Solar PV Hints, Tips & Troubleshooting

I currently have heat pump and tks to the guys here I installed a shelly relay.

Comes on at 6.30 and off at 19.30 from march to September. Winter will be different though..

Also have EV car which can be charged by night rate or during pv excess when batteries are fully charged.

However when I need to charge EV at night the batteries will drain down..so I'll have to charge car and batteries through the invertor (BOTH) if that makes sense.

That may have been me recommending a battery Alan. So many post/people, hard to remember names.

I'd still (generally) stand by that viewpoint. With an EV, it would on the surface seem that you have a huge battery there to soak up the excess, and in some respects that's right. However, a couple of things have to happen.

1. The EV has to be sitting in the driveway, meaning if you use the EV to drive into work and the sun is shining.....then its difficult for the EV to soak up the excess if it's sitting in the carpark outside of where you work! Unless you have a very (very) long extension cable! :-) If you work from home, this problem goes away though right?
2. No - or at least not really. Your working from home and your EV soaks up 20Kwhr on (say) Monday and the battery gets charged. Brilliant! 20Kwhr is about 100km of driving distance. Will you (from sundown on Monday to Tuesday morning) drive 100Km to "make space" for another 20Kwhr to be there in the battery for Tuesday's .... considering you work from home.

Course these are just generalities. Sure at the weekend, the car might be there but it's worth thinking about these things if your planning things so that you don't get a shock that you might not have thought about when deciding.

(In general - of course there are edge cases) With an EV i think 5Kwhr is "about right", anything larger is covered by the EV as a "excess dump". As with all house batteries..... you NEED to crunch the numbers. Make sure that it's "fit for purpose" for your house and that your not paying WAAAY over the odds for a battery. There are of course other reasons for buying a battery (grid balancing etc), but one would presume that you want it to at least break even in 10-12 years.

Thanks folks,

The heat pump pulls an average of 30kwh but only 10kwh in the summer for hot water alone.

We will have 2 hybrids that will each prob take 3hrs to charge and won't be stuck at home all day.

Looking for advice guys.

Want to max out the panels now that I've ordered the batteries :D

Just wondering what people would recommend for this space?

It is south by south west facing.

I was thinking I could slope them down to the garden potentially or maybe have them above the ones that are there leaning off the wall.

What is the max recommended slope?

Also what is the best value PV Panel at the moment, I see 700w which would suit the space but are they a lot more expensive?

Ignore that, added picture then couldn't delete it..

Those higher wattage panels (like the 450 or even the 700w jobbie you mentioned earlier) have their purpose, but they are also bigger than the "standard" 370Watt panels that are the norm. Basically it's roughly the same power for every sq meter of panels irrespective of if it's 370W or 700W, it's just that your buying fewer larger ones if you follow me? But getting the same power. As mentioned larger panels have their purpose and depending on your surface area you might be able to fit 5 large panels in a space but only 5 "regular ones", you need to see what works for you with the dimensions you have.

Eyeballing it, i would doubt you will fit the large 700 watt ones there on your existing roof. You can get dimensions for a lot of the panels from midsummer.ie e.g. Midsummer Renewables (not endorsing qcells over any other one, but just wanted to give you a link to the site) or Solar PV Panel for Residential Commercial use (solartricity.ie)

Aside: Generally it's not a great idea for solar power -> to charge house battery -> charge EV. You have a few losses along the way that would be best avoided. It's not "wrong" but if you could charge solar -> EV that would be best and you'll maximise your system production.

Sadly don't know enough about it, as I don't have a EV/Zappi, but if you haven't already posted.....lots of knowledge here from more informed people than me. Someone might be able to steer you right.

As a interim solution using the granny plug and not the Zappi would probably circumvent the problem albeit you'd probably be limited to 2-3kw charging. I know it's a bit of a waste of the Zappi though, I get that. Your inverter should just see the load from the EV as a part of the house and divert whatever solar production your getting to the house load (which would be effectively the EV) . You might have to set a low charge rate on the car (say 1.5kw), but you'd avoid those losses which could be 20-30% of your production. Shame to see that wasted.

I think I can set the export margin to 100W which might also help.

https://support.myenergi.com/hc/en-gb/articles/4716922623633-Hybrid-PV-and-Battery-How-to-stop-your-myenergi-devices-draining-the-battery-in-ECO-

In the meantime I will look at the size of the roof and see what I can do there.

If it was me I'd go with a new hybrid inverter and just leave out the battery pack for now. You might need to upgrade anyway if you're adding a lot more panels.

If you've 6 * 290 at the moment technically your max capacity is already over the inverter @ 1,740, I'm no expert but I don't think you can go too much over the inverter.

Apologies for thread pollution....but I just looked at our electricity usage.bl over the last 120 days we used 10k kWhs... (old heat pump and big house, in hilly exposed site)

I've a day and night reader but nearly all usage is on the day rate

Trying to confirm the battery size I'd need charge the battery at night rate and drawdown during the day; am I right am using 83kHW a day I'd need a battery that size, if so I assume that would be very costly.

Thanks in advance

Based on my research so far, doesnt seem to be many companies offering solutions on this. Seem to read about ealry adopters having equipment which is expensive to fix and hard to find people to service.

The combination of wind and solar is very appealing and I assume wind might be good source in the winter months when solar is not so good