On-grid domestic battery storage

orrery · 1 February 2018 at 4:03PM

EricMears wrote: »

Not quite true ! In particular, Immersun lets you choose your own threshold.

But there is a reason for having such a threshold : if you're diverting every single watt and the sun intensity changes slightly (perhaps a cloud pops in front of it) then you run a risk of starting to buy electricity for a brief period. having a threshold reduces that risk and the 'loss' of energy probably costs less than you might otherwise have had to pay for.

Ditto, my solarImmersion also has configurable levels down to 0. To expand on the argument, the current transformers are notoriously bad at detecting low levels of current in either direction. So a 'zero' reading could be several tens of watts of export, or import. Having a threshold means that the unit has to see a real level of export before it will divert and it needs to see that maintained or it will reduce the level of diversion. The trade off here (for me) is that in one direction you could miss out on free leccy that displaces 3p/unit of gas and in the other direction at the expense of using imported leccy at 14p/unit - I'd rather miss a few units of free leccy than be charged extra at that rate.

Martyn1981 · 4 February 2018 at 9:47AM

Anyone fancy a free Powerwall II? How about a 'virtual powerplant' of 675MWh?

Tesla Tapped by South Australia Anew in Virtual Power Plant Plan

South Australia plans to roll out solar panels and Tesla Inc. batteries to at least 50,000 homes to form what its government says will be the world!!!8217;s largest virtual power plant.

Beginning with a trial of 1,100 public housing properties, 5 kilowatt solar panels and 13.5 kilowatt-hour Tesla Powerwall 2 batteries will be installed free of charge and financed through electricity sales, the state government said Sunday ahead of a state election. This will be expanded to another 24,000 public housing properties, and then a similar deal will be offered to all South Australian households, with a plan for at least 50,000 to participate in the next four years.

Edit - Pretty much the same info in another article:-

Labor offers solar panels and Tesla batteries for 50,000 South Australia homes

Martyn1981 · 6 February 2018 at 2:35PM

Really stretching the definition of battery storage here, but I watched this and thought of Z.

It's a beautiful (or crazy idea) using water as thermal mass and also as a rather pretty feature. The idea is that the thermal mass of the water will reduce temperature changes in the house, thus raising minimums, and lowering maximums.

Passive solar water wall battery

pile-o-stone · 6 February 2018 at 3:37PM

Martyn1981 wrote: »

Really stretching the definition of battery storage here, but I watched this and thought of Z.

It's a beautiful (or crazy idea) using water as thermal mass and also as a rather pretty feature. The idea is that the thermal mass of the water will reduce temperature changes in the house, thus raising minimums, and lowering maximums.

Passive solar water wall battery

This is used a lot in greenhouses. The heat during the day warms water barrels in the greenhouse, which then give off heat in the night. This helps to regulate temperatures and prevent excessive swings from hot summer days and cool summer nights.

Martyn1981 · 6 February 2018 at 6:07PM

pile-o-stone wrote: »

This is used a lot in greenhouses. The heat during the day warms water barrels in the greenhouse, which then give off heat in the night. This helps to regulate temperatures and prevent excessive swings from hot summer days and cool summer nights.

Thanks, yes I recall something about this, a DIY system using black painted barrels on the northern 'wall'?

Reminds me of the PV greenhouses I read up on, they have approx 1 PV panel for every 2 or 3 glass panels, as the plants don't need all the sunlight in the growing season, it can actually harm them.

I also seem to recall some sort of outdoor PV farm/rice paddy (or I'm going mad) where the overhead framing has occasional panels, rather than constant panels (if that makes sense), which again seem to benefit the rice.

Really scratching my brain and memory but it may have been Korea or Japan, and to get PV subsidies the farmers have to make sure that rice output doesn't drop.

Man I've gone miles from domestic batts here .....!

zeupater · 6 February 2018 at 7:55PM

Martyn1981 wrote: »

Really stretching the definition of battery storage here, but I watched this and thought of Z.

It's a beautiful (or crazy idea) using water as thermal mass and also as a rather pretty feature. The idea is that the thermal mass of the water will reduce temperature changes in the house, thus raising minimums, and lowering maximums.

Passive solar water wall battery

Hi

Mention 'Thermal Mass' and as if by magic, the shopkeeper appears!

No water here, just over-engineered internal walls, but the idea of using high-mass materials to regulate temperatures certainly works!

HTH
Z

Martyn1981 · 8 February 2018 at 6:22PM

This is commercial storage, following a residential scheme, but I assume more storage sooner, means lower prices sooner ..... so all good news. Also some domestic news at the very bottom.

Puredrive launches commercial battery PPA offer following social housing success

Puredrive Energy has launched a power purchase agreement (PPA) offer for installations of battery energy storage facilities up to 50kWh to address the different needs of the commercial sector.

The company is touting its own Pure Storage CM solution, which can be offered alongside solar PV, to small businesses with a bespoke deal matched to the customers’ needs.

In December the company began trials of the technology package – using a 4.8kW battery and 3-4kW solar PV systems - in homes managed by Severn Vale Housing under a fully funded offer using finance from an unnamed investment partner.

Miller explained that these trails has “gone well”, with one resident noticing saving within just one week of installation.

The company now has approval to move towards addressable stock, targeting 350-400 homes with the free installs in an effort to build enough capacity for aggregation and dynamic frequency response. Installs are likely to begin next quarter with systems completed within a year.

Martyn1981 · 10 February 2018 at 8:45AM

There's a discounted battery trial (and hot water tank replacement) for 500 folk in the Cornwall and Greater London areas. It's called The PETE Project, and there's more info here:-

Purpose of the Project

django01 · 13 February 2018 at 10:06PM

Mart, thanks for the heads up on the PETE project.
Got in touch with them to understand the numbers..£2899 for lithium ion 4KWh (warranty 10 yrs) or £1899 (warranty 5 yrs) for lithium ion 4KWh (second life). The prices are all inclusive.
From the forum I understand that this may suffice for powering the heartbeat of the house, during night time.
Does this look to be good value?

tony541 · 14 February 2018 at 12:20AM

I've had a solar electric system on a house in Spain a few years back and I came to the conclusion that the cost of batteries makes these battery storage systems as not being cost effective unless subsidized. I'm not up to date with modern battery technology but I doubt that in practice they will perform as stated and are too expensive. It wouldn't be so bad if modern technology was bringing the price of batteries down but it isn't at the moment.
Solar energy is a wonderful thing but the problem is that accountants become involved and price any motive to use them out of bounds of most sensible people.

On-grid domestic battery storage

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