So been on the sun proper since July '23 and I honestly thought that the winter months would be my worst, but unless it's been a total cloud day, then it's actually been above okay. I've also been educating myself with what the system can and cannot do. 

Prior to solar our household was using around the 450-600kWh a month, but yeah that's expected with two teenage girls and a wife that doesn't really share the passion of saving. 

Currently August was my best month with a 669kWh pull from the sun and only 10.7kWh from eksdom, Prior to that we were doing mid 500'skWh and about 1/10th of that coming from eskom. The family is on board now. Wireless Cbi timers on my pool and geysers have allowed me to pretty much run 95% of my house from the sun. 

I wake up to around 45% of my batteries that are used to just top up the geysers in the morning and my day at 7am normally starts on 25% or pretty damn close to it. Hey, you try and have a household of three woman having to have cold water..............it's a price that I'm willing to pay. 🙂

Just had my best pull day yesterday of 28kWh for the day from the sun. I'm actually struggling to find more pull, I know that once the rains start and my mower, then that'll be another 2-3kWh pull......I hope. 

12 x 470w Jinko panels,
8KW Sunsynk inverter
2x 5.5KV greenrich batteries

 

Edited September 25, 20232 yr by flatfourfan

 

So been on the sun proper since July '23 and I honestly thought that the winter months would be my worst, but unless it's been a total cloud day, then it's actually been above okay. I've also been educating myself with what the system can and cannot do. 

Prior to solar our household was using around the 450-600kWh a month, but yeah that's expected with two teenage girls and a wife that doesn't really share the passion of saving. 

Currently August was my best month with a 669kWh pull from the sun and only 10.7kWh from eksdom, Prior to that we were doing mid 500'skWh and about 1/10th of that coming from eskom. The family is on board now. Wireless Cbi timers on my pool and geysers have allowed me to pretty much run 95% of my house from the sun. 

I wake up to around 45% of my batteries that are used to just top up the geysers in the morning and my day at 7am normally starts on 25% or pretty damn close to it. Hey, you try and have a household of three woman having to have cold water..............it's a price that I'm willing to pay. 🙂

Just had my best pull day yesterday of 28kWh for the day from the sun. I'm actually struggling to find more pull, I know that once the rains start and my mower, then that'll be another 2-3kWh pull......I hope. 

12 x 470w Jinko panels,
8KW Sunsynk inverter
2x 5.5KV greenrich batteries

 

Glad the system is working so great for you.

The 28 kWh is also a great yield for your best day.

Hit 30 kWh today (highest ever) from our 4.55kWp array; system installed May/June; located in JHB. Winter averaged around 20-25 kWh per day; spring has been closer to 25-30kWh per day.

 

Per-Month solar generation is 800 kWh; usage from Eskom dropped from as high as 1700kWh (yeah the 6 of us were pretty heavy!) down to 750kWh this month as submitted to CoJ; the drop is a combination of PV (saves 800kWh) and using the inverter graphs to curb general usage (killed some old light bulbs/servers/night-time geyser use - added a further 150kWh of non-solar-related savings). Thus current usage is around 50%-50% Eskom-to-PV; with most of our Eskom usage happening when the sun is down (mainly cooking and additional water heating). Might be time to move over to gas cooking and add an additional geyser (and extra panels to heat it); with perhaps a second battery to handle night-time base-load.

Bar-chart for the last few days attached as well as today's usage graph.

Water usage costs are now a tad higher than electricity usage costs (never thought I'd ever see that happen)... so is it time for a borehole? Or should we further upgrade the PV system to start covering our night-time usage? Tough decisions! 😆

ROI (including projected CoJ tariff increases) should be less than 5 years.

Planned properly, specced properly, and installed properly - a good solar installation can certainly make a significant difference; and we installed on a relatively conservative budget to boot...

Edited September 26, 20232 yr by JayMardern

 

Glad the system is working so great for you.

The 28 kWh is also a great yield for your best day.

Yup and that was a day with less than 1kWh pull from eskom. The target has always been to pull as little as possible from the grid. 

Edited September 28, 20232 yr by flatfourfan
wrong attachment

 

Yup and that was a day with less than 1kWh pull from eskom. The target has always been to pull as little as possible from the grid. 

Very well balanced system between use and production. Thanks for sharing. 

