57 AM, Crossy said:

 

That is how I would interpret the description in the manual.

 

They only way to find out if it really does work like that would be to test it.

 

In theory a 5.5kW inverter should process a maximum of 24A on the AC side, and even if it allows a 10% overload that would only bring the max. to about 26A. So 6 sq.mm in/out wires should be plenty on the AC side.

 

However, if the inverter really just shifts to bypass mode in case of an overload, that would mean that the AC in/out wires could theoretically be exposed to currents of up to 50A, at which point the 50A breaker on the incoming supply from PEA would cut out. So since I have 16 sq.mm. wires left over from when we built the house, I think that I will run 16 sq.mm. the whole way from incoming supply to the inverter, and out from the inverter to the wires for the house (assuming the ports in the inverter can handle the size). 

 

Is my reasoning sound, or am I missing something?

[Crossy]

4 minutes ago, Sophon said:

Is my reasoning sound, or am I missing something?

 

I think you're good to go, I have a lot of 10mm² on 50A breakers.

[Sophon]

Having decided to go ahead with the project, I have started ordering some of the smaller stuff from AliExpress. The solar system will be located on one of the wetter parts of our land, so building the structure for the panels will not be done until we are into the dry season - so sometime in October/November depending on the weather. But as we know, deliveries from AliExpress can sometime take a couple of months or more.

 

As we still have 2-3 months to go, I will be spending the next few months looking for good prices on the PV panels, Inverter and batteries and pounce if I see a deal I like. I was considering if I should buy the JinYuan panels from Global while they are on sale until the end of this month):

 

I can't find a spec sheet for this panel on the web, the closest I got was specs from JinYuan's own website for the panel series JYXXXP72, but that only covers the 320W, 

325W and 330W models.

 

According to Global:
Voc: ?

Vmp: 38.2V

Imp: 8.94A

 

According to seller on Alibaba (and his information correlates with the JinYuan spec sheet for 320W, 325W and 330W):

Voc: 47.1V

Vmp: 38.7V

Imp: 8.79A

 

Price per Watt: 3,490 Baht/340W =  10.26 Baht/W

I would buy 12 panels for a total cost of 41,880 Baht for 4,080W of panels.

 

I would have to arrange the panels in two strings of six panels (S6P2 configuration), as 12 panels in series would total Voc of 565V, more than the maximum PV array open circuit voltage rating of the inverters I am looking at (max. 500V). The combined Vmp of the panels in series of 458V/464V (depending on who you trust) would also exceed the MPPT's voltage range of 120-450V.

 

I have also been looking at this panel:

From the spec sheet:

Voc: 46.2V

Vmp: 38.2V

Imp: 8.90A

 

The Vmp/Imp doesn't quite add up with it being a 345W panel (comes out to 340W), but using the 345W figure the price per Watt would be: 3,700 Baht (210 Baht shipping)/345W = 10.72 Baht/W

 

Again, I would buy 12 panels for a total cost of 44,400 Baht for 4,140W of panels.

 

Like with the JinYuan panels, I would have to arrange them in a 6S2P configuration to avoid exceeding the inverters maximum open PV array open circuit voltage and stay within the MPPT voltage range.

 

The third and final panel, I am currently considering, is this one:

From the spec sheet:

Voc: 49.3V

Vmp: 41.1V

Imp: 9.49A

 

Price per Watt: 4,400 Baht (210 Baht shipping)/390W = 11.28 Baht/W.

 

If I go for this panel, I will buy either 10 or 12 panels for a total cost of:
10 panels: 44,000 Baht for 3,900W of panels.

12 panels: 52,800 Baht for 4.680W of panels. 

 

Like before, 12 panels would have to be in a 6S2P configuration, but 10 panels could theoretically be connected in series. The total Voc of the string of 493V would be awfully close to the inverters maximum PV array open circuit voltage rating of 500V, though. To err on the side of caution I think I would go with a 5S2P configuration. 

 

The producers of these panels Jinko (JinYuan) and Risen (BlueTech) are both major producers of solar panels, so I would expect that the quality of the panels would be more or less on par.

