anyone heard of micro inverters ?

elantan

i have had a guy on the phone trying to sell me p.v panels, i explained the situation that are currently in ie: not cost effective for us, he explained to me this is because of we are on a string something or other and should in fact look at the new technology which is call micro inverter,

he explained that every panel is independent of each other and that the micro inverter is better than standard inverter's, he named a company called Enphase and said some guff about them being in california so know all about sun etc ... he was a bit shocked when i explained i was in california last year and there were very very few solar panels kicking about as i was looking for them .

i have done a quick google but couldnt find anything of note about either a micro inverter or Enphase, just wondering if any of you good people have heard of them ?

still working on the right renewable energy system for ourselves

thanks in advance

el

EricMears

Micro inverters would be a worthwhile investment if some of your panels are shaded more than others.

But if there are no shading issues with your roof the extra cost of micro inverters over one 'ordinary' one probably isn't justified.

rogerblack

If you have an unshaded roof, then microinverters have almost no benefit over a large inverter.
A large inverter is connected to one or more sets of panels - 'strings'.
Each string must be equally illuminated, or performance drops markedly.
Microinverters can be good if you have a roof with partial shading.

The have absolutely no impact on payback if you do not have a shaded roof.

elantan

Thanks everyone, we don't have shading issues on our roof so it wouldn't be worth out while investigating anymore

Martyn1981

elantan wrote: »

i have had a guy on the phone trying to sell me p.v panels, i explained the situation that are currently in ie: not cost effective for us, he explained to me this is because of we are on a string something or other and should in fact look at the new technology which is call micro inverter,

el

Hiya El, I've got a similar system on my WNW roof, but instead of a small inverter per panel, I have a single 'dumb' inverter, that talks to power optimsers (PO's) one per panel. These do the same sort of job of micro-inverters by allowing all panels to act individually, so if one panel on a string is in shade it won't drag the rest of the string down too. It adds a bit of cost, the inverters are a bit cheaper, but the PO's are about £40 per panel.

My shaded WNW roof is performing roughly on target with unshaded estimates.

The hype about PO's or micro-inverters, is that they'll outperform 'normal' inverters by maximising individual panel performance, even if there is no shading, but I can't imagine the difference is great, as some of the string inverters have shade management, and high efficiencies. Also means you have extra kit where it may be hard to access if there is a fault.

Given that your problem is the combination of being a little too north, a little too off-south and a little too steep (individually ok, but cumulatively too much), I can't see these helping you ... but ....

You mentioned a possible ground mount, but subject to too much shading, if TOO much, then forget it, but if the shading is small and variable, and you can place the panels due south at an optimum pitch, then micro's or PO's might be a solution, since access not a concern.

Here's a video of PO's made by SolarEdge (the system I have):

http://www.youtube.com/watch?v=lsa9rHpDVmQ

It should link in to pts 2 & 3, about 10mins in total.

Marty.

elantan

Thanks as always Marty

We would have some shading on the south facing ground panels, and one guy wasn't too keen on ground panels where as another guy said it shouldn't be a problem ... I think for us it's probably still best to try and work out the situation on turbines

It was just when this guy phoned today with claims of double the amount of output compared to regular set ups and talk of micro inverters I though hmmmm might be interesting

elantan

That's a very good video Marty, makes it easy for me to understand ... I think if we were to get a system we would be better getting one of those systems compared to the one we were offered before ... But even with a 25% increase in out put I don't know of it would be financially viable now are the FIT tariffs have just changed ( or just about too?)

Deff more stuff to look into though ... And I spose you never know lol

Martyn1981

elantan wrote: »

That's a very good video Marty, makes it easy for me to understand ... I think if we were to get a system we would be better getting one of those systems compared to the one we were offered before ... But even with a 25% increase in out put I don't know of it would be financially viable now are the FIT tariffs have just changed ( or just about too?)

Deff more stuff to look into though ... And I spose you never know lol

Evening El. I think the vid is pretty good too. At least I could understand it. Putting the obvious shading benefits aside, I don't doubt the 'extras' such as maximising individual panel variations etc etc, but I do doubt they make a big difference.

The shading aspect however is pretty impressive. My WNW is shaded by a small bay roof and a large chimney we share with the other half of the semi-detached, but unfortunately we are the north half, so the chimney is to the south. In fact one panel 'Slim Shadey' (SS) pretty much jams up against it. As the sun moves from the ESE roof to the WNW roof it is common in strong sun for SS to be producing 20W, whilst the other 7 are running at about 200W.

You can view all this on-line via the SolarEdge (SE) monitoring site.

With a normal string inverter, I'd expect SS to severely impact the rest of the string, but in this situation the install can be generating 1,400W from what is now effectively a 1,750Wp system (since 1 of the 8 250W panels is doing nearly nothing).

If the potential ground mount will get a lot of total shading, say from a wall of trees when the sun is low (morning, evening and winter months) then a SE system won't help much. But if the problem is varying shading travelling across several panels at differing times, then this is when PO's (or micro-inverters) shine!

Obviously being a ground mount, pitch is no longer an issue, but you'd still need to have a spot allowing for good orientation, if so, then that's two of your problems solved. Location can't be altered, but on it's own, not so bad.

My SE system is nearly 11 months old and generated 1,111.7kWh's, if generation is average from now till late July, then currently predicting a total of 1,380 against a PVGIS estimate of 1,359 which is straight off the site, no adjustment/allowance for shading, so I'm pretty chuffed so far, quite shocked if I'm honest.

Trying to be informative, not selling PV (as wind in Scotland is often pretty good) but don't worry too much about the FIT change on 1/7/13, it's only a drop of 3.5% to 14.9p (from 15.44p). Also this doesn't affect the export rate which still goes up with inflation, or the leccy savings which go up with energy bills.

Happy hunting, and I'm always here to bounce numbers around if you need.

Marty.

elantan

Marty as alway thanks ... It's great to get your input really helps