Panel direction/mppt

[Rory Kilpatrick]

Hi All,

Looking at going off-grid.Use about 250 kw/h per month. Heavy day is 10 vs 5 on a low day(24 hrs). Thoughts are 5kw S/S Inverter and 15kw S/S battery.  Sunsynk is the product most of my friends have. Clearly powerdraw would have to be managed.

90%  of food prep and cooking happens before sunset.Gas and solar hot water into electric geyser with timer on mains

I am hoping for genuine independent advise from all of you sages so that I can make informed decisions when calling for quotes in East London.

Direct Eskom customer paying R40.00/day for the privilege and R4.50 /unit..With 12% increase each year would be in for ABOUT 200k after 5 years.

Financially keeping Eskom is therefor not an option if wanting to go solar.

Would  obviously watch weather forecasts and live accordingly. Two of us over 60 and able to adapt.

Would like to be able to connect 5kva genset to trickle charge while consumption is low in the event of cloud.

I have roof space as follows with no shade issues.

Would like to run existing 2200 watt underfloor heating mid-winter whilst sun shines .  Slow warmth release during the evening.

ROOF SPACE.NO SHADE ISSUES ALL DAY

4 panels n/w 26 degree pitch tiles. Mid-winter sunset is direct  onto this roof.

4 panels  n/e  26 degree tiles

4/6 panels north on a carport to be built  with adjustable tilt for winter/summer.

1. Could I do North on MPPT1 and the balance on MPPT2

2. What size panels do I go for

3.Anybody willing to guess what annual increase would be for the next few years

4. I have read on this forum that genset connection is possible as long as Hertz is correct.

5.Would anyone have a guess as to cost of this scenario.PV array about 15 meter away from DB.

6.Any suggestions welcome. Bear in mind capex is from retirement funds.

I am very excited to get any reply

 

[Scorp007]

9 hours ago, Rory Kilpatrick said:

Hi All,

Looking at going off-grid.Use about 250 kw/h per month. Heavy day is 10 vs 5 on a low day(24 hrs). Thoughts are 5kw S/S Inverter and 15kw S/S battery.  Sunsynk is the product most of my friends have. Clearly powerdraw would have to be managed.

90%  of food prep and cooking happens before sunset.Gas and solar hot water into electric geyser with timer on mains

I am hoping for genuine independent advise from all of you sages so that I can make informed decisions when calling for quotes in East London.

Direct Eskom customer paying R40.00/day for the privilege and R4.50 /unit..With 12% increase each year would be in for ABOUT 200k after 5 years.

Financially keeping Eskom is therefor not an option if wanting to go solar.

Would  obviously watch weather forecasts and live accordingly. Two of us over 60 and able to adapt.

Would like to be able to connect 5kva genset to trickle charge while consumption is low in the event of cloud.

I have roof space as follows with no shade issues.

Would like to run existing 2200 watt underfloor heating mid-winter whilst sun shines .  Slow warmth release during the evening.

ROOF SPACE.NO SHADE ISSUES ALL DAY

4 panels n/w 26 degree pitch tiles. Mid-winter sunset is direct  onto this roof.

4 panels  n/e  26 degree tiles

4/6 panels north on a carport to be built  with adjustable tilt for winter/summer.

1. Could I do North on MPPT1 and the balance on MPPT2

2. What size panels do I go for

3.Anybody willing to guess what annual increase would be for the next few years

4. I have read on this forum that genset connection is possible as long as Hertz is correct.

5.Would anyone have a guess as to cost of this scenario.PV array about 15 meter away from DB.

6.Any suggestions welcome. Bear in mind capex is from retirement funds.

I am very excited to get any reply

 

1. Yes North panels to MPPT. Then the NW 4series go in parallel with the 4 series NE panels. 

2. On a 5kW I lean towards 455W but 545W can also work. Is is possible to fit 5 on the NE and NW if needed. 

3. Perhaps around 15% but who would know as Eskom tie their increase to reducing numbers using the grid to cover the cost of generating power. Not a great business plan going forward. 

4. Not just the speed(Hz) but need a stable speed when loaded. 

5. Starting perhaps at R180 000. Without a generator. A wild guess so let's get installers to guide you and get quotes. 

As you can adjust your habits and use if price is above your budget then start with panels proving the savings and move use to day time. You could start with less battery power as this is a high cost item and can be added if you start with 1x5 kWh. Time will guide you if you can go off grid. 

@TaliaB

Edited February 10 by Scorp007

[Rory Kilpatrick]

Just wanna say THANKS.

The fact that you and others on this forum are prepared to share knowledge and advice is fantastic.

