Solar Dream

[d3nominat0r]

Hi all,

I am new to the group, thank for letting me in. I am based in Alberton, Gauteng.

The sheer amount of information on this forum is mind blowing, difficult to find straight answers as everyone's needs are different and as as result the amount of permutations on solutions is mad. I basically have a green fields solution, albeit existing home which will require DB Board wiring etc.I 'm attempting in building a google spreadsheet to figure out solution with calculations etc, hopefully something other people could find of use.

Essentially, if you could start clean today, how would you design a system based on what is currently available in the market.

To outline what I would like to achieve.

• Saving Money
• Generating Cleaner Energy hopefully becoming less and less dependent on Eskom, but always have them as a grid-tie backup, if they go down I can always power up the generator.

Current power usage pattern and requirement. These are not exact measurements, but will give more or less an idea. We currently pay around R 1.92 (incl. VAT) per kwh from Ekurhuleni in Gauteng.

• Monthly usage: 1400 kwh units (Don't have a solar geyser or geyser timer, but have a gas stove top),  R 2700 per month on electricity.
• Constant daytime usage:  45 kwh per day 
  • Electric Geyser (averaging 9 kwh per day), 5 people in the household
  • Pool Pump (0.75 kw - running for 8 hours, 7 kwh per day)
  • Iron (2 kw for 2 hours, 4 kwh per day)
  • Other stuff like Fridge, PC, Fans, Oven, Microwave, TV's, decoders, vacuum cleaner, etc (1 kw for 24 hours, 24 kwh per day)
• If geyser is removed from the electricity requirement, and our behaviour changes a bit to around 1 kw average usage per hour in total, this would be ideal
• It would be great if I can take care of the this off solar, and still charge batteries to take care of the nightly requirement.
• I am comfortable to keep a plug or two permanently connected to the Grid for Ironing and the Microwave if really needed.

Naturally, my bank account does not have indefinite funds, currently looking at limiting my spending to around R 150 000.

Based on what I have read:

1. First step, I need to start off with a solar geyser, it will be the best bang for buck with cost saving in mind.
   - At 279 kwh units per month for the geyser alone, if all of this can be swapped out with solar (minus 3 months of winter sun - basic modeling ;-)), the payback looks to be around 4 years (R 5000 p.a savings) for a R20k investment without even taking into consideration the annual increases in the electricity unit cost.
   - Are there any recommendations for solar geysers? Make, provider, pricing?
   - Also, I'm not to keen on a conversion kit with pumps etc, would probably prefer going single unit, although I am open to be convinced otherwise.
   - This will ultimately remove 9 kwh from the daily requirement 
    
2. Second step, start with solar panels. The Canadian Solar 355W Poly PERC KuMAX panels look like good value, seems the PERC panels are the best of bread, not to sure, any advice would be appreciated. Based on my roof area and angle, I can easy fit 24 panels based on their size (2m x 1m), but would probably prefer starting out with 12-14 panels.
   - My calculations brings the max generation capacity on a good day to 4.2 kwh to 5 kwh.
   - This is where I start tripping up, I'm unsure what hybrid inverter I should get. (ultimately I want to go with a lithium battery pack, see step 3 but still be able to fallback to the grid or a generator if needed)
   - What other parts are required? I would like to have app monitoring etc. as well as I'm a bit of a data freak and of course be able to monitor my investment.
    
3. Third step, add some batteries to start moving off the grid for even more savings. It seems there are 3 options for lithium battery packs: Freedom Won Lite, BYD and PylonTech. The Pylon US2000B Plus 4.8kwh Lithium Battery seem very popular on the forum and the ability to expand and stack is very appealing.
   - What I am unsure of is, how fast these can be charged, work out how much excess solar power is required to get it done, etc.
4. If all fails, at least fallback on the grid during high peaks, as I don't want to build the 20% use case, but more cover the 80% use case.
   - Generally it seems that payback on a system should be around 5-6 years, with panels lasting 20 years and the Lithiums around 10 years.
   - I read somewhere that PylonTech can probably get close 15 years if looked after.
   - At least there should be around 5 years of totally free electricity, of which 1 year should be able to fund the replacement batteries.

So far I have the following in mind:

• Solar Geyser @ R 20 000
• 12 x Canadian Solar 355W Poly PERC KuMAX panels @ R 30 000
• 2 x Pylon US3000B Plus 3.5 kwh (7 kwh Lithium Battery Rack) @ R 40 000
• Hybrid Inverter (not sure about this one, probably a 5KVA model)  @  R 30 000 

Total: R 120 000 plus R 10 000 for bits and bops (R 130 000 in total)

Any advice would we highly appreciated.

