Tesla Energy Plan

The theme of our (sparse) news posts has generally been about the way in which the energy market is changing. That, and the way we are thinking about and using energy changing as a consequence is also really interesting at the moment. Now the next chapter is starting, with the full release of the Tesla Energy Plan.

Tesla Powerwall 2

Time of Use

With generation on your site, plus some storage we’ve been in a really good position to take advantage of Time of Use energy tariffs. Using the technology to our advantage we can minimise energy use from the grid, and when we do need it we can chose when to buy this for the cheapest cost and/or at the times when the grid is at its cleanest.

This operation, known as Time Shifting, results in us being able to achieve really low average electricity costs over the course of a day/week/year. As a side effect we are helping the grid out, as we’re shifting our reliance upon it to the times when there tends to be a surplus of generation – overnight usually, though sometimes during good solar generation output on the grid too. We also reduce our demand when the grid is at its most expensive.

The main tariff, “Agile” from Octopus Energy is the only tariff that tracks the wholesale price and really encourages this behaviour, with the benefit of very low average costs eing achievable.

Tesla Energy Plan

The Tesla Energy Plan, which is operated by Octopus Energy, is a “grid services” tariff. It is open to all Tesla Powerwall 2 owners. In signing up, we lose control of what our battery does to carry out this time shifting, instead handing control to Tesla to operate in order to best benefit the grid using both grid energy and energy from our generation system.

As a result of the battery charging and discharging to do this, we as consumers receive a single tariff for both imported electricity and electricity exported. This rate is currently 11p/kWh.

The other advantage is no standing charge, so a further saving.

This means that we can use electricity whenever we want for the same cost, meaning it’s very simple to use and saves us having to alter our consumption patterns as we may feel the need to with other tariffs.

In essence, Tesla are turning their fleet of Powerwalls into a Virtual Power Plant with users sharing energy between eachother, using the grid as storage.

Note that if you also own a Tesla vehicle the tariff works just the same, but at a rate of 8p/kWh.

There’s a nice video of how it all works on the Tesla page for the Tesla Energy Plan. Note that Backup Operation requires Tesla Energy Gateway 2 to be installed…

Is this for me?

Whether this suits you and your consumption/generation profile depends!

If you have a lot of export, it probably does as the rate is much higher than on FiT Export or SEG Export rates.

If you’re a high consumption household with reasonable generation capacity then it may also suit, as the average cost is reasonable and has the advantage you know what it is compared to the variable nature of Agile, or the potentially higher average rates on a simplified time of use tariff like Go (also Octopus Energy).

In any case, any of these tariffs are likely to result in cheaper costs than a non-variable tariff.

Sound good?

Everyone’s needs are different, consuming different amounts of energy at different time of the year, per day and so on but there is probably a solution for you to reduce your average cost of energy using this technology.

For more information, or to see how this might work for you please get in touch!

No FiT? No problem!

It’s been some time now since the end of the Feed in Tariff (FiT) in 2019, and the way we thing about energy is changing fast. It has commonly been thought that because we can only get paid a small amount for our export from microgenerators that it’s not worth generating. The “replacement to the FiT” is the Smart Export Guarantee (SEG), which is the mechanism for this payment.

Why pay 15p/kWh for import and only receive up to 5p/kWh for export?

Well, think about it this way instead!

As technologies including solar PV, battery storage, heat pumps and electric vehicles are becoming attractive for many reasons, not least environmental, the electricity market is adapting. We were always confident this would come along before too long (as you can see from this article we wrote in April 2017), and it’s now here and it works.

In order to support the grid’s continuity and quality and to increase the contribution from renewable energy to the UK’s grid energy suppliers are adapting, too. Notably Octopus Energy are pioneering this concept with their Agile tariff, and others will be close to follow suit.

Agile price example

2 days worth of Agile pricing, with price plunge – being paid to use electricity! (from excellent resource at – https://www.energy-stats.uk/octopus-agile-southern-scotland/)

Octopus Agile is a Time of Use Tariff, which uses smart meter technology to alter the unit cost of electricity every half an hour. This means that the cost tracks the wholesale price of electricity, which in turn is strongly related to the renewable contribution from wind generation, and increasingly from solar. It costs more to burn fossil fuels to run gas (or coal) power stations, so the more renewables the cheaper the cost. Also supply/demand also plays a significant role in this, so when demand is high the cost is high and vice-versa – but we can deal with that!

From the graph above, we can see that the price varies a lot over time, but take out the high peaks (using your battery) and use the lowest price instead the average is very low. Note that this is quite unusual to go negative at the time of writing, but last weekend had a windy spell early morning with low demand resulting in this negative pricing. It’s helping the grid, your costs and the environment to make full use of these times!

