Solar for Beginners [ask your questions here]

cloughy · 27-04-2022 2:25pm

On a similar theme, should an E/W array be on a single string connected to one inverter input, or better to have seperate strings and a two input inverter to ensure output is optimised.

Supplier proposing Solis 5kW inverter, just don't want one side of the roof to affect the other.

Have put question to installer, but waiting for response, but would like best practice so that I'm not fobbed off.

bullit_dodger · 27-04-2022 2:37pm

https://www.boards.ie/discussion/comment/118983962#Comment_118983962

Most inverters have two string inputs, so if you have east/west then it makes sense to have one on east and the other on West.

To caveat that (and this is unusual - but will work) if you did have 3 roofs that you want to put panels on (let's say east, west and south). You could put south on 1 string input and then east & west on the other string. This only works if you have the same number of panels on east as you do on West....and they have to be the same make/model too. It's "unusual" though.

kowloon · 27-04-2022 2:47pm

Quick question: In order to have the battery kick in and isolate the house from the grid in case of a power cut I need a deadman switch, right? What kind of system do I need to ensure an uninterrupted supply as opposed to there being enough of a blip in the supply to affect everything in the house?

slave1 · 27-04-2022 2:49pm

https://www.boards.ie/discussion/comment/118984052#Comment_118984052

If you are doing that E/W you'd want to have optimiers else you will be badly impacting the E generation early morning when W in shade/visa versa in the evening.

bullit_dodger · 27-04-2022 3:11pm

https://www.boards.ie/discussion/comment/118984165#Comment_118984165

I knew someone would chime up :-)

Actually, no you don't need optimizers. But.... as mentioned you do need to have the same number of panels on both the east and the west. If you don't, or the panels are of a different type, it won't work as the internal resistances will be different. The reason is that you will be wiring the east and west arrays in parallel with each other. I read about the issue some months ago

East West Facing Solar Panels On A Single String Can Work Well (solarquotes.com.au)

If you want the technical white paper on it.... Technical_Articel_East_West_Fachartikel_InterPV_EN (energymatters.com.au)

It's probably a bit more than "solar for dummies" though :-) ..... but it's a useful tibbit of information for people to remember if they need to add a few panels to their house and they are wondering how to do it without getting a 2nd inverter.

kuang1 · 28-04-2022 1:07am

https://www.boards.ie/discussion/comment/118902980#Comment_118902980

No response from SEAI, 2 weeks later.

Another question though...

Got my pv panels done. Decided against a battery originally, but now with the exporting to the grid being an absolute joke, have changed my mind and am going to add 2 x 5.2kw batteries.

Does the part of the SEAI grant that applies to the battery also require a BER done after completion?

I think not, but can anyone confirm for me that the presence (or size of) a battery has no impact on a BER calculation?

graememk · 28-04-2022 7:35am

https://www.boards.ie/discussion/comment/118986577#Comment_118986577

Battery has no effect on the ber.

John mac · 28-04-2022 7:20pm

https://www.boards.ie/discussion/comment/118986577#Comment_118986577

think the grant is gone from Battery install , (used to be €300 max , now its €2400 .

AckwelFoley · 28-04-2022 7:24pm

https://www.boards.ie/discussion/comment/118989974#Comment_118989974

Grant is definitely gone on batteries for new applications

MAULBROOK · 28-04-2022 8:15pm

https://www.boards.ie/discussion/comment/118989974#Comment_118989974

Was €600 but sadly gone

John mac · 01-05-2022 9:30pm

https://www.boards.ie/discussion/comment/118989974#Comment_118989974

typo there . should of course been €3000 .

John mac · 01-05-2022 9:34pm

when looking at https://globalsolaratlas.info/ and other sites how would i calculate the pv output , for east west config .. ?

just separate calcs for east and west and add both and average them ?

Daveq · 01-05-2022 9:37pm

Looking for some advice on panel location and shower choices!

Hoping to get PV next year, so starting research now, thankfully the posts on boards have sorted most of the info. But still have some questions....

1970's built house, 2 bed semi in south west Dublin with a Hipped roof.
2 Adults working from home (and will be 3-4 days a week going forward) usage last year was approx. 3600kw, looking like this year will be similar.
Have a smart meter already installed, oil central heating and a hot water cylinder with immersion.
For PV planning on panels, battery and an eddi, with EV in the next 2 years.

House is as per image below. I'm hoping we'd fit maybe 5 panels on the front and 5 on the back?

House Roof.JPG

Wondering if its worth trying to get 2 or 3 onto the hip? from reading on here I can only get 2 strings on the inverter so I'd have to put the back with maybe 1 side panel and the front with the other side panel? Would that work? or is that just getting messy and awkward?

Next issue, at the moment we're shopping for a new bathroom. We have a electric shower now but I'm wondering if we should go for an electric one in the new bathroom?