Thank

Edited January 2, 2019 by d3nominat0r

[phil.g00]

1. Reduce consumption, fit Led lights, consider gas stove. 10K

2.Solar geyser agreed. 20K

3. Then get an inverter generator, arrange DB so that all non-critical loads can be switched off. 20K

From now on your in official compliance territory,(10K -sign off)) and on a 4.6kW limit. 25kPV ( Those panels are over R7/watt, you can get down to closer to R5/watt)

4.Then panels and grid-tied inverter, (I suggest Fronius) 20K (MPPT built in), and move everything you can to day time loads.

10 +20+20+10 +25+20 = 105K grand total. (Add another 10K for bits and bobs)

Alternatively, instead of 3 and 4 @ 75K, you can get a hybrid inverter with the same PV capacity limitations. ( 25K PV +30k inverter + 10k MPPT + 10K sign off as well + 40K batteries = 115K)   Grand total = 145K (including 1&2) (Add another 10K for bits and bobs)

So 40K more to go hybrid, and still with limitations of batteries as opposed extra capacity and run -time capability of a generator.

But, more than this, it is perhaps a more practical argument, that given that legal PV capacity limitation,  you will not have sufficient PV to charge your batteries. In other words, your present electrical loads are such that you'll use everything you make as soon as you make it. So it's not even a technically viable option.

So I think it's pretty clear cut, (if you want to remain legal, (and I am no judge)) a hybrid inverter is a complete waste of your financial resources.

 

 

[phil.g00]

3 hours ago, d3nominat0r said:

The Canadian Solar 355W Poly PERC KuMAX panels look like good value, seems the PERC panels are the best of bread, not to sure,

Not so sure either:

https://mcelectrical.com.au/blog/big-problems-with-mono-perc-solar-panels-technology/

 

[d3nominat0r]

Thanks

Point 1, is in place.

Point 2, Solar Geyser next up, need to shop around for a good deal.

Point 3, Already have a generator with manual switchover CoC'ed, albeit not an inverter. Will take a look.

Point 4, Any recommended panels? Can the Fronius be monitored with an App?

[d3nominat0r]

Any opinions on the InfiniSolar: On-Grid Inverter with Energy Storage? 

Edited January 2, 2019 by d3nominat0r

[phil.g00]

Regarding the geyser, I had a retrofit done recently it cost about 20K, the circulating pump is solar powered. I already had my existing geyser(s) at ground level, outside ...which I recommend if that's an option.

Inverter type generator was suggested if you didn't have one, but use what you have if it's already there. The better the sine wave the more future options, which is why suggested an inverter -type.

Yes Fronius can be monitored and also has grid limiting capability optional extra. It is expensive but reputable, (buying twice is more expensive).

https://www.fronius.com/en/photovoltaics/products/home/system-monitoring/visualisation/fronius-solar-web-app/fronius-solar-web-app

 

There is a specific model of Fronius made for the Australian market, that you want. Aus regulations dictated a 4.6kW 600V max for PV, the Fronius is good for 1000V and 5kW, but in order to satisfy the power rating, Fronius had install the current capacity of an 8.2kW model, with an 18A capability, not the 12A capability of the normal 5kW Fronius. And then Fronius called it a 4.6kW, but it's still good for 1000V and 5kW, but the Aus regulators are happy. In SA, a 1000V is the regulation, this also you over-paneling possibilities of East-West arrays while still being legal.

If you can get that model in SA, thats the one you want,so that you can have a dual string on each MPPT.  ( The Fronius has 2 Mppt's) It gives more flexibility for your arrays.

Panels, google ARTsolar.  There is also a pricelist that has well-priced panels on this forum's store.

[phil.g00]

20 minutes ago, d3nominat0r said:

Any opinions on the InfiniSolar: On-Grid Inverter with Energy Storage? 

If you are dead set on hybrid, Victron is the brand equivalent of Fronius, imho. They also work together, but I'd get the grid tie Fronius first , then look at your remaining budget.

I don't know infini, ( I am sure others will chip in) but the inverter expense is not the place to save a penny.

[d3nominat0r]

@phil.g00, thanks.

 I assume the 4.6kw limit is what is currently imposed in Cape Town. I could easily generate in 10kw based on space and panel capacity. Should this be a concern for me in Ekurhuleni, Gauteng?

 Fronius really looks like awesome kit, will it automatically supplement the PV with Grid Power during days when the PV is lower? I know some inverters purely only switch between two inputs and cannot merge them.

[phil.g00]

Yes, I think 4.6 kW is a legal limit, for single phase according to National law.

I also think it is an arbitrary BS limit.

