question on power usage following a new PV installation

[johnb2713]

Now I'm getting confused again. I'm not suggesting that the /inverter/ is consuming that power, I'm saying (as I did at the start of this thread) that our IHD shows a /household/ consumption of around £0.50 (inc standing charge) at the beginning of the day. I could not understand why the household should have consumed /any/ grid power at the moment when we have been generating around 25 kWh a day filling the 5.2 kW battery and exporting the rest.

From earlier discussions I had concluded that the power draw was because of the inverter continually monitoring the grid supply (and thus necessarilly pulling some power) and also pulling in some power in early morning and late evening as it self tested. I /still/ don't understand why that should amount to aoumd 1-1.5 kWh but was prepared to believe it as the irreducible minimum consumption.

I now think my IHD is lying to me so I am taking meter readings to check it.

Having looked back you answered my reply to Mizunoid which I hadnt realised you were a different person, apologies.

Mizunoid had said 'The inverter uses some energy just to stay on don't forget.' and the you came back when I said it was an insignificant amount with 1 to 1.5kWh which is still high for keeping the inverter powered. Your consumption however is probably a mix of inverter power (circa 4W) and the constant dance they do with the grid supply in order to feed more / less into your consumer unit etc. It will also have any startup surges in there before your inverter has had time to adjust to new load conditions.

 

[solar-forum]

HI all

Rather than start a new thread I thought I would add to this because it is a follow up to my earlier experience of a new installation. If the moderators think I should post elsewhere I am happy to do so.

Following the discovery that I was pumping out over half what I am generating I decided that we should have had a PVA diverter (solic 200 or similar) added to our installation. So I contacted our installer for a quote to retrofit one (they cost about £200-250 depending on supplier).

He has responded in the terms below. The price quoted seems steep to me so I'd welcome a santy check from others here with more eperience than I.

"This Solic installation is not quite straight forward as the hw circuit
would need to be extended from the CU location in your kitchen to the
incoming main switch position to enable accurate CT measurement.
With our present work and labour schedules it is about 8 weeks before we
can attend to fit this unit and our price would be £780."

Thanks a lot

 

[binky]

HI all

Rather than start a new thread I thought I would add to this because it is a follow up to my earlier experience of a new installation. If the moderators think I should post elsewhere I am happy to do so.

Following the discovery that I was pumping out over half what I am generating I decided that we should have had a PVA diverter (solic 200 or similar) added to our installation. So I contacted our installer for a quote to retrofit one (they cost about £200-250 depending on supplier).

He has responded in the terms below. The price quoted seems steep to me so I'd welcome a santy check from others here with more eperience than I.

"This Solic installation is not quite straight forward as the hw circuit
would need to be extended from the CU location in your kitchen to the
incoming main switch position to enable accurate CT measurement.
With our present work and labour schedules it is about 8 weeks before we
can attend to fit this unit and our price would be £780."

Thanks a lot

have you got a separate immersion cct?

 

[johnb2713]

Use MyEnergi EDDI instead, you then use WiFi connected CT's. The installation is very straight forward and any electrician should be able to install it. No adjustments to your solar PV system would be required.

 

[Gian]

Tech is fantastic and makes life so easy. Why run cables.

 

[johnb2713]

Tech is fantastic and makes life so easy. Why run cables.

LOL, the MyEnergi CT using HARVI sends the data via WiFi, one brilliant move is the HARVI unit is powered by the CT! no batteries or seperate PSU.

 

[solar-forum]

have you got a separate immersion cct?

I'm not sure what you mean binky (I'm not an electrician). The immersion has its own RCD in our consumer unit and is separately switched at the wall in our kitchen. The CU is about 5 metres from the incoming main switch in our utility room where the PVA installer has fitted our PVA to grid connection.

 

[solar-forum]

Use MyEnergi EDDI instead, you then use WiFi connected CT's. The installation is very straight forward and any electrician should be able to install it. No adjustments to your solar PV system would be required.

But that is about twice the price of a solic 200 and I'm sure our installer would quote appropriately. Of course, if the fact that it is wireless means there will be no need for any additional cabling that might reduce the installation costs. But at the moment I'm not entirely sure I need to spend that sort of money. It would need to save quite a lot of oil through our boiler to justify the up front costs. As an aside, I'm not sure how long our immersion rod is. It is fitted at the top of the tank and looks to me as if it might only heat the top half (so enough for a shower or two) and not the whole tank. It draws 3kW and when I turn it on manually during peak periods of export it only stays on for about 15 minutes before the thermostat stops it.

