As some of you will know we took stock of the Deye micro inverters a week ago and we always test out what we sell so that we know exactly how they work, the performance and any problems that our clients may see as a result of buying from us. but lets look at how we found it as most of Europe have these as “plug in solar” or also know as Balcony Solar.
Disclaimer- We do NOT recommend testing solar at home if you do not know the risks and the legal requirements and protection that you should have in place. this article is for educational purposes only.
UPDATE: Our First year of micro solar inverters Click here for our update
Plug in solar has had somewhat a wide birth in the UK, any generator with live pins ( aka the plug) can expose users to live mains power, and in fact most legal standards and requirements forbit the plugging in of a generator (be that petrol or solar) using a plug and socket.
we have covered the “legal” side of this here https://www.renewsolar.co.uk/plug-in-solar-micro-solar/plug-in-solar-the-balcony-solar-system/
The particulars in the legislation is:
(ii) A generating set shall not be connected to a final circuit by means of a plug and socket-outlet
In Europe however there is estimated to be around 400,000 of these systems installed, they have the same legal framework and standards as the UK, however they have not blanket outlawed them, but are working on a resolution and standards to “make it work”.
The requirements for UK installation differs as I had set out in the post linked above and within the forum. the more detailed post is in the forum here which looks at the legislation of solar and electrical safety.
In a more simple form the solar would fix into a system with the normal protection as any other solar installation.
In Germany they are looking into special plug and sockets or rather connections to make this more safe as the plug sockets and plug used they’re are not good in the wet, however why you would have a wet socket or exposed outdoor socket is another mythological scenario by the sometimes creative minds of H and S.
While the image above image is fake, I did test the system failsafe by pulling the plug on a live system and immediately checked to see if there was any voltage. The fake image and reality was the same. the reason the image is fake, is because its impossible to hold a camera and do it.. but you get the idea?
Don’t try this at home, they are called a Suicide cable for a reason!
The key here is that the power at the plug must drop voltage in milliseconds and there has been some challenges to meet that standard. The Deye unit and others, come with a “relay box” this is between the inverter and socket and turns off when there is no grid detected. while I haven’t pulled on apart, I would assume that the grid being present would hold shut a relay, which is release when the grid vanishes. a very simple yet effective solution, the inverter is then left isolated for its own shut down times secured behind the relay. This is my best guess anyway.
Solar in the UK is subject to planning regulations stand alone and roof top or pergola solar is a mixed bag of side stepping expensive routes, though for most the “permitted development” seems to be a free for all, which it is not. P and L still applies so solar on the roof requires building control, and the same with electrical installations. However some “installations” are not notifiable.
Balcony solar is for the most part a renter or low cost solar option; its meant to off set the power use until larger installations on roofs or ground mounts take place, but they can be used permanently. There has been a recent change to 800w ( as of 01.4.24) which brings us up to a more “reasonable” power offset, and I would assume that it meets most users requirements, but not larger home office installations.
You are limited to 1 installation as far as I am aware and the risks grow with the more installations there are on a single property with this plug in type of installation.
This article DIY Solar PV Installation: Building a Balcony Power Plant | Elektor Magazine goes into more detail as getting a solar kit is not going to work for everyone and there are pros and cons as well as a wide range of considerations to take into account.
“count on an annual solar irradiance value of almost 1,200 kWh per m2 under optimal conditions. Assuming an efficiency of 20% for monocrystalline solar cells, I could produce up to 240 kWh per m2 and year. A two-panel setup will be more suited for me, a modern panel in the power range of 320 to 370 Wp has a usable area of around 1.6 m2. So, a yearly harvest of almost 770 kWh should be possible from two panels. Using this yield with the current price (30 ¢ per kWh) for electricity in Germany my balcony power plant would save me up to € 230 per annum.”
“Wieland plug-in connection (Figure 2), because in Germany we are allowed to use a plug and socket to connect the system output while observing safety and certain restrictions. In the UK this is not allowed; you need to connect the output via a dual-gang fused isolator switch.“
note that the last quote paragraph is in error…
They, may have a point but for cost effective minded people the output would be a off set in the cost of living. We would make the system peak annual output to be 1320 kWh this would be a fairly ideal installation. But a good installation would yield around 792kWh
At 0.29p kWh thats £382.80 and £229.68 respectively. Our kit is £399 ( not including the protection for UK installation) Therefore the return on the investment would be about 1 year.
Our estimates of Yields are based on average sun hours over 275 days of the year, we use known reductions (de-ratings) which then is roughly the annual yield, it is a within a accurate margin of less than 5%
As most homes do NOT have balconies they will probably be mounted on the ground or a shed roof, or flat roof. They Wont be against the fence like this as it is NOT allowed. This temporary system is not ideal, however there is little space and this would represent a ” joe average” installation in terms of the panels, its fairly early in the year and the sun is low. We already know what the power that is available from pervious tests in the same location. The panels are angled which may be more optimal that a balcony installation or flat wall mount.
