Right now I have a good income from my software engineering job and want to supplement that with a small solar power plant (costing between 5000€ - 7000€) and sell power to the grid.

I would be happy if I could earn 300 - 500€ per month (which is a typical wage in Greece, but way less than my current income). AFAIK a typical ROI is in 5 years on a typical solar power plant.

Do you think it is a good idea to use this approach, so I can have an income not based upon software engineering?

My idea is to have small steady income from selling electricity, so I can use this income to fund a future software project I want to start.

Though my plan may have some drawbacks:

  1. Maintenance: Usually how much is the maintenance cost for a solar power unit?
  2. ROI: Does a typical solar power plant take 5 years to pay for itself?

The unit will be installed in Greece.

  • 5
    It is impossible to provide a 'good idea' / 'bad idea' answer to this question without actually knowing what the expected revenue is. You will need to do local research on that based on typical energy production from a similar solar panel + price of selling back energy to your utility company. In some areas, lack of sun or lack of good utility regulation can make solar panels almost worthless. Commented Sep 15, 2020 at 13:17
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    @DimitriosDesyllas This isn't a solar power Q&A site, so determining how much power you should expect to produce, what it would cost to install, etc., is not really on topic here. Start by contacting local solar power installation companies near you and begin getting quotes from them on installation, and ask for information they have on what you can expect to produce. You will want to verify they are being honest by then researching online the claims they make. Commented Sep 15, 2020 at 13:28
  • 15
    I don't follow your math. "small solar power plant (costing between 5000€ - 7000€)" and "typical ROI is in 5yrs" does not yield "300 - 500€ per month". At 300/mo over 5 years that would be 18,000 in revenue. Is your initial cost missing a 0 and should be 50,000 - 70,000?
    – BobbyScon
    Commented Sep 15, 2020 at 13:36
  • 7
    hi @DimitriosDesyllas , unfortunately I do have to say, your figures are "incredibly" out. You would be lucky to make one hundred euros in a year selling the electricity from the unit you mention. I'm sorry to say.
    – Fattie
    Commented Sep 15, 2020 at 15:28
  • 9
    I had a £5k solar installation five years ago in the UK and it makes about £500 a year (not month) in subsidies. Those subsidies are no longer available to new installations here, and it looks like they aren't in Greece either.
    – pjc50
    Commented Sep 16, 2020 at 8:23

5 Answers 5


Whether any investment makes good financial sense depends on a few factors - let's see how this project lines up:

(1) What are the projected revenues from the investment?

  • Looks like you have an expectation of how much this will earn you. Is that based on an actual scientific assessment of how much sunlight would hit your proposed installation area? Make sure you aren't simply assuming the energy output based on, for example, a salesperson telling you what to expect.

  • Do you have actual contracted rates to sell back to your local utility company? This is going to be very jurisdiction dependent. Best case scenario would be a guarantee to buy back electricity at the same cost to use it [meaning they can't undercut what they would pay you compared to what they charge a regular customer].

(2) What are the projected expenses to cover the investment?

  • Installation you have listed as 5-7k, but does that include the land needed to install it? Perhaps you are installing this on the roof of your house - is that the best way to get sunlight based on direction you face? Is it legal in your municipality to have a structure added like that? Are there permits you might need to buy? Would you need to re-shingle your roof in anticipation of having these installed?

  • Maintenance will be the big question - do you have assurance over what long-term maintenance will cost? [especially - has this company / technology been around long enough to even know that?]

(3) What are the risks / how likely is your projected outcome?

  • If you can't get any firm answers on some of the above, then what is the likelihood you are correct? If your revenues are not so guaranteed, you should consider reducing the projected impact of having them.

  • In a 'worst case scenario' where for whatever reason you are unable to sell the power back to the grid, would this produce more power than you need personally? Would you need to buy some large batteries to store energy, and how long would it take to pay off that additional cost?

(4) What is the 'opportunity cost' of spending that money initially?

  • You could take that same 5k and invest it, maybe even buying shares in a diversified renewable energy company. Perhaps that has a lower risk, or a higher risk, and a lower return, or a higher return, than doing it yourself. But it would be less of a headache, too.

