SauRoN's SomeWatt Solar Install

derp90 said:
What will this power and for how long? E.g. could a full charge last through the night, or for a cloudy day without power?
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He's getting 15kw of battery iirc - so it should.

I have 20kw - and providing my battery is full by 17:00 I start the morning with about 50% battery (as a household of 2) - but I turn the geyser off at 17:00.

Obviously if the weathers shitty then this changes things...
 
shadow_man said:
He's getting 15kw of battery iirc - so it should.

I have 20kw - and providing my battery is full by 17:00 I start the morning with about 50% battery (as a household of 2) - but I turn the geyser off at 17:00.

Obviously if the weathers shitty then this changes things...
Click to expand...
Battery is usually then full by +-11:30am - at which point I can run whatever the hell I damn please - as I've got 9.72kw of panels. I then (assuming it's sunny) only start moderating my usage from 17:00 - e.g. not run geyser.
 
So is the idea that you use this as much as you can throughout the day and only when it runs out you switch to city power?
 
derp90 said:
So is the idea that you use this as much as you can throughout the day and only when it runs out you switch to city power?
Click to expand...
Power is free during the day essentially - the idea is if you don't use it --> e.g. your battery is 100% of your house isn't consuming --> then you lose it (as your inverter will regulate input to output) --> and as it's got nowhere to go e.g. battery is full or nothing is using --> it's lost.

Thus a lot of people here bake during the day, or run heat pumps / pool pumps etc. Then they calm down on their usage overnight.

I have my inverter set to only use Eskom if my battery drops below 25% (and keep my battery on 25%, no more).

Then when the sun kicks in again --> the battery tops up --> draw from battery.
 
shadow_man said:
Power is free during the day essentially - the idea is if you don't use it --> e.g. your battery is 100% of your house isn't consuming --> then you lose it (as your inverter will regulate input to output) --> and as it's got nowhere to go e.g. battery is full or nothing is using --> it's lost.

Thus a lot of people here bake during the day, or run heat pumps / pool pumps etc. Then they calm down on their usage overnight.

I have my inverter set to only use Eskom if my battery drops below 25% (and keep my battery on 25%, no more).

Then when the sun kicks in again --> the battery tops up --> draw from battery.
Click to expand...
So cool. Is there a recommended calculator to see how long these installations take to pay for themselves with electricity savings?
 
shadow_man said:
Power is free during the day essentially - the idea is if you don't use it --> e.g. your battery is 100% of your house isn't consuming --> then you lose it (as your inverter will regulate input to output) --> and as it's got nowhere to go e.g. battery is full or nothing is using --> it's lost.

Thus a lot of people here bake during the day, or run heat pumps / pool pumps etc. Then they calm down on their usage overnight.

I have my inverter set to only use Eskom if my battery drops below 25% (and keep my battery on 25%, no more).

Then when the sun kicks in again --> the battery tops up --> draw from battery.
Click to expand...
How'd you decide on 25%?
 
derp90 said:
So cool. Is there a recommended calculator to see how long these installations take to pay for themselves with electricity savings?
Click to expand...
solaradvice iirc has some calcs - but it's relatively simple.

1.) Grab your electric bill, confirm your usage.
2.) Get a solar quote and divide by the electrical bill to determine payoff in months
3.) Factor in the pain of loadshedding
4.) Factor in that Eskom WILL increase tarrifs - so your payoff point will actually be better than the calc in point 2
5.) Wonder why you haven't done it already :ROFL:

Essentially for most people now it's probably a 10 year or so payoff --> drops down to 7-8 when you factor in Eskom increases.

Obviously - your mileage may vary depending on your usage etc.
 
derp90 said:
So cool. Is there a recommended calculator to see how long these installations take to pay for themselves with electricity savings?
Click to expand...
A crude method is to divide your installation cost by about 75% of your current electricity cost.
 
Speedster said:
How'd you decide on 25%?
Click to expand...
1.) Mostly on the fact that I didn't want to drop the battery below 20% (for some longevity).
2.) That if there's loadshedding and I've had a kak generating day - that I still have some battery left when the Eskom mains go off.
3.) Manufacturer recommendations - warranty

DoD = Depth of Discharge, recommended up to average daily 80% DoD for extended life, 50% average DoD for ultra-long life. Max allowable DoD is 90%.
 
Am I making a silly assumption that the batteries need to be mounted upright? Guessing the brackets would only work that way right?
 