 

Hit 30 kWh today (highest ever) from our 4.55kWp array; system installed May/June; located in JHB. Winter averaged around 20-25 kWh per day; spring has been closer to 25-30kWh per day.

so looking at that graph, there is a LOT of meat still left on the bone in order to reduce your eskom usage by quite a bit more you know? What % are you running the battery down to? I'm thinking that a little more PV could make a serious knock in your 08h00-14h00 usage. 

Looking at your graph. Don't think there's sense at all to run down the battery as long as the daytime consumption exceeds your solar generation because you'll just have to replenish charge from the grid and that ultimately costs more. Loadshedding the obvious exception.

 

But if you have say 10kWh of storage, there looks to be scope for 2-3kW of additional panels to help generate more in the day to use from storage later and at night.

@flatfourfan @GreenFields Insights much appreciated! 5kWh Battery is set to cycle down to 65%; and you're right: on this particular day cycling was not beneficial at all (other days are better though!)

In this case the heavy-afternoon-use-culprit was the most usual of all usual suspects - the geyser. Daily hot-water-consumption in our house is around 12 kWh per geyser: a 3kW 150l and a 4kW 200l pair; so total of around 24kWh of heating per day. It's high.

The challenge is that we also use a lot of our hot water at night; so the geysers get done heating during the day (consuming about 9 kWh [larger geyser] and 15kWh [smaller geyser] respectively by sunset, since the smaller one is used by the kitchen during the day). Unfortunately they still need to be topped up later in the evening for an hour or so otherwise they run cold; which burns at least 8 kWh a night directly from Eskom.

 

On a typical day (graph attached),

• Smaller geyser (3kW) powers on at 8:30AM
• Larger geyser (4kW) powers on at 10:30AM, powering the smaller one off while it heats
• Larger geyser is typically at full temperature by around 1:00PM; when it's power drops to 0 the CBI Astute Timer switches the Smaller geyser back on immediately (details on this rule, here)
• Smaller one finishes by around 4PM.
• They both get heated again (over shorter periods) at night since we'd unfortunately run out of hot water otherwise. These are the evening spikes visible in my attachment to this post: a combination of a some Geysers plus some night-time electric dinner cooking.

When the larger geyser is done during the day there's often enough solar to recharge the battery; so cycling makes sense on those days (like in this attachment); as well as when there's load shedding (since both geysers are on non-essentials and hence powered down during grid-down).

On the day in my previous post, the kids all showered during daylight so the geysers never finished heating in the day (which is why there wasn't spare capacity to charge the battery). That's not usually the case though; but it did allow me to manually cut the evening-heating that day.

I've considered moving the smaller geyser to Aux (to keep it powered when grid goes down); this would potentially take us a bit close to the inverter/battery max (which I could deal with by undervolting - though that has other side-effects). Downgrading the element is another option but that would cause heating it to overshoot daylight hours.

 

The two potential longer-term solutions would be:

1. The Small Upgrade Option:
   • Add a pair of Geyserwise's to target lower temperatures in the evening.  No solar benefit, but this reduces grid-waste in the evenings and means it matters less if I forget to bypass the night-time heating timer if the family happens to finish with the hot water in the day.
   • Add a few more panels to cover daytime load-vs-PV overshooting; maximum array size is unfortunately just 5kWp (barely more than my current array) if I want to avoid clipping at mid-day. (I'd need a second battery to take advantage of the 6.5kW DC-to-DC PV-to-battery-charging capability on a larger PV array offered by the Sunsynk).
2. Alternatively: Double the Whole System (aka The Nuclear Option!):
   • Double battery to 10kWh
     • ...and use the two batteries to power all essentials at night (via time-of-day power limiting)
   • Double panels to 9kWp
     • This would provide enough extra capacity to charge the new battery, new geyser, and cover daylight-hour load-vs-PV over-shooting
   • Double inverter (2 x 5kW in parallel)
   • Add an additional small 150l geyser (with a small 2kW element) in series to leave that heating the whole day; and power-down all geysers at night regardless, knowing we've absolutely got enough hot water for the night-time under all circumstances (and hence reducing geyser grid-usage to zero on a sunny day)
     • ...and put the two smaller geysers on Aux (without worrying about inverter/battery capacity limits) to have them stay powered on during load shedding

The biggest benefit would be had from the second option; but since the current system dropped us below the magic 1000-unit-per-month breakpoint, it's all diminishing returns from here. Doubling up would take us down to just a handful of units a month but because they're now cheaper units than before, return on investment (even with reductions in hardware pricing), will still climb somewhat for the system as a whole; from around 5 years (with current system) to 7 years (if doubling up). Still worth it in the long run , I guess!

