Tuesday, June 12, 2012

Immersun, make use of spare power

12 June 2012: I recently became aware of this new product, Immersun, that is due to be launched during 2012 by a company based in Lincolnshire. The idea is to monitor the output of your PV installation, and when it is reaching a good peak and you are not using it for something else, to divert power to a device of your choosing - mostly likely to an immersion heater. This doesn't in any way interfere with your OfGem meter or installation because it comes after the consumer unit and is merely measuring the flow of power out to the grid.
     It is programmable, so you can decide what the power level is at the point where you slice off the surplus and feed it to devices in the building. An Immersion heater is the most suitable receiver, because it is able to manage intermittent operating. If you used it to power say a washing machine or TV, the device would keep turning off whenever a cloud crossed the sun - which would be very annoying. If the water in the tank is already fully hot, then the thermostat does not take any power and the power continues on to the grid as normal.

Comparison with Solar Thermal: I have a slight ideological objection to this, in that a solar thermal panel is highly efficient when it is working, whereas a solar PV is only converting solar energy at 10-15% efficiency. But if you have a house where you have enough PV but no further space for a solar panel, or you cannot manage the complex plumbing for a solar thermal panel, this is one interesting idea - the power source is free, from the Sun, and the wiring is simple. Normal solar thermal systems are surprisingly inefficient because they spend much of the time in Stasis. The tank gets up to temperature on sunny days, nobody is taking a shower, and the panels have nowhere else to deliver the heat. So the efficiency drops from a theoretical 90% to less than 30% or even less if the family are not using the hot water.
     A full solar thermal installation requires a lot of plumbing - a preheater tank, pump, solar controller, expansion tank and a lot of pipes and insulation, and the solar thermal panel itself - probably £2000. Some houses could not accommodate or afford this. The roof might not take a solar thermal set up because there isn't enough remaining surface area or volume in the loft. Given the current payback and tariffs, it's more effective to maximise the PV on the roof. It takes vastly less effort to divert mere electrical wires in the house compared with the high temperature insulated plumbing paraphernalia of solar thermal water heating.
      Cost wise, it makes sense. It's likely to be offered for £300, and it requires electrician installation. With a solar thermal system, each primary component costs more than that, and plumbers are more costly than electricians. If you are a low-consumption water user, then it takes a short time to pay back on £300, but several lifetimes to pay back on £3000.

Many PV-users make a lifestyle adaptation, for example, waiting for a sunny day to do the ironing, the baking, or to run the washing machine (we do this). A programmable device like Immersun enables that choice to be made automatically.
   We could not use Immersun in the Peveril Solar house because we use a Heat pump with integrated tank. I am just telling the blog-readers about it.
   I wonder if you have to modify the programme depending on the month. For example, in summer I could set it to work if PV power exceeds 3kW, but that wouldnt work in winter. We are glad to exceed 1 kW in winter months.
(PS I am not paid to post this article, I am writing my own assessment of its potential )

1 comment:

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    ReplyDelete

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