SauRoNZA said:
Am I making a silly assumption that the batteries need to be mounted upright? Guessing the brackets would only work that way right?
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They don't have to - mine and @Mike Hoxbig have ours mounted onto the wall with the terminals at the top. I've seen the Dyness bracket illustrating that they can be laid horizontally (as opposed to vertically) on the ground when the bracket is used

1653047240718.png
 
SauRoNZA said:
Am I making a silly assumption that the batteries need to be mounted upright? Guessing the brackets would only work that way right?
Click to expand...
It shouldn't batter for the batteries themselves, but the enclosure may only have mounting points for a particular orientation
 
derp90 said:
What will this power and for how long? E.g. could a full charge last through the night, or for a cloudy day without power?
Click to expand...
Everything.

I am not doing any essentials/non-essentials split and the entire DB is going on the inverter which is also why it's a larger 8kW with the passthrough function under overload (which shouldn't happen).

So the full charge should just about put me through the night in summer if I consider the 1.2kW base load of heater panels in the bedrooms, but I'll likely experiment with turning the one off in the room that has an aircon and seeing if that pans out better and then determine if I'll need another battery by next winter, because I'll likely be draining it quite low.

In summer it should be golden and happily drive me through the night with plenty to spare.

I'm fortunate in that I cook dinner quite early (17:00) and should even in winter be able to get through it with virtually no battery use.

I'm also keeping my geyser on the entire system but plan to run it only when there's PV and never use it from battery short of ad hoc cases where we are maybe out late at night and the temperature has dropped too much. This will all be monitored via Home Assistant and I'll figure out the logistics later.

Intention for now is to set the geyser temp a little higher and let it run during daylight and then turn off the moment the sun goes away which should carry us through a normal night.

I may look at changing the geyser element to a fancier lower kW one, but that remains to be seen after some usage.
 
Mzezman said:
They don't have to - mine and @Mike Hoxbig have ours mounted onto the wall with the terminals at the top. I've seen the Dyness bracket illustrating that they can be laid horizontally (as opposed to vertically) on the ground when the bracket is used

View attachment 1312624
Click to expand...
Sorry I meant specially when wall mounting could one put them sideways, but I figured the brackets let them "hang" into them so that probably won't work.
 
Speedster said:
It shouldn't batter for the batteries themselves, but the enclosure may only have mounting points for a particular orientation
Click to expand...
Yeah that's my thinking.

Either way not really going to score all that much space going sideways.

Figure I'm just going to let them go in a square pattern, two at the bottom and two on top leaving one blank space for a fourth down the line.
 
SauRoNZA said:
Yeah that's my thinking.

Either way not really going to score all that much space going sideways.

Figure I'm just going to let them go in a square pattern, two at the bottom and two on top leaving one blank space for a fourth down the line.
Click to expand...
It shouldn't make much difference, the batteries are almost a square.

Here's the brackets fyi.

Top:
20220520_140554.jpg

Bottom:
20220520_140425.jpg
 
derp90 said:
So cool. Is there a recommended calculator to see how long these installations take to pay for themselves with electricity savings?
Click to expand...
I think you'll find it very hard to find a universal truth there, because not everything is a hard fast rule of X amount of use against X amount of generation.

My goal is to have more power to use than ever before and do things like run my aircon all day without worrying about the blinking red light on the prepaid box.

So yes load shedding is my primary objective to overcome, but then more so locking in my future electricity costs less so than "saving" outright and then having more to use without worrying to pay for it because it's "free".

Looking at a 10 year projection my cost works out to R1600-ish a month. Currently I pay Eskom about R2000 a month. So let's assume I use R400 on average from Eskom still with the entire setup installed, then I'm not paying any more than I did before.

Going forward I'm not beholden to price increases any more.

On the flip side I may install another battery which puts my cost up.

Other side of the coin again I can shift my usage to daylight and go pretty nuts, using the aircons and tumble dryer which were both swear words in my household before.

My heater panels will now just stay on (until the thermostat kicks in of course) instead of only running at night like they did in the past.

I'll use this thread as an honest guide of what the whole thing ends up looking like as I'm probably in for a few surprises myself.
 
shadow_man said:
He's getting 15kw of battery iirc - so it should.

I have 20kw - and providing my battery is full by 17:00 I start the morning with about 50% battery (as a household of 2) - but I turn the geyser off at 17:00.

Obviously if the weathers shitty then this changes things...
Click to expand...
10kWh overnight usage for 2 people is rather high, what do you have running using that much
 
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