 

@flatfourfan @GreenFields Insights much appreciated! 5kWh Battery is set to cycle down to 65%; and you're right: on this particular day cycling was not beneficial at all (other days are better though!)

In this case the heavy-afternoon-use-culprit was the most usual of all usual suspects - the geyser. Daily hot-water-consumption in our house is around 12 kWh per geyser: a 3kW 150l and a 4kW 200l pair; so total of around 24kWh of heating per day. It's high.

The challenge is that we also use a lot of our hot water at night; so the geysers get done heating during the day (consuming about 9 kWh [larger geyser] and 15kWh [smaller geyser] respectively by sunset, since the smaller one is used by the kitchen during the day). Unfortunately they still need to be topped up later in the evening for an hour or so otherwise they run cold; which burns at least 8 kWh a night directly from Eskom.

 

On a typical day (graph attached),

• Smaller geyser (3kW) powers on at 8:30AM
• Larger geyser (4kW) powers on at 10:30AM, powering the smaller one off while it heats
• Larger geyser is typically at full temperature by around 1:00PM; when it's power drops to 0 the CBI Astute Timer switches the Smaller geyser back on immediately (details on this rule, here)
• Smaller one finishes by around 4PM.
• They both get heated again (over shorter periods) at night since we'd unfortunately run out of hot water otherwise. These are the evening spikes visible in my attachment to this post: a combination of a some Geysers plus some night-time electric dinner cooking.

When the larger geyser is done during the day there's often enough solar to recharge the battery; so cycling makes sense on those days (like in this attachment); as well as when there's load shedding (since both geysers are on non-essentials and hence powered down during grid-down).

On the day in my previous post, the kids all showered during daylight so the geysers never finished heating in the day (which is why there wasn't spare capacity to charge the battery). That's not usually the case though; but it did allow me to manually cut the evening-heating that day.

I've considered moving the smaller geyser to Aux (to keep it powered when grid goes down); this would potentially take us a bit close to the inverter/battery max (which I could deal with by undervolting - though that has other side-effects). Downgrading the element is another option but that would cause heating it to overshoot daylight hours.

 

The two potential longer-term solutions would be:

1. The Small Upgrade Option:
   • Add a pair of Geyserwise's to target lower temperatures in the evening.  No solar benefit, but this reduces grid-waste in the evenings and means it matters less if I forget to bypass the night-time heating timer if the family happens to finish with the hot water in the day.
   • Add a few more panels to cover daytime load-vs-PV overshooting; maximum array size is unfortunately just 5kWp (barely more than my current array) if I want to avoid clipping at mid-day. (I'd need a second battery to take advantage of the 6.5kW DC-to-DC PV-to-battery-charging capability on a larger PV array offered by the Sunsynk).
2. Alternatively: Double the Whole System (aka The Nuclear Option!):
   • Double battery to 10kWh
     • ...and use the two batteries to power all essentials at night (via time-of-day power limiting)
   • Double panels to 9kWp
     • This would provide enough extra capacity to charge the new battery, new geyser, and cover daylight-hour load-vs-PV over-shooting
   • Double inverter (2 x 5kW in parallel)
   • Add an additional small 150l geyser (with a small 2kW element) in series to leave that heating the whole day; and power-down all geysers at night regardless, knowing we've absolutely got enough hot water for the night-time under all circumstances (and hence reducing geyser grid-usage to zero on a sunny day)
     • ...and put the two smaller geysers on Aux (without worrying about inverter/battery capacity limits) to have them stay powered on during load shedding

The biggest benefit would be had from the second option; but since the current system dropped us below the magic 1000-unit-per-month breakpoint, it's all diminishing returns from here. Doubling up would take us down to just a handful of units a month but because they're now cheaper units than before, return on investment (even with reductions in hardware pricing), will still climb somewhat for the system as a whole; from around 5 years (with current system) to 7 years (if doubling up). Still worth it in the long run , I guess!