Pretty sure that you guys have  saved a lot of anguish and frustration for many many un-informed folks.

What are pro's and con's of 3X5kw battery vs 1X15kw please

For me it's all or nothing.

Again Many Thanks

[Rory Kilpatrick]

Oops forgot.

4 panel ne and  4 nw on  1 mppt,

Max panels north on mppt2 ?

 

 

[Scorp007]

1 hour ago, Rory Kilpatrick said:

Oops forgot.

4 panel ne and  4 nw on  1 mppt,

Max panels north on mppt2 ?

 

 

The problem with 1x15kwh is when you want to increase capacity for another 15kwh about R60 000 it's expensive. You want to add the same size and make. 

When using 5 or 7.2kwh it is less capital in one go. Normally you can add up to 16.

Also if your 15kwh fails and the claim is rejected you end up with a ton in weight as a door stop. 

Depending on the specs of the panel you could for 455W panels go up to about 9 panels in series on a MPPT. Max out the number to the north on MPPT. Then you can have a string into E and another W and parallel them. But in order to do this the 5kw inverter could have a 13A maximum current and clipping will take place and it would be against the maximum rating of the inverter. This is more suited to a 8kw Deye or similar inverter. 

Once we know the maximum panels to North, East and West we can give better guidance. 

Also this is not seen as advice but an opinion. Advice is what you pay someone

Purely based on your total consumption I would max out panels and start with no more than 2x5kwh batteries but that is my view and would differ from others and based on my own very small system with the same power use per month. 

I hear your all or nothing. I have lots of friends that even after 15 yrs of LS are still at the nothing and using torches and no TV during LS. No phone charging. Just another lifestyle. 

Have you explored the option of prepaid power from Eskom. 

Edited February 11 by Scorp007

[Rory Kilpatrick]

I spoke to my guy today . He says that combining ne and nw onto MPPT 1 will result in ne dragging nw output down in the afternoon and the opposite in the morning . He also wants to go with 460w panels to stay within amperage safety range. 

He is gonna do quote options on 3X5 S/S or Hubble AM2

Got my wife trying to find out more about pre-paid

[Scorp007]

3 hours ago, Rory Kilpatrick said:

I spoke to my guy today . He says that combining ne and nw onto MPPT 1 will result in ne dragging nw output down in the afternoon and the opposite in the morning . He also wants to go with 460w panels to stay within amperage safety range. 

He is gonna do quote options on 3X5 S/S or Hubble AM2

Got my wife trying to find out more about pre-paid

NE and NW will react on light and should not differ much.(volts) The output amps will vary between the 2 but each string will provide the amps it can during the day. The different amps will just combine as they are in parallel. 

 

Edited February 20 by Scorp007

[Rory Kilpatrick]

PLEASE bear with me. Early morning sun hits NE array at 07h00 fully. NW is out of shadow at 11h00 and getting minimal angle sunlight . For those 4 hours I will get whatever power is available from NE without having NW throttling the system .From reading other posts here this is what I understand .

Times are hypothetical .

[Kalahari Meerkat]

On 2024/02/20 at 5:28 PM, Rory Kilpatrick said:

I spoke to my guy today . He says that combining ne and nw onto MPPT 1 will result in ne dragging nw output down in the afternoon and the opposite in the morning . He also wants to go with 460w panels to stay within amperage safety range. 

He does not know what he is talking about... daylight (not direct sunlight) will produce ample Tension, but very little current (mucho Volts near nada Amps), whereas direct sunlight will add the Current to the Tension... thus, panels in parallel have practically no influence on each other...

 

Off grid proper, here since early December... water heating is done by solar hot water cylinder, 12 X evacuated glass tubes into a 100 litre  hot water cylinder (low pressure, Jojo tank on 6 or 8m stand), no municipal anything here... your Eskom fees look half way reasonable, compared to what they charge here... hence, off grid.

Doing hot water with evacuated tubes, saves lots of electrons, lots of people on this forum prefer electrically heating the hot water cylinder, but direct solar is about 60 to 70% efficient, I read the other day, and solar panels, maybe just above 20% by now, then add in MPPT efficiency etc... so here in summer hot water will give you 3'd degree burns, if you don't mix in copious amounts of cold (luke warm, Kalahari...) water.