I'm thinking that will make use of the Eddi in the summer, we'll have a tank of hot water from the central heating in the winter, which when we get now anyway isn't used fully because it's only used in the sinks. In the summer we do flick on the immersion for a short while now and then.

bullit_dodger · 01-05-2022 10:04pm

You could have the 3 roofs done. 1 string on the south facing roof, and then the east and the west would be on the other string. The number of panels on the east and the west roofs have to be identical for it to work, but it would allow you to use all 3x roofs.

if you go for electric shower, are you going to plumb the immersion into the shower as a seperate outlet? Otherwise the hot water that you heat via the Eddi won't be usable (in the shower).

Daveq · 01-05-2022 10:19pm

Ah, ok that makes sense with the two strings.

Yes that would be the plan with the electric shower. The hot press is right beside the bathroom.

Irish Steve · 02-05-2022 12:17am

Your best bet with the shower is a mixer shower with pump, as that can use the hot water from the cylinder.

Another negative with electric showers is that unless you put in a very powerful inverter for the solar, you won't be able to run the shower without drawing power from the grid, as the inverter can't drive more than the maximum capacity, which for most domestic installs is a maximum of 6 Kw, so a modern electic shower of 9 Kw will be drawing 3 Kw from the grid, at least, and that's the case even if you have a battery on the solar side.

Nearly 20 years ago, we put in an Aqualisa Quartz shower, it was seriously expensive, but it is a superb shower, there are similar makes now that are not as expensive. It will for sure be an advantage when we get to put solar in, hopefully soon, I'm working out the exact requirement at the moment, the problem being trying to decide the best way to replace oil, as gas is no longer first choice that it was 12 months ago, and if a heat pump is going to be in the mix, that has implications for the solar system and battery capacity, especially during the low output winter months, where night rate battery charging may be relevant.

Another thought that is now new as a result of the energy issues that are happening now, it may be cheaper to heat hot water in winter using solar if available, or night rate electricity rather than gas or oil, even though the boiler may be running for house heating, the whole gamut of how energy is being used needs to be looked at in a very new light as a result of what's happened with gas, oil and electric pricing.

slave1 · 02-05-2022 3:53pm

How big is your back garden, from the end of the Summer you'll be able to put ground mounts up to 4m without planning permission....an option perhaps given it opens a South facing array and ye at home during the day

SouthWesterly · 02-05-2022 9:21pm

Thought this might help people looking at solar.

Just did the maths on my electricity bill for the last 2 months. Generated 615kw of solar. Used 400kwh less (day usage) than the same time last year when we didn't have solar pv (Feb - April). Saved 89 euro on just the energy. Add vat and it becomes €101 saving.

Also saved 139kwh night rate which was €17 savings. I assume it's down to the heat pump drier we have.

3.24kw system facing west

Daveq · 03-05-2022 9:06pm

It's long

https://www.boards.ie/discussion/comment/119006018#Comment_119006018

It's long enough but quite narrow, just a garden in a housing estate in Dublin so not sure the wife, or neighbours would like panels up 4m along the wall.

slave1 · 04-05-2022 1:57pm

Neighbours are always an issue, herself absolutely needs to be onboard but at the end of the day if the Gov have decided no planning then work away, you can't lead your life worrying about upsetting the neighbours, they could move in 6 months time!

bullit_dodger · 04-05-2022 2:36pm

herself absolutely needs to be onboard

Just tell her solar panels = less money spent on leccie bils = more handbags for her! That usually gets them onboard. LOL

Jokes aside, depending on the situation you can do some novel things that may not mean building some monstrosity.

Build a little pergola and have the panels offering shade
If the fence/wall dividing the garden was facing due south, and didn't suffer much shade you could vertically mount half a dozen panels on there as well. Not great production in the summer, but in winter.....that works well. (Ideally you'd need more than just the wall mounted panels)
If you have a shed already, might be a good place for 5-6 panels.

Irish Steve · 07-05-2022 11:51am

Had a very interesting link sent to me by a friend who's doing a degree course in environmental studies, a chinese supplier of solar products, (https://www.mppsolar.com/) and yes, there's plenty of them out there, the interesting aspect of this particular supplier is that they are claiming that some of their inverter range can be paralleled to increase the load that can be supported by the inverters. All the inverters have to be from the same range and capacity, but even with those restrictions, there could be some significant advantages to their concept.

Most of the suppliers I've been reading up on make no mention of this capability, so I guess the question to be asked is if paralleling is something new, or something that only some suppliers are offering?

In this particular case, they are suggesting that it's also possible to run 3 phase AND paralleling, which for the specific system I am looking at could be a massive help, being able to effectively support significant single phase loads alongside 3 phase loading could be very significant going forward.

graememk · 07-05-2022 4:35pm

https://www.boards.ie/discussion/comment/119027374#Comment_119027374

while 3 phase is marked as 440 or 415v, Its the power from the 3 phases are 120 degrees out of phase with each other, with each line being 230-240V from Line to Neutral. but the voltage between each phase is 400 odd volts.

