Help with solar I boost

Good evening. Please post me some pictures so I can see how things are wired and how the element or elements are connected. I need too the exact model of eco mega flow cylinder.

marconi said:

Good evening. Please post me some pictures so I can see how things are wired and how the element or elements are connected. I need too the exact model of eco mega flow cylinder.

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Thank you, all we have been told is the top flats have solar panels to heat hot water when enough is generated, but don’t really understand why the timings that have been entered are fist thing in morning and late in the evening

Thank you. I will reply when I get up tomorrow. I am an early riser.

Thank you

marconi said:

Thank you. I will reply when I get up tomorrow. I am an early riser.

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https://www.marlec.co.uk/wp-content...-iBoost-User-Manual-111215.pdf?v=6805cdfd0c7a

Page 9

Dual Immersion Heater Operation The Solar iBoost+ automatically detects when two immersion heaters are connected. As hot water is drawn from the upper part of the tank, it is important the heaters are connected as shown so that the Solar iBoost+ can automatically give heating priority to the top heater. Excess generation is diverted to the top heater until temperature is reached and the heater thermostat opens. Solar iBoost+ then automatically switches to the lower heater to continue to divert excess generation until the lower heater is also satisfied and ‘Water Tank HOT’ is displayed. When diverting to the lower heater the Solar iBoost+ will periodically (every 15 minutes) switch to the top heater and the cycle of heating begins again. This maintains the temperature in the upper part of the tank. An indication of the current heater being supplied is shown on the ‘Heating by Solar’ display, see page 13. This operating mode is the same whether diverting excess generation or in boost function.

Page 15

Timed Boosts Timed Boost periods can be entered against Summer and Winter seasons. This enables longer boost times to be set in Winter periods when solar generation maybe less. Two boost periods are available each day and can be programmed on a 5 day weekday/2 day weekend basis. Programme the start time and duration of the boost using the A and B buttons as described above. Start times are selectable in 15 minute steps and the duration of the boost in 30 minute steps. e.g. a setting of 07:00 1.5hrs will switch on the boost at 7 am for 1 hour 30 minutes. An unused boost is left at 00:00 for 0:00 duration. The operating boost season is set manually using the Boost Season feature found at the end of the normal Display Cycle, see page 14. Boosts may be temporarily disabled (e.g. for holiday periods) by selecting ‘Timed Boosts OFF’.

Or in my words: There is an upper and lower immersion heater (IH) element. The top is used until the water is hot enough to turn its thermostat off. The SIB then supplies power to the lower element until the lower layer of water is hot enough to turn its thermostat off. The SIB then looks at each IH periodically to see if their thermostat has closed and thus require power; if the'stat is closed then it will be supplied until the stat opens.

What the Solax inverter does is generate solar electricity which it supplies to your consumer unit. The first call on this solar electricity is to power anything electrical in your home which demands it instant by instant. If more solar power is being generated than can be consumed then the difference is exported back in to the mains cable to your home. The sensor inside the consumer unit is connected to the sender dangling below the consumer unit. It sends a signal to the SIB whose level is proportional to the power being exported. The most economic way to use solar power is self-consumption not export. The computer inside the SIB controls the turning on of the IH element (top or bottom) so that it consumes an average power equal to that which would have been exported . I use the term average power because if say a 3kW power rated element is turned on and off regularly the amount of power it consumes depends on the ratio of the on time to the off time.

The SIB turns on the IH to consume 3kW but only for a fraction of time t/T such that 3 x t/T = the power which would have been exported. eg: if t= 5 seconds on and T = ton + toff = 10 Seconds the element is on average on half the time and thus consumes an average power of 3 x 5/10 = 1.5kW

Therefore, 3kW of solar power could power the 3kW element assuming no other demands. 4kW of solar power would result in 1kW of export if there were no other demands. 800W of solar would result in an import from the mains of 3000-800 = 2.2kW to power the IH (again assuming no other demands).

I will cover Boost in another post.

Programmed Timed and Manual Boosts; See pages 14 and 15. The boosts always operate the IH at 3kW ie toff is zero so that t/T=1. The same is so for the Manual Boost. The Boost feature ensures you can have some hot water when you need it according to your lifestyle and usage pattern and the time of the year. Even so the cost of electricity to power the IH during Boost phase may be offset to some extent by any solar power exported. The key thing about operating in Boost is that the elements power consumption is not being calibrated by the SIB to match the power being exported.

let me know if I have answered your query please.

