Affordable and DIY solar tend to go hand in hand, as prices have dropped here are some of the most low cost options, but they do have some catches.
Deye Micro Inverter -800w
by far one of the more simple set ups, now that they have addressed the thirds party software which is wholly a pain in the butt to get working. a kit is available for £400 including delivery.
This system is easy to install as its plug and play… ish. Firstly we supply the hardware needed for a legal installation. but with the wide range of applications and ways someone may install, we made the solar kit rather simple leaving off the final connection possibly which means that you could install to the henley block or on the ring main, or on a circuit ( see our information on BS7671).
there is also the gen port which allows the “plug in solar”. We would advise a new circuit install with these, as we have to, but not only do these kits have a “built out” protection, but to ensure compliance we have included a dual pole RCBO. this is 6 amp which could be fine for those on a dual sourced cable connection. it is certainly fine for a new circuit.
(note a home owner DIY cannot install legally a new circuit)
The Catch.
While the unit is compact and supports two solar panels there is the 800 watts which dents the electrical bill. but wont cover people with “low usage”, so you may want to upgrade, you could add the same kit again as you can link 6 kits together. or you could have 1200w micro inverter which supports 4 panels. When we turn to the cost of 6 kits at £2400 you would be much better off with something else.
What I am tell you is that these do not scale well, but would be a stepping stone, which can work with some inverters, meaning that you can integrate them. or would be the choice of those of you with small multi angle roof areas.
The Options
You can buy a string inverter, which means that you can have a lot of solar panels connected together, ideal for a single angled roof, but by the time you but a grid tied system, say around £700 + panels, you could jump a little more for a hybrid system, A system with a battery. so you then start adding £650-750 for the battery, but with some solar inverters, you do not need a battery for them to work.
As you can see we have jumped £1000 in cost, but the upgrade path I think it is very important. and grid tied micro inverters are a “bit of a fun way to save money”. with there lower costs and making around 5.4kwh a day, they offer a reasonable pay back time, at around £1.24 per day saved (if your using what you’re making), that’s 322 (sunny) days to pay you back.
Smaller and bigger solar micro inverters
When it comes to micro inverters size matters from two perspectives, the output power and the space/angle that you are trying to draw solar power from.
Lets take for example the smaller units, a 400w solar micro inverter, is around £15 cheaper, but will support a single panel. the 800w supports two panels and the 1200-1600 supports four panels but then has a price tag or around £500. These are limited to four panels when you are comparing these to a string inverter, and further more if you think of over paneling for winter, the micro cannot do this where as the string inverter could have 6 or so panels. However the string inverter would not fair well in shaded conditions as a micro inverter due to the independent MPPT controllers per panel.
Lets talk about a bigger grid tied solar inverter
Bigger does not mean better, and for most the common 3.6kw solar inverter would work for them with 8 solar panels and mounting kit. (thats one of our kits which costs £1400).
You would have to have space for 8 solar panels in a string from the outset.
You will ONLY save what you use.
You will only have solar power when the suns up, as you have no battery.
For the informed, you would have around 8 hours of sun, and if you are out working, well the house may use about 350watts.. clearly here the micro solar system wins.
Lets say you work from home, the wife and a small pre schooler is at home, then you may use 750w, the kettle 2300 watts and the washing machine at around 2100w.
If you time them you can make the most of the solar power during the day and for the most part you will have peaks of around 2kw for short periods; the 750w would amount to £1.38 per day; and if you were paying attention you can see there is not a big difference between the two systems. it does make a difference with the higher power draw.
This is where solar can be a compromise and this is in more than the first thing that came to your mind. What about when its not sunny?
it has not been a good year this year and solar has been running around 65%, That’s 520w on average. this clearly is a short fall for our 750w scenario. The larger system would offer around 2300w of power meeting the needs of our higher demand items.
Then; here we are thinking well the big system would meet more of my needs and you would be correct, but you would be exporting a lot of power that you will not be using. lets think about this:
3.6kw of solar would make around 18.7KWh of power per day, and this is pretty much what a home uses in 24 hours.
From this you export 12.7Kwh of power… This will eat away at you and therefore you would want a battery, the export then becomes stored energy for you to use over night.
The Added Value is £2.92
Solar would make around £4.30 per day but your battery would bring your time for the pay back to 3 years.
A little off spec.
Solar installations are a bit one sided, they are not designed and installed for you and this was one of the big solar scams. with most installers and “experts” being from grid ac power dependence, they tend to have a limited scope. However off grid and independence is a totally difference matter. you could save a lot more money by using the grid as the back up system, and you could be saving 65% or more.
Venturing down the off grid route is popular and does hold the standing charge for the fall back power you will use around 90 days of the year. unless you can get them to connect and disconnect you for summer. you will pay around £400 for the inverter as apposed of £1300. the panels will remain the same and you would buy a battery depending on your needs. lets say £1250 and panels at £390 would be around the £2,400
AC coupled inverter.
This may seem like a odd name, but this is a inverter that may not have solar connected to it, but works by detecting export power, which it uses to charge the battery. This is the other option for those who have a grid tied inverter and do not want to have a hybrid inverter system as a side offer to the replacement. The catch here is that the inverter total would likely fall into G99 applications.
You can find all the hardware in our solar shop, or under our project management, check out the forum or leave a comment.
Conclusions
A micro inverter is great for small scale solar projects, they are cost effective and allow you to use larger inverters in shaded areas or where the roof space limits the single angle of the panel. When up scaling up however, with bigger arrays they become more costly that a string inverter.
You could attach the micro inverter to some of the Hybrid inverters which allows for the input, this therefore gives you an upgrade path.
Micro inverters are grid tied and do not have any options for a battery, save for something like the Eco flow system. You can add a SC coupled inverter which would have a battery, but its a choice between micro inverter and hybrid. Therefore this may work for upscaling in some circumstances, but its always wise to look at the longer term rather than a “test” system.
if you are looking to offset in a cost effective way, you will find that the micro inverter is one of the better options.
Comparisons.
This is a comparison as of September 2024 between the micro and string inverter for small scale solar off set kits.
800W Micro inverter kit- £399 (+60 mount and extras) 2 panels.
This is a 2mWh ROI ( summer yield 1.76mWh)
1000W Growatt string inverter 4 panel £750 ( including extras).
This being a 3.26mWh ROI ( summer yield 2.2mWh)
3300W Growatt string inverter 8 panels and installation kit £1300.
This is 5.65mWh ROI ( summer yield 7.2mWh)
No responses yet