Solar PV + Battery quotes

Reed_Richards

Solarchaser said:

11kw system is going to be generating 4-5 kw in the middle of an average day, so even on full power, the iboost can only sink 3kw, so the rest would go to battery regardless 

So if for the majority of the time you are generating enough power to run the immersion heater then what is the iBoost doing for you?  If an iBoost costs £250 and electricity costs 15p per kWh then you can run a 3 kW immersion heater for 555 hours on the cost of the iBoost.  If the iBoost only does anything worthwhile on a really cloudy day then you may be looking at many years before the iBoost pays for itself and that's on the assumption that you would not intervene manually if you did not have the iBoost.    

Solarchaser

Well yeah, I mean if you had no life you could watch the export until it got to 3kw and flick a switch, and then flick it back off if clouds come over.

The iboost / immersun/whatever is there for convenience.

However you also assume you have nothing else running, like washing machine, dryer, dishwasher etc etc.

So if you were exporting 2kw for 3 hours, you wouldn't manually switch on immersion,  but the solar immersion would have diverted 6kw.

I'd assume a 2-3 year payback, but that depends how much you pay.
I picked up a solic 200 for £100, some pay £400 for other named brands

Petriix

I'm struggling to envisage any scenario (post FIT) where an iboost or similar could possibly make sense.

If you're on mains gas then you're far better paying 2p/kWh to heat water and earning 5.5p/kWh to export the electricity. An iboost would cost you 3.5p for each kWh of useful water heating plus 5.5p for each kWh of wasted water heating.

With a battery you can reduce your grid imports to the very cheapest overnight rate (say 5p on Go) so you would still be better off exporting your excess and then running your immersion overnight. Not that I would recommend anyone get a battery today because they will never break even within their usable lives.

Solarchaser

Oh I disagree on the useable life, that's just silly.
If you change it to within ten years, I'll agree with you.

If you look at solar from a money making point of view, you would not install a diverter, but if you want to self consume, it makes more sense than batteries at the moment

Petriix

I can't understand why anyone would want to 'self-consume' at a net loss. It made sense under the FIT with deemed exports but absolutely doesn't for metered exports. It doesn't even save any CO². 

Solarchaser

It doesn't save co2 to heat with electricity you have generated yourself, rather than burn gas??

mickyduck55

Solarchaser said:

Well yeah, I mean if you had no life you could watch the export until it got to 3kw and flick a switch, and then flick it back off if clouds come over.

The iboost / immersun/whatever is there for convenience.

However you also assume you have nothing else running, like washing machine, dryer, dishwasher etc etc.

So if you were exporting 2kw for 3 hours, you wouldn't manually switch on immersion,  but the solar immersion would have diverted 6kw.

I'd assume a 2-3 year payback, but that depends how much you pay.
I picked up a solic 200 for £100, some pay £400 for other named brands

My Solic was absolutely perfect until I got batteries.. now sometimes it dumps 3 kw into the immersion from the battery.  In summer when this is going to "most likely" be replaced   I just leave it alone.  This time of year I turn the immersion off and IF I can be bothered / remember turn it on if the sun is bright  or batteries full.  The clips from the Solic and Inverter are not quick enough to work properly together.. Just my actual experience

Solarchaser

I've seen a comment on another forum from a user who took the live feed from the diverter and ran it through the grid CT of the batteries and felt this solved the problem, the idea being that the batteries were then blind to the current used by the diverter, but I haven't tried this myself.
My plan is to set the diverter to look for 200w of export before switching on, but again,  haven't tried it.
Because I don't have a hot water tank yet.

Might be worth you trying it since you have it already?

Petriix

Solarchaser said:

It doesn't save co2 to heat with electricity you have generated yourself, rather than burn gas??

No, because (at best) immediate demand for electricity in the UK is met by burning gas at a power station. By exporting to the grid you will power your neighbours' fridges etc. and prevent the need for that power to be generated at the nearest gas power station along with all the associated transmission losses.

If your only way of heating water is with electricity then there is an economic argument for an iboost but with Go or Agile you're likely to still be better off using cheaper overnight rates. In terms of CO², you're almost certainly better exporting during the day and importing again overnight.

mickyduck55

Solarchaser said:

I've seen a comment on another forum from a user who took the live feed from the diverter and ran it through the grid CT of the batteries and felt this solved the problem, the idea being that the batteries were then blind to the current used by the diverter, but I haven't tried this myself.
My plan is to set the diverter to look for 200w of export before switching on, but again,  haven't tried it.
Because I don't have a hot water tank yet.

Might be worth you trying it since you have it already?

The solic does not have the ability to set a minimum export so no able to wait until 200 W.  Do you have the ink to the other forum post?