Thank you, I’m sure you have answered it brilliantly, but still not sure what I’m paying for and what I’m not, sorry, and what times are best to have boost, also not sure why my consumption makes a difference as the solar only powers the water, probably best to just leave it as it is and hope for small bills, but thank you so much for taking the time to explain

Ordinarily, the solar pv installation is connected so that it could supply or make a contribution to supplying anything electrical at 240V in your home. The aim of the solar pv is reduce your home's requirement to import electricity from the mains which you would pay for at the kWh tariff of your supplier. There will be times when solar pv generation is enough to supply the prevailing demand and what is excess is exported into the mains; if you have this set up with your electricity supplier you can be paid for what you export albeit at a much lower rate then they charge you for imports - this is why self consumption is the best way to use solar pv.

At times when you have excess solar pv the solar iboost detects this and stores the excess electrical energy as heat energy - hot water in your mega flow tank. Out of a Boost period you do not pay for any electricity to heat up the water in this tank. It all comes from the sun. Obviously on really sunny days you will generate much more solar electrical energy than on overcast days or at night. During summer there may well be enough excess solar pv to heat the water in the tank to provide all your hot water needs.

If there is insufficient excess solar pv because of reduced sunshine or maybe you have had a high days use of electrical energy running say a tumble dryer, washing machine or dishwasher, there may not have been enough excess solar pv to be diverted to heat the water in the tank. To take account of this you can deliberately programme the immersion heaters to turn on and off at their full power of 3kW to heat the water in the tank until their thermostats operate at 60C. This is either a timed boost or a manual boost.

If the megaflow was the only load requiring energy during the boost mode the electricity you pay for to heat the water is 3kW less (solar pv kW generation). But if the washing was running and it was consuming 2.2kW you would pay for electricity equal to (3+ 2.2) less solar pv kW generation. A little while later the freezer turns on and requires 150W. Prevailing solar generation is 2.7kW. You have to import and pay for (3 + 2.2 + 0.15) - 2.7 = 5.35 - 2.7 = 2.65kW

If you have to use the timed boost function then it should be programmed to use cheap rate off peak electricity. At other times the boost should be kept short term and preferably only to the upper element.

marconi said:

https://www.marlec.co.uk/wp-content...-iBoost-User-Manual-111215.pdf?v=6805cdfd0c7a

Page 9

Dual Immersion Heater Operation The Solar iBoost+ automatically detects when two immersion heaters are connected. As hot water is drawn from the upper part of the tank, it is important the heaters are connected as shown so that the Solar iBoost+ can automatically give heating priority to the top heater. Excess generation is diverted to the top heater until temperature is reached and the heater thermostat opens. Solar iBoost+ then automatically switches to the lower heater to continue to divert excess generation until the lower heater is also satisfied and ‘Water Tank HOT’ is displayed. When diverting to the lower heater the Solar iBoost+ will periodically (every 15 minutes) switch to the top heater and the cycle of heating begins again. This maintains the temperature in the upper part of the tank. An indication of the current heater being supplied is shown on the ‘Heating by Solar’ display, see page 13. This operating mode is the same whether diverting excess generation or in boost function.

Page 15

Timed Boosts Timed Boost periods can be entered against Summer and Winter seasons. This enables longer boost times to be set in Winter periods when solar generation maybe less. Two boost periods are available each day and can be programmed on a 5 day weekday/2 day weekend basis. Programme the start time and duration of the boost using the A and B buttons as described above. Start times are selectable in 15 minute steps and the duration of the boost in 30 minute steps. e.g. a setting of 07:00 1.5hrs will switch on the boost at 7 am for 1 hour 30 minutes. An unused boost is left at 00:00 for 0:00 duration. The operating boost season is set manually using the Boost Season feature found at the end of the normal Display Cycle, see page 14. Boosts may be temporarily disabled (e.g. for holiday periods) by selecting ‘Timed Boosts OFF’.

Or in my words: There is an upper and lower immersion heater (IH) element. The top is used until the water is hot enough to turn its thermostat off. The SIB then supplies power to the lower element until the lower layer of water is hot enough to turn its thermostat off. The SIB then looks at each IH periodically to see if their thermostat has closed and thus require power; if the'stat is closed then it will be supplied until the stat opens.

What the Solax inverter does is generate solar electricity which it supplies to your consumer unit. The first call on this solar electricity is to power anything electrical in your home which demands it instant by instant. If more solar power is being generated than can be consumed then the difference is exported back in to the mains cable to your home. The sensor inside the consumer unit is connected to the sender dangling below the consumer unit. It sends a signal to the SIB whose level is proportional to the power being exported. The most economic way to use solar power is self-consumption not export. The computer inside the SIB controls the turning on of the IH element (top or bottom) so that it consumes an average power equal to that which would have been exported . I use the term average power because if say a 3kW power rated element is turned on and off regularly the amount of power it consumes depends on the ratio of the on time to the off time.