 

The JinYuan panels is the cheapest option, but for only 10% more per watt I am very tempted to go for the 390W BlueTech panels. With them being Mono crystalline and half-cut, they should supposedly perform a little better under low light, very hot and partially shaded conditions. It also gives me the flexibility to start with 10 panels with only a 200W decrease in total power of the array, and then later add two more if needed. 

 

On the flip side, I do like the idea of inspecting the panels when I buy them and taking them home myself, which buying at Global offers. That way you don't have to deal with panels broken in transport or the seller sending the wrong items. And should a panel be defective, Global is very good at taking products back and refunding you.

 

What to do, what to do, what to do....

 

What would you do?

 

[MJCM]

7 minutes ago, Sophon said:

What would you do?

 

Personally, I would recommend buy the panels at Global, yes you save some money buying from Lazada, but if one fails (oke their return policy seems to be oke) but is still a hassle. For the couple of THB you save, IMHO it's not worth it.

 

So I am buying mine at a known Retail Store with a good return policy!

 

[Sophon]

3 minutes ago, MJCM said:

Personally, I would recommend buy the panels at Global, yes you save some money buying from Lazada, but if one fails (oke their return policy seems to be oke) but is still a hassle. For the couple of THB you save, IMHO it's not worth it.

 

So I am buying mine at a known Retail Store with a good return policy!

 

If I end up going with the 390W BlueTech panels, it won't be to save money. The panels would actually be more expensive, both per watt and in total, than the option from Global. But I would get a better panel (mono crystalline and half cut), and that would be worth the extra money to me.

 

What's holding me back is the risk of having to deal with panels broken in transport, so if I could find a brick and mortar shop selling this panel for a comparable price, I would definitely go pick them up myself. I have been scouring the internet, but haven't been able to find any solar shops in the Chiang Mai region. Lots of companies doing big projects, but none that just sell the equipment. So if someone knows of a shop in or around Chiang Mai with a good selection of solar panels (and other equipment), I would definitely go check it out.

[Danderman123]

For a beginner with a low electric bill, I would suggest a grid tie inverter, maybe 2000 watts. This just plugs into an existing socket. You can hook up 2000 watts of solar panels, making sure the voltage of the combined panels can be accommodated by the inverter. 

 

I like to use 48V, since the power cables don't have to be thick, and shocking yourself won't kill you. 

 

[Sophon]

3 hours ago, Danderman123 said:

For a beginner with a low electric bill, I would suggest a grid tie inverter, maybe 2000 watts. This just plugs into an existing socket. You can hook up 2000 watts of solar panels, making sure the voltage of the combined panels can be accommodated by the inverter. 

 

I like to use 48V, since the power cables don't have to be thick, and shocking yourself won't kill you. 

 

Probably sound advice from a financial point of view, but personally it would have no interest to me. If this was just about saving money I wouldn't bother with the project, the savings wouldn't be that substantial anyway. The primary purpose isn't saving money, I just like the idea of being (mostly) independent from the grid, and not being in the dark when the grid is down.  

 

Of course, I don't like the idea of burning money so installing solar has to make at least some kind of financial sense. I am happy if I can achieve savings in the region of 10% annually of the initially invested amount.

[Danderman123]

21 hours ago, Sophon said:

Probably sound advice from a financial point of view, but personally it would have no interest to me. If this was just about saving money I wouldn't bother with the project, the savings wouldn't be that substantial anyway. The primary purpose isn't saving money, I just like the idea of being (mostly) independent from the grid, and not being in the dark when the grid is down.  

 

Of course, I don't like the idea of burning money so installing solar has to make at least some kind of financial sense. I am happy if I can achieve savings in the region of 10% annually of the initially invested amount.

If you go the grid tie route, you can modify your system later to go off grid, once you have some expertise. 

 

But, don't forget that off grid requires power storage, which is an order of magnitude more difficult and expensive. 

[Sophon]

How have you guys grounded your solar panels? My solar panels will be ground mounted and each panel will be attached to the support metal structure (which will be bonded to the ground rod) with 8-10 screws/bolts. Will that be enough grounding, or should I run wires from the panels to the metal support or even to the ground rod?  

