So now I have a solar PV system how do I make the most of it???

Martyn1981

edwink wrote: »

Hello Mart

Just to update you I have just received an e-mail from SMA regarding the suitability of a single inverter with 2 roof pitches.

They said "We would always advise when selecting an inverter, with 2 different orientations to use either 2 smaller inverters or an inverter with 2 mpp trackers.

When I spoke with the Technical Officer at our solar company he said "that they would change the Sunny Boy 2500 for an Sunny Boy 1200 and 2 stacker 500 inverters.

What do you think? It has left me a little confused!!!!

ED

Hiya Ed, been reading up, and scampering around forums to get more bits and bobs.

Did post #1728 help?

My technological knowledge of inverters is growing, but still very, very basic. Dual MPPT would be best, but finding a suitable sized one for your installation, may be tricky. Next would be an inverter with GlobalPeak to better manage a single string, but same problem of size again, as the SMA TL range is 3000 and above. Next would be the SB2500HF (I've got one) with OptiTrac, which would suit better than the SB2500, but not as good as a TL model.

Have also found info on the Steca inverters. One SB1200, and 2 Steca's would effectively give you 3 MPPT's. Apparently the Steca's are quite efficient, but you'll then have 3 inverters!

Personal message (PM) sent with more detail, and sources for more technical advice.

Mart.

KevinG

Kernel_Sanders wrote: »

I got precisely half that figure today, Eric. Was yours also halved?

Lucky you - I got less than a seventh of what I got yesterday!

edwink

Martyn1981 wrote: »

Hiya Ed, been reading up, and scampering around forums to get more bits and bobs.

Did post #1728 help?

My technological knowledge of inverters is growing, but still very, very basic. Dual MPPT would be best, but finding a suitable sized one for your installation, may be tricky. Next would be an inverter with GlobalPeak to better manage a single string, but same problem of size again, as the SMA TL range is 3000 and above. Next would be the SB2500HF (I've got one) with OptiTrac, which would suit better than the SB2500, but not as good as a TL model.

Have also found info on the Steca inverters. One SB1200, and 2 Steca's would effectively give you 3 MPPT's. Apparently the Steca's are quite efficient, but you'll then have 3 inverters!

Personal message (PM) sent with more detail, and sources for more technical advice.

Mart.

Hello Mart can not get the pm as I have pop up blocker on and it won't allow them.

I 'll wait to see the electriacian when he comes and speak with him about the new set up. It sounds ok. The Technical officer was sure it would work ok.

Keep you posted. Thank you!!!

ED

Can not

Martyn1981

edwink wrote: »

Hello Mart can not get the pm as I have pop up blocker on and it won't allow them.

I 'll wait to see the electriacian when he comes and speak with him about the new set up. It sounds ok. The Technical officer was sure it would work ok.

Keep you posted. Thank you!!!

ED

Can not

Ed, that's odd! At the top of the page, to the right of your log in name, can you click on the words 'Private Meassages (PMs)'? Is that blocked then?

Mart.

EricMears

Kernel_Sanders wrote: »

But I haven't accepted that he did!
I am maintaining that in early winter, the only time that the sun would appear be 'over the horizon' north of an east-west line through your array would be well before sunrise (and consequently long after sunset), therefore negating his perceived advantage for a flatter roof.

At no point did I ever make a claim that 'flatter was better'; I simply agreed with (I think) you that there were occasions (season unspecified) when a steeper pitch would receive less light than a shallow one but did point out that it would only be happening when light levels were pretty low anyway.

Incidentally, before sunrise or after sunset the sun doesn't appear to be anywhere - it is by definition out of sight !;)

Struggling to remember the planar geometry but I think the sun rises at true East & sets at True west on equinox days; during longer days the sun will rise & set North of true E & W respectively and during shorter days it would be S of that before it becomes visible.

Kernel_Sanders wrote: »

Over to you, Eric!I got precisely half that figure today, Eric. Was yours also halved?

I got 6.08 today compared to 9.7 yesterday - so rather better than half. A peak of 2.5kw at 11am then increasing cloudy spells with occasional breaks for rest of day.

Kernel_Sanders

EricMears wrote: »

At no point did I ever make a claim that 'flatter was better'

EricMears wrote: »

There really are times of day when the Sun is (very slightly) to the North of the East-West line through your roof and whilst that condition is true the flatter your panels are, the more sunlight they'll collect.

EricMears wrote: »

I simply agreed with (I think) you that there were occasions (season unspecified) when a steeper pitch would receive less light than a shallow one

EricMears wrote: »

A shallow pitch would certainly be better for first & last hours of daylight at any time of year.

The seasons were specified; you included all of them!

EricMears

This continual nit-picking is getting really boring.