The SIB turns on the IH to consume 3kW but only for a fraction of time t/T such that 3 x t/T = the power which would have been exported. eg: if t= 5 seconds on and T = ton + toff = 10 Seconds the element is on average on half the time and thus consumes an average power of 3 x 5/10 = 1.5kW

Therefore, 3kW of solar power could power the 3kW element assuming no other demands. 4kW of solar power would result in 1kW of export if there were no other demands. 800W of solar would result in an import from the mains of 3000-800 = 2.2kW to power the IH (again assuming no other demands).

I will cover Boost in another post.

Click to expand...

The iboost unit will not top up electricity from the grid. In the instance of 800w of solar energy this is what will be used in the element. The unit is designed to use any surplus whether it be 200w or 2700w and apply it to a resistive load, in this case one or two elements

Macsamillion said:

The iboost unit will not top up electricity from the grid. In the instance of 800w of solar energy this is what will be used in the element. The unit is designed to use any surplus whether it be 200w or 2700w and apply it to a resistive load, in this case one or two elements

Click to expand...

Good morning. I think we are agreeing on how the iBoost functions. What I was trying to say is that the IH element always draws 3kW or circa 12 Amps whenever there is solar export- but the element is turned on and off with a mark space ratio such that the time averaged power the element consumes is equal to that amount of solar generated power which otherwise would have been exported. eg One kW solar export would result in an on to off ratio (based on cycles of the mains sinusoid) of 1 on : 2 off as then the average power consumed by the 3kW element is 3 x [ 1/(1 +2) ] = 1kW.

Got a question regarding solar iboost. Thought I’d grab the back of this existing one.

i have fitted loads and i understand the operation and concept.

I have a 250L cylender with 2 immersions.



what im proposing to do.:

connect the bottom immersion to the solar iboost and set temp to 70 degrees on the immersion.

connect the top immersion on separate circuit through a timer for a boost function to top up each day if nessisary, but I just want to set the top one to 55 degrees.

this way I hopefully won’t ever need to top up, but if I do it will be to the minimum 55 legenella level.

my question can I some how wire up both immersions through the iboost and just have the top immersion on the boost function from the grid so it just takes it to 55 degrees.

hope that makes sense.

Paignton pete said:

Got a question regarding solar iboost. Thought I’d grab the back of this existing one.

i have fitted loads and i understand the operation and concept.

I have a 250L cylender with 2 immersions.



what im proposing to do.:

connect the bottom immersion to the solar iboost and set temp to 70 degrees on the immersion.

connect the top immersion on separate circuit through a timer for a boost function to top up each day if nessisary, but I just want to set the top one to 55 degrees.

this way I hopefully won’t ever need to top up, but if I do it will be to the minimum 55 legenella level.

my question can I some how wire up both immersions through the iboost and just have the top immersion on the boost function from the grid so it just takes it to 55 degrees.

hope that makes sense.

Click to expand...

Paignton pete said:

Got a question regarding solar iboost. Thought I’d grab the back of this existing one.

i have fitted loads and i understand the operation and concept.

I have a 250L cylender with 2 immersions.



what im proposing to do.:

connect the bottom immersion to the solar iboost and set temp to 70 degrees on the immersion.

connect the top immersion on separate circuit through a timer for a boost function to top up each day if nessisary, but I just want to set the top one to 55 degrees.

this way I hopefully won’t ever need to top up, but if I do it will be to the minimum 55 legenella level.

my question can I some how wire up both immersions through the iboost and just have the top immersion on the boost function from the grid so it just takes it to 55 degrees.

hope that makes sense.

Click to expand...

No, as the iboost can only support 1 x 3kw output. It's designed to heat the top first then the bottom. Manual asks for HTR 1at the top as this is where your draw off is. I run both elements off the solar I boost. You can still have a timed or manual boost which uses grid supply. This function just bypasses the CT measuring device. Isn't this the functionality you are looking for?

Macsamillion said:

No, as the iboost can only support 1 x 3kw output. It's designed to heat the top first then the bottom. Manual asks for HTR 1at the top as this is where your draw off is. I run both elements off the solar I boost. You can still have a timed or manual boost which uses grid supply. This function just bypasses the CT measuring device. Isn't this the functionality you are looking for?

Click to expand...

Yep! Thought so. Jus5 hoped I could do something to stop the bottom immersion being heated during boost.

the bottom immersion being set at 70 degrees and top one set to 55, I didn’t want the boost to take it up to 70 d3grees. Wasting money on needless grid electric.


I have actually just fitted it. I’ve put a separate circuit with timer for the top one as mentioned in post 12

I am out at the moment waiting for my wife. I looked up the iboost+ which is for dual immersion element tanks and found this:

The Solar iBoost+ automatically heats up to 2 immersions on one hot water tank. When the first immersion reaches the pre-set temperature the energy cascades to the second immersion. The system prioritises immersion 1 by checking back to it at 15 minute intervals.

MegaFlow PV Ready cylinders are fitted with Solar iBoost+

Does this help?