You dont seem to consider a heat pump/s that can reduce your 24kwh per day to 8-12kwh per day no matter what the source is. No info on the distance apart for the geysers and essential to know if a heat pump can/might work or not. 

Also bear in mind that the 3rd geyser with much larger surface area could cause you to use 6kwh a day just to keep the 3 geysers at the same high temperature if no hot water is used. 

 

@flatfourfan @GreenFields Insights much appreciated! 5kWh Battery is set to cycle down to 65%; and you're right: on this particular day cycling was not beneficial at all (other days are better though!)

In this case the heavy-afternoon-use-culprit was the most usual of all usual suspects - the geyser. Daily hot-water-consumption in our house is around 12 kWh per geyser: a 3kW 150l and a 4kW 200l pair; so total of around 24kWh of heating per day. It's high.

The challenge is that we also use a lot of our hot water at night; so the geysers get done heating during the day (consuming about 9 kWh [larger geyser] and 15kWh [smaller geyser] respectively by sunset, since the smaller one is used by the kitchen during the day). Unfortunately they still need to be topped up later in the evening for an hour or so otherwise they run cold; which burns at least 8 kWh a night directly from Eskom.

 

On a typical day (graph attached),

• Smaller geyser (3kW) powers on at 8:30AM
• Larger geyser (4kW) powers on at 10:30AM, powering the smaller one off while it heats
• Larger geyser is typically at full temperature by around 1:00PM; when it's power drops to 0 the CBI Astute Timer switches the Smaller geyser back on immediately (details on this rule, here)
• Smaller one finishes by around 4PM.
• They both get heated again (over shorter periods) at night since we'd unfortunately run out of hot water otherwise. These are the evening spikes visible in my attachment to this post: a combination of a some Geysers plus some night-time electric dinner cooking.

When the larger geyser is done during the day there's often enough solar to recharge the battery; so cycling makes sense on those days (like in this attachment); as well as when there's load shedding (since both geysers are on non-essentials and hence powered down during grid-down).

On the day in my previous post, the kids all showered during daylight so the geysers never finished heating in the day (which is why there wasn't spare capacity to charge the battery). That's not usually the case though; but it did allow me to manually cut the evening-heating that day.

I've considered moving the smaller geyser to Aux (to keep it powered when grid goes down); this would potentially take us a bit close to the inverter/battery max (which I could deal with by undervolting - though that has other side-effects). Downgrading the element is another option but that would cause heating it to overshoot daylight hours.

 

The two potential longer-term solutions would be:

1. The Small Upgrade Option:
   • Add a pair of Geyserwise's to target lower temperatures in the evening.  No solar benefit, but this reduces grid-waste in the evenings and means it matters less if I forget to bypass the night-time heating timer if the family happens to finish with the hot water in the day.
   • Add a few more panels to cover daytime load-vs-PV overshooting; maximum array size is unfortunately just 5kWp (barely more than my current array) if I want to avoid clipping at mid-day. (I'd need a second battery to take advantage of the 6.5kW DC-to-DC PV-to-battery-charging capability on a larger PV array offered by the Sunsynk).
2. Alternatively: Double the Whole System (aka The Nuclear Option!):
   • Double battery to 10kWh
     • ...and use the two batteries to power all essentials at night (via time-of-day power limiting)
   • Double panels to 9kWp
     • This would provide enough extra capacity to charge the new battery, new geyser, and cover daylight-hour load-vs-PV over-shooting
   • Double inverter (2 x 5kW in parallel)
   • Add an additional small 150l geyser (with a small 2kW element) in series to leave that heating the whole day; and power-down all geysers at night regardless, knowing we've absolutely got enough hot water for the night-time under all circumstances (and hence reducing geyser grid-usage to zero on a sunny day)
     • ...and put the two smaller geysers on Aux (without worrying about inverter/battery capacity limits) to have them stay powered on during load shedding

The biggest benefit would be had from the second option; but since the current system dropped us below the magic 1000-unit-per-month breakpoint, it's all diminishing returns from here. Doubling up would take us down to just a handful of units a month but because they're now cheaper units than before, return on investment (even with reductions in hardware pricing), will still climb somewhat for the system as a whole; from around 5 years (with current system) to 7 years (if doubling up). Still worth it in the long run , I guess!

