Solar PV Hints, Tips & Troubleshooting

graememk

https://www.boards.ie/discussion/comment/118159838#Comment_118159838

Excess just great exported. Don't get anything for it yet. And don't expect much from it either.

No risk of any damage it's just how they are designed

bullit_dodger

https://www.boards.ie/discussion/comment/118159838#Comment_118159838

Yeah, you'll have a fair bit of excess.....in the summer. If you think about it very simply, your using about 10Kwhr a day as you say. With 6Kwp of panel production if you get 80% of that (losses etc), then 2 hrs of bright sunshine you've completely generated what you need for the day. All the other 10-12 hrs of brightness we have in the summer you'll be generating excess which you should put into your battery (for when it's dark), or heat your immersion.

You might be thinking that you have too much production then, but sadly there are many months of the year where we don't get hours of bright sunshine and your arrays will be generating 10-20% of your stated max. it's for these days that you want a big array (like 6Kwp) as for these marginal days, you will be able to be self-sufficient for more months of the year. Nov-Feb though you probably will have a shortfall and have to import from the grid, but that's ok.....even on these days they panels will still do "something", but maybe 3-5 Kwhr of your 10 needed

Your quote is very competitive, and I doubt you'll beat that quote, or if you do, it probably won't be by much. FIT (Feed-in-tariff) you will get paid for some excess, but there's talks of a €200/year cap on it and you could be taxed after that. The general feeling here on the forums it that we should look at FIT as a bonus. Sure, a nice thing to have, but it shouldn't really move the needle much to sway people. I'll echo what the lads have said about the "savings" generated. Lies. Still don't let that put you off. You'll do the right thing for the environment and in ~10-12 years you'll have paid for the system and be quids in from that point onward.

championc

I always feel that Solar is more giving you a form of control over the bills going forward, rather than looking at the overall payback.

We all know what it's like to have €200 or whatever bills come through the letterbox. Whereas after installation, you know there's not much chance of a nasty surprise (which always seems to come at the one time you don't want !!)

AndyBoBandy

https://www.boards.ie/discussion/comment/118160863#Comment_118160863

That’s exactly it for us… don’t mind paying for the system now as we both have decent jobs so won’t feel it so much, but we don’t want to be doing our jobs forever, so doing the solar now (making hay while the sun shines) is not about payback time for us, it’s about minimising future expenditure down the line…

buzz11

https://www.boards.ie/discussion/comment/118128359#Comment_118128359

Thats fantastic - very clever. Can you outline how you did it?

championc

https://www.boards.ie/discussion/comment/118166580#Comment_118166580

Very simple. Hinge along the long edge and prop it up. I got 12v linear actuators on AliExpress, but you could simply use broom handles.

The one thing I did do was to grip the two edges of the panels together with a threaded bar, since a broom handle could separate the aluminium frame from the panel itself. So that is the thin steel bar on the underside, from top to bottom.

Going the actuator route just simply needed each end of the actuator to be bolted to panel edge at one end and the shed roof at the other

buzz11

https://www.boards.ie/discussion/comment/118166795#Comment_118166795

OMG thats so cool, are they controlled manually or is it automatic.....don't say its automatic by a photocell ? !! 😲

championc

I have the photocell module but for now, they are hoisted up and stationary. I will bring them down if we get any Orange wind warnings. I''ve more built it for the craic and the experimentation rather than really needing it. However, those two panels in summer could be the difference between having EV surplus and not

graememk

https://www.boards.ie/discussion/comment/118167342#Comment_118167342

I suppose that could be automatic from met.ie (and the movement can be timed for sunrise/sunset too)

SD_DRACULA

How far you want to take it, you could adjust the angles based on optimum angles for the season :)

They calculate them a bit weird, from vertical as opposed to from horizontal so I guess it would be (90 - the angles below)

http://www.solarelectricityhandbook.com/solar-angle-calculator.html

Out of curiosity did anyone pay attention to angles or just whatever the roof would allow?

graememk

https://www.boards.ie/discussion/comment/118168221#Comment_118168221

Just worked with what I got!

Even went Ne/SW to get longer generation in the summer. Could have put them all on the sw side if I wanted

AndyBoBandy

Whatever the roof would allow in my case, which was 45 degrees, which I think is a good all round angle to have when looked at over a 12 month period....

Currently generating 1kW from my 1st string (3.74kW worth) which is spread out over 2 aspects (SE & SW), the sun being fairly low in the sky...

david200

Hi, I have Solar thermal (evacuated tubes) installed on the roof, and am starting to look seriously at the Solar PV for electricity generation. I would rather not dispense with the existing Solar Thermal solution, as its working great. My question is whether the two systems can work side by side (no issue with space on roof). I guess I would only need PV panels and a battery, as there would be no need for the hot water diverter that I see discussed in various conversations on here. ( I have an EV which can take up some of surplus electricity potentially I guess) Are there any other difficulties, limitations or disadvantages to running the 2 systems in parallel? Any tips to optimise this kind of setup to get the very best out of it? Thanks

graememk

https://www.boards.ie/discussion/comment/118185459#Comment_118185459

Works perfectly as they are 2 completely separate systems. The only place where they could interact at all with each other if you have hot water diverter that runs your immersion.

AndyBoBandy

I'd lose the thermal and go all PV

In summer when the water is hot, the thermal panels are doing nothing right?

With PV, when the water is hot, the PV panels are still working for you, either charging your car, or earning cash by selling back to the grid (when FIT eventually happens...)

graememk

https://www.boards.ie/discussion/comment/118185641#Comment_118185641

But why pay money + hassle to take something out that is working perfectly. if its already in. I have both, wouldn't get rid of them at all. They always heat the coldest water in the tank at the very bottom. Sure on the perfect days, the whole tank is hot from top to bottom.

