2 minutes ago, The Terrible Triplett said:

Does not work like that, grid tied.

In the most simplistic terms, ones I like:
The pump runs off Eskom right, so no worries about spikes.
The moment the pump starts, Solis sees with the CT that there is power being pulled from the Eskom side, so it adds whatever it can / is needed to the DB board.
So instead of the power coming from Eskom, it comes from the solis.

All because of the CT clamp measuring it all.

ah, so the grid starts the pump and Solis takes over... makes sense, then a 1.5kW will do just fine.

In fact I could even run the washing machine off the same inverter as well. just keep the timing of the 2 in mind.

13 minutes ago, Antony said:

In fact I could even run the washing machine off the same inverter as well. just keep the timing of the 2 in mind.

The trick with grid tied is to run the loads in such a manner that the panels give all they got per hour, and not one watt from Eskom.

So pump runs, pulls all it can from the panels, then the washing machine follows, then a kettle ... but not all together.

Spread the loads.

From what I am now watching on my system, tweaking it, it is so tempting to add more panels. But then I look and see, hold on, I have not use all the panels can give in that hour, the next hour was drawing from Eskom again ... with full array supplementing what it could give.

Spreading the loads ensures maximum usage of available panel watts per hour.

Easy solution: Gooi a lot of panels and a big Solis and be done with nitpicking ... pump and washing machine can run together.
Alternative: Go step by step adding them panels till you find the balance, and schedule the loads per hour.

Edited September 30, 20187 yr by Guest

@Anthony like so, at 4pm in Cpt:

Critical loads are all computers, the loads that are on most of the day.
AC loads the entire rest of the house, 2 separate homes.
1330w array can max give 834w this time of the afternoon. 
So it is nicely off-set against what comes from Eskom - ALL the panels can give is used. Solis will do the same.

Edited September 30, 20187 yr by Guest

51 minutes ago, The Terrible Triplett said:

@Anthony like so, at 4pm in Cpt:

I have just noticed that at roughly 4pm onward a serious shadow starts growing over my future panel roof space.

by 5:10pm its completely covered.

I have another roof facing north, north west which can take up the slack for another 2 hours but possibly not at full strength, maybe just enough for critical loads for a while longer.

Problem is that roof will only allow 6 panels next to each other in a landscape orientation.

So do I put 6 x 330 watts here for as much watts I can maybe get 2 hours of late afternoon?

If so I will need 2 MPPT's? so that the inverter draws from the active array/s what it can? 

18 minutes ago, Antony said:

If so I will need 2 MPPT's? so that the inverter draws from the active array/s what it can? 

Ditsim. Good use for 2 x MPPT's.

With grid tied systems, the higher the panel volts, the better the MPPT works. Solis I think is 600v. Nice.

Here is also something to look at, what Erastus is busy with. See here: MBOT aka MBB

 

Ps. I'm still worried re. grid tied in Ekurhuleni., if the whack you with grid fees and charges once they get their ducks in a row.

28 minutes ago, The Terrible Triplett said:

Ditsim. Good use for 2 x MPPT's.

With grid tied systems, the higher the panel volts, the better the MPPT works. Solis I think is 600v. Nice.

Here is also something to look at, what Erastus is busy with. See here: MBOT aka MBB

 

Ps. I'm still worried re. grid tied in Ekurhuleni., if the whack you with grid fees and charges once they get their ducks in a row.

that means I need to the the Solis with 2 MPPT's which is the:

• Solis 2.5kW 4G Dual MPPT - Single Phase

versus 

• Solis 3.0kW 4G Dual MPPT - Single Phase 

I see the 2.5kW is the same price as the 3kW, with subtle difference.

5 hours ago, Antony said:

Hi Chris,

I understand the 15kWh would be based on 5 hours of possible sunlight, but how would I ensure those potential 3kW spikes are allowed for?

For instance if I eventually go for the 1.5kW inverter, which is rated at MAX output of 1.7kW, it would not handle a spike greater than 1.7kW?

The really nice thing about a GTI is it does not need to handle the spikes - Eskom does.

