2 hours ago, The Terrible Triplett said:

What made me pay an installer was the new panel mounts was right in the path of the North Western storms winds hitting us smack in the face.

Check your building regulations. In some places adding a PV array to the roof of the house requires a structural engineer to design it and sign it off. More hidden costs.

That was one reason I have mine on the carport roof. That... and it is pretty much the only north(ish) facing flat area I have available 🙂

2 hours ago, d3nominat0r said:

square tubing frame

Square tubing can crack if it flexes (personally seen this), so don't use thin stuff. But I pretty much don't advocate using steel at all, even if you galvanise it. You want the frame to last the life of the PV modules, 30 years in other words. Also, as me and @Jaco de Jongh discovered, the aluminium premade things aren't necessarily much more expensive than say solarstrut or other materials.

Sliding a tile out of the way and attaching a bracket to the beam isn't that hard and is going to look so much neater. I'm also pretty certain you will use less material overall.

Take a look at the Renusol assembly manuals. And see here. I really like the Renusol stuff, I will use it again.

11 minutes ago, plonkster said:

Check your building regulations. In some places adding a PV array to the roof of the house requires a structural engineer to design it and sign it off.

Correct, if it is above a certain hight above the nok of the roof, you must get a structural engineer in, and approval.

If it is below the roof's nok, then no issue.

3 hours ago, d3nominat0r said:

18.5 degrees

Oh, and I know this isn't optimal, but honestly I'd just put them flat on it. See here. Angles are from vertical (ie subtract it from 90). At almost 20 degrees you are just about bang on for November and February. It would be better to aim for October/March in my opinion (around 30 degrees), but weigh up the cost as well as the aesthetics.

2 hours ago, plonkster said:

Oh, and I know this isn't optimal, but honestly I'd just put them flat on it. See here. Angles are from vertical (ie subtract it from 90). At almost 20 degrees you are just about bang on for November and February. It would be better to aim for October/March in my opinion (around 30 degrees), but weigh up the cost as well as the aesthetics.

Valid points, is there a way to calculate the potential loss by mounting at 20 degrees? I can then perhaps oversize the array by a panel or two to compensate for the loss.

14 hours ago, d3nominat0r said:

mounting at 20 degrees

You multiply the irradiance by the cosine of the angle of incidence.

So in summer you are 10 degrees off, 0.175 radians, cos(0.175) = 98.5%. So 1.5% loss.

In early autumn/late spring you're just about bang on.

In winter you're off 72-48 = 24 degrees, 0.42 radian. cos(0.42) = 91%, so 9% loss. Also in winter you have the additional loss in the atmosphere (1.5 atmospheres), but that is unavoidable.

So an extra 300W module ought to do the trick 🙂

15 hours ago, d3nominat0r said:

Valid points, is there a way to calculate the potential loss by mounting at 20 degrees? I can then perhaps oversize the array by a panel or two to compensate for the loss.

Bias the array towards the winter angle as in summer you have more hours of sunshine, but in winter more power drawn because of heating geysers etc.

Awesome info in this thread, thanks to the contributors.

I would like to compare the grid tied setup suggested here: 
Victron Multiplus II 48/3000 + Victron BlueSolar 150/100MPPT + VenusGX to the Solis 3.0kW Mini 4G Single Tracker

The Victron setup is obviously much more expensive (more than 3 times) but after reading this thread and some others I am very keen to go for it, but what do you sacrifice if you go for the Solis.

10 minutes ago, Beefy said:

The Victron setup is obviously much more expensive (more than 3 times) but after reading this thread and some others I am very keen to go for it, but what do you sacrifice if you go for the Solis.

Solis and a Axpert UPS would be a great combination.

The Victron setup is not that much more than a 5kva Goodwe, and it has more options over time.

Solis seems a pretty decent grid-tie at a good price. With the Victron setup you can connect it to the output of the inverter which means you get to use your solar off-grid or during grid fail. For this to be possible the Solis needs to have its power throttled so it only provides for loads (and perhaps the battery). The Victron inverter can do this for both ESS and UPS setups by utilizing frequency shifting (The Solis regulates from 50.5 to 52.0 Hz as per NRS-097 requirements).