It has since been upped to 10 kW in Aus, and in my opinion there was no technical basis for SA to originally copycat this limit.

It smacks of a Copy & Paste, so nobody local had to apply any their mind. I can't believe that thorough analysis of two independent country's power system yielded the same result to the watt.

No, it is a lazy, blame-them- not us limit adopted by SA.

That said:

I am all for electrical safety, my life depends on it on a daily basis in my job.

A reasonable person and his solar set up, should do his damndest to make sure his installation has a safe and compliant point of isolation between himself and the public grid.

After that,  my opinion is what happens on the other side (your side) of that grid interface, ( once it's safe),  is your business.

( A driving analogy) Driving without a licence is downright reckless, but if you increase your PV capacity beyond the legal limit, it's not akin speeding, it's more like having a bigger petrol tank.

Of course, I am not going to advise you to do something illegal¿, but I would advocate being clear in your own mind of your goals.

And to quote Forrest Gump, "that's all I'm going to say about that".

PS: there is a micro-inverter by Enphase called an IQ8, that is due out in 2019 Q1 that should be a game-changer if it's not vaporware.

[seant]

On your solar geyser you want to work roughly on about 70 litres of hot water per person, so I'm guessing you will be looking at between 350 to 400 litres of capacity which would be two solar  geysers. I'd go and get the geyser side sorted and then perhaps look at the swimming pool side, cut the run time back and change the sand in the filter to clinobrite. It does a better job keeping the water clean so you don't have to run the pump as long. Once you have an idea of your new electrical consumption then look at your solar needs again. See if you can lighten the 1kwh for 24 hours, especially over night when you need the batteries to work. The idea is to be able to do what you need to do with solar generation, with the idea of being able to expand into the wants .

[Guest]

18 hours ago, d3nominat0r said:

4. If all fails, at least fallback on the grid during high peaks, as I don't want to build the 20% use case, but more cover the 80% use case.

Makes a lot of sense.

[d3nominat0r]

Next step based on the replies and from some other threads. Buy an energy monitor, had this one in mind - EFERGY Electricity Energy Power Monitor, will this do the job?

Still not convinced about converting Electric Geyser to Solar. Seems some people prefer rather investing in a larger PV array and powering their electric geyser from the inverter.
It seems to more or less equivalent PV vs. Tubes at around 20K to get the job done, but you get the benefit of excess PV power generation when the geyser is not running other than the additional cost for a larger inverter.

Your thoughts?
 

[Guest]

42 minutes ago, d3nominat0r said:

... larger PV array and powering their electric geyser ...

I got advice yonks ago, posted here on PF somewhere, that if you take 1sqm of EV tubes versus one 1sqm of PV, that EV tubes will kick PV to the curb.

And if you have regular clouds, EV tubes for the 2nd time beats PV.

EV tubes, not flat panels.

If one sizes the geyser correctly, the users adjust their schedules, you may have a case for very little Eskom use per annum. 

Schedules like all shower evenings / mornings, to not cool they geyser down in between. That saved us a whopping amount of cash when we started with EV tubes, before we got solar. And we have a 200l geyser between 4 people.

Add water saving like we now do in CoCT and one has surplus hot water, heated by EV tubes only. :-) 

My 2 cents.

Edited January 3, 2019 by Guest

[phil.g00]

Knowing where your power is being used is always valuable info. - There are many ways to skin that cat, a clip-on ammeter and some extrapolation is all you really need, but each to his own.

Energy is all about the losses incurred each time it is converted, the more conversions the more losses. Direct heat transfer and vacuum insulation must be up there with optimum efficiency.

PV requires  light to DC at about (18% eff.), DC to AC (97% eff.) , (If batteries are used, well between 3-30% losses depending), electrical wiring losses and still has to deal with the same heat transfers losses at the end of all that.

My thoughts are that it still pans out from a physics point of view. Its a number-crunching exercise that has to take your roof size into account.

There are many people who would argue that PV should attract a premium value in that electrical energy is more valuable than heat energy as it is more flexible.

But really you don't have to bother with all this debate, it until you can answer this question:

If you're only allowed 4.6kW of solar, why waste it on doing something that there is no legal restriction on?

 

 

Edited January 3, 2019 by phil.g00

[Gabriel_2018]

Hi d3nominat0r,

 

I had a similar project a few months ago. We solved Geyser and pump with the same solar pannels. A string of 8x330 w pannels, a 2.2 kw driver for pump and a system designed to feed geyser. It is a very cheap solution, without inverters, batteries...

[d3nominat0r]

5 hours ago, phil.g00 said:

If you're only allowed 4.6kW of solar, why waste it on doing something that there is no legal restriction on?

