Heating News Autumn 2019

Extinction solutions

Rebelling is OK; better to actually do something.

So we could save the planet could we? Well yes, we could certainly do our bit in a big way. Recent advances in solar technology mean our homes can be made self sufficient in energy and leave us better off financially at the same time. The off-grid theme is all electric, quite simple and more DIYable too if that’s your thing. About 20 panels, a heat pump, some tanks of water and we are pretty much there. We can’t ignore an electric car, even though depreciation is going to slay us, so that could be in the mix too. So let’s chat about some of the issues that arise.

DIY power – cheaper than nuclear?

In the EU nuclear power costs $5,500 per kilowatt of capacity (each Kw producing 8,760kW.hrs a year). We pay that cost via our taxes and then pay again to buy that power. Put that way it sounds a bit perverse; could there be an alternative? A domestic PV array with battery storage could make almost as much energy for the same money and, as the owner pays for it, there is zero cost to the government. Could a mass take up of home energy production do away with a power station? Take the $10bn cost of a new nuclear power plant and instead give it to the 1.5m customers it would service and you’d have a subsidy of over $6,000 per person. You could twist a lot more than 1.5m arms with that sort of money yet the government has just ceased to pay feed in tariffs!

Heat pumps and the Renewable Heat Incentive

The RHI on a ground source heat pump is a government bung, to you, of something like £20,000 – £30,000 over 7 years. That’s high because a GSHP is expensive; but what if it wasn’t? The Original Twist hybrid GSHP concept (with air assistance) makes everything cheaper and more efficient. And by cheaper we’re looking to go well below that RHI contribution so your project cost is easily nil and beyond. It is all explained here.

Photovoltaic panel prices and power.

PV overclock and tilt

The power of new PV panels is increasing by the month. 350W, even 400W (at a price) is possible now.

As power rises the cost keeps falling quite noticeably. My old 4.6kW car port roof, – 20 panels – would now be good for 6.1kW and under £3,300 with some 305W Jinko Smart Solar Panels. The latter are not particularly cheap but they limit their own output voltage which makes inverter choices easier and helps with the overclock and tilt concept.

Feed In Tariffs – a new paradigm

It was all doom and gloom last March as the government FITs came to an end. Presumably PV kit had become cheap enough to make us self incentivised without a nudge from the government. You might remember, in the last newsletter, I pointed out that prices had fallen significantly, grid parity had arrived making off grid a viable option.

However, FITs have revived in an interesting way. With Octopus leading the way, the energy providers will be introducing their own FITs. ‘Outgoing Octopus’ is a plan which works alongside a smart energy meter and if you have energy to sell, from any source, they’ll give you 5.5p/kW.hr and it gets added to your account with them. Unfortunately for an 8kW PV system running a heat pump etc you’d be lucky to sell enough surplus to bag more than £200 a year but a grid connected system would not need any expensive batteries so you can get going at a much lower cost.

‘Octopus Agile’ is another offering which charges and/or pays you according to half hour market rates, typically between 4p and 10p.  Even negative rates can occur where you would actually be paid to take in power. With some fancy software and a hook up to the car batteries we could all be future energy traders but, that aside, I think the off grid brigade will be going with this one.

Octopus Go. Charge your electric car for just 5p/kW.hr for four hours a night. This is better than trying to charge your car with your off-grid arrangement. It’s just not sensible to charge your house batteries during the day in order to charge the car by night. That would be an expensive heavy duty battery hammering. So going completely off grid is probably not for electric car owners. That 5p looks very attractive especially when combined with a little night-timed appliance and heat pump running, so we’ll consider below how to add it to an off-grid set up. You can’t combine this deal with Octopus FITs deals.

How to be off-grid but still connected.

OK, you have the car charging deal so you have access to the grid. You can’t sell to the grid so the flow can only be incoming. With that in mind you want an off grid set up – panels and batteries – with no two way connection to the mains. For a solution there is just one and only type of link – the mains can run a battery charger and charge the house batteries but they can’t return the flow. Similarly the mains is connected to the car battery charger. The net result is:

The car gets charged at 5p/kW.hr

Timed appliances and the heat pump can run cheaply at night if they need to

The house system is off-grid but has mains back up

A less mission critical off-grid system can be smaller and cheaper.

If all the panels get snowed up for a few days it doesn’t matter.

The lights stay on if there is a power cut.

Solar thermal panels are obsolete?

Why no mentions of the wet panels?  Well PV is relatively cheap now so it is easier to just add more electric power rather than get involved with a more complicated installation. In weak winter sun wet panels don’t do much especially when the water tank is already hot. In summer there is enough excess PV solar power to run an immersion heater so, again, we don’t need the wet panels. That’s a big expense to cross off the list. Paradoxically you can get RHI payments on wet panels but not on PV – the government backing the wrong horse again?

Underfloor heating is obsolete?

Good insulation makes UFH an unnecessary waste of thousands of pounds. Fan-coils (basically a radiator with a fan on it) make more sense and can cost very little. Here’s the Original Twist DIY fan-coil which is arguably better than a tailor made one. This change of tactic alone could fund your off-grid move.

Gas is obsolete?

The Chancellor Philip Hammond has announced that gas heating will be banned for new build homes by 2025. A seemingly innocuous announcement but what it means is that the most used energy source (costing a quarter as much as electricity) will gradually be removed from our future heating choices. Apart from adding massive insulation the only way to restore reasonable expenditure is to drive a heat pump with electricity and we can expect to see a lot more of them from now on. The RHI payment on heat pumps will inevitably subside when they become practically mandatory so have a good think about locking into that now. Once boilers go, gas hobs and ovens will follow them into obscurity; there is no point in paying daily supply charges for minimal use when electric hobs and ovens are arguably better anyway.

Conclusion

It’s interesting to see the knock-on effects of falling PV prices and to react appropriately with the right heating/energy strategy. The all electric home looks much simpler and cheaper as a result. The bottom line is that going off grid saves you money, the government will pay for most of it anyway, and you can do your bit to save the world.