#1 Nov. 2, 2016 09:50:00

rogerhoward
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Solar iBoost immersion switch

On sunny days lately I've been diverting my spare solar to one of my Storage Heaters in anticipation of a cold evening. 3kWh/day of solar lost to unnecessarily high water temperatures does indeed sound a little high when it could be put to some other useful purpose.



Economy 10 tariff provides 6.9p/kWh off-peak import between 12am-5am, 1pm-4pm and 8pm-10pm; http://www.pvoutput.org/aggregate.jsp?id=21047&sid=18934&v=2&t=m on approx. 63% off-peak usage, 22% solar usage, and 15% peak-rate usage.
1,900kWh annually is exported, mostly in summer, on approx. 3,200kWh generation. Approx. 4,500kWh/year is imported, mostly for (a) winter and springtime off-peak Storage Heaters, and (b) off-peak hot water Immersion heating (which is “dumb”, i.e. not linked to the solar PV).
PV array is split East-West. Income is from Phase II 21p/kWh Feed-in-Tariff plus smart metered 3.2p/kWh Export Tariff.

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#2 Nov. 2, 2016 10:02:38

bhommels
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Solar iBoost immersion switch

Since reading this thread I got worried and extracted some more numbers from the (PV)electricity data logger:
With the store at 70 deg C, the corresponding heat loss is about 2.1 kWh/day. My 2-3 kWh was rather pessimistic it seems. Unless we are away, the store hardly ever sits at this worst-case temperature for any length of time, as it is slowly heated up during the day, and peak hot water consumption is in the evening and early morning. The losses are proportionally lower, for example with the store at a very useful 50 deg C, the losses are 1.2kWh/day.

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#3 Nov. 2, 2016 10:13:31

TerFar
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rogerhoward
On sunny days lately I've been diverting my spare solar to one of my Storage Heaters in anticipation of a cold evening. 3kWh/day of solar lost to unnecessarily high water temperatures does indeed sound a little high when it could be put to some other useful purpose.

It does seem high. I'm still investigating, but our boiler is now over 14 years old and I am anticipating that it is probably reaching its end of life, so I don't want to invest too much time and money on the current installation. But I may just slip over a cheap tank wrap and slip pipe insulation over the exposed pipework that I can easily reach. It should at least act as a stop gap for now.

I'm also looking at the new wall-mounted battery storage options that have just been released. The batteries seem to be more compact and the costs have fallen. Looking at my generation pattern, I will probably go for a smaller capacity (7kWh) because we only generate sufficient extra electricity to fill it to capacity in the summer months… unless, of course, it is possible to use cheap night rate electricity in the Winter to top it up for use in the day.

Loads more equations to try to fathom out!

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#4 Nov. 2, 2016 10:56:13

TerFar
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bhommels
Since reading this thread I got worried and extracted some more numbers from the (PV)electricity data logger:With the store at 70 deg C, the corresponding heat loss is about 2.1 kWh/day. My 2-3 kWh was rather pessimistic it seems. Unless we are away, the store hardly ever sits at this worst-case temperature for any length of time, as it is slowly heated up during the day, and peak hot water consumption is in the evening and early morning. The losses are proportionally lower, for example with the store at a very useful 50 deg C, the losses are 1.2kWh/day.

I've just been reading up about the heat loss from the tank at the Department for Energy website. It recommends to look for a tank with an R value at R24 but preferably R36.

More importantly, it says not to have the temperature about 130degF (yes, they still use Fahrenheit!) which is just 55degC. They don't state why either.

I hadn't thought that the higher the water temperature, the greater the energy loss. So there are downsides to keeping my water at 70degC.

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#5 Nov. 2, 2016 10:57:04

TerFar
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Solar iBoost immersion switch

bhommels
Since reading this thread I got worried and extracted some more numbers from the (PV)electricity data logger:With the store at 70 deg C, the corresponding heat loss is about 2.1 kWh/day. My 2-3 kWh was rather pessimistic it seems. Unless we are away, the store hardly ever sits at this worst-case temperature for any length of time, as it is slowly heated up during the day, and peak hot water consumption is in the evening and early morning. The losses are proportionally lower, for example with the store at a very useful 50 deg C, the losses are 1.2kWh/day.

I've just been reading up about the heat loss from the tank at the Department for Energy website. It recommends to look for a tank with an R value at R24 but preferably R36.

More importantly, it says not to have the temperature above 130degF (yes, they still use Fahrenheit!) which is just 55degC. They don't state why either.

I hadn't thought that the higher the water temperature, the greater the energy loss. So there are downsides to keeping my water at 70degC.