On 2018/09/29 at 11:28 AM, Antony said:

Good morning guys,

I estimate the flat peaks at 1.5kW for short bursts and uses about 3kW during the day at most.

I read that as a 1.5kW peak and 3kWh usage. It appears that your ideas have evolved and your usage is going to be greater.

6 minutes ago, Chris Hobson said:

I read that as a 1.5kW peak and 3kWh usage. It appears that your ideas have evolved and your usage is going to be greater.

Its the dual MPPT option which is only available on the 2.5 / 3kW and higher models.

I may have to consider because of the possible double placement of panels to compensate for the horrible late afternoon shadow.

It may also allow me to load the inverter with more than I originally planned.

Edited September 30, 20187 yr by Antony

1 hour ago, Chris Hobson said:

The really nice thing about a GTI is it does not need to handle the spikes - Eskom does.

You can also calm down any panic when you sell something like this to a customer, by explaining that you don't pay for the peak (well, sometimes there might be a peak penalty on some tariffs, but most people don't). You pay for the "area under the graph". So a 3kw element that is on for one hour, if you were to plot that on a kw vs time chart, would make a 3kw x 1h square, and the area under it would be 3kwh. A 3kw spike for a few seconds costs essentially nothing.

In addition, almost all your big time consumers are small loads. Believe it or not. With the possible exception of your hot water cylinder. It's that one computer you leave on permanently with the 100w supply that adds 2.4kwh a day. It's that old fridge with the 250W compressor that runs 10 hours a day... and so on. Small loads. If you cut off everything under 1kw you will be absolutely amazed at just how much you save.

Edited September 30, 20187 yr by plonkster

5 minutes ago, plonkster said:

It's that one computer you leave on permanently with the 100w supply that adds 2.4kwh a day.

I have 2 that are permanently on...

2 minutes ago, Antony said:

I have 2 that are permanently on...

Oh me too. They are laptops though, and closer to around 40W.

10 hours ago, plonkster said:

Oh me too. They are laptops though, and closer to around 40W.

If you use them for some form of hosting and need a Windows environment consider replacing them with a Intel NUC

You will drop that 40W to 7-11W

1 hour ago, PJJ said:

You will drop that 40W to 7-11W

What am I missing? (replace figures as you see fit - logic stays the same)

Laptop uses 40w per hour for 24hours per day and one day it will need replacement, bit not today.
40w x 24h = 0.96kwh per day x R1.68 per kw = R1.61 per day = R588.67 pa.

NUC = +-R4.5k as it needs memory + HDD using Linux.
11w x 24h = 0.264kwh per day x R1.68 per kw = R0.44 per day = R161.88 pa.
(Excludes screen power if you connect one.)

So to save R426.78 per annum (588.67 - 161.88) you spend +-R4.5k?
So +-10 years later the savings pays for the NUK?

NUK won't last 10 years.

My logic says once a laptop must be replaced - after I chucked the batt as it tends to go first - is to then replace it with a TABLET (uses 3-5w with screen off). Tablet has a screen, memory, hdd and a small batt built in for cheaper than a NUK. Unless a laptop / NUC is needed for other functions that require more processor power.
 

 

2 hours ago, The Terrible Triplett said:

What am I missing? (replace figures as you see fit - logic stays the same)

Laptop uses 40w per hour for 24hours per day and one day it will need replacement, bit not today.
40w x 24h = 0.96kwh per day x R1.68 per kw = R1.61 per day = R588.67 pa.

NUC = +-R4.5k as it needs memory + HDD using Linux.
11w x 24h = 0.264kwh per day x R1.68 per kw = R0.44 per day = R161.88 pa.
(Excludes screen power if you connect one.)

So to save R426.78 per annum (588.67 - 161.88) you spend +-R4.5k?
So +-10 years later the savings pays for the NUK?

NUK won't last 10 years.

My logic says once a laptop must be replaced - after I chucked the batt as it tends to go first - is to then replace it with a TABLET (uses 3-5w with screen off). Tablet has a screen, memory, hdd and a small batt built in for cheaper than a NUK. Unless a laptop / NUC is needed for other functions that require more processor power.
 

