Solar panels and feedback to the grid, or not?

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rickj
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Solar panels and feedback to the grid, or not?

Postby rickj » Thu Jul 20, 2017 4:26 pm

I'm investigating a solar panels installation for my house in Almería. I understand that as long as you stay below 10kW the "solar tax" does not apply. But, there is still is the matter of the feedback of your surplus energy to the electricity grid. I'm getting mixed opinions on that. Some say you can NOT feed back your electricity to the grid, so you need a "zero feedback" installation that will throttle energy production if you don't need it. Others say you CAN do a feed-the-grid system, but contracts are hard to come by. (We have Endesa here.)

Personally I don't care much about selling my surplus energy, as long as I am allowed to send my surplus power into the grid, because the installation I want cannot do zero feedback. I don't care about being paid, as long as my bill gets smaller. (And no, I don't want batteries.)

This is not just about money for me, but about being responsible, as I have installed a swimming pool, and the pump uses 1.2kW about 8-10 hours a day.

So, can I install a grid feeding installation without getting into trouble..?

This article http://www.andalucia.com/property/solarpower.htm says :
If electricity is generated from domestic photovoltaic panels any surplus electricity generated may be sold to the network. The electricity supply company must buy this electricity by law.

Any reference to that please?

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Re: Solar panels and feedback to the grid, or not?

Postby TorreDelAguila » Thu Jul 20, 2017 7:01 pm

Your ambition to install solar PV panels is excellent, and I hope you can work out an arrangement.

On the pool pump front, though, although a 1.2kW pump is common enough, running it for 8-10 hours a day seems excessive.
We run ours on timeswitch for five half-hour bursts a day, three of which are off-peak (valle) times. Water crystal clear, even with heavy family use. In winter, two of those slots are knocked out, with everything off-peak.
Chris

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Re: Solar panels and feedback to the grid, or not?

Postby rickj » Thu Jul 20, 2017 9:35 pm

It's a saltwater pool, the chlorinator and pump must run 8hrs+ per day..

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Re: Solar panels and feedback to the grid, or not?

Postby Flexo » Fri Jul 21, 2017 5:49 am

Last time I checked all grid ties were affected by the solar tax, however I believe they are to change it so everything below 15kW is exempt. You need to talk with a gestor. Even if the panels are very cheap now you also need a good grid tie inverter and with the tax it is not likely going to pay off.

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Re: Solar panels and feedback to the grid, or not?

Postby TorreDelAguila » Fri Jul 21, 2017 7:49 am

rickj wrote:It's a saltwater pool, the chlorinator and pump must run 8hrs+ per day..

Gosh.
Chris

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Re: Solar panels and feedback to the grid, or not?

Postby Alcala Barry » Mon Jan 08, 2018 2:00 pm

Domestic Solar Power

Excuse my ignorance, but has the law changed recently regarding generation of solar power?
Am I right in assuming that if you generate less than 10KW and don't wish to feed onto the grid, then there is no tax applicable?

Regards

Barry

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Re: Solar panels and feedback to the grid, or not?

Postby rickj » Mon Jan 08, 2018 3:31 pm

Yes, there is no tax applicable for systems smaller than 10kW.

But, the problem (here) is more in feeding the grid. Here Endesa does not want you to do that. An installer here described to me they use a device that will shut off your connection between grid and your pv system if you generate more power than you use. Which actually means your pv system is shut down, as it needs a grid connection to operate, as it needs a stable voltage and phase from the grid.

Getting paid for the power you generate is yet another matter.

Verry odd, in The Netherlands, France , etc this is all simple and readily available. Here in Spain, with so much sun, they are MAD to make it this difficult.

I have given up for the time being, till I can purchase a system that will scale back it’s production according to my use. I had hoped Enphase micro-inverters can do that, but the versions they sell in Europe (M series) can not. Another manufacturer can do it (SolarEdge), but for political reasons I won’t buy from them.

I’ve tried to get info from Endesa about connecting to the grid, but all they do is ignore your questions, and forward you to a company Enel. And later they send you a customer satisfaction questionnaire. (*not writing down very rude thoughts here*)

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Re: Solar panels and feedback to the grid, or not?

Postby Alcala Barry » Mon Jan 08, 2018 4:34 pm

Is there any sort of battery system or similar that could store the excess power you generate?

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Re: Solar panels and feedback to the grid, or not?

Postby rickj » Mon Jan 08, 2018 4:46 pm

Yes, various types even. Tesla has the Power Wall, for example.

I’m not too keen on storage in batteries. They are expensive, don’t live very long (10years?), and are inherently a bit dangerous, as they contain a lot of energy.

My big energy consumption is during the day (pool pump @ 1.2kW, cooking, oven, washing, dish washer ), in the evenings a computer, lights, a tv. A few hundred watts, max, only. At night the fridge @ 75W. I’d be happy to provide the bulk of my own power during the day, and use Endesa when no sun. And even do things I now do at night, like washing dishes, during the sun hours.

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Re: Solar panels and feedback to the grid, or not?

Postby Flexo » Tue Jan 09, 2018 1:57 pm

Alcala Barry wrote:Is there any sort of battery system or similar that could store the excess power you generate?


