Would it make sense for me to include a Battery and/or Eddie diverter with my solar PV panels?

PGL · 26-01-2024 09:53AM #1

Hi folks

I intend to get solar PV panels installed on my semi-d home later this year. It would appear the maximum capacity I will manage to get installed will range somewhere between 2.5 and 4kWp.

To give a small bit of background, it is a 4 bed home that I live in with my wife and 3 kids (ranging in age from 6 to 14). Our electricity usage last year was 5,800kWh. Our radiators and hot water cylinder is heated by gas, and we also have an electric shower. I work from home 4 days a week. I will soon be getting my hands on an EV, and have ordered a Zappi EV charger - this EV will be the "second" car used only by me (as its a company car) so won't be doing very big mileage (considering I work from home 4 days a week), so I would imagine I might only need to charge it maybe once every 2 weeks.

I obtained quotes for solar panels back a few years ago, but between the jigs and the reels, I didn't go ahead with it, and have regretted it since considering how prices have increased, and also bearing in mind how expensive energy has become. Back then, I was also closely following the various threads on this website. At that point the general consensus seemed to be that the vast majority of people were getting the Eddie diverter for their hot water cylinder, while there were more mixed views when it came to batteries. My question is would it makes sense for me to include a battery and Eddie when I hopefully get solar panels installed later this year?

Thanks a lot!

Sleamhain · 26-01-2024 10:07AM

Others may have differing opinions, but I think the Eddi might be a good option for you but not the battery.

Similar to your situation, I have a 4.3 KW array, and an EV. I don't charge the car anymore via solar as the feed in rate is 3x the night rate. So I sell almost all excess to the grid (bar a little bit to keep hot water topped up via Eddi) and can buy back 3 night units for every 1 I export. (Energia EV Smart Tariff). This way is essentially using the grid as a battery. I would find it tough to get payback on the battery unless I had some other large electricity consumer, like a second EV. You could top up the battery at night though also and discharge in the day to offset cost of daytime electricity rates - useful if someone in the house during the day.

I do like the Eddi though. I mostly just use it on a boost at night to heat water cheaply and then let it top up during the day. If your primary concern is cost, it's probably cheaper to heat water via gas boiler. But if you are more concerned about emissions then night rate is good, as it's generally a pretty high volume of wind on the grid at that time of night. Then topped up with solar in the daytime. So I can have a full tank of hot water everyday for little environmental impact.

There is a few things to consider when choosing your setup such as what tariff your going on, what your usage profile is like, EV mileage, cost vs environmental concerns etc

cython · 26-01-2024 10:10AM

I have neither, but I got solar panels installed last year. So anything I say is based solely on my own experience and situation, which is different to yours with no kids in the house, etc.

To me at this point (since feed in tariff, or FIT has kicked in) the Eddi is more a convenience factor (hot water on tap with less planning) than it is about pure economics, unless perhaps you'd be heavily reliant on electricity to heat water after having exported a surplus, as you'd be buying a back at a higher price than you sold it. However, you've said you're using gas for space and water heating, so it probably makes sense to keep with that if it's zoned, etc. and you can heat just water in the summer with gas. Typically heating from the gas and getting paid for the surplus will be more cost effective these days. I steered clear from the Eddi with a view to investing the same funds in heating controls upgrade, FWIW.

As for the battery, with the advent of the FIT, again the economics are less clear cut with only solar in play, as you're dependent on the difference between your export unit cosr and import unit cost to pay for the battery then. For me this alone didn't make sense up front, but I've a hybrid inverter so I can change my mind and retrofit if I want to. However, if you want to go all-in, you could switch to a day/night meter or smart plan (be very careful with the latter, there's no way back, and if used wrongly or chosen inappropriately they can often be more expensive!), and charge the battery from the grid at night rate, minimising your day rate import, and perhaps selling back unused import and your solar yield at a higher rate than your night import rate. This will accelerate repayment overall, and has a benefit of working/paying off during low yield winter days too), but you need to size the battery right for your daily consumption then too.

Looking at the consumption you posted and the size of the system (you don't say aspect/s or split, is it all south, east or West facing, or some combination?), I'm not sure you'll have much surplus a lot of the time to warrant a battery, especially if you WFH four days a week and can run appliances, as well as eventually having an EV to take surplus, so I'd personally only look at a batterycij your position if you want to leverage export/import differential as well.

Of course if you're not on a smart meter and don't expect it rolled out to your area for some time (unlikely, I'd say) then it's a whole different conversation as your FIT is estimated and you should be retaining/directly using as much as possible as you can of what you produce as it won't impact that. Then battery and Eddi make a lot more sense until you get metered export.

slave1 · 26-01-2024 11:54AM

If you can DIY a minimum 10kWh battery to eliminate your need for Day rate then I would consider it, if you will only go for a ready supplied battery then financially a total no no.

Would it make sense for me to include a Battery and/or Eddie diverter with my solar PV panels?

Comments