 

 

Well your figures are mostly right, but lets use a optimistic glass half full  scenario figures

1) a NUC I would build would be that barebone + 128GB SSD (R500 +-) +4GB of DDR4 Ram (R700+-) = R4089

2) The 30W power savings shouldn't be looked at from a generation side, but rather a battery side, 30W difference might not sound like a lot, but this really comes in more than handy if this device forms part of your critical loads equitation (Like in my case) if there is no Eskom or Solar available and this load should remain on you can save 12 hours (lets say your mains are off and the sun is gone since its 6 PM) x 30W = 360Wh, 360Wh worth of battery capacity is nothing to sniff at, especially on a LFP bank.

3) Your 10+- years repayment time assumes that the price of electricity stays the same for the next 10 years, if we assume a 8% annual increase (I suspect  with Eskoms financial position it might even be more than that) and a R4100 base cost of a NUC we get 7 and a half years, which I am almost very certain a NUC would be able to reach.

22 minutes ago, PJJ said:

... 360Wh worth of battery capacity is nothing to sniff at ...

If that is a huge factor, and one is off-grid, then I would most definitely look at the glass half full. (I smiled - well played!)

 ... if I cannot switch it off OR run the laptop on its battery for extended periods. Screens are a large draw.

Tablets can be cheaper, and lower consumption, than NUK's as tablets are designed for portability. Mine draws 3-5w when screen is off, was R1500 at the time.

Any case. My point was just to show that which we sometimes may forget ... that savings could in actual fact be a increase in costs.

I have to sit on my hands frequently, more so when SWAMBO asks "silly" (read bone crushing) questions. Like "Why do you need it? How does it save money?".

Edited October 1, 20187 yr by Guest

21 minutes ago, The Terrible Triplett said:

more so when SWAMBO asks "silly" (read bone crushing) questions. Like "Why do you need it? How does it save money?".

I know that question all too well, if you are interested here is my answer "It saves money, because physics"  

Wrong @Anthony @Antony

16 hours ago, PJJ said:

I know that question all too well, if you are interested here is my answer "It saves money, because physics"  

I have this debate annually about medical aids.

She: "Shouldn't we upgrade to a better plan?"

Me: "The next plan up is 20k a year more expensive. Our out of pocket expenses are still less than that.

She: "Are you sure, did you check?"

Me: "I will check again, but I am pretty certain nobody is going to be dumb enough to give us more money than they get from us..."

She: "*grumble...*"

5 hours ago, plonkster said:

Me: "The next plan up is 20k a year more expensive. Our out of pocket expenses are still less than that.

I forgot to add... Medical aids always have rules as to how much stuff should cost. So they take a whole bunch of your money, put it into a savings account for day-to-day cover, and then decide how much of that money you can spend on the things they decide they will cover. So you pay extra for that cover... and then you pay for the shortfall too, that is to say, the 20k you spend extra doesn't actually buy you 20k extra cover. Whatever extra you spend on risk items... that is worth it. Whatever you spend on day to day is almost never worth it. I know that's off topic and all, but that is my personal opinion and/or experience.

42 minutes ago, plonkster said:

I forgot to add... Medical aids...

I want to join a support group (medical aid anonymous - MAA)for my medical aid dilemmas, do you think my medical aid will pay for it...

Edited October 2, 20187 yr by Antony

49 minutes ago, Antony said:

I want to join a support group (medical aid anonymous - MAA)for my medical aid dilemmas, do you think my medical aid will pay for it...

You might joke about it, but they are required by PMB to provide you with 21 hospital days per annum for  certain mental illnesses

And you can even convert those 21 days into sessions for a psychiatrist (I can't remember the ratio I think its like 3-1, 3 hospital days = 1 visit at the Psyc)

Living with 3 long haired bipods, I might just consider this

2 hours ago, Antony said:

Living with 3 long haired bipods, I might just consider this

Braveheart would have stood in awe of you, Antony, when you joked about hairdryers yet living with 3 long haired bipeds.