Edited TerFar (Nov. 2, 2016 10:58:03)

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#6 Nov. 3, 2016 09:41:09

rogerhoward
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Solar iBoost immersion switch

Thanks for the great tip about the Rnn values, Terfar.
Can you point us in the direction of that weblink so that we can see what other interesting recommendations the Department of Energy make?

(P.S. Do you think the Fahrenheit thingy is some precursor to our new Brexit regime taking us back to all those Victorian measures instead of the globally recognised ones ?!)



Economy 10 tariff provides 6.9p/kWh off-peak import between 12am-5am, 1pm-4pm and 8pm-10pm; http://www.pvoutput.org/aggregate.jsp?id=21047&sid=18934&v=2&t=m on approx. 63% off-peak usage, 22% solar usage, and 15% peak-rate usage.
1,900kWh annually is exported, mostly in summer, on approx. 3,200kWh generation. Approx. 4,500kWh/year is imported, mostly for (a) winter and springtime off-peak Storage Heaters, and (b) off-peak hot water Immersion heating (which is “dumb”, i.e. not linked to the solar PV).
PV array is split East-West. Income is from Phase II 21p/kWh Feed-in-Tariff plus smart metered 3.2p/kWh Export Tariff.

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#7 Nov. 3, 2016 11:22:05

TerFar
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rogerhoward
Thanks for the great tip about the Rnn values, Terfar.Can you point us in the direction of that weblink so that we can see what other interesting recommendations the Department of Energy make?(P.S. Do you think the Fahrenheit thingy is some precursor to our new Brexit regime taking us back to all those Victorian measures instead of the globally recognised ones ?!)

LOL. They'll have to rename Fahrenheit 451 to Celsius 233 if they stop Brexit!

It was found at the energy.gov website. This particular page talks about water heater storage:

http://energy.gov/energysaver/storage-water-heaters

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#8 May 31, 2017 22:10:01

texacowestminster
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I had an immersion heater device but it did not work well and the information was patchy.I was thoroughly fleeced on this equipment paid £1000, but it was proposed by the company which fitted the German made solar panels, it was quite a simple device fitted in the electrical panel.

A year later some sponsors were carrying out collection of data for Berkshire area and they were offering to fit free EMMA make device, companies involved were GE,, DNV GL, ea technology, University of Reading, Honeywell etc. This device fitted free under programme Thames Valley vision. Most houses in this area with
solar panels were offered. I had the use of it for a year. The device was split in two areas one fitted near the Electric panel and the second device by the immersion heater, which received radio signals from the first device to operate and control electricity distribution. It worked very well, the sponsors maintained the devices. Regretfully it was removed after the experiments were complete, one year.

Recently I have fitted a new device which is also very good and has similar radio signal control and also works like a smart meter, it displays real time info and stores data as well. This device is Solarcache, sold by DSM Energy Control, supplied and fitted by specialist. I feel quite happy with this, I think the data is checked every three seconds

Has any one of our colleagues undertaken washing of solar panels, I would like to know. On Google site I have read that this is not necessary and rogue traders are offering this service.


mustafa jaffari

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#9 May 31, 2017 22:26:27

TerFar
Registered: 2014-06-21
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Solar iBoost immersion switch

texacowestminster
I had an immersion heater device but it did not work well and the information was patchy.I was thoroughly fleeced on this equipment paid £1000, but it was proposed by the company which fitted the German made solar panels, it was quite a simple device fitted in the electrical panel.A year later some sponsors were carrying out collection of data for Berkshire area and they were offering to fit free EMMA make device, companies involved were GE,, DNV GL, ea technology, University of Reading, Honeywell etc. This device fitted free under programme Thames Valley vision. Most houses in this area withsolar panels were offered. I had the use of it for a year. The device was split in two areas one fitted near the Electric panel and the second device by the immersion heater, which received radio signals from the first device to operate and control electricity distribution. It worked very well, the sponsors maintained the devices. Regretfully it was removed after the experiments were complete, one year.Recently I have fitted a new device which is also very good and has similar radio signal control and also works like a smart meter, it displays real time info and stores data as well. This device is Solarcache, sold by DSM Energy Control, supplied and fitted by specialist. I feel quite happy with this, I think the data is checked every three secondsHas any one of our colleagues undertaken washing of solar panels, I would like to know. On Google site I have read that this is not necessary and rogue traders are offering this service.mustafa jaffari

I've been using the Solar iBoost for controlling my hw heater. It works the same way as yours with a current flow detector clamped on the incoming mains supply which connects to the immersion controller wirelessly. When excess solar power is being generated, it detects power flowing out into the grid. It sends a signal to the immersion controller to heat the water until the tank is hot or the solar power falls. The iBoost also has a second output to divert excess power (to a battery store, for example) when the tank is hot.

Solar panels have self cleaning surfaces and shouldn't need cleaning.

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