  • You could also use that 5k for 'regular' investing, in a diversified index fund or similar, and earn something that way.

  • The point is that if you project that your solar panels would earn you, say, 5% a year, and the stock market could earn you, say, 7% a year, you need to consider if this is higher risk than the stock market.

  • In your case, since you plan on doing a software engineering project 'down the road', installing this solar project would cost you 5k that you could even just use to immediately start funding your project.

And, specifically for something like renewable energy: (5) Are there any government incentives / restrictions to consider?

  • It is quite possible your government could give you some type of tax credit for installing renewable energy equipment. That could be a big impact to the profitability of the idea.

At the end of all the above, from a strictly financial perspective, the simplest mechanical way to figure out the $ impact would be: how many years until the investment pays for itself. My understanding of solar projects is that majority of the cost is simply installation, and they can be mostly self-sufficient as long as: (a) little snowfall occurs in your area; and (b) you can very easily sell energy back to the utility grid without negotiating.

In short, how much energy do you expect to produce, what is the price to sell it back to the grid, and therefore how much do you expect to earn per year? Once you know the annual earnings of the investment, consider how many years it would take to pay for itself, and how many years you should expect the panels to last. If it pays for itself in 5 years, and lasts 20 years, for example, that would be one way to see this as valuable investment.

Edit because this has hit Hot, I've done a bit of digging and thrown in some more specific numbers:

I'm relying on a couple of external sources for the following data, see here: http://www.schellas.gr/en/categories.asp?catid=90 https://www.researchgate.net/publication/261366438_Cost_of_PV_electricity_-_Case_study_of_Greece

In short, it looks like you might be able to get 40MWh of power annually from a very large rooftop installation , like over 800 sq ft [hard to tell exactly because technology has advanced a lot over the past 10 years, so old figures of output may be outdated], unsure of the cost of that installation. Looks like you can sell back to PPC at a cost of about 80 Eur / Mwh, so maybe as much as 3,200 EUR per year, or about 260 EUR per month. Looks like your initial estimate of earning about 300 Eur per month might be possible, and if you could get that installed for 7,000 EUR, it would pay for itself in about 2-3 years.

So at a first pass of reasonability, looks like payoff in 5 years could be possible, assuming you are roughly in the ballpark for installation costs, and have a large enough roof. You will note that this is heavily dependent on technology efficiency and government support for electricity buyback. If the government further promotes the idea great, but if they remove support you might no longer get the return you desire. Definitely looks worth it to investigate further!

  • 10
    There’s no way you’ll get a 20kW installation for anything like €7,000. You might just about be be able to buy 20kW of cheap panels for that price, leaving nothing for an inverter or installation.
    – Mike Scott
    Commented Sep 15, 2020 at 15:15
  • 2
    Regarding the 5 excellent points, is it worth adding (6) Is there any capital recovery possibilities? Statistically all businesses fail, and it's ideal if there's some equipment or other capital that can be sold to recover some cash when it fails.
    – Fattie
    Commented Sep 15, 2020 at 15:26
  • 4
    @Fattie Keep in mind [and I'm no expert on solar by any means] Greece [2,771 average sunny hours / year] is going to be a far more profitable place to run solar than the UK [1,354 average sunny hours / year]. Commented Sep 15, 2020 at 15:41
  • 8
    The very largest utility scale solar installations are going in at under $1 per Watt. So the absolute floor of the cost of this hypothetical system is $20k = 17k EUR. Realistically, OP has neither the bargaining power nor the economies of scale to get it down that low.
    – stannius
    Commented Sep 15, 2020 at 19:45
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    And let's not forget about insurance costs. Otherwise the first hailstorm could destroy that solar panel and you remain with nothing.
    – vsz
    Commented Sep 16, 2020 at 5:41

As usual, Bacon's answer is excellent. I'd like to direct some feedback to the data you specifically provided.

Your anticipated cost of the solar power system is 5000€ - 7000€ and you expect to earn 300€ - 500€ per month. If that was a legitimate expectation, I believe everyone would go and make the same investment and Greece would have more solar panels than square meters to place them. Sign me up!