Your best immediate option is to max your inverters PV input. I would also consider a solar geyser with 2kw backup element. 

When you talk about ROI are you factoring in that in 5 years time electricity will probably be double the cost that it is now? 

  

 

You dont seem to consider a heat pump/s that can reduce your 24kwh per day to 8-12kwh per day no matter what the source is. No info on the distance apart for the geysers and essential to know if a heat pump can/might work or not. 

Also bear in mind that the 3rd geyser with much larger surface area could cause you to use 6kwh a day just to keep the 3 geysers at the same high temperature if no hot water is used. 

Heat pumps are incredibly efficient but their short-ish lifespans (especially under heavy use) and high-ish upfront cost is a bit of a downer: I've got three reverse heat-pumps (aka air conditioners!); and the two that are most frequently used are out of action; including a nice, overpriced Carrier unit that was only 7 years old (and had a non-mechanical electrical problem that no technician could economically repair without an expensive mainboard replacement; such is the nature of these things!). I'm thus inclined to avoid equipment with moving parts for this reason.

I'm currently heating 350l of water almost entirely from the sun using cheap, easy-to-replace (insurance will do it for free!) regular geysers; via inverted PV. It's just those last extra 50-100l or so I need to cover; to treat another geyser like it's a giant, cheap battery for nighttime use!

Or I need to enforce daytime-showering in my house!

PV is typically rated at 25 years - during which time I'd probably go through 3 heat pumps - so the cost savings are likely to be at least partially negated... or am I mistaken?

What would the requirements be for heating 400-500 litres of water per day via heatpump? In my case, the distance between the two geysers is about 15m. Could I get away with a single 2kW unit?  Or perhaps a pair of 2kW units running sequentially? Do they last longer than I've been lead to believe if properly maintained?

The other potential deal-breaker is that the smaller geysers would be run via the inverter Aux, which would hard-power-down depending on PV availability - to do heating primarily from the sun. Even on an overcast day, this would work nicely. That's fine for a geyser but cutting power to air cons is considered destructive, are heat pumps the same?

 

 

Your best immediate option is to max your inverters PV input.

 

I'm pretty close to the max already (4.5kWp on a 5kW unit - unless I add another battery to do DC-to-DC); I could push it up and just clip in the middle of the day, though. And of course paralleling a second inverter is looking tempting (to double the max!)

 

 

When you talk about ROI are you factoring in that in 5 years time electricity will probably be double the cost that it is now? 

Yes, this takes into account increases based on the historical 5-year average. And right now, hardware costs are even lower so this figure would be even better if I purchased now. To anyone on the fence: go for it!

 

One other idea: perhaps I should crank up the thermostat of the current geysers to let them get hotter in the day? Is this possible/legal? Then this, plus a few extra panels (even with clipping) could potentially sort my household out?

 

  

Heat pumps are incredibly efficient but their short-ish lifespans (especially under heavy use) and high-ish upfront cost is a bit of a downer: I've got three reverse heat-pumps (aka air conditioners!); and the two that are most frequently used are out of action; including a nice, overpriced Carrier unit that was only 7 years old (and had a non-mechanical electrical problem that no technician could economically repair without an expensive mainboard replacement; such is the nature of these things!). I'm thus inclined to avoid equipment with moving parts for this reason.

I'm currently heating 350l of water almost entirely from the sun using cheap, easy-to-replace (insurance will do it for free!) regular geysers; via inverted PV. It's just those last extra 50-100l or so I need to cover; to treat another geyser like it's a giant, cheap battery for nighttime use!

Or I need to enforce daytime-showering in my house!

PV is typically rated at 25 years - during which time I'd probably go through 3 heat pumps - so the cost savings are likely to be at least partially negated... or am I mistaken?

What would the requirements be for heating 400-500 litres of water per day via heatpump? In my case, the distance between the two geysers is about 15m. Could I get away with a single 2kW unit?  Or perhaps a pair of 2kW units running sequentially? Do they last longer than I've been lead to believe if properly maintained?

The other potential deal-breaker is that the smaller geysers would be run via the inverter Aux, which would hard-power-down depending on PV availability - to do heating primarily from the sun. Even on an overcast day, this would work nicely. That's fine for a geyser but cutting power to air cons is considered destructive, are heat pumps the same?