I am not sure if/which other inverters can readily provide this functionality.

If the inverter cannot frequency shift (or provide other means to control the grid-tie) then it needs to go onto the inverter input. This means you cannot use PV during grid fail or off-grid operation. This may be acceptable but really is a big negative for a solar backup system.

One advantage of using the Victron with Solis at the output is that your peak power during PV production times is effectively what the Victron can provide PLUS the grid-tie power during grid outage. That might be worth taking into account. This configuration can be used both for feed-in and zero feed-in (or limited feed-in which means you can upsize your inverters relative to COCT limits).

Thanks so much TTT and Bulldog for your replies. I obviously have a lot to learn and don't want to waste your time asking stupid questions - can you maybe point me to some online resource where I can get more detail on different grid tied options and their capabilities. 

35 minutes ago, Beefy said:

Thanks so much TTT and Bulldog for your replies. I obviously have a lot to learn and don't want to waste your time asking stupid questions - can you maybe point me to some online resource where I can get more detail on different grid tied options and their capabilities. 

There is only one way to grid tie. The question you are asking, different options and capabilities of various grid tied inverters?

Suggest one starts with the CoCT list, work through those inverter website, which in itself is a eye opener. 

Or maybe someone starts a Solis / Goodwe / ABB thread, to not confuse this Victron one?

On 2019/03/25 at 11:26 PM, plonkster said:

On the Victron inverters you can set the AC input limit. Then it holds the input at that limit and charges the battery with whatever remains after you subtract the loads. Same effect, generator runs at close to 100%, but it doesn't trip if you turn on a load.

Same for the infini. 

When Heinz did the setup parameters that was the figure decided on. I had no inside knowledge. 

When I charge it like this (after 4 days no power) I know not to use other power eaters 🙂

I would appreciate feedback from lead acid battery users on how long their systems take to charge using a gennie (and what amps they use). The pylontechs charge pretty quickly.

Edited March 31, 20197 yr by Johandup

So I though, let me email the DA "chief in charge" i.e. Mmusi Maimane re. our solar plight, same email I sent last to the local guys.

Low and behold, they acknowledged the receipt and it was forwarded, I gather it is from "top dog" to "top dog" locally.

Lets see where this goes ...

 

I sent this email - like I said, it is not engineer against engineer, it is non-engineer to official whom must "help" me. 🙂

 

Edited March 31, 20197 yr by Guest

The point I am pushing is that if I have spoken locally, then gone up the chain a bit, then to the very top. Somewhere someone may realize, probably in a meeting, that the same person is pressing all the buttons up and down the chain taking up "their time" - that WE pay for - so deal with this matter sooner.

It MAY just be that one last straw, I can dream, that allows the CoCT engineers to start talking to  the voter payed for engineers and not having some oak somewhere pushing an ulterior agenda. They got badly burnt with Zille / Lille saga's.

@Rautenk @The Bulldog @plonkster @Fuenkli - join me in the emails? Send it to Mmusi Maimane's office, let them send it down the chain?

Would be really nice Plonkster, if our mutual friend at Victron can also send a email via the same office, with some more technical details?
Rautenk, maybe you have a few people that could send a email or two?
Bulldog, your engineer, maybe you?

It is a shot in the dark but guys, we need to get the attention of the right person somewhere inside this official structure.

Edited March 31, 20197 yr by Guest

17 hours ago, The Terrible Triplett said:

join me in the emails

I will send an email to the DA councillor here in Plattekloof.

Thanks @Fuenkli

Makes me wonder, how many people will do as we did?

This is no longer a engineering debate, that ship has sailed, because if it was an engineering debate, then it would have been resolved.

This is a political / Eskom hot potato. A voter / citizen of Cape Town debate. We are being stopped to be part of the solution, because "someone" is going to lose income.