 

 

Thanks, the closing argument holds “hot” water excuse the pun.

Is it 4.6kw in total or per phase? I have 3-phase power albeit only using 1-phase. The previous owner has a 3-phase point in the garage for a pottery oven.

 

[phil.g00]

Ah, you should have said.

It's 4.6kW per phase.

(You should really check your local authorities.)

It also has to spread across the 3 phases, you don't get to (legally) triple up on one phase unfortunately. 

This extra capacity allowance can make a meaningful difference.

Of course, now you have to consider the next set of limitations, like viable roof space and budget.

 

[d3nominat0r]

@phil.g00, roof space not an issue, 450 m^2 house, roof about 180 m^2 available for fitment North facing at 20 degrees. So budget is probably the only constraint. My entire house has got mono pitch roof sections which means I have a lot of usable roof space, facing in multiple directions, thinking if the inverter supports 2 MPTT's, is it worth while fitting an additional array of panels facing in NW to catch more of the afternoon sun? 

Edited January 3, 2019 by d3nominat0r

[d3nominat0r]

Also, forgot to mention, I am on a prepaid system, Landis Gyr+, seems they are very sensitive to feeding back into the grid and the correct inverter and settings are important. Can someone perhaps elaborate on the issue, what should be done not to get disconnected from the grid.

Edited January 3, 2019 by d3nominat0r

[phil.g00]

12 hours ago, d3nominat0r said:

is it worth while fitting an additional array of panels facing in NW to catch more of the afternoon sun? 

Yes, but I would recommend two different facing strings into the same MPPT, East -West if possible.

The idea is to maximize the time one has production, the midday peak will happen anyway, - try and flatten it towards AM & PM.

10 hours ago, d3nominat0r said:

Can someone perhaps elaborate on the issue, what should be done not to get disconnected from the grid

Various makes of inverters have grid-limiting possibilities. They involve monitoring the power direction on your incoming supply.

[___]

18 hours ago, d3nominat0r said:

Can someone perhaps elaborate on the issue, what should be done not to get disconnected from the grid. 

The Landis Gyr meters have something called Significant Reverse Energy (SRE) detection. The default behaviour is simply to bill you for it, but it can be factory programmed to treat reverse power as a tamper condition. And if it is programmed in this manner, and it does go into tamper mode, then usually it disconnects your power until a special unlock token is entered on the keypad (which the council has to obtain from the meter manufacturer). It is unclear if this is always the case. This document says it registers reverse energy when 50Wh has gone the wrong way. It does not say within what time window (Per event? Per day? Lifetime of the meter?).

50Wh is a pretty big value if it is per event. Most systems with a feed-in limit should be able to stay below that easily. As an example, on  typical day with fluctuating loads I will push between 50wh and 100wh into the grid accidentally (inverter backs off too slow, etc). That's per day. So the Landis seems generous... if it is per event.

Edit: Upon closer reading, it says "when there has been a continuous reverse power measurement of 50wh". So this is per event. That's 50W for an hour, or 180k watt-seconds, or 6kw for a full 30 seconds. It seems pretty lenient... compared to some others (Conlog is more like 600Watt-seconds... but at least doesn't go into tamper).

Edited January 4, 2019 by plonkster

[phil.g00]

Just guessing, but I'd think it would work like this:

 Wh's are counted up in reverse but cancelled by a forward count. So 49 forward would count a 49 reverse back down zero.

So basically, yes per event.

[___]

So on a Victron system, setting a grid setpoint of 50W (ie it tries to hold it around 50W at all times, ie a small import rather than zero), it should be just fine.

[phil.g00]

I'd have to assume a few things, but let's say that the ESS system was 3kW and it took 30secs to close down full production when some internal MCB tripped.

( I think I am being overly conservative)

That would be 3000/120 = 25Wh pumped back into the grid.

So firstly you could afford to have that happen twice in a row, before you're in trouble.

Secondly, at a grid setpoint of 50W, it would be 30min to cancel that out.

The onus would be on the meter to be conservative as to power direction, because a meter maker couldn't afford to have a product that resulted in nuisance trips for no load conditions.

Unless, your system was prone to this sort of thing happening, I think really cut it down to a grid point of even less.

[___]

1 hour ago, phil.g00 said:

Secondly, at a grid setpoint of 50W, it would be 30min to cancel that out.

I doubt the meter will keep track of your sins that long. The window it works with is usually seconds in size at most. Also, an ESS system adjusts every 2.5 seconds, but it recalculates the setpoint once a second and it adjusts by feeding in 60% of the "error" (ie how far away you are from the setpoint). So you can use that to work out how it approaches the proper level :-)