 

I'm pretty close to the max already (4.5kWp on a 5kW unit - unless I add another battery to do DC-to-DC); I could push it up and just clip in the middle of the day, though. And of course paralleling a second inverter is looking tempting (to double the max!)

 

Yes, this takes into account increases based on the historical 5-year average. And right now, hardware costs are even lower so this figure would be even better if I purchased now. To anyone on the fence: go for it!

 

One other idea: perhaps I should crank up the thermostat of the current geysers to let them get hotter in the day? Is this possible/legal? Then this, plus a few extra panels (even with clipping) could potentially sort my household out?

Max PV input on that inverter is 6500W. Since you hardly hit your kwp due to losses you could overpower a little and get more morning and afternoon power with only midday clipping. 

Another option is to ac couple a micro inverter to your non-essentials if your meter can back feed. 

 

  

Heat pumps are incredibly efficient but their short-ish lifespans (especially under heavy use) and high-ish upfront cost is a bit of a downer: I've got three reverse heat-pumps (aka air conditioners!); and the two that are most frequently used are out of action; including a nice, overpriced Carrier unit that was only 7 years old (and had a non-mechanical electrical problem that no technician could economically repair without an expensive mainboard replacement; such is the nature of these things!). I'm thus inclined to avoid equipment with moving parts for this reason.

I'm currently heating 350l of water almost entirely from the sun using cheap, easy-to-replace (insurance will do it for free!) regular geysers; via inverted PV. It's just those last extra 50-100l or so I need to cover; to treat another geyser like it's a giant, cheap battery for nighttime use!

Or I need to enforce daytime-showering in my house!

PV is typically rated at 25 years - during which time I'd probably go through 3 heat pumps - so the cost savings are likely to be at least partially negated... or am I mistaken?

What would the requirements be for heating 400-500 litres of water per day via heatpump? In my case, the distance between the two geysers is about 15m. Could I get away with a single 2kW unit?  Or perhaps a pair of 2kW units running sequentially? Do they last longer than I've been lead to believe if properly maintained?

The other potential deal-breaker is that the smaller geysers would be run via the inverter Aux, which would hard-power-down depending on PV availability - to do heating primarily from the sun. Even on an overcast day, this would work nicely. That's fine for a geyser but cutting power to air cons is considered destructive, are heat pumps the same?

 

I'm pretty close to the max already (4.5kWp on a 5kW unit - unless I add another battery to do DC-to-DC); I could push it up and just clip in the middle of the day, though. And of course paralleling a second inverter is looking tempting (to double the max!)

 

Yes, this takes into account increases based on the historical 5-year average. And right now, hardware costs are even lower so this figure would be even better if I purchased now. To anyone on the fence: go for it!

 

One other idea: perhaps I should crank up the thermostat of the current geysers to let them get hotter in the day? Is this possible/legal? Then this, plus a few extra panels (even with clipping) could potentially sort my household out?

I am holding both my thumbs. My ITS is now 12yrs old and I only had the pump replaced 5yrs ago and without a strainer it was destined to fail. So even with heat pumps choose the installer carefully. 

We used to be 5 in the household but now just 2. I rate us as low users with the heat pump only operating about 2.5hrs a day plus the time after a bath. 

 

Max PV input on that inverter is 6500W. Since you hardly hit your kwp due to losses you could overpower a little and get more morning and afternoon power with only midday clipping. 

We can't invert more than 5000W to AC - so the balance would go to the battery via DC-to-DC, correct?

So if I pushed up the array to 6500W (another 5-ish panels - not all that expensive), then on peak-production days, as long as the battery is below 100%, the 1500W balance above 5000W could go to the battery - and then it'll only get clipped to 5000W if the battery is full?

And of course there'd be benefit in the hours further away from mid-day where were're further away from that maximum; right?

 

We can't invert more than 5000W to AC - so the balance would go to the battery via DC-to-DC, correct?

So if I pushed up the array to 6500W (another 5-ish panels - not all that expensive), then on peak-production days, as long as the battery is below 100%, the 1500W balance above 5000W could go to the battery - and then it'll only get clipped to 5000W if the battery is full?

And of course there'd be benefit in the hours further away from mid-day where were're further away from that maximum; right?