PS. If she does not respond, forward that email to the DA leader, CC her in. Put some pressure all round. 😉 

41 minutes ago, The Terrible Triplett said:

because "someone" is going to lose income

I doubt that is the reason. Cape Town makes their money from property taxes. In the case of electricity it is already structured in such a way that they are not going to lose money: they are bringing back the grid connection fee, and prices are such that you'd be mad not to buy the first 600KWh from them (at around R1.85). Whatever they have to buy using SSEG (rebate) they resell at profit too. Eskom has said the same thing about IPPs... they IPPs are not the problem, Eskom passes the cost on to customers and doesn't lose money. No, something else is going on.

6 minutes ago, plonkster said:

I doubt that is the reason.

I have been told a Eskom person is behing the CoCT silly regs - therein my comment - therein the loss of income - for AN.., sorry, Eskom.

4 minutes ago, plonkster said:

No, something else is going on.

I agree money might not be the main reason, but it is part of it. I think the municipalities and the government are concerned that they will loose the grip on generation/distribution and selling of electricity.

Titbit. @plonkster

After 36 hours of power failures in a PTA suburb, my cousin starts his gennie.

Nothing he does, being a electrical engineer, can get the MPII to charge the batts from the Honda generator, and it is not a cheap one either.

52.3Hz and 227V is what he measures. He suspect that is the problem, the frequency.

Turns out that because the inverter is set to SA's NRS standards, being grid tied, it will ignore that generator.

The NRS setting was disabled by a dealer, now the MPII is happily charging the batts. Ps. He has no solar panels installed yet.

Man, we both are seriously impressed.

Edited April 1, 20197 yr by Guest

4 minutes ago, The Terrible Triplett said:

Titbit. @plonkster

After 36 hours of power failures in a PTA suburb, my cousin start the gennie.

Nothing he does, being a electrical engineer, can get the MPII to charge the batts for the Honda generator, and it is not a cheap one either.

52.3Hz and 227V is what he measures. He suspect that is the problem the frequency.

Turns out that because the inverter is set to SA's NRS standards, being grid tied, it will ignore that generator.

The NRS setting was disabled by a dealer, now the MPII is happily charging the batts. Ps. He has no solar panels installed yet.

Man, we both are seriously impressed.

Mine charges (MP ii 3000) but i don't use ESS, maybe the differance ?  (honda eu30)

Edited April 1, 20197 yr by 2una

3 minutes ago, 2una said:

Mine charges (MP ii 3000) but i don't use ESS, maybe the differance ?  (honda eu30)

It depends on the selected grid code. If you select "Other" in the dropdown it will probably also be perfectly happy to charge.

4 minutes ago, 2una said:

...  i don't use ESS, maybe the difference ...

Nope, NRS setting on the inverter must be switched off or set to Other as Plonkster says.

Because although Victron can take some seriously bad "shore power", if you have it set up as NRS for SA, then it does not allow silly high volts / frequencies, as per design.

One thing to read about it, something totally different to see it in action I tell you. If Eskom was dishing out 52.3Hz, I would not want my stuff that is on the inverter, running on that. 

Edited April 1, 20197 yr by Guest

Yes nrs not set

18 minutes ago, The Terrible Triplett said:

Nope, NRS setting on the inverter must be switched off or set to Other as Plonkster says.

Because although Victron can take some seriously bad "shore power", if you have it set up as NRS for SA, then it does not allow silly high volts / frequencies, as per design.

One thing to read about it, something totally different to see it in action I tell you. If Eskom was dishing out 52.3Hz, I would not want my stuff that is on the inverter, running on that. 

I have a serious generator - three phase 55KW unit sophisticated control unit, four quadrant metering, fully automated and heated at all times so ready to rock at a moments notice. Has its own sound proof room and barely makes a noise at all. Even that thing can't handle ESS. If you throw three Multies at it trying to charge batteries it goes bananas as the victrons synchronization affects even a big generator like this. Even with UK codes and LOM "B" - that just barely makes it work - but not reliably.

It loads the generator with about 12KW sending around 10KW of that into the batteries - works well without ESS. Would be so nice to have some quick means of suspending ESS in the CCGX for when you want to charge the batts from the genie.

This is perhaps one of the weak points of ESS at the moment - at least in my application.