Solar iboost.. ebay or keep?

Tony Hoyle

I've just had panels fitted and the installers also fitted a solar iboost, which is apparently for immersion heaters.  As we don't have a working one of those it sits on the wall, unused (my wife tells they tried to wire it up and there was a big bang so they didn't try again).

I'm not sure of the justification for this device.  Clearly if you only had an immersion heater it could save by only heating the water when you're not drawing from the grid, but we have a gas boiler (which is old and crusty and will be replace with a combi as soon as we have money to spare for it).

So with the iboost, I either sell the electricity back to the grid at 12.94p/kwh, or heat the water using gas at ~4p/kwh.  So running the iboost is a net loss of ~9kwh?  Clearly either the manufacturers/installers have gone completely nuts or I'm missing something...

SteveCritten

In the long run it is more efficient to use the I boost. If you are trying to be as energy efficient as possible I would go for a condensing boiler with a pressurised cylinder.
I am pretty sure you don't get the same amount for selling back as you pay. I believe I receive 3.5p and it doesn't matter how much you use of your solar electric you still get paid for 50% regardless. So it's best to use 100% as you still get 50% as they don't measure it, it's is just an average.  

I will take a pic of my bill shortly to show you how much I receive.

Nerox

Exactly, ideally you want to use all the electricity you generate, you are paid twice for it anyway!

SteveCritten

Well reminded here is my last bill, bear in mind I didn't get my reading in on time last month so this is 2 months FIT.This is my export amount at the bottom.                                                                                                                                                                                                                                         

IronGiant

You are paid for the electricity you generate, you aren't charged for using it.  So it makes sense to "store" anything you aren't using. the easiest way of "storing it" in a domestic environment, is to heat water with it.

IronGiant

Doh, I think we just bumped a dead thread. The OP hasn't returned to the forum since the day he started the thread .  

Never mind, it's a useful thread as I'm thinking of getting one of these sorts of devices myself.  

First I need to check what I'm exporting because we are a high use household and I doubt it's anything like 50%.  So I've ordered a proper PV/household monitor from OWL.

SteveCritten

Good idea IG. I only answered because I realised I had said I would put my bill up.

SteveCritten

I am actually waiting for the battery storage technology to improve I would love to be self sufficient and not rely on the rip off utility companies.

IronGiant

Well it took me a while to get the monitor up and running.  Partly user incompetence and partly contradictory instructions (but mostly the former )  But it seems that we generated 7.00kW since 14:00 today and exported a massive 0.4kW.  

So if we are missing out on about 5-10p a day worth of electricity I think investing £250 to dump it into the hot water system might have a rather long pay back time.  I will of course monitor it for a couple of months to see whether that pattern is consistent.

SteveCritten

That is interesting, I thought our export would be low as we tend to do the dishwasher and washing machine etc during daylight hours but less than 10% wow!!