With over panelling your geysers could be turned on earlier and switched off later and you could still have a full battery. 

Your PV is maxing at 4k on that graph. If you could push it higher you could cover your geysers totally from PV in the day and charge battery faster. 

 

We can't invert more than 5000W to AC - so the balance would go to the battery via DC-to-DC, correct?

So if I pushed up the array to 6500W (another 5-ish panels - not all that expensive), then on peak-production days, as long as the battery is below 100%, the 1500W balance above 5000W could go to the battery - and then it'll only get clipped to 5000W if the battery is full?

And of course there'd be benefit in the hours further away from mid-day where were're further away from that maximum; right?

If the battery is full and you don't have about 5kw of load connected the PV production will not be 5kw as whatever PV you produce must go towards a load. 

 

If the battery is full and you don't have about 5kw of load connected the PV production will not be 5kw as whatever PV you produce must go towards a load. 

Exactly; peak PV will now be beyond the 5000W AC rating of the inverter. Hence if PV goes above 5000W (whilst AC load is equal to - or even greater than - 5000W), I'd need to make sure the battery isn't full so that we can dump the balance of the PV (up to an additional 1500W - for a total of 6500W PV supported by the inverter) into the battery to minimize wasted PV. This is since DC-to-AC is capped at 5000W, whilst DC-to-DC can do the full 6500W if I'm not mistaken,

 

 

Your PV is maxing at 4k on that graph. If you could push it higher you could cover your geysers totally from PV in the day and charge battery faster. 

Yes!! And push up the thermostat to the max (anyone know if there're limits on this?) - to maybe score that last 30% extra heat needed to handle the evenings using the existing geysers. (Or so I hope!)

Edited October 2, 20232 yr by JayMardern

 

Hi all...

 

Thought I'd share my usage stats, system was installed and online from 26 May 2023.

System info:

12 x 550w Longi Panels (North Facing)
2 x 5kVa Sunsynk Inverters
1 x 15kWh BSL Powerwall

 

Two main goals were reduce the reliance on the grid and also kick load shedding to the curb.

Initially I used the Sunsynk data logger and app, but soon realized its not going to help maximise the system to get the most for our buck...or quite alot of bucks.

So I got Solar Assistant and installed on the 16th June...definitely worth that investment.

 

We are essentially 2 x households here so everything is doubled...2 x geysers (4kW and 2kW elements), 3 x fridges and a small chest freezer, 6 x TV's but mostly two are used consecutively...lighting in both houses are 99% LED's with the exception of 2 x sensor floodlights that are 230w bulbs these are on from 6pm - 6am daily. Dishwasher, 2 x washing machines. We have adjusted to running all the heavy lifting appliances during sun hours...washing machines, dishwasher, ironing, vacuuming etc. Everything but the ovens and 1 x stove is on the system. The other stove is converted to gas recently and planning for the other stove to be converted soon.

 

Battery is currently set to 50% across ALL time slots, could maybe go a bit lower to further reduce the reliance on the grid. For now its working out.

Geysers run early morning for hot showers both for 2hrs each - controlled by CBi Astute switches, manually set each night based on load shedding times so not to use the battery.

Then once the sun is up the 2kW goes on at 08:30 producing enough by then to carry that load with the normal house load until 10:30.

At 10:30 the 4kW goes on and runs until 13:00. Then at 13:00 the 2kW goes on again to top up.

Battery gets charged on good days up to about 70-80% by 10:30 and then we hit 100% by early afternoon.

 

Most days the generation is between 31-33kWh on better days maximum produced so far was 37kWh to date.

 

Couple of bad days in July used alot more grid the expected and also I was still learning the best fit for our use.

In mid-August I stopped running the geyers early morning on Saturdays and Sunday's and that's probable saving us about 25-30kWh alone now per weekend.

Small blip on the 12th-13th Sep, I got an SD card for Solar Assistant...I imported the back up fine but then on the 13th I hit the wrong button and it re-restored the backup so I lost about 24hrs of data.

Looks like we on track to have a better month in terms of grid usage.

Prior to solar we would spend about R3000 - R4000 a month on prepaid, we are now spending between R1000-R1500.

 

We run on battery from about 16:00, still producing some PV under 500w but the load at the time is minimal.

