Jump to content

Recommended Posts

Hi all, completely new here but have done some reading around and would like to get some pro suggestions..

Currently on tshwane prepaid using about 18kwh on avg (April/May with stage 4-6 loadshedding and no backup) and looking to start my solar journey. Priority is to combat loadshedding, then getting best bang for buck from the system, then minimal management and life changes. Not interested in completely offgrid but I suspect best value is 80%+ off grid?

I have one 150l geyser in a household of 3 which chomps the most power. Stove+oven are gas.

If I consider these 3 options (inverter, array (460w panels), batteries)

A. 5kw Deye, 4.1kwp, 2 × 5kwh

B. 8kw Deye, 4.6kwp, 2 x 5kwh

C. 8kw Deye, 5.5kwp, 3 x 5kwh

With about a R20k jump from A to B and another R35k jump to C.

Where would you start? How would you treat the geyser in terms of ess/aux/non-ess? SOC and time settings to minimise grid usage? What micro management expected for change in loadshedding stages and times?

Link to comment
Share on other sites

Not a pro, just another user with his personal 2c to chip in, but here goes. The 18kWh of daily usage is a good start to know. Next question would be what is the maximum peak at any given time? Under 5kW? Under 8kW? Question after that would be when, what time of day do you use this power, basically what type of loads are you running and for how long, and are you willing or able to make any lifestyle changes to shift to using of more power during sunlight hours. Would be useful to know when the geyser would be running, to figure if it's more sensible to get a heat pump instead of extra panels or extra batteries.

Without knowing more, my gut feeling is that your usage is modest enough, that any of these will be virtually enough to take you at least 70-80% off-grid on clear days. 5kW of panels and 2 batteries will nearly give you your life back if managed well. If going with a 5kW, I'd put the geyser on non-essential. if you're going for an 8kW, you've got more breathing space to consider putting it on essential or smart/aux. It's tough to have just one set-it-and-forget-it configuration for all weather and loadshedding scenarios, so a remote assistant could be useful for changing settings from anywhere.

Link to comment
Share on other sites

7 hours ago, solazzz said:

Where would you start? How would you treat the geyser in terms of ess/aux/non-ess? SOC and time settings to minimise grid usage? What micro management expected for change in loadshedding stages and times?

I can't give you specific advice about strategies for the deye/sunsynk because I have a different brand of inverter. But we all face these problems, and so describing my situation might offer some insights.

You can see my system in my signature. 

Situation: Before converting to PV, the meter showed about 13 to 14 kWh per day. Two geysers
1) Main geyser. 200l. Heated by a heat pump which draws around 1.4kW. Lots of added insulation.
2) Guest geyser. 150l. Heated by an element. We don't use this often with just two of us in the house.

(1) runs twice a day on a timer. Early morning (this moves around a bit with load shedding schedules), and midday. It is given 1 hour in the morning, rarely takes more at midday. This is backed up. I can do this because of a general strategy which is to do as much as possible in the sunlit hours. This usually leaves me with a fully charged battery at about 16:00, and because we don't run any appliances at night (just the kettle a couple of times), because the geysers are on timers, because we have got into the habit of keeping our consumption low after 16:00, there is usually better than 60% of the battery available in the morning, and so I have enough in hand to run the heat pump. By midday I will almost always have PV or grid, and will still have juice in the battery.

The key thing here is that when you use anything with the word "solar" in the name, you have to make it work when the sun shines. Solar geyser? Same thing. And this means you may have to modify your own routines. When we had a solar geyser at our previous home, we tried to do everything involving hot water in the afternoons and early evening. 

The second geyser is not backed up. It is on a timer so that it doesn't run the same time as the heat pump. It is run in the early afternoon. The element has been downgraded and the thermostat is set to 55. On a sunny summer day this geyser heats up in 2 hours without alarming Eskom. So once a day, in the early afternoon. Not great, but better than a kick in the pants. And it costs me very little.

I move the timing on the heat pump around out of cautiousness. I can run it early in the morning, but I like to run it when the grid is up. Just in case. If my inverter trips (is overloaded) then it will restart given the presence of PV or grid. So that informs my cautiousness.

