Alternatives to Robin's solar diverter?


I see that Robin’s diverter is currently unavailable from his shop and I can’t find an email address to ask him some questions.

Such as how much is it approx ?
And when does he hope to be able to supply kits again ?

If this is likely to remain unavailable for the foreseeable future what other devices do people recommend using to divert excess Solar PV to an immersion heater to avoid exporting to the grid?

My dumb meter will flag an error if I start exporting thinking I’m trying to fiddle it so I’m holding off installing solar panels until I have the means to use all that is generated.


The price depends on the options. His last published price was £85 + £5 postage for the basic kit, excluding the c.t.

As his website says, he’s been overwhelmed with orders and is busy making up kits and shipping the backlog of orders. I think he will be re-opening the shop within a few weeks. I suggest you keep checking regularly, I think it’s worth holding on - as far as I’m aware, he has got stocks of all components, but he didn’t have the time to make up the kits.

I’m not up-to-date on the present system, but surely if you have a generation meter and notify your supplier that you have a PV installation, after you’ve done that it’s their problem?

1 Like

My Mk2 PV Router designs that were posted here some years ago should all still work given suitable hardware. They are based around the emonTx or the Arduino Uno.

In the UK, no financial penalty should arise when surplus PV energy is exported to the grid. But it makes more sense when it can be used for some on-site benefit.

As Robert has said, I recently found myself overwhelmed by enquiries and orders and decided to close the shop for the rest of this financial year. I’m hoping to open again for business from 6th April.

1 Like

I don’t have a generation meter only a standard import meter that will throw up an error if energy flows the wrong way through it, it assumes you’re trying to fiddle your meter readings.

I currently don’t have any solar installed, my plan was to put up 1 or 2kw of solar panels and use a grid tie inverter to reduce what I pull from the grid. Because I can’t export without causing problems with my meter and actually I don’t want to export only to be paid peanuts I was going to use a diverter to send all my excess to make hot water.

Perhaps I’m going about it all wrong…

Can I join the queue then of people wanting one of your kits then ? :slight_smile:

I’d much rather buy something off a one-man outfit who is doing it because they can and they enjoy it than from some soulless corporation.

Thanks to you both for the quick replies, it’s much appreciated.

I’ve had my emonPi running ever since I got it after supporting the kickstarter campaign, I’ve been meaning to add some solar for a long time but never got around to it, well now I’ve decided to actually do it this year.

What do you plan to do when all the water is hot - do you have sufficient other load to use all the excess, or are you going to shut the inverter down?

Will it not be better to export and get paid “peanuts” when you can’t use any more, rather than shut the inverter down and get nothing? Or is your plan to have a dual-load diverter and burn off the excess in a heater and release it to the environment?

I assume you’re not aware that you need to notify your DNO if you do have grid-connected generation. This is so that they are aware of it so that they can take the steps necessary to ensure system stability.

I plan to have alternate loads that will usefully use the excess.

Ahh… I mistakenly thought that was if you wanted to be able to export electric. Hmm I might have to rethink my plans.

The bottom line is I don’t want to let a “professional” install it because I’ve seen the corners they cut to do a quick job. I’d much rather install it myself and know it’s all been done correctly and is safe.

My day job is electronics & electrics on boats, I’ve years of experience with wind, solar and hydro generators, battery banks, inverter/chargers etc so I am more than competent to install a few solar panels and an inverter on my own property.

Is it possible to install all the kit myself and then get it signed off and if so how much would the sign off cost ?

My base load is around 300w so anything I can do to avoid importing that from the grid is my primary aim.

I know the feeling.

There are two ways to approach that: (1) Ask your DNO if they will accept your proposed approach and allow you to sign it off yourself, or (2) find someone whom the DNO will accept to sign it off and see what they quote you.

My other thought is to go completely off grid with my solar setup.

Solar panels charge up a decent size battery bank,
the battery bank runs an inverter to make AC for the items that run 24/7,
Robin’s diverter dumps excess solar to immersion once battery is full,
a monitor system that charges the battery bank from mains if the sun doesn’t shine and the battery SOC is low.

The server I run 24/7 could easily be moved to this setup, my fish tank is the other big user of power 24/7 and that would be much harder to rewire…

Downsides to this approach is more expense and complexity,
Upside is I can’t think of anyone whose permission I’d need to get to do this.

Any other suggestions ?

In the meantime I’ll ask my DNO about getting a DIY install signed off.

thanks for the help so far.

Here are two more:
You’ll need a battery bank large enough to get you through 3 to 5 days
(possibly a bit more) of no productive sunshine.

Given any particular battery technology has a limited number of discharge-recharge cycles,
they’ll need to be replaced every ~3 to 5 years.

@Wookiee as an alternative to roblin solar diverter – you can try my version –

GitHub - krywenko/auto-sensing-energy-diverter-wemos-uno-wifi-espeasy

it does alot from self contained automation or external control by home automation programs

not all batteries have such a low cycle rate as most lead acid and ternary lithium batteries are from 300 - 1000 cycles to 100% DOD… LiFePO4 batteries are 2500 - >3000 cycles to 100%DOD … I got a BYD battery box some years ago it doing fine after the initial hick ups i had ( bad BMS controller) – and supposedly the price has come down significantly since I bought it which was about double the cost of lead acid - now it below lead acid at $65 -$85 per kw and in 3 years it suppose to be below $50 per kw – and they are alot safer then ternary lithium batteries very very low risk of fire

Which is one of the things that shortens battery life.

Either way, as I mentioned earlier, any given battery technology has a finite lifespan,
hence batteries using said technology will eventually need to be replaced.

Thanks for that, something for me to read about. A different approach to the same problem.

Reminds me of the old saying… “Few batteries die a natural death, most are murdered”

As part of my day job I’ve replaced plenty of batteries, most of which have been badly treated usually by over discharging them. The most recent one was a 12v leisure battery that was down at 0.7v, suffice to say the owner initially refused to believe his battery was now only fit for use as ballast.

I’ve installed some large battery banks (usually AGM) and we stress to the owner that the lower DOD you do the longer the batteries will live.

A few years ago we had one guy wanting to boil a 3kw kettle via an inverter with only a couple of 70Ah batteries, eventually we convinced him to buy a metal kettle and just stick it on his gas hob.

thumbs_up thumbsup

Please let me know how this goes. I want to do the same.

When you do the install, make sure to have a quick butchers over the MCS installers guide for solar PV design and installation and for roof fittings. You don’t have to comply to this higher standard but why not?