It is called a Grid tie hybrid. It is the most expensive type for a small setup but given you can scale down on the batteries it might be more affordable than an offgrid setup. It all comes down to the kWh and at what time of day and year you are using it.

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Re: Solar panels and feedback to the grid, or not?

Postby Alcala Barry » Tue Jan 09, 2018 3:58 pm

I have only just started reading up about this.

So if you want to avoid being involved with the grid at all (except for normal domestic connections) and intend to generate less than say 6Kw, what might be a cheap(ish) way to store the excess power generated from your solar set up?

Regards

Barry

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Re: Solar panels and feedback to the grid, or not?

Postby Flexo » Tue Jan 09, 2018 9:08 pm

It all comes down to at what time of day and year you want to use the energy. If you are going to use 6kWh of energy at night you need to either have a 6kWh deep cycle battery (expensive) or 12kWh of flooded led batteries. You are not going to get an easier answer from anyone unless you calculate your energy consumption yourself, how many watts you use at what time of day and year.

You also need a good charge controller, preferably an MPPT controller that charges the batteries effectively and takes care of them so you don't need to check up on them every week.

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Re: Solar panels and feedback to the grid, or not?

Postby Alcala Barry » Mon Jan 15, 2018 3:06 pm

All that sounds very sensible Flexo. I've got a pretty good idea what we may need and when. Also have a reasonable idea when we would have to resort to using Endesa for the heavier out of season times. I'll put all of that together and re-post. I had a quick look at some of the power ratings/outputs that Tesla claim for their domestic range. It is very impressive but I am not sure about their availablity or what customer feedback is like.

Barry

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Re: Solar panels and feedback to the grid, or not?

Postby Flexo » Mon Jan 15, 2018 9:10 pm

I wouldn't go with Tesla batteries yet, they are still quite expensive and we don't know how many years they last. If you buy Tesla you lock yourself into their system and you probably have to use their charge controller and so forth. It is likely you need a different capacity than they offer aswell.

Also, consider doing a 48V system instead of 24V and consider replacing some gadgets in the house, like get a fridge that opens like a drawer instead of a door, those are much more energy efficient.

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Re: Solar panels and feedback to the grid, or not?

Postby championc » Thu Jul 05, 2018 10:36 am

Hi all

I have an apartment in Mojacar and I leave the power on all the time because we leave the fridge, the solar water heater (controller for filling etc) and some IT bits are running constantly. I have an Efergy meter monitoring the power usage constantly. The daily usage is just under 2Kw. The real-time usage goes between 0.06kw and 0.11kw.

So I was considering trying solar by buying a 24v panel. I would consider a charge controller and battery so that it can deliver the required power all day. I was then considering a Grid Tie inverter. I suppose the main thing would be that I would oversize some components so that I could increase the size of the setup at a later date.

However, regarding the Grid-Tie inverter and connecting to Endesa. I have no will to gain any way financially by selling back to the grid. I just want to supply as much of my power requirement as possible, when not there in Mojacar. Ultimately, it sounds like I will need a Zero Feedback inverter - yes ?

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Re: Solar panels and feedback to the grid, or not?

Postby peteroldracer » Thu Jul 05, 2018 1:08 pm

You have a low consumption of power at the moment, and assuming you will not be disconnecting totally from Endesa would still have to pay all the fixed costs, which in many cases are more than the kwh consumed. Not worth the hassle I think?
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Re: Solar panels and feedback to the grid, or not?

Postby championc » Fri Jul 06, 2018 9:54 am

Absolutely, but I am more interested to see the potential and evaluate. You have to start somewhere. It was absolutely with this in mind that I would also possibly look to oversize some bits to allow for later expansion should feedin become an option. I've a contracted rate with Endesa of 5.75kW so could I get a small panel and battery to start but get a larger Inverter that we "future proof" me ?

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Re: Solar panels and feedback to the grid, or not?

Postby rickj » Fri Jul 06, 2018 10:11 am

Zero feedback - yes. You will get a breaker device that disconnects you if you do try to feed the grid.
What could be interesting for you is a (one) regular solar panel with a micro-inverter, like Enphase makes.
With the currently available old models in Europe (M215 and M250) however you cannot create a zero feedback system, but with the IQ7 that they start delivering real-soon-now (Q2 2018 was promised), you can. So you can buy one panel and one inverter (est. price < €100 for the inverter) and a control/monitoring device called Envoy (ca 300€), and see how you fare. You can buy more panels and inverters later and extend your system.

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Re: Solar panels and feedback to the grid, or not?

Postby rickj » Fri Jul 06, 2018 10:22 am

championc wrote:
peteroldracer wrote: so could I get a small panel and battery to start but get a larger Inverter that we "future proof" me ?


Careful there, string inverters also have a minimum number of panels (voltage) that they need to start operating. The ones I looked at you cannot use with just one panel. See my previous reply for info on micro-inverters, those do work with one panel.

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Re: Solar panels and feedback to the grid, or not?

Postby rickj » Fri Jul 06, 2018 12:40 pm

peteroldracer wrote:You have a low consumption of power at the moment, and assuming you will not be disconnecting totally from Endesa would still have to pay all the fixed costs, which in many cases are more than the kwh consumed. Not worth the hassle I think?


I agree with the above. A few euros a week to keep your fridge running isn’t worth the hassle, I think.


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