So if you put an inverter on each phase it would see each phase as a single phase system. (and in some housing estates, for example, house 1 gets L1, 2 gets L2, 3 gets L3 and 4 is back on L1)

Irish Steve · 07-05-2022 4:49pm

The interest for me was that this particular supplier has parallel working up and running, so it would be totally feasible to have (say) 5 inverters of 6Kw output, with 3 paralled in to the "domestic" phase, so 18 Kw available to the house and one each on the other 2 phases, so as long as the battery power was available, that would run (say) a 6Kw 3 phase heat pump, and the other domestic appliances like showers or cookers or whatever, and all happy with the imbalance, which is not so easy to deal with on a single 3 phase inverter. That opens up a whole range of possible solutions, and to make it even more attractive, it seems that their inverters can also be generator and or grid coupled, so that makes it even more interesting. Some checking to do yet, to make sure that they're not using low voltage generators, but if it works with mains voltages , that solves a huge number of issues.

slave1 · 09-05-2022 8:34am

....or secondary battery inverter like the Sofar for less hassle if looking for higher "off grid" power e.g. I'll shortly have two 6kW string inverters and the Sofar, if a sunny day PV/Battery could easily have 13kW power available even with panels not maxed out due to heat.....less so during Winter but principal remains

Irish Steve · 09-05-2022 10:55am

https://www.boards.ie/discussion/comment/119034885#Comment_119034885

OK, in the absence of much useful information from potential suppliers, which Sofar are you using, as there's a huge range from them, and while there's a lot of helpful information in this forum, there's not a good in depth guide to some of the technical aspects of the Solar systems, and the suppliers are not being particularly forthcoming with the information either.

Making sensible and properly informed decisions about the right configuration is not easy, especially if the application is non standard, which mine is, and I don't think that it makes sense to downgrade the existing installation here, but integrating things like Solar and (maybe) a heat pump further down the road is not Plug and Play, and getting it wrong will be expensive.

slave1 · 09-05-2022 11:15am

Inverter #1 = Solis string inverter (not a hybrid), 6kW

Inverter #2 = Solis string inverter (not a hybrid), 6 kW

Inverter #3 = SofarMe3000 (battery inverter, it is NOT hooked up to PV panels), thread here but in summary can output at 3kW from the box and higher by tweaking the settings

Sofar ME3000SP — boards.ie - Now Ye're Talkin'

arch_stanton · 13-05-2022 6:55pm

Looking for some advice here on sizing and setup. I’m hoping to install PV in the next few months. I’m based in the Midwest and the house is a typical semi-d facing west. My current usage is fairly low, at around 3300 kWh annually. I have an EV but don’t yet have a home charger so that usage will jump by at least another 2500 once that’s installed. I’ll be working from home 3 days a week so the car would have a good chance to soak up power.

The roof is pretty much unobstructed east and west so would the best option be to do a 50:50 split of panels? If doing so is there a minimum in each side to make it viable?

On the battery front I’m leaning against it or maybe just going for a hybrid inverter to keep my options open. Any advice welcome.

Another factor is that I’m looking at going down the retrofit route and currently waiting for one of the one stop shops to get back to me. The indicative prices for solar on their site seem high so I’d probably do that myself independent of their service. I know solar won’t power a heat pump in winter but in months like March or April when it can still be cold but sunny can the solar help out with that? If so it would be another point against getting the battery

A hot water diverter sounds nice to have but it’s a one person household with low water usage and ripping out the electric shower would be more hassle than it’s worth

Any and all suggestions welcome

bullit_dodger · 13-05-2022 7:16pm

In absence of net-metering (basically a 1 for 1 exchange of imports and exports to/from the grid) there's virtually no scenario that I can think of where a battery wouldn't be useful. People can of course argue the toss here, but even a small battery 2.5Kwhr or there abouts is beneficial. My default sizing is 5kwhr, but with the car there.....you could probably get away with 2.5kwhr

For example, a random day in the middle of march you might only be generating 1.3-1.6kw (or thereabouts). With most car chargers wanting 1.5kw as a minimum start, there isn't enough left over after covering base load (400watts?) to kick in the car charger. So those units will go out to the grid for the FIT (which will be pittance). With a battery, you can capture that over 3-4 hrs and then turn on the tumble dryer without importing from the grid.

With 3300 units/year, I'd say somewhere in the 4.0-5.0 Kwp range would see you right. More won't hurt you, and will help cover the load on the "marginal days", but anything more than 6Kwp is probably overkill.

Yes, there is a minimum start up voltage on a string. It depends on the inverter but usually is in about 100-120v. Since most panels are about 40v, you will normally need 3-4 panels mimumum on a string, unless you go microinverters route.

The 50-50 split is really up to you. Most people slightly use more power in the evenings, so you might go 40-60 (east-west), but if you have a battery it's much to a muchness. The other thing to consider, shading. If there is one of the house roofs which gets more/less shading from trees etc. that might decide it.

arch_stanton · 13-05-2022 7:25pm

There’s one narrow tree to the east, although set well back from the house, that would cause a shadow for maybe 30 minutes in summer, more in winter. Usage in the evening is a good point. I wasn’t sure if something like a 6-8 split would work.

Another pro for the battery is that I have a smart meter and the night rates with the current price inflation are up to about 18c a unit. I’ll change suppliers again in august but looking at bonkers there isn’t much better

Solar for Beginners [ask your questions here]

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