What’s all this got to do with microgeneration and storage?

With a time of use tariff and storage we can pick and choose when it’s cheapest and cleanest to import, storing energy in a battery for use in the home when require…or in an Electric Vehicle (EV) to offset fossil fuels…or as heat in our homes or hot water. This is known as “time shifting”. We can then include also “free” energy from our on site generation, too!

And the flip side, we can also use our storage to ensure that we have no need to import the dirtier, expensive energy at peak times without having to change our energy consumption requirements (if your system is designed appropriately…). And the best bit is that with Tesla Powerwall this is all done without having to change settings daily!

So this technology along with smart tariffs have made an important shift – we don’t pay what we used to for electricity, it’s actually far less per kWh on average. In fact, it could even be that the average import rate is LOWER than the average export rate! If you thought the export rates were far too low, then read on…

Want Proof?

For example a home with Solar PV, Tesla Powerwall and EV on a tariff with 4 hours of 5p/kWh each night and 14p/kWh the rest of the time in December 2019-February 2020 consumed 1996kWh from the grid at an average of 5.04p/kWh. The export rate is 5.5p/kWh (on Octopus Outgoing), though this site was getting ~5.38p/kWh as part of the Feed in Tariff scheme. The solar generated about 270kWh over this period, which was all consumed in the home. Note that this covered the whole home inc electric cooking, plus a larger percentage of the fuel costs for transport (around 4,000 miles or over £400 of petrol/diesel!).

Sure, there’s not really any export in the depths of winter…but in the summer the import remains about the same (charging vehicle at the cheap rate, perhaps we can discount the household consumption as this is self consumed from solar) but export increases due to the surplus generation – so the average import cost stays close to 5p and we export at a little more than 5p. So, we’re using the grid to store electricity generated in summer for use in the winter…in essence!

Sound good?

Everyone’s needs are different, consuming different amounts of energy at different time of the year, per day and so on but this concept remains the same. It’s now possible to reduce your import costs massively with the use of technology.

For more information, or to see how this might work for you please get in touch!

Set for the future

Gone are the days of South facing 4kWp solar PV systems. These were Feed in Tariff accumulators, which happened to help you reduce bills a little bit. System design has changed as a result of changes to the Feed in Tariff rates and bandings, but mostly down to the change in how use and we pay for electricity. These changes are powered by ever improving technology.

With ever increasing electricity prices, paired with the roll-out of smart metering, a much more technology driven approach could well reduce a household energy cost. Much more dynamic electricity cost structures are starting to appear where night rate electricity is cheap, day is more expensive and increasingly peak rate very high cost electricity. This may sound like a bad thing… but here’s how to take advantage!

EV ChargingThe reason behind these tariffs is to discourage use of electricity at peak times, when electricity is expensive and dirty to generate – much more fossil fuel generation is in the fuel mix. When demand is low, the grid tends to be much cleaner. By implementing these tariffs, much greater use can be made of the cheap, clean electricity in place of the dirty expensive stuff.

Most households use more electricity during the day, for obvious reasons. To insulate yourself from the higher day rates a solar PV system can be installed, offsetting import with clean locally produced electricity.

For the very expensive peak rates, battery storage can be included to ensure that little or none is imported from the grid during these times. These can be charged for free from excess solar and/or from cheaper grid electricity.

Battery SOC and EnergyAnd then it’s possible to also make more use of the benefits of cheap night time electricity using more technology. Either charging batteries such as the Tesla Powerwall for daytime use, or going even further and charging an Electric Vehicle. An EV would then be very cheap to run, and is using the cleanest electricity possible – cleaner low-demand times from the grid, paired with using any excess solar PV which you saved in your battery.

We are seeing our enquiries turn into these kinds of complete solutions at the moment, and we expect this to be a continuing trend. We would love to speak with you further about it, or adding to your existing set up (EV already, or solar already…) to find out if we can keep you right on how to use all this technology to be as green (and low cost) as possible! Just get in touch…


Renewables taking over

It’s not just us and our customers generating our own clean energy. Recently there has been numerous records for renewable generation set, and that’s only going to continue. Read more narrative here.

Solar contribution is difficult to track, as there’s so much smaller “distributed” generation, but this manifests itself as a reduction in demand. This is really becoming tangible and is starting to notably reduce the reliance on other forms of generation.

The below is our Tesla Powerwall and Solar PV working flat out, charging the battery at full power, feeding our loads and some left over!

Solar & Battery Flat Out

The next challenge is to make best use of cheap and clean energy when it’s available to avoid wasting resource. Nobody likes seeing wind farms shut down as there’s not enough demand for the energy. Battery storage on both domestic and grid scale is the obvious solution – charge batteries with cheap clean “excess” energy and use it in place of expensive dirty energy.