As you can see the test in carried out with partial shading, though the reflection from the panels is not quite as it would appears in the image and real life..
First impression:
Its not hard to set up, but its not easy either. The software is not as simple as you would think, routing cables and keeping safe is not that simple, but when you get over the software installation and the rain.. ( living in the uk and trying to do anything.. it always rains) it was straight forward.
Plug panels into the micro inverter, plug relay into the inverter, wire plug to cable, plug in cable. faff for an age ensuring there was a good connection and then realizing that the easy way is install the software and it will scan and install rather than missing about trying to get it to connect and then spend an age trying to find its IP on your own network.
Its fairly Poor. That’s my short view but then when you have used or installed a wide range of systems, the “pro” view is rather spoilt. Low voltage tend to make bad returns. and this is really how solar works because its using the conservation of energy and ohms law; AKA physics… the higher the voltage, the easier it will be to make power. Typically solar will be around 30-40 volts per panel, and voltage is easy to make, its the current which is provided by the sunline intensity that adds together to make the power.
Here is an example.
400V x 0.2 amps =80w
31v x 2.5806 amps = 80w
As you can see the higher voltage system will produce in lower currents so a winter sun with its low current will make the smaller system suffer in performance. The result would mean that the solar power provided will be limited, if any in winter. With upright panels in summer, you are also limiting your power output. We also have to take into account that the panels may not be facing southwards too.
As of writing the summary array is providing 3.9amps , the balcony is at 4.5 and 6.5 but the information from the balcony is delayed by 5 minutes, and keeps losing connection. so like for like is a chore at best.
The Deye micro inverter has a input voltage of 60v that’s about right for two panels. but would allow for single panels in the 500+ watt range, which would be okay as the voltage is just under 50v or just over depending who you get your panels from. This is sill not ideal for England where a higher voltage system would fair better. This means that the balcony is more reliant on the sun shine (radiance) to make its power and will be up and down in power production making them slightly un reliable to meet a set need.
the Hoymiles HMS-800-2T has a input of 65v however this still will not mean two panels could be connected. for that to be possible the input voltage would need to be around 80v in a more ideal hardware development stage.
What is the alternative?
A sting inverter would offer a wider range, and the small and good looking Growatt Min inverters are slightly bigger, more deeper, but look okay on a wall. you get to install voltages to 500v for the array and over size your solar to ensure that you can “power though winter”. They have a 56v start up and 0.1 amp current is needed from the array. The Growatt 1500 costs more but for the extra you can add to the system over time. while you may have to consider that upgrading the balcony system would be more costly when adding two micro inverters and two sets of panels which would be around £800. The Growatt and 4 panels would be around £512
it is worth noting that the Growatt can work with 2 panels if space in a concern.
verdict on first impression
The performance from the balcony and the summer array is roughly the same, while there is a actual peak output power difference of 20%, we are fairly though the day and the panels are south facing, they have made 0.7kWh by 13:43 the other has made 1.4kWh as a comparison. This shows that the lower voltage solar is not great, both have some form of shading which is almost equal, the panels angles are very different. The balcony having the best position newer panels, etc.
Unless you can position the system in the best sun, have the better angles then I really don’t think they are great, you could install a Growatt and some more panels which would be better in winter.
for small wall mounted system, or ground mount, the ability to fix to the frame and be small, would appeal to many.
I hate the software and information delays of the monitoring system. but that’s the same with a lot of inverters and there WIFI experience, the Deye has WIFI built in. Growatt does not but we have the shinex alternative which is far far better than Growatt offering.
to be “value” or “worth it” it will really be down to the use case and setup its all about functionality and provisions that it offers. Therefore I cannot dispute it has a place and is a “solution” but I would not go down this route unless it was necessary.
plug and play or plug in solar is more a gimmick than a realistic installation as you would cut the plug and fit the system with additional protection for a uk installation, that’s no different to any other standard installation and it can be a little more costly here too.
While we offer the 800w is has to be down graded to 600w to comply with its ENA register type test. its easy to do, but you are really buying a lesser value item with the Deye, the Hoymiles will run as is and there are more power options, and hacks.. however these are normal micro inverters rather than a plug in system with the special relay.
Could they work as a winter stand in support? with the low voltage they wouldn’t offer much more than the winter array due to the available current from the sun, but you could angle better to pull some more power than summer arrays, the value and performance would depend on the other system it is supporting.
is it safe?
it would appear that its safer, swiss professionals seem to think a two fault would render them a risk, however RCD in two faults will also not work… the direction would appear to lead the market to “professional installation only” which in my view could be scare mongering risks based on hysteria rather than real life scenarios. not to mention their plugs are not as good as ours; in terms of plug safety what we have had for decades, and this is not just the swiss but most of the world.
What I would like to see is additional in system RCD protection, this would really make the things safer, it is after all a upstream device that’s fitted down stream..
if the relay failed, would there be a risk?
lets see your views in the comments, keep it nice.
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