 

[johnb2713]

But that is about twice the price of a solic 200 and I'm sure our installer would quote appropriately. Of course, if the fact that it is wireless means there will be no need for any additional cabling that might reduce the installation costs. But at the moment I'm not entirely sure I need to spend that sort of money. It would need to save quite a lot of oil through our boiler to justify the up front costs. As an aside, I'm not sure how long our immersion rod is. It is fitted at the top of the tank and looks to me as if it might only heat the top half (so enough for a shower or two) and not the whole tank. It draws 3kW and when I turn it on manually during peak periods of export it only stays on for about 15 minutes before the thermostat stops it.

Fair enough, I didnt know if you were aware of it.

 

[solar-forum]

Having looked back you answered my reply to Mizunoid which I hadnt realised you were a different person, apologies.

Mizunoid had said 'The inverter uses some energy just to stay on don't forget.' and the you came back when I said it was an insignificant amount with 1 to 1.5kWh which is still high for keeping the inverter powered. Your consumption however is probably a mix of inverter power (circa 4W) and the constant dance they do with the grid supply in order to feed more / less into your consumer unit etc. It will also have any startup surges in there before your inverter has had time to adjust to new load conditions.

Final note about my consumption. I think I now understand why I start the day with a grid charge of around £0.40-£0.50. I have now read the installation manual for the solis inverter and it looks as if the installer may have set it to manage the battery state of charge by drawing from the grid if the SOC falls below a certain threshold. That threshold looks to be a default of 20%. So, as the battery discharges overnight, if it reaches a level of only 20% full it will start to draw from the grid to prevent discharge below this level. Looking at the historic inverter stats, I seem to normally end the sunlit period with a charge of 85%-95% (which will of course change as we move to shorter days over autumn and winter) and drop to around the 20% level by morning when the PVA starts to pick up generating again. This now makes sense.

So far as I can ascertain, there is no way for me to alter this behaviour from the cloud montoring system.

 

[solar-forum]

Final note about my consumption. I think I now understand why I start the day with a grid charge of around £0.40-£0.50. I have now read the installation manual for the solis inverter and it looks as if the installer may have set it to manage the battery state of charge by drawing from the grid if the SOC falls below a certain threshold. That threshold looks to be a default of 20%. So, as the battery discharges overnight, if it reaches a level of only 20% full it will start to draw from the grid to prevent discharge below this level. Looking at the historic inverter stats, I seem to normally end the sunlit period with a charge of 85%-95% (which will of course change as we move to shorter days over autumn and winter) and drop to around the 20% level by morning when the PVA starts to pick up generating again. This now makes sense.

So far as I can ascertain, there is no way for me to alter this behaviour from the cloud montoring system.

I should add that the only reason I would want to modify this behaviour would be to set a particular time to pull energy from the grid to the battery (so if I were on an eco 7 type rate overnight - I'm not at the moment).

 

[johnb2713]

I should add that the only reason I would want to modify this behaviour would be to set a particular time to pull energy from the grid to the battery (so if I were on an eco 7 type rate overnight - I'm not at the moment).

I'm on Octopus GO and use it as much as I can off peak:-
00:30 to 04:30 - Battery Charging, 2 x EV's, dishwasher, washing m/c, tumble dryer and immersion heater.
04:30 to panels starting - the house runs on the battery
Panels starting to Panels stopping - House supplied, battery charging, EV charging, energy diverted to hot water tank and if any excess export to grid.
Panels stopping to 00:30 - House runs on battery.
It depends on how good the day has been to how much charge the battery takes and the immersion heater also. The current battery is 7kWh I'm adding another 14 kWh shortly to cover heating through winter.

The Octopus GO rates are 7.5p off peak and 29.2p peak which makes it very cost effective to use battery / solar.

 

[stuboy]

For any of you chaps considering a Solic 200. I recently had one break and contacted Solic for support, there was NONE! Buy it, and it has a fault you may as well bin it, save yourself time and hassle dont but a SOLIC!

 

[johnb2713]

For any of you chaps considering a Solic 200. I recently had one break and contacted Solic for support, there was NONE! Buy it, and it has a fault you may as well bin it, save yourself time and hassle dont but a SOLIC!

MyEnergi EDDI does the job, more expensive but reliability seems excellent, buy cheap, buy twice!

 

[solar-forum]

For any of you chaps considering a Solic 200. I recently had one break and contacted Solic for support, there was NONE! Buy it, and it has a fault you may as well bin it, save yourself time and hassle dont but a SOLIC!

My understanding is that the solic has a 10 year warranty, but it is a "return to base" for fix type.

 

[stuboy]

My understanding is that the solic has a 10 year warranty, but it is a "return to base" for fix type.

Solic never even replied to my several emails! so total fail!

 

[Murdoch]

Solic never even relied to my several emails! so total fail!

I would phone them