BillBullock

Go to https://www.edp.pt/particulares/servicos/energia-solar/ which can be in English or Portuguese. Here you do the simulation exercise for your circumstances. I was offered only 1.5 KW with 5 panels for a considerable capital outlay and I think the 20% discount was time limited.

westernliving

Ok thanks for that I'll have a look.

uk_grenada

For anyone using electricity overnight - to heat - are you aware that there is logically sort of the equivalent to pv/batteries available.

During the day the sun heats things, then the things radiate it back at night. You can build or buy kit to do this to your advantage. In desert areas we all know people build thick walls/roofs that absorb then radiate energy. The israelis now have thick reversabke vertical blinds that absorb in the day, and you turn round at night so they radiate back into the room. A pool is a great big heat sink, connect it to a heat pump and use it to warm the house overnight or even put the pool on the roof...

westernliving

The blinds sound quite interesting, have you anymore information on them?

uk_grenada

I just saw them 2 years ago in eilat, they are about an inch thick, look like normal vertical blinds from a distance but are actually some sort of foamed concrete/plaster - weigh a ton and require serious mounting kit in the window frame. One sides dark ones light, you just have dark out to absorb in the day then rotate to put dark in where it radiates in the evening. At midnight, its hot to touch, i imagine they are very efficient in cost/energy terms, but really if your walls were a foot of mud or concrete i suspect you’d get a similar result.

westernliving

Ok thanks, I'll have a look to see what I can find.

BillBullock

Yes, I know this and it works really well in the summer. In the winter the sun is really low in the sky in the Algarve. The heat gained by my 22 year old house is nowhere near as great and the structure cools down rapidly in the late afternoon. Insulation gets in the way of heat transfer to the house interior. Not many window blinds would be struck by the sunlight as the verandas provide the shade that is needed in the summer. Basically, my house is not designed for heat gain in the winter and a huge expense would be needed to make the alterations.

My pool is only 15 degrees Celsius in the winter so there is not much to be gained there if I installed water-filled radiators in the house and altered the pipework on my pool heat pump.

So, for an existing house, there are limitations on what can be done at a reasonable price. Solar-generated electricity is surely the future and Portugal is well advanced in this direction. If only the electricity companies could find a way of reducing the cost to households so that we don't have to think about the huge capital cost.

uk_grenada

While here solar water heating is a no brainer / even the cold water supply warms up appreciably, i understand that modern hi tech solar water heating works, even in britain in the winter, so im guessing 15 degrees should be quite workable, and if you heat water then keep it insulated and use it overnight???

I believe its based on collectors described to me as - as good as black faced heat pipes connected to glass thermos flasks at capturing/not losing heat.

westernliving

I fully understand how the solar hot water works and to me it's a no brainer.

Score76

I recently had a 10kw solar system installed along the roof of two south facing apartments. Had to pay EDP a one off 250€ for a licence to "feed in" and they indeed pay 4c per kWh. The trick is to use what you produce, saving yourself the 20c per kWh you'd otherwise pay. Between the various appliances in the house and a 7kw heat pump on the pool, I don't end up exporting much to the grid at all. This will save me a fortune in the long run.

zoff

How much did this 10kw system cost?

Score76

It was nearly 19,000€ + iva. With the electricity I no longer buy from EDP it saves me about 3,500€ each year so will pay for itself in about 7 years.

BillBullock

Are there any tax implications now you are an electricity generator?

Score76

Not as far as I'm aware. The 4c per kWh is never going to make anything significant, the return comes from not having to pay the 20c per kWh during the day which is definitely not taxable. The system comes with software that analyses what you use, produce and export so makes it easy to know when you have spare to use up.

BillBullock

Where did you get your system and what is the procedure for commissioning it with EDP?