This is possible using the likes of the Tesla Powerwall on a domestic and small commercial scale. Alongside enough renewable generation on site this can reduce the reliance on the grid’s energy and reduce cost, too.

These are exciting times! We will be keeping you posted on developments in this fast moving sector via this website and our Facebook page.

Opening Hours – Winter 2016

We  will be closed from 12pm on Friday 23rd December until Tuesday 3rd January. If you need to get hold of us, leave us a voicemail or drop us an email and we’ll be in touch as soon as we can.

We are excited to see what 2017 brings, but already we have some exciting prospects on the horizon which we will keep you updated on. Stay tuned on our website and Facebook!

Merry Christmas and a Happy New Year, from all at Solar and Wind Applications!


Tesla Powerwall Testing – Now LIVE!

The Journey to Self Sufficiency…with Tesla Powerwall


Having recently become Tesla Energy Certified Installers, we were really excited to get hold of the newest version of Tesla Powerwall as soon as it became available. We feel that carrying out testing the products and the process as a whole on behalf of our customers is crucially important in being able to provide the best products and services in the future.

After many hours of comparing products, training, research, gaining qualifications, we finally arrived at committing to purchase a self consumption battery system for ourselves. We chose the very desirable Tesla Powerwall paired with the SolarEdge inverter system.

It’s very important to note that these types of products are complicated, and what works in one scenario wont work for all. If you’re interested…ask us, we’ll help guide you!

For several reasons, in part surrounding grid connection permissions, we opted to go for a DC coupled arrangement. This means that the battery is connected between the module array and the inverter.

This is what our original “test bed” looked like, before the changes made recently….


beforeAdvantages of DC Coupled system

– Being able to compare yield performance of our array on the module level “optimised” SolarEdge system compared to our previous single MPP tracker set up. Our ground mounted array has some shading, so this will be interesting. There are many advantages to SolarEdge, and we already have many installed systems, but real comparison data will serve to back this up nicely.

-Being able to observe any degredation of our 4 year old modules, or any mismatch.

-Reducing grid connection costs and lead times.

Disadvantages of DC Coupled system

– Battery system losses will negatively impact on the generation meter reading, reducing FIT payments. It’s not yet clear overall what this will be in annual terms, but we do know that there will be some small loss here. We are confident that the advantage in SolarEdge optimising our system will outweigh these losses.

-Decreased peak inverted power. With DC coupled the maximum load covered by the battery system is the single inverter output, in our case 3.6kW (16A) of our grid connection. With AC Coupled, if the generator was also outputting, the peak load would be the sum of the generation plus the max power from the battery. We do not think that this will equate to much of a disadvantage for our system, but definitely a consideration in some situations.

The Decision


We felt that the Tesla Powerwall was suitable for us due to the high charging and discharging power available compared to others on the market. This makes best use of generation from the South facing array, as well as covering peak demands in the office (too much tea and coffee!!).

The whole system previously and going forward has monitoring of various descriptions, so any advantages or disadvantages will be found!


And Finally…


SWA Tesla Powerwall


A bit of a spruce up to the installation/test set up included, we think the finished product is stunning. We have chosen to install it indoors, in our hallway, as part of our complete installation. However, it’s much more suited to going in a garage, and is actually designed and built with being installed externally in mind. Lots of options to best suit your installation.




On getting set up, everything appeared to work really nicely. However, the weather did not help, with just a short spell of sun to get some charging done.

Tesla Powerwall Charging

We will keep updates coming on performance (mostly on Facebook, so give us a like to keep informed!), and do get in touch if you would like access to our monitoring to see for yourself how it performs.

We would also be happy to welcome you along for a look – just be sure to give us a ring to make sure there’s somebody around to give you a demo and have a chat about what the Tesla Powerwall can do for you.


Energy is changing

We at Solar and Wind Applications believe that for the sake of the environment, the face of small scale generation has to change in everybody’s minds, from being about money to about energy. From each and every householder, to business owner, to council to policy maker.

Tesla Energy Powerwall

Tesla Energy Powerwall

One of the factors that put many off investing the relatively large sums of money in a Solar PV system in the past was the fact that their installation would not cover significant amounts of their consumption, and a majority of their very own clean, locally generated electricity was exported for little benefit to them.

This changed somewhat with the introduction of proportional controllers to heat water, making use of much more of the energy generated on site. However this is/was not always a suitable solution. Either low or no (combi boilers) requirement for stored hot water meant that the energy advantage was small.