I think I've seen this sort of thinking quite a lot on this forum, and I see it with friends who have recently installed solar (our system is 4 years old now). Especially with the current stages and regularity of load shedding and, as I said, to maximise the benefit, you have to make some compromises. We don't run our dishwasher over night any more. We try to do everything involving more than a TV set or a light bulb during the sunlit hours. The main geyser seems to retain heat until well into the evening - my wife sometimes showers at 21:00 - and I am guessing that this is helped by the insulation on the geyser itself and on the hot water pipes. We also take care to not have (for EG) the kettle, the microwave, the heat pump, the toaster all running at the same time (I also have a ... principle more than a rule that when we replace anything, the replacement may not use more energy, preferably uses less). 

Anyway, PV households have to modify their routines. The trade off is always having the WiFi up, the fridges running, the TV and the lights and the security on, etc. Four years ago this was sometimes a hard concept to sell. Right now it is much easier.

Edited by Bobster.
The more you read these things, the more the browser introduces spelling errors! Read once and keep the error rate down.
Link to comment
Share on other sites

8 hours ago, solazzz said:

If I consider these 3 options (inverter, array (460w panels), batteries)

A. 5kw Deye, 4.1kwp, 2 × 5kwh

B. 8kw Deye, 4.6kwp, 2 x 5kwh

C. 8kw Deye, 5.5kwp, 3 x 5kwh

With about a R20k jump from A to B and another R35k jump to C.

Where would you start?

Me UHgain. 

Knowing what I know now, after living with my system for 4 years, and with what I have picked up from the generous and helpful folks on this forum, if I had to start again today, I would go for the 8kW inverter to get the extra headroom. My system is limited to 20A on the backed up side. That sounds a lot if you say it quickly. But early on we had several trips - usually early in the morning. This was when we started learning that we couldn't run the kettle, the microwave and the toaster all at once. We handle things much better now, but every now and then we run into that same barrier. Not always for reasons that are easily identified or avoided. 

I wouldn't use that 8kW limit most of the time, but it would come in handy.

My own opinion: 10kWh of battery is what a household needs. I understand that some folks can't afford that, and it may be that much of the time it doesn't make a difference. But when it's an overcast morning and there's a load shed at 6 or 8, and I still have 6kWh of battery available, then I'm grateful to have the extra battery.

So that's a long winded way of saying that if you can stretch as far as 15kWh of battery you will have a very high degree of security.

Link to comment
Share on other sites

Thanks! That is valuable info and does help. I will have to look into the option of a water pump, shocked your usage is so low with 2 geysers!

To give more info on my side and where my head is at from all my previous reading.. Would prefer the extra headroom and future-proof so almost 100% decided on the 8kw. in terms of geyser usage, we currently shower in the AM and in the PM, household of 3 with very mixed and random shower schedules so hot water is required morning (from 5AM) and night (say 11PM latest would be a fair adjustment to make). Other than that, just the usual appliances with about average usage, no aircons (yet). Dishwasher and washing machine run around 10AM already.

I'm comfortable with the price of the middle system. Expensive, but i do feel it offers a good balance of convenience, savings and risk mitigation (lols corp speak). This all started as a R45k for 5kw growatt + 5kwh battery for backup, and now it's cascading into a solar system. So the thought did cross my mind if it will be worth sizing up from the get and really just taking out the management portion. But from the comments i guess that would really be overspending and the norm is to do basic shifting around of timers depending on outlier weather and some stage 6 loadshedding.

So I think the most prudent approach would be to start with 4.6kwp and 10kwh. And later look to scale it if i REALLY can't manage the system and/or feel more is needed to get a better balance of cost vs savings.

Link to comment
Share on other sites

Then the last piece is whether to put the geyser on essential, non-essential, or aux/smart. Even on this forum I see a lot of struggles with the aux and I will likely have a generator input into inverter, so that leaves the other 2. Assuming an 8kw inverter, i think there is room for keeping it on essential with a timer.

But i don't want to drain the batteries in the evening to power the geyser. Would be awesome if fully charged batteries at 4pm could carry me to the next sunny day.

So my question is, what are some common geyser timer setups to ensure hot water morning and night? Or does non-essential just make more sense here as long as CT coil is setup properly and i guess could still use a timer for the days i know no morning shower, so geyser only starts pulling power when PV is pouring in.