The inverter is a 5kW SunkenSynk and initially with a 8.2kWh BSL battery, end of December I added 16 X 304?5? whatever, call it 16 X 300Ah cells with a JK BMS in parallel with the existing 8k2Wh BSL, works fine, I don't have comms yet with the bigger battery and the inverter, but it tracks the data from the smaller battery roughly, at least good enough that the 300Ah is within 4 to 6% SOC of the smaller battery. So don't panic about needing to match up batteries to be the same, the only thing that has to be the same is the cell chemistry (pretty much should be LiFePO4) and the amount of cells in the battery, should be 16 cells, this then would allow you to add any capacity battery to the existing one. Here the 23-or so kWh battery is usually anywhere from 53 to 61% SOC by the time I roll out of bed and after kettle, coffee etc., by the time the sun puts a bit of charge back into the battery, we're anywhere from 46 to 51%, or so charge remaining... we had to manage things here and there when a cloudy day came along (rare here, seems to be happening more in recent time, though) but have not had to shut the house down yet, luckily.

Once you're off the grid, you may become an energy Nazi, like me, monitor on, on standby, draws too much power, switch it off, better yet, yank the power cable, when not in use/needed. You will in time look at everything that consumes energy and get cheesed off at certain items being seriously wasteful in consuming 30 or 40W, for no reason whatsoever... you're likely to find out these things in the fullness of time

[Rory Kilpatrick]

So I risked life and limb on my roof and with a tape measure established that I can fit 6ne and 6nw not 4/4 as I thumbsucked before. That will remove the need to build a structure which would affect my budget for xtra pv. Voltex are doing pretty good rates (IMO) on SOLIS  S6 6kw and HUBBLE 5kw  battery. Mid to late last year theree was a lot of folks complaining about HUBBLE voltage. Is that issue resolved ?There seems to be a little bit of negativity around SUNSYNK service on the forum at the moment.I also have to work within a budget.So I am close to going with 3X5 battery and the 12  panels 6/6 and the SOLIS.. Should I find a way to alter panel pitch from 26* to 33*  which is my latitude keeping mid winter in mind.Does anyone have a 'checklist'of things  to check with installer .As a total novice I could easily be conned wrt fuses,earth ,breakers, cable size etc.  I would much rather be over safe. Appreciate very much all contributions  to date.

Forum is FANTASTIC  for the ignorant .

[Rory Kilpatrick]

After many quotes have decided on solis s6 6kw inverter,10 trina 550w panels [5 nne 5nnw per mppt] and 3 f1 e-tower 5kw  batteries .Plan is still to go off grid completely .During good weather where should I set my  d.o.d As per eskom  meter I  use about 4/5 kw per night .My thoughts are at about 60%  and then can maybe change to 90% during inclement times . Will that help with cycle life ?

I will have my generator to assist. I think that I can set inverter to pull about 4000watt , idle the house down to 500watts which my 5.5  gennie should handle easily .  Installer will set hz accordingly .I will keep eskom for a month or so via changeover switch just in case . One disapointment is roof angle  of 26  deg as opposed to ideal 33 deg for my latitude . Will monitor through winter  and  maybe build  adjustable structure..

Thanks Guys 

[Scorp007]

5 minutes ago, Rory Kilpatrick said:

After many quotes have decided on solis s6 6kw inverter,10 trina 550w panels [5 nne 5nnw per mppt] and 3 f1 e-tower 5kw  batteries .Plan is still to go off grid completely .During good weather where should I set my  d.o.d As per eskom  meter I  use about 4/5 kw per night .My thoughts are at about 60%  and then can maybe change to 90% during inclement times . Will that help with cycle life ?

I will have my generator to assist. I think that I can set inverter to pull about 4000watt , idle the house down to 500watts which my 5.5  gennie should handle easily .  Installer will set hz accordingly .I will keep eskom for a month or so via changeover switch just in case . One disapointment is roof angle  of 26  deg as opposed to ideal 33 deg for my latitude . Will monitor through winter  and  maybe build  adjustable structure..

Thanks Guys 

As far is cycle life goes it is stated that at 80% DOD one can expect 5500 cycles that with only marginally increase to 7500 at 50% DOD so not so much of an increase. Also not sure it's worth the effort to increase from 26 to 33 degrees for a small increase in yield. If it was free standing then perhaps worth it. 

[Kibim]

@Rory, 

 

If it makes your decision any easier, i've been off-grid with 6 panels and a 5kva inverter with 2x 5kwh batteries for a few years now. Gas water heating and cooking. We only struggle after day 3 of thick cloud cover, and i have a small 2kva inverter gennie to keep the essentials running (which i've only started twice in 2 years...) Only recently looking to upgrade to 12 panels which will of course help those cloudy days anyway, and to assist running the aircons in the hot lowveld afternoons. 

 

 

Edited April 22 by Kibim