I don't know the power and solar markets in Greece, but I can't imagine it's so drastically different than the US that you would be able to earn that kind of monthly income compared to such a low up-front cost. In the US, the average cost for a 6kW solar system is somewhere around $15500, or 13000€. This is enough to cover the power needs of an average home and maybe put a small amount back into the grid. US power companies rarely offer to pay cash out for what you put back in, but will give credits to your account so when you don't produce enough to cover the home, you might not go out of pocket. Let's call the average monthly power cost $200 when looking at a whole year, that means we would need to go up to a 15+kW system to generate the lowest end of the monthly earnings you suggest. (Apologies, I don't know the power measurement conversions to provide an equivalent system size for Greece.)

  • 7
    I think you're being ripped off in the US if a 6kW system costs $15500. We would pay about half that here in the UK.
    – Simon B
    Commented Sep 15, 2020 at 15:10
  • 5
    Most owners of small-scale solar project consume as much of their own power as they can. When they buy a kWh from their electric utility, they pay retail rates. But when they sell a kWh to an electric utility (assuming they can find one to even buy the kWh without being a customer) they only get paid the wholesale rate.
    – stannius
    Commented Sep 15, 2020 at 19:49
  • 6
    @stannius In Canada as an example, power is sold back to the utility company at retail rates. As mentioned previously, this is a very jurisdiction-dependent question. Commented Sep 15, 2020 at 20:27
  • 7
    @DimitriosDesyllas - You would sell without consuming? Are you able to sell for higher than what you would pay? Otherwise, that seems illogical. It would make far more sense to boost your earnings by lowering your monthly expenses rather than sell the electricity for less than you have to pay for it. Again, I have 0 knowledge about Greece's power costs and infrastructure. Please let me know if I'm way off the mark!
    – BobbyScon
    Commented Sep 15, 2020 at 21:21
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    "In the US, the average cost for a 6kW solar system is somewhere around $15500" - That seems excessive. Or at least, in Australia you can get a 6.6kW system supplied and installed for around AU$3000 (US$2200). Granted that's after assigning your STCs to the installer. However those are only worth around AU$3000 on a 6.6kW system, not AU$10k plus. Call it AU$6500 with the incentives taken off the table, and US$15k still looks extortionate. Someone over there is raking in the profits.
    – aroth
    Commented Sep 16, 2020 at 1:58

Another aspect that hasn't been mentioned so far, is that the low voltage system in Greece is not capable of maintaining stability while handling energy injections by distributed generation at arbitrary connecting points, and it is currently under stress from the existing installations.

Thus, unless OP is lucky and his land is at a favourable location, the distribution system operator is unlikely to accept to connect to the new installation.

Here is the current availability map, where green is where there is capacity for further absorption:

enter image description here


  1. https://apps.deddie.gr/WebAPE/main.html#
  2. https://apps.deddie.gr/WebAPE/map.html
  • 2
    One alternative way to make money in such an environment is not to add to the peaky and oversaturated solar generation, but instead to invest in grid storage. Where solar is over provisioned the issue is that the grid can end up with too much energy and not enough consumers. Grid storage is one way to profit from this situation since it allows you to buy up power cheaply any time there is excess and to sell it back to the grid later when it is needed.
    – J...
    Commented Sep 17, 2020 at 21:17
  • @J... That's very true. Storage, though costly, by and large solves the problem of uncontrollability of the generation. The problem of injecting into the system is not completely solved though, as the direction of the power flow affects the voltage and phase shift on the entire branch, so there is still a limit on the power you can inject without negatively affecting the grid, especially when the situation is near capacity and with limited measurement points.
    – user000001
    Commented Sep 17, 2020 at 21:40
  • @user000001 Yes, but it's a solved problem, and all of those questions have to be answered when you go through the planning process for grid connection. Nothing gets approved without the utility operator saying OK, so you usually have to plan and locate carefully to ensure that your installation and the grid can mutually accommodate each other. In any case, the situation is easy for grid storage because you're adding capacity when the grid needs it most and shaving excess production when the grid needs it gone.
    – J...
    Commented Sep 17, 2020 at 21:56

Do you think it is a good idea to use this approach, so I can have an income not based upon software engineering?