I've never said my panels are set flatter to collect more light - the roof pitch was chosen for completely different reasons.

As Martyn tried to point out earlier, there will be light reflected from more than one area of the sky at beginning and end of the day and - when there isn't very much light about anyway AND when the very shallow sideways beam of light is being attenuated by long passage through the atmosphere - that can very easily amount to more light coming downwards than there is directly from the sun.

If it really bothers you, get up on the roof at 7am tomorrow morning and point a light meter at different areas of sky:D

edwink

Martyn1981 wrote: »

Hiya Ed, been reading up, and scampering around forums to get more bits and bobs.

Did post #1728 help?

My technological knowledge of inverters is growing, but still very, very basic. Dual MPPT would be best, but finding a suitable sized one for your installation, may be tricky. Next would be an inverter with GlobalPeak to better manage a single string, but same problem of size again, as the SMA TL range is 3000 and above. Next would be the SB2500HF (I've got one) with OptiTrac, which would suit better than the SB2500, but not as good as a TL model.

Have also found info on the Steca inverters. One SB1200, and 2 Steca's would effectively give you 3 MPPT's. Apparently the Steca's are quite efficient, but you'll then have 3 inverters!
Personal message (PM) sent with more detail, and sources for more technical advice.

Mart.

Hello Mart

Yes thank you post 1728 did help. Although all of it is still confusing me a little. If I was technically minded it may help. As I am not i'll just have to plod on the best I can. My concern slightly is having 3 inverters. I thought the installers would change the SB2500 for 2 inverters. One for the higher pitch and one for the lower. Maybe it is not that simple. I am confused as to why they are going to install 2 inverters of 500 each for the lower pitch. Maybe because the panels are south facing they are taking into consideration the shading in the morning on 2 of the lower panels (from the east) and later in the day the shading on the other 2 (from the west). That is what it sounds like to me.

Would the 3 inverters use a lot more energy to run than 2?

ED

Martyn1981

edwink wrote: »

Hello Mart

Yes thank you post 1728 did help. Although all of it is still confusing me a little. If I was technically minded it may help. As I am not i'll just have to plod on the best I can. My concern slightly is having 3 inverters. I thought the installers would change the SB2500 for 2 inverters. One for the higher pitch and one for the lower. Maybe it is not that simple. I am confused as to why they are going to install 2 inverters of 500 each for the lower pitch. Maybe because the panels are south facing they are taking into consideration the shading in the morning on 2 of the lower panels (from the east) and later in the day the shading on the other 2 (from the west). That is what it sounds like to me.

Would the 3 inverters use a lot more energy to run than 2?

ED

Hiya Ed. I believe I understand the logic regarding the lower 4 panels, but any advice from others would be appreciated. So here goes:

The 4 panels won't quite produce enough voltage to meet the minimum for the SB1200 inverter (effectively it looks like the SB1200 is too oversized), so the next move is to find an even smaller inverter.

The Steca inverters are small and modular, so you can build them up one at a time till you get the right panel to inverter match. Or as in your case, I think you've described the situation perfectly, where each pair of panels receives different levels of shading, so splitting the 4 into 2 sets of 2 also looks advantageous.

Here's a link to Steca

http://www.stecasolar.com/index.php?StecaGrid_300_500_Control_en

This line from that site, explains their role, but remember this is their site and their sales pitch;

Thanks to the modularity, this is the inverter of choice in systems with differently aligned or partially shaded roofs, and on smaller surfaces (garage roofs, summer houses).

The more inverters you have, the more system losses logic would suggest, but apparently these are very efficient, and this set up looks (to me) to be a way to optimise your particular requirements of multi roofs and varying shading. Also inverter losses are relatively low, it's the matching of inverters to panels to circumstances that is important.

Don't worry about the tech side, but it might be worth you asking the installers if they know of a single small enough inverter that is a dual MPPT, or one that has GlobalPeak Tracking. But I suspect the smaller 4 panel array will cause issues due to its size - 5 panels or more offer more flexibility, as far as I can see.

PM sent with some more tech 'stuff'.

Mart.

sly_dog_jonah

seagull09 wrote: »

Total for Feb based on my position and power *should* be 83 kWh. :mad:

Does that account for the fact the commissioning date was mid-month? If not, then your system is running about 71% of PVGIS estimate, ignoring today and tomorrow.

Our 3.7kWp system in Somerset SSE facing @ 45 pitch is estimated to make 160kWh on PVGIS for Feb. We're at 188kWh right now, fingers crossed the sun comes out this afternoon and tomorrow so we'll hit 200kWh (PVGIS+25%).

For us the best week of Feb was the first week, but the rest of the month has only been about 10% less per week. There's been lots of rubbish days though, offset by some crackers.