Tbh, the middle option made sense but then the geyser had me thinking I should just do it on non-ess (in which case i thought then ok might as well save on inverter size - option A). Then the option C thought of ugh just size up and geyser is sorted. So this is really the driving factor. Option B feels correctly sized, and needs to be managed properly and simply.

Last Q, to change the inverter settings remotely, what software and hardware do i need to ensure the installer uses? Or is just generally accepted that these are included in installs.

Thanks

Link to comment
Share on other sites

36 minutes ago, solazzz said:

Thanks! That is valuable info and does help. I will have to look into the option of a water pump, shocked your usage is so low with 2 geysers!

Well, the one geyser was usually left turned off. Then we got PV. Then I started thinking about how I could use up all the free power in the afternoons that was often left unused. I'd have to go back into historic data to see what the consumption was, but it wasn't included in the 13kWh per day that I mentioned, and even now it will only get heated ONCE. The heat pump does make a difference in comparison to an element.

Also we heat to 55 degrees. Thermostats are often set too high IMO.

36 minutes ago, solazzz said:

To give more info on my side and where my head is at from all my previous reading.. Would prefer the extra headroom and future-proof so almost 100% decided on the 8kw. in terms of geyser usage, we currently shower in the AM and in the PM, household of 3 with very mixed and random shower schedules so hot water is required morning (from 5AM) and night (say 11PM latest would be a fair adjustment to make). Other than that, just the usual appliances with about average usage, no aircons (yet). Dishwasher and washing machine run around 10AM already.

We all have our own routines, and we all have the amount that we can shift those. The real moral of my story is that there's a learning period where you figure this thing out and how you can use it and what changes you can make. Might be things like using timers to control certain heavy loads so that they don't all run at the same time. You'll figure out what works for you.  

Link to comment
Share on other sites

16 minutes ago, Bobster. said:

Might be things like using timers to control certain heavy loads so that they don't all run at the same time. You'll figure out what works you

With good geyser insulation i switch on prior to using hot water normally in the evenings and heavy loads not part of my essential loads.

Link to comment
Share on other sites

Have decided (will confirm next week) on the 8kw inverter, 10x 460w panels, and 2x 5kwh batteries. Will keep the geyser on essential and a timer from the start, will move to non-essential if I can't manage the monitoring.

Panels are higher voltage (62V), so will connect 5 (in series?) on each MPPT. Does third cut really perform better than half cut? Not too concerned either way but this is why 460w and not the 550w.

Batteries.. the supplier has Vestwoods, and I have the option to wait for Shotos coming in soon. Is it worth the wait (maybe a week or 2) or  is it much over much? Both are max 1C and seem similar.

Link to comment
Share on other sites

  • 4 weeks later...

Prices have come down a bit. I've got an 8kw Sunsynk, and 2x 5kwh Shoto SDC10Box5 batteries waiting to be installed.

Just looking for some advice w.r.t panels. I'm looking to get around 5.5kwp, that should be over-spec enough for my 18kwh per day usage (June).

I have 2 panels to choose from: 545W (50V VOC, 14A ISC) and 600W (42V VOC, 18A ISC)

So in my head, I can do 1 string of 9x600w on 1 MPPT and keep the other for future (very unlikely to expand over 5.5kwp).

OR 2 strings of 5x545w, one on each MPPT. Will this be a more efficient option? Or voltage too low? Can shuffle panels if i decide to expand.

See roof pic below, straight up is North, can see neighbors string for size reference. :)

Any suggestions?

image.thumb.png.858e7a1edcc14e5e5c139936d8a329fa.png

Link to comment
Share on other sites

Personal 2c. That middle section that's facing slightly North-West... almost parallel to your neighbour's panels... try to maximise the number of panels that can fit on that space without any risk of shading. If you can only fit around 5-6 panels there, go for the 545W panel, and face the other string towards the East.

If you can fit all of the 600W panels in that space, great, but I wouldn't go with a 5-4 split of that panel over 2 MPPT's, and facing all of them on the long East-side seems like a bit of a waste.

Link to comment
Share on other sites

Awesome, had similar thoughts as well, thanks! Will keep this thread posted.

That ideal section should hopefully fit 5 panels, just need to see how the chimney shade moves. Will get the installer to come have a proper look.