Depending on usage we can either hit 50% by 22:00 or earlier or on very good days we only hit 50% battery by like 01:00 - 02:00.

So coming back to the original topic of the thread 😝

September, best month so far in terms of grid usage…also with warmer temps of late I am now getting away with running the 4kW geyser for only 90min early mornings.

 

Exactly; peak PV will now be beyond the 5000W AC rating of the inverter. Hence if PV goes above 5000W (whilst AC load is equal to - or even greater than - 5000W), I'd need to make sure the battery isn't full so that we can dump the balance of the PV (up to an additional 1500W - for a total of 6500W PV supported by the inverter) into the battery to minimize wasted PV. This is since DC-to-AC is capped at 5000W, whilst DC-to-DC can do the full 6500W if I'm not mistaken,

 

Yes!! And push up the thermostat to the max (anyone know if there're limits on this?) - to maybe score that last 30% extra heat needed to handle the evenings using the existing geysers. (Or so I hope!)

It's your geyser. Set the temp up😉

On 2023/10/03 at 6:33 AM, Chris_S said:

It's your geyser. Set the temp up😉

This worked. Brilliantly.

Thermostat was around 55-60, pushed it to the max (70) which added about 30-40 minutes of heating time during the day; cut it off at 4PM - the water was piping hot for everyone. Thought it might be fluke (because I absolutely couldn't do this last week before the thermostat change) - but 3 consecutive days have been perfect. Geyser consumption per day is roughly the same; but said consumption now happens entirely during daylight hours.

Winter might require me to to do the same on the other geyser (and move one shower there).

This is also one less thing for me to worry about since I no longer have to manually skip the nighttime heat-up when everyone's done for the day during daylight.

Basically added a 2.5kWh battery to my system, at zero cost, which happens to hold water!

Thanks PowerForum!

1 hour ago, JayMardern said:

This worked. Brilliantly.

Thermostat was around 55-60, pushed it to the max (70) which added about 30-40 minutes of heating time during the day; cut it off at 4PM - the water was piping hot for everyone. Thought it might be fluke (because I absolutely couldn't do this last week before the thermostat change) - but 3 consecutive days have been perfect. Geyser consumption per day is roughly the same; but said consumption now happens entirely during daylight hours.

Winter might require me to to do the same on the other geyser (and move one shower there).

This is also one less thing for me to worry about since I no longer have to manually skip the nighttime heat-up when everyone's done for the day during daylight.

Basically added a 2.5kWh battery to my system, at zero cost, which happens to hold water!

Thanks PowerForum!

When I set mine right up it is still hot enough the next morning to shower. 

You can also insulate the geyser with a geyser blanket

Edited October 6, 20232 yr by Chris_S

On 2023/10/06 at 12:15 PM, JayMardern said:

This worked. Brilliantly.

Thermostat was around 55-60, pushed it to the max (70) which added about 30-40 minutes of heating time during the day; cut it off at 4PM - the water was piping hot for everyone. Thought it might be fluke (because I absolutely couldn't do this last week before the thermostat change) - but 3 consecutive days have been perfect. Geyser consumption per day is roughly the same; but said consumption now happens entirely during daylight hours.

Winter might require me to to do the same on the other geyser (and move one shower there).

This is also one less thing for me to worry about since I no longer have to manually skip the nighttime heat-up when everyone's done for the day during daylight.

Basically added a 2.5kWh battery to my system, at zero cost, which happens to hold water!

Thanks PowerForum!

Do you use low flow shower roses? That reduces your water and electricity consumption. Install a flow restrictor as test but tell nobody. The people with the long hair sometimes moan it is difficult to rinse the soap out of their hair but the get used to rinsing a little bit longer. 

On 2023/10/13 at 8:44 AM, Vaal said:

Do you use low flow shower roses? That reduces your water and electricity consumption. Install a flow restrictor as test but tell nobody. The people with the long hair sometimes moan it is difficult to rinse the soap out of their hair but the get used to rinsing a little bit longer. 

Yes! Low-flow/low-pressure roses are absolute magic; we use them on both showers.

Even under the cooler weather this past week, the thermostat trick has held up nicely.

Our issue is that select family members like to spend longer than they should in the shower as part of their daily unwind process; wasting both water and energy in the name of 'relaxation'. I'd complain bitterly to them - if I wasn't one of them!