Solar for Beginners [ask your questions here]

Hi everyone.

Couldn't find a thread specific for my query, so gonna chance my arm here.

Recently got solar panels installed, working well, v happy.

My issue is with the claiming of the SEAI grant. My house is almost 3 years old, and allocated a BER of A2 on completion of build.

SEAI require me to get another BER done in order to claim the grant successfully.

Given that SEAI's requirement is for the BER be equal to, or better than C after completion of the work, Getting a BER assessment on my place is entirely redundant for this purpose.

I appreciate that part of the grant is dedicated to the cost of the BER being done, but I'm happy to give up that portion of the grant. It's just another example of bureaucracy gone daft imo.

I've just emailed them with all of this, and provided a copy of my existing BER, so will post back here if/when they respond.

Was also curious if anyone here found themselves in the same boat.

(Apologies if this has been covered before. Had a quick search but couldn't find anything.)

On the surface, I agree with you - it looks daft. The BER is good for 10 years I believe. To be balanced though (and I'm not agreeing with it, just being balanced) you could argue that you've done some modifications on the structure of your house. For example, while you put in solar and it's working, let's say the installers left a gaping hole in the roof where a shed load of heat is escaping, or some other issue. Of course, that shouldn't happen, but I see why they might want a BER post installation. Again, not agreeing with it as it's a bit "reaching" if you ask me, but ok.....

Aside: Didn't they get rid of the BER to "C" level with the changes in the grant scheme in Dec'21 ?

Same here. Hit a pre install bet done to endure I'd pass muster with panels.

House was a C1 up from D1 when bought and went to B3 with panels

Two Simple Questions - How much (ballpark) to install solar panels on a average size bungalow like this...

and would solar panels in themselves be enough to power a house for a year? or would i still have to rely on the grid?

That looks nearly the same as my house, currently have 20 panels and have space for 6 more.

Its been very successful in keeping the bills way down. I'm not off grid but can run 100% self sufficient for many months of the year. In the poor months solar helps to take the edge off the bill.

To fully disconnect from grid you will need to fill that roof and I'm guessing at least 15 to 20kwh of battery minimum. A generator will also be required. The costs for the extra battery and generator will be substantial.

There are plenty of options available if you stay connected to the grid at lower costs.

TLDR: At the risk of sounding evasive.... it depends. :-)

Longer explanation ->

The reason I say that is that there are a lot of factors to consider. For example, if you only have say 10 panels on the roof (circa 3.8Kwp) then you might struggle to heat a 300 liter tank, but conversely if you had 20 panels then you'd have no problem in heating it. But this is somewhat academic.

A better question to ask is to forget about solar for a minute and ask "What size tank do I need for the house?"

That question is dependent on a number of factors such as, how many people in the house? Are they teenagers who tend to spend ages in the shower? How many showers a day, or do people take baths? Are all the showers at the same time or close together, or well spaced? What's other use for hot water is there. What size hotpress (or other area) do I have which will house the tank. No point in wanting a 500 liter tank if the hot press can only house 200L.

Once you have the requirements for hot water then you can size your tank appropriately. You don't want to have a needlessly large tank as (again forgetting solar for a min) you don't want to be having to pay to heat 300L where you might only want to use 50L.

With the tank size appropriate for your needs, solar will then put energy into the tank. Ideally you will get solar to heat it completely, but even if it doesn't - that's ok. Energy will still be put into the tank. You may only get it from (say) 20 Celsius up to 40 Celsius (where your target is 50C), but that means that your oil/gas/grid heater will only have to "top it off".

200L to 300L would see most houses right. Average shower uses about 50-60L.

Honestly (and I mean this)....there really isn't such thing as a silly question. We all have to learn somewhere. The forums only "work" when people help each other. There is a pretty decent FAQ on the forum.

Interested in Solar PV? Read this FAQ first. — boards.ie - Now Ye're Talkin'

To answer your question directly, probably about 4-5 panels (each panel would be about 380 watts, so about 1.5-2.0 Kwp) however, that's not the right way to look at it. Ultimately your house uses energy, some of that energy is the immersion (assuming you use electricity to heat the water) and of course some energy is the fridge, TV etc. etc The main reason for getting in a solar instllation is to cut down on your overall electricity usage.

The average home in Ireland uses about 4000-4500 units of electricity a year. Installing solar would help reduce that. How much it will reduce is dependant on the size (and cost) of the installation, but ballpark 50-60% usage covered. Summer will be 100% usually, but winter with the short darker (rainy) days, not so much.

So a better way to look at it is, what is the right size panels for my house (which will also help heat the water as a side benefit) Looking at the bigger picture is 90% right for most people. That said, there are edge cases where hot water is the priority, and then there are alternatives (evacuated tubes) which heat water better than solar PV (electric generation)

That is interesting. 4 metres would be high for a domestic "ground" array. 4 metres is also the max height for an exempted development shed with a pitched roof so perhaps there is some connection there.

In any case, a ground array could be useful to people if they can store cars and other items under it.

Does anyone know if it's okay to run a gas boiler off backup power from batteries in the event of a power cut?

As in give the boiler and associated electronics and pumps enough power to operate, since the gas supply should still be fine

Logic says the boiler should be happy bit I'm wondering if there's some weird regulations to consider

Sorry yes I should have mentioned there'd be an inverter in between the batteries and boiler. Can't imagine the boiler would be too happy getting DC 😂

I know only some inverters can supply backup power so I'd be taking care to ensure I pick one that does

For the hipped roof with panels in three directions you can do that with a single inverter like a SMA Sunny Boy. But the number of panels on the small strings need to be identical.