 

Link to comment
Share on other sites

  • 1 month later...

So ended up with an 8kw Sunsynk inverter, 2x 5.32kwh Sunsynk batteries and 8x 550w canadian solar panels.

Went with the recommended installer from the place where I bought the inverter. My thinking was that should minimize some of the risk of faulty components vs faulty install.

Inverter and batteries were installed in a day, and panels arrived few days later and also installed within a few hours.

System has been running with panels for almost 4 weeks and I'm happy with the performance, exceeds expectations.

The 8 panels are neatly squeezed onto that North-most facing roof, been getting decent production. Will post some stats later. There was a bit of shading in July with the low sun around 15:30 from the larger chimney (didn't see that coming at all, just made sure to avoid the smaller one). But seems to be getting better by the day. And most days I'm getting to 17:30 with 95%+ battery so not a big deal.

Installer was a nice guy and really helpful with tons of experience on all types of systems. However, I think his experience was mostly with older types of inverters and he lacked some of the Sunsynk-specific or hybrid experience. So since I have everything on essential and geyser on a CBI ASC, this isn't a problem for me. But he was not able to get non-essentials powered from the inverter. This was tested with one plug that's not on the essential side, and also the geyser has a changeover switch to move from essential to non-essential, but it now operates as essential or completely off inverter. I suspect the CT is in the wrong place, as it does pick up grid coming into the inverter as a positive value but none of the usage from the non-essential plug. We were also not able to get the petrol generator to charge batteries via the aux port, nor from the grid side. Other than that, I'm happy with the install and the system.

Next steps are to optimize a bit, will try taking a stab at HA. For now I manually adjust the first time slot SOC% and geyser times depending on the LS stage/times and weather/solcast forecast.

Glad I went with the 8kw over the 5kw, it is very noisy though when the fans kick in. Fortunately, I have it tucked far away in the garage, which is a good 15m away from the db, but well worth it. Surprised to see 60%+ of my usage is from the geyser, so about 11.7kwh avg from the 18.2kwh avg per day. This is a 150l geyser with 3kw element and 2 adults 1 kid in the house. Have been able to reduce grid usage down to 3.3kwh avg, so around the 80% reduction, I'm happy. 

What's really bugging me is that the prepaid meter (wifi module) shows higher usage than the inverter import+export. I have everything on essential, the "non-essential" plug isn't in use, so no idea what could be causing this. Anyone experience similar?

Link to comment
Share on other sites

40 minutes ago, solazzz said:

What's really bugging me is that the prepaid meter (wifi module) shows higher usage than the inverter import+export. I have everything on essential, the "non-essential" plug isn't in use, so no idea what could be causing this. Anyone experience similar?

Is this a bi-directional meter? Are you sure that your prepaid meter is capable of distinguishing between import and export? If not, I strongly suggest that you don't export any power, especially if you are not registered for it with Eskom/Municipality.

Link to comment
Share on other sites

I don't export any power, or atleast try not to, I see small bits sometimes flow through. But rounds off to 0kwh almost everyday, once or twice was 0.1kwh. My settings are limit to UPS load only. Maybe I wasn't clear, but I was expecting import to equal the prepaid meter usage. But I know some meters take export as usage so just included that as well.

I had 3days with total import of 1.5kwh, 0kwh export, but prepaid meter used 3kwh. Still monitoring further.

Edited by solazzz
Link to comment
Share on other sites

I've noticed my inverters using power on the Clearline Single Phase Over/Under Voltage Protection I have between the prepaid meter and the inverter DB whilst it claims that it's not using any power on the inverter screens. I believe this is due to a change they made on the firmware to prevent the inverters from draining the batteries and instead take from the grid for their internal usage. I wish they will give an option to enable/disable this behaviour. And yes, if I drop the MCB before the inverters that usage drops to 0, so it's not the Clearline that's misreading.

Edited by p_i
Link to comment
Share on other sites

With the Sunsynk it does seem like it uses the battery for its own usage. Am I correct in assuming that the pv+import+discharge-charge-export-load = inverter usage? Are you using the SS 8kw as well?

And also the battery discharges 40w-80w throughout the day that isn't in the load, so assumed that is all it's own usage and losses in conversion.

I don't have any voltage protector.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...