I don't have a HW diverter. It would never pay me to put one in. I am usually in at lunchtime though so if the battery is full, and the water isnt at 60c, id stick the immersion on for 15-30 mins. that V quickly boosts it up to 60.

I wouldn't recommend putting both in if there was a choice now, but if they are already in, don't touch them.

bullit_dodger

https://www.boards.ie/discussion/comment/118185459#Comment_118185459

Nope - no issues whatsoever in having them both there. Your right, you probably won't need a immersion diverter (EDDI/iBoost) as you have hot water there already from the evacuated tubes. In fact I read somewhere that when it comes to capturing solar energy, evacuated tubes are ~50% efficient, and solar panels are about ~20%. So in terms of getting hot water, you'll do better with the tubes than you ever will with PV doing that specific work.

Your first task now is to understand your usage. Your electricity bill history is something that you can do right now, and many providers on their websites provide a bill history so you can work out what you use over the year. From that you can sort of work out the size of your panels + battery.

General starting point for most houses in Ireland would be a 4-5Kwp in panels and ~5Kwhr battery. Personally I'd go large on the panels, 5-6Kwp if you have the space on your roof. Electricity usage is only going to increase with EV usage, and of course the never ending price rises - so more panels the better.

david200

https://www.boards.ie/discussion/comment/118185641#Comment_118185641

Thanks for the comment. I do take your point that on a good day, once you have achieved the max hot water that the solar thermal kit can deliver, then it is not doing anything else. The better the day, the more 'dead time' the thermal system would then have, as on the better days, it will max out earlier in the day. I guess its hard for me to consider taking down a system that is working well. I actually doubled up on the number of solar tubes just 2 years ago to further improve the performance. It is only now with the rising energy costs, buying an EV, and increased energy use from sustained working & schooling from home, that makes me think of the PV solution.

david200

https://www.boards.ie/discussion/comment/118185690#Comment_118185690

That kind of sums up how I feel about it. I was concerned that there would be some technical barrier in getting the 2 systems working side by side. thanks

AndyBoBandy

I guess is roof space was not an issue, and you could still install a 4-5kW+ system of PV panels, then probably yes its worth keeping.. but if say keeping them limited your available roof space to less than 3kW of PV panels, then it might be more of a consideration..

MAULBROOK

https://www.boards.ie/discussion/comment/118159501#Comment_118159501

The quote is in the right direction.

david200

https://www.boards.ie/discussion/comment/118186425#Comment_118186425

I'm not an expert in this but I recently upgraded the Gas Boiler and put in a new HALO control unit. Having played around with it a bit, I can see that unit can give you the kind of control you are describing. In my case, I tell the HALO unit not to use the Gas boiler to make any hot water, until at least 5pm every day. In that way, my Solar Thermal system gets to generate what hot water it can do during the day, and come 5pm, if it hasn't reached my preset threshold, then the HALO system will fire the boiler to top it up. There must be similar systems related specifically to the Solar PV, that can be used in the way you describe.

Ps. In your quote, what is the isolated price on the EDDI diverter, as I probably don't need one of those.

david200

https://www.boards.ie/discussion/comment/118185766#Comment_118185766

Thanks, yes I spotted the Usage history section in my account. My last 12 months usage is as follows: Total 4652 units. Would you be able to hazard a guess as to the optimum size of my target PV solution, based on this? Thanks again

reklamos

The general consensus is put as many as you can. You can limit export to the grid and since you have EV it will eat most of it anyway while connected.

MAULBROOK

https://www.boards.ie/discussion/comment/118186616#Comment_118186616

Go as much as you can fit/afford. You will never regret having to many panels but you will regret having too few.

SD_DRACULA

https://www.boards.ie/discussion/comment/118186616#Comment_118186616

6kws will cover you for the good months, don't expect anything over 20% for Nov-Feb but again without battery you will export a lot unless you can fill the EV on every good day.

MAULBROOK

Anyone got a site for solar predictions/forecast

bullit_dodger

I'd also echo what the lads have said above that "as many panels as you can" is a good strategy. Of course you don't want to go ridiculous either and completely over engineer the solution with say 10Kwp of panels (as your usage wouldn't warrant that amount) If you did in that case, most of the electricity you generate would be going to the grid for (most likely) a marginal FIT rate.

As Dracula says, 5-6Kwp should see you right in panels. Err on the high side if anything though. It's an extra €400 for 2x panels as a part of the initial install. To get the guys out again and put on 2x panels a year later might be €800-900 (guessing) as you have to pay for their time a 2nd time to come out etc.

The usage also helps determine the battery size. Do you planning on having the EV there present in the driveway during day time when it's sunny? If so that will definitely curb your generation going to the grid. If not, you probably would want a 5KwHr battery or there abouts. With 4652 units/year, your using 13 Units/day on average, a 5Kwhr batter would help get you through the night for a lot of the months of the year, and in winter.....you can charge the battery at night rate and consume that during the day when the electricity is more expensive. Probably wouldn't go much over 5Kwhr here, you won't cycle it enough not with the EV.

randomname2005

https://www.boards.ie/discussion/comment/118187562#Comment_118187562

This is the only one I know about and you will have to remove the spaces (or search for pvgis):

https:// re.jrc.ec.europa.eu/pvg_tools/ en/ #PVP

SD_DRACULA

I use this one, https://forecast.solar/ but expect met.ie accuracy in general from these services for Ireland

I basically just check the number to see if there will be any sun, usually anything under 10kwh means no sun.