Author Topic: Scubadude's 8kW Solar Installation  (Read 3704 times)

Offline tiaand

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Re: Scubadude's 8kW Solar Installation
« Reply #75 on: December 09, 2021, 10:49:53 AM »
Im not sure how much those batteries cost - but adding another one might help get more out of your system. I have about 15kwh of batteries and its perfect for our mid size home. This is for many reasons, cloudy times during the day, irregular usage patterns, high morning loads etc.

The biggest issue I see with most systems advertised is that they go big on the inverter and small on the panels and batteries. Probably because a big kw inverter sounds good. That is usually wrong. You need to go big on panels (to use your other equipment to the fullest for the maximum amount of time). And you need the max batteries you can afford (if you have some charge left in the morning you can get through the morning load without taking a lot from the grid). A medium sized inverter will be fine for most homes.

This was not obvious to me until I installed a system and saw its performance and usage.

Offline tiaand

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Re: Scubadude's 8kW Solar Installation
« Reply #76 on: December 09, 2021, 11:08:00 AM »
P.S. with my 5kw inverter and 5.5kw charge controller I have produced up to 38kwh per day and rarely use anything from the grid. I think in high summer I could produce 40kwh or more on very sunny days.

So with some system optimization you could be basically off grid with your system quite easily.

Offline fdlsys

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Re: Scubadude's 8kW Solar Installation
« Reply #77 on: December 09, 2021, 11:09:36 AM »
... You need to go big on panels (to use your other equipment to the fullest for the maximum amount of time). And you need the max batteries you can afford ...
100%

The other reason for maxing, even going overboard with batteries, is that additional capacity reduces your daily cycle depth of discharge which benefits you in much longer useful batteries life. You can easily go from 4000 100% DOD cycles to 7000 and more at 70% or less DOD. Battery life of over 20 years, no problem .
« Last Edit: December 09, 2021, 11:30:33 AM by fdlsys »
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Offline tiaand

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Re: Scubadude's 8kW Solar Installation
« Reply #78 on: December 09, 2021, 11:33:30 AM »
100%

The other reason for maxing, even going overboard with batteries, is that additional capacity reduces your daily cycle depth of discharge which benefits you in much longer useful batteries life. You can easily go from 4000 100% DOD cycles to 7000 and more at 70% or less DOD. Battery life of over 20 years, no problem .

Precisely. There are a lot of reasons to have some juice left in the batteries most mornings.

Offline Gerry

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Re: Scubadude's 8kW Solar Installation
« Reply #79 on: December 27, 2021, 08:50:26 PM »
Apologies if this topic has already been covered, but I'm too frustrated to do the search.

I recently had a Sunsynk 8kw inverter and 2 Pylontech UP5000's installed, together with some JA panels. The pv array is nowhere close to meeting the total demand, but I thought I could save a few bob on eskom while I'm finding my feet.

The installer has been struggling for over a week to configure the system to utilise the available solar first, then draw on the batteries (down to 50%) and thereafter access the grid. And then replenish the batteries during the evening.For some reason the the load draws on solar and the grid only. Batteries SOC stays on 100% unless I physically switch-off the eskom feed on the db.

I think he is somewhat out of his depth, or is what I'm after not do-able?

Thanks.





Offline tiaand

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Re: Scubadude's 8kW Solar Installation
« Reply #80 on: December 28, 2021, 09:31:24 AM »
I dont know the sunsyncs, but since it is supposed to be full hybrid, what you are trying to achieve sounds 100% feasible. So Im pretty sure your installer just doesnt know how to configure it. Its probably in backup mode in stead of power supplementing/blending mode.

Offline Scubadude

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Re: Scubadude's 8kW Solar Installation
« Reply #81 on: December 28, 2021, 09:32:42 AM »
Installers are, in my experience, absolutely useless when it comes to even basic settings, let alone optimise it. I suppose bad setup + good relationship = more business. Or maybe they are just incompetent.

I posted a reasonably comprehensive write-up on the 8kW Deye setup here https://powerforum.co.za/topic/11111-guidance-on/ Sunsynk is broadly similar. Your specific problems sounds like Use Timer / Time of Use box is not ticked, and/or battery charge % set too high. Also check your CT coil is correctly installed just after the main breaker, and zero export to CT is ticked.
« Last Edit: December 28, 2021, 09:38:11 AM by Scubadude »
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Offline Gerry

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Re: Scubadude's 8kW Solar Installation
« Reply #82 on: December 28, 2021, 11:59:51 AM »
Thanks for the response gents.

Offline chrisc

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Re: Scubadude's 8kW Solar Installation
« Reply #83 on: December 28, 2021, 04:36:13 PM »
The manual that came with my Mecer inverter is fairly convoluted

Then there was another manual that came with a Blue Nova lithium-ion battery.  On this battery is a "State of Charge" indicator and at best, with a whole day's sunshine, it would reach 70%

After a fair bit of reading I increased the "Float" charge to 28 volts and the priority to Solar First, and only reverting to bypass with both solar was inadequate and the battery had dropped to 24.5 volts.  Within 5 days the State of Charge was now reading 100%

There are 4 different priority settings and the explanatory language somewhat ambiguous
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Offline Gerry

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Re: Scubadude's 8kW Solar Installation
« Reply #84 on: December 28, 2021, 09:52:32 PM »
And as you guessed, the "use timer" box was'nt checked, apparently as directed by the distributor :facepalm:. So now we seem to have the source priority (solar, battery, grid) sorted. But the system is not replenishing the batttery in full from the grid. SoC sitting at 70% with no inflow into the battery. So somewhere we have set a limit incorrectly.

Really helpful write-up by Scuba on powerforum, will work through that in the morning.

Thanks again.

Offline Scubadude

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Re: Scubadude's 8kW Solar Installation
« Reply #85 on: January 12, 2022, 12:02:38 PM »
A quick update three weeks after going live properly ... despite the very wet and overcast conditions my solar fraction is above 80% on most days, and as high as 98% on a couple of days that we weren't home (only housesitter at home). Unfortunately, two very low production (and high consumption) days dropped the overall solar fraction to 79%, so I am meeting my goal of 75% off-grid at this stage. Average savings R 55 per day and counting ... happy I am!



@Mods please change title to "Scubadude's 8kW Solar Installation" and move to Alternative Power section.
"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass