alentejo monte

Buying an Aljezur farmhouse

Aljezur farmhouses for sale

Algarve west coast climate; the best weather in Europe?


Odeceixe beach

Control of the red palm weevil

Vicentina natural park wildlife

Heating options

The truth about coastal property

What is natural park Costa Vicentina?

Building and renovating in western Algarve

Portugal land scams

Fishing on the Vicentina coast

Western Algarve agriculture


Utilities in Portugal

Schools in Aljezur

 Solar home heating plans
Build your own, DIY Solar home heating

Please note that this is about a thermal solar setup, NOT solar electricity generation. Sorry about stating the obvious, but people are constantly confusing these subjects.



This is for the hard-core DIY person.

Skills you’ll need;

Measuring, cutting, fitting a variety of materials.

Basic math and a willingness to use it.

Plumbing [lots]

Knowledge of electrics; there will be some complex wiring.

An understanding of basic thermal physics; heat gain and loss.

Welding, brazing, and soldering steel and copper.

Knowledge of heating systems would be useful.


All temperatures are in Celsius

DIY stratified heat storage tank and how to build a stratification valve

A couple of easy and useful circuits for circulation control

Free solar collector design program;

Download it into your computer and play with different designs. single glass or double? how much back insulation? You can figure it all out with this.

This page has solar irradiance data for Europe;

How much heat can you get, and how much energy? Fixed or tracking, this site has your answer.

This is the collector material I bought;         

This is the company that sold it to me in the Netherlands;    Heliomax

First, I have to admit I haven’t yet had time to build mine. Normally, I like to do it myself before giving any advice on a subject, but I’ve done a LOT of research on this already, so here goes.

Solar hot water is quite easy, and there are plenty of ready made solutions available.

But home heating is much harder; firstly, because a lot more energy is needed, and secondly, because we need that energy at exactly the time that there is the least available, in the coldest and darkest time of the year.

Solar hot water heaters mostly work 8- 10 months per year, and mostly no one even tries to make them work in mid winter.

When I went to my local "solar energy" shop, the system they wanted to sell me would have cost €10,000 and wouldn't have supplied much useful heat in winter.

Mainly, because the storage tanks sold by these companies are much too small. Why? because you can't make money selling tanks that take up a half a truck during shipping, and then fill the warehouse, don't fit through your customers front doors, and need more space to install than most of your customers will have available.

I noticed that nearly all the solar collectors around my area are set at a 30 degree angle, when 60 would be the optimum for winter. Why? because the installer knows it won't work in winter. They set it up to give you hot water 9-10 months in the year, the rest is done by the backup system.

In other words, those systems will not [significantly] heat your house in winter, even though that's what they're supposedly for.


One of the biggest stumbling blocks for DIY solar heat systems is creating a big stratified heat store. Read about it here


Frustrated by the exorbitant prices for thermal solar collector panels in Portugal, I decided to make my own.

There is a lot of advice available on this, but most advocate using copper plate as the collector surface.

That was ok 10 years ago, but the price of copper is way too high these days to make that interesting.

Here’s how solar collectors are made in factories;

“Solar strip” is manufactured by 2 companies, one in Canada and one in Denmark.

Solar strip is an aluminum plate with a copper tube bonded to it [this can’t be done in a home workshop], coated with a special “selective” or “semi-selective” paint that absorbs radiant heat [infra red radiation] better than it emits it.

I wrote to the factory and asked if there was anywhere I could buy their solar strip in either Portugal or Holland [as I was moving from there at the time], and they recommended this company;  Heliomax

They’re in the Netherlands, and they can ship anywhere in Europe. Or write to the factory like I did, maybe they can recommend someone close to where you live.


I bought enough solar strip for 18 M2 of solar heat collectors for about €1,500. They’re cut to length and the tubes cupped for brazing at the ends [I could do that, but they have a nice machine]. Pipe joints inside a solar collector have to be brazed as opposed to soldered, since it’s possible [if there is no water in them] for the temperature to rise high enough to cause failure in soldered joints.



I still need glass, insulation, a backing material, and a frame surround for the panels, but it will still be far cheaper than anything I can buy complete.

I'm thinking of making cast concrete boxes for the collectors; it's heavy, but cheap. and it will last forever. If you don't have a weight problem [if you want to put a lot of these on a roof you'll have to check on things first].

The pipe joints will need to be brazed [a small oxy-acetylene or oxy-propane torch is used for that].

The next expensive part is the stratified heat storage tank.


Then you’ll need between one and three heat exchangers, and several circulation pumps. I got all of it second hand; heating systems are being changed all the time in northern Europe, and a lot of material is left over. Check ebay or classified ad websites, depending on where you live or have a base. Those pumps are over €100 new, but I got them for around €12 each. They can always be swapped out for new ones if they fail later, once all this is paid for.


The controls are the most difficult part. Some people have made their own microprocessor controllers, but this is beyond my abilities. I’ve decided to build a dumb circuit that does the job; easier to service, too. Especially by someone other than the builder.  Solar heat circulation control wiring


It will need a “smart” thermostat to operate the floor heating loop, but those are available off the shelf from plumbing supply shops.


One problem a system like this will have is that in the summer, when there is huge amounts of sunlight hitting your collectors and no demand for heat [except a little bit for domestic hot water], you can have boiling. That would be bad.

The answer to this is, mainly, to set your collectors at a high angle; so that they absorb maximum sun in winter but less in summer.

For the Algarve, this would be 60° from horizontal; in other words, close to standing up as opposed to lying down.

It would be advisable to set up the collectors so they can be adjusted if necessary; for instance, they would give you more heat set at 50° in October and march, if you find you need more heat in those months.

The collectors will need to have a glycol/water solution to protect the tubes from corrosion [which would kill your efficiency] as well as protect against boiling and freezing. In addition, there should be an over-pressure valve in the loop [regular heating / plumbing material].

The glycol [same as car antifreeze / coolant] solution is pumped through the collectors and a heat exchanger that will feed the heat into the storage tank.


At first, I wanted to use the same fluid in the tank as the collectors, and avoid the expense and complication of the heat exchanger and additional circulation pump; but the tank should have several tons of water in it, and the collectors need glycol. That much glycol would cost too much, and if you wanted to drain the system for any reason [repair a leak, add a fitting…] you’d need another tank of equal size to store the fluid in. With water, you can just let it out and put in new water.

I will be adding to this section piece by piece.

Coming soon; affordable DIY solar tracking for a large system