If you think you are better at running a solar plant than you are at being a software engineer, yes.

If you're really good at being a software engineer but have no idea how to run a solar plant, no.

We have no idea what your competencies are, but your expectations for profit margin tell us that perhaps solar energy is not a particular area of expertise for you. Given that you don't seem to have a plan for how much power or money you require to meet your objectives, what your operating costs would be, etc, we can also conclude that running a business is also not a particular field of expertise for you.

5000 euro might buy you enough solar panels to make electricity for your own personal use, or perhaps a household of two. There would be little, if any, left over to sell back to the grid. At best you would be able to offset your monthly cost of electricity and perhaps make a small amount back.

The energy sector is one with very thin margins for profit. If you intend to make income, you need to spend more money. Much more. Only with scale and efficiencies of size can you bring your costs down enough to be competitive. You can't dabble in the energy industry — small fish do not survive.

I'd stick with software engineering.

With that said, investing in domestic renewable power like solar really can be a great idea, so all this is not to say that you should not consider adding solar generation to your home, I just wouldn't look at it as a money making venture. It would help offset your energy costs long-term and is an environmentally conscious move to make. It can end up generating a small profit, but nowhere near 300-500€/month.

If you were looking to make significant income from such a project you would be really considering at least 1€ million and up for outlay, and you would need a suitable piece of land to install the number of panels it would take. Maybe with a small piece of land somewhere you could start something smaller, but just to pay the maintenance and carrying costs you will need at least a certain number of panels to provide that income - and you still want to make profit. Whatever the case, it would be a much larger investment than 5k euro.

  • 2
    This answer wrongly assumes that investing in the solar panels comes at the opportunity cost of doing more software development. This would work if e.g. you were choosing between X or Y career. In this case however the solar panel represents a passive income source from investment, and whether OP is good or bad at software engineering is completely irrelevant. The choice to invest should be made on its own merits and compared against the actual opportunity cost (e.g. investing the money in stocks etc.) OP isn't quitting software development in order to make the investment.
    – JBentley
    Commented Sep 17, 2020 at 13:19
  • 1
    @JBentley A solar farm is not like a security - it requires ongoing maintenance, service, and upkeep. Planning and installing such a facility requires a well considered business plan, it requires investment capital, and it requires ongoing operational costs. It is very much an opportunity cost consideration because OP must invest considerable effort in bringing this project to life. The only way to make it fully hands-off would be to also outsource management and construction - this increases the cost and required scale of project to maintain profitability. It's out of OP's depth.
    – J...
    Commented Sep 17, 2020 at 13:53
  • 1
    We're not talking about a solar farm here. OP wants to invest 5000€ - 7000€ i.e. in the ballpark of a home/roof installation. The management time at this scale is not going to make any kind of noticeable impact on OP's ability to do his day job.
    – JBentley
    Commented Sep 17, 2020 at 14:10
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    @JBentley OP wants to make 500EUR/month profit. They think that investing 5k in solar will achieve this - it will not. The point of this answer is to give a better idea of what size that investment would have to look like before OP could start making profits in that range. A home installation will not impact OP's ability to do their day job. It will also not provide them any income. An installation that would provide them income would require more work, planning, and the execution of a considered business plan.
    – J...
    Commented Sep 17, 2020 at 14:45
  • I agree. Hence why I said the choice to invest should be made on its own merits, not the opportunity cost. As you have pointed out, in this case there is no merit to the investment (or at least not as far as OP's expectations are concerned).
    – JBentley
    Commented Sep 17, 2020 at 14:46

Projections are uncertain. Especially when concerning the future. There is no guarantee that the grid owners will pay you in 2 years what they pay now. Many people have the same idea and revenue will drop below profitability. If you do it, do it because you like to provide some 'green' electricity for the sake of doing it. Don't do it if you want to make money. For example, 20 years ago they promised a 4%/year gain in pension funds, now we are at 0.2%/year.

  • It´s a pretty save bet that the price of energy will go up when you consider Europe still claims to be committed to the Paris agreement ...
    – Daniel
    Commented Sep 18, 2020 at 15:05

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