Now though, technology to store electricity as electricity is at the point that it’s viable. Known of course as batteries. It’s now possible to get to the point of significant self consumption, and in doing so directly offsetting the inevitable imported electricity that has frustrated those already with solar, and put off potential purchasers of systems.

The above, you will note, does not mention the financial side of matters. This is not because it is not important – of course it is critical – but because there are so many other reasons we want or need to do better.

LG Chem Resu

LG Chem Resu

We are seeing a new round of early adopters for this step change in technology – either the same early adopters we met when Solar PV started to become viable (yes, even before the Feed in Tariff!) now back for more, or the new round of those excited about the self sufficiency delivered by the new technology.

Money – Solar PV is now about the price it will be for a significant period of time, is our belief. For lots of reasons. Ask us if you’re interested. And that price is “affordable”, the financial side makes the energy reasons for investing achievable.

Money – Battery Storage is viable, as above. It’s not yet cheap. But it works. And it is accessible (not without issues though). A properly designed and appropriate system using good quality equipment will last for many years and at least pay for itself by the end of life. In energy terms though, it can increase self consumption of generation vastly and in turn reduce imported dirty electricity from the Grid.


DC Coupled Battery with StorEdge

So, what are we saying? We think that the time for investing in solar for home or business is now, either with storage in mind for future installation or involved from the outset. The game has changed, for the better, and we hope it triggers much more uptake for reasons of energy, not simply for financial gains.

Early adopters are critical – its why we invested in our own battery storage system, and why we think you should consider getting involved too.

Stay tuned for more on this vast and complex (but mostly interesting!) subject, including data from our own site, both on our website and Facebook Page.


We are now a Tesla Energy Certified Installer

Solar and Wind Applications have recently become a Tesla Energy Certified Installer, and now able to supply and install the Powerwall battery system.

The Powerwall is a battery unit which allows your renewable generator to provide energy to your consumers when your generator is not available, decreasing your reliance on imported electricity and maximising self consumption.

We will be installing the Tesla Energy powerwall alongside both SMA and Solar Edge inverters to suit the particular installation. New installation alongside Solar PV and retrofit are both possible.

We will complete our first installation of the product as soon as we can get the new version of the Powerwall in August, and will be posting photos and performance data on it from our own test site.

Front Angle_web

Tesla Energy are very particular about who can install their product, and rightly so, so we are very pleased to have shown ourselves to be suitably qualified. Their company ethos also promotes competition from their competitors, and in keeping with this we will only install what we deem to be the correct self consumption system for you from a host of options from many manufacturers.

Love to graph?

For those of you who take a real interest in your electricity/energy use, a good monitoring system is essential! In my eyes, it certainly beats taking endless notes and writing pages of numbers.

The Coolpower EMMA system, with the monitoring system ELMON provides loads of great data, specifically the net import/export of electricity from your complete system. It also shows what’s going into your hot water tank with the Throttle, where fitted, and/or to the Blusine Stack battery system.

We have an EMMA fitted at our office, and we thought we’d share today’s very interesting data. Broken cloud and bright sun mean the solar output is all over the place. EMMA is doing a perfect job of ramping the feed to the heater (space heating this morning, water heating later on) to ensure there’s no energy being exported and “wasted”.

We also have a fairly unstable grid connection, and this behaviour without EMMA would result in solar PV cutting out from high grid voltage on the sudden peaks in power output. EMMA prevents this and keeps everything running flat out.

Click on the image to see full size…

EMMA Output


Whilst the graph appears daunting, with loads of data shown on one set of axes, it’s by far the most convenient way (when you get used to it!) to see precisely what’s going on at any given time.

You can see that the load in the office is fluctuating too (electric heating, boo-hiss!) by the tan “appliances” line, the green “generated” line is ramping up and down with the sun, but crucially the blue “exported” line is at or very close to zero, with corresponding power over the load  to ensure no import and close to zero export.

Get all that?! It’s less confusing on a nice day on a system without fluctuating loads as per below. Lots of energy going into the tank, low import (red) and minimal export (blue).

graph - nice day cropped

In any case, all of this information is interesting and useful when trying to ensure low bills and efficient use of energy.

You can have this fitted by us, with or without EMMA to heat water or Bluesine Stack battery system. Just get in touch for more details or pricing.

Home Energy Fair

We will be along at the Energy Agency Home Energy Fair, held at the University West of Scotland from 10am-3:30pm Saturday 19th March. Come along and have a chat with us about what we can help you with, as well as all the usual great advice from other companies and of course the Energy Agency.

Details on the flyer below. Hope to see you there!

Energy Agency Fair - 19/03/2016


Use excess generation to heat water, or limit export on larger systems!

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