[Crossy]

2 hours ago, Sophon said:

How have you guys grounded your solar panels? My solar panels will be ground mounted and each panel will be attached to the support metal structure (which will be bonded to the ground rod) with 8-10 screws/bolts. Will that be enough grounding, or should I run wires from the panels to the metal support or even to the ground rod?  

 

Officially, you should bond the panels together and then to the support structure and ground.

 

In reality, what you are suggesting will be more than adequately grounded. You can always verify with your meter is worried.

[Sophon]

2 minutes ago, Crossy said:

 

Officially, you should bond the panels together and then to the support structure and ground.

 

In reality, what you are suggesting will be more than adequately grounded. You can always verify with your meter is worried.

Thanks. Verify with my meter how, by measuring the resistance between panel and supports?

[Crossy]

1 minute ago, Sophon said:

Verify with my meter how, by measuring the resistance between panel and supports?

 

Yup, on the lowest resistance range you have. If it looks like a short circuit you're good.

 

[Sophon]

Completely unrelated question. Isn't there such a thing as blanking strips/plates for DIN mount CUs? I will have two boxes in the solar installation, but in one of them some of the spots will not be filled or filled with UKK80 terminal blocks that don't fill out the gap in the front plate.

[Crossy]

21 minutes ago, Sophon said:

Completely unrelated question. Isn't there such a thing as blanking strips/plates for DIN mount CUs? I will have two boxes in the solar installation, but in one of them some of the spots will not be filled or filled with UKK80 terminal blocks that don't fill out the gap in the front plate.

 

Yes, I suppose you are going to ask where you get them.

 

I'll check with my man, the last lot came in a big bag as "surplus" on a major project

 

[Sophon]

16 minutes ago, Crossy said:

 

Yes, I suppose you are going to ask where you get them.

 

I'll check with my man, the last lot came in a big bag as "surplus" on a major project

 

Thanks again. I have been searching Lazada/Shopee/AliExpress but have been unable to find anything. Maybe they are there, but unfortunately I don't know what they are officially called.

 

The only thing I can find are "blanks" like these:

But they don't work if the spot is already filled with a UKK80 terminal block. Of course, I can make something myself, but it won't look very nice.

[KhunLA]

18 minutes ago, Sophon said:

Thanks again. I have been searching Lazada/Shopee/AliExpress but have been unable to find anything. Maybe they are there, but unfortunately I don't know what they are officially called.

 

The only thing I can find are "blanks" like these:

But they don't work if the spot is already filled with a UKK80 terminal block. Of course, I can make something myself, but it won't look very nice.

https://www.google.com/search?q=UKK80A+Din+Rail+1+In+N+Out+Terminal+Block+Distribution+Box+Universal+Power+Junction+box&client=ms-android-xiaomi-rvo3&sourceid=chrome-mobile&ie=UTF-8

 

https://m.th.aliexpress.com/item/4000050333779.html?gatewayAdapt=Pc2Msite

[Sophon]

18 minutes ago, KhunLA said:

https://www.google.com/search?q=UKK80A+Din+Rail+1+In+N+Out+Terminal+Block+Distribution+Box+Universal+Power+Junction+box&client=ms-android-xiaomi-rvo3&sourceid=chrome-mobile&ie=UTF-8

 

https://m.th.aliexpress.com/item/4000050333779.html?gatewayAdapt=Pc2Msite

I already have the UKK80 terminal blocks, what I am looking for are blanking strips that can block the opening in the DIN box front plate in front of the UKK80 blocks. Like these (for a Schneider box):

[Crossy]

These are the chaps I have, unfortunately that's all I have left, so I'm hunting for more (they are grey, blue tinge is a camera artifact).

 

 

The ABB part number may aid in our quest.

 

 

EDIT OK it's called a "6 way DB Blank" now to find a local supplier ???? 

 

[Crossy]

[sezze]

14 hours ago, Crossy said:

1 solar panel won't hurt you , a string of 500 or 700V won't take long to get you fried . Especially since its DC (which is worse for your body then AC )