Energy integration Intermittency investment market share Renewables solar subsidies tech

How much subsidy does solar need, and for how long?

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Schalk Cloete presents his newest paper taking a look at what impacts the profitability of an funding in an influence sector. After reviewing onshore wind and nuclear, he now seems at photo voltaic. His evaluation of coal and fuel are to return. Intermittency, market share, upkeep, integration prices and different elements are modelled intimately to assist predict photo voltaic’s future.

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  • A cumulative money circulate evaluation is introduced for utility-scale photo voltaic PV.
  • The massive impact of low cost price on levelized prices is illustrated. 
  • Worth declines and integration prices trigger a $60/MWh improve within the levelized value underneath the base-case assumptions. 
  • This interprets to a really giant 13% lower in annualized funding returns if photo voltaic market share will increase by 1% per yr over the plant lifetime.
  • This funding danger just isn’t as giant because it appears as a result of the regular will increase in photo voltaic market share that trigger these destructive returns won’t ever occur if photo voltaic turbines will not be shielded from their worth declines and integration prices.   


That is a part of a collection of articles providing some qualitative discussions on the dangers concerned in a number of mainstream power choices. Following the earlier articles on onshore wind and nuclear, the subsequent three articles will current a quantitative evaluation of the dangers for utility-scale photo voltaic PV, pure fuel and coal. The evaluation might be introduced for a typical developed world state of affairs. Creating world know-how value ranges are very totally different and can be coated in a future article.

All probably the most influential assumptions might be clearly defined and their influence on the outcomes will probably be quantified. It will give the reader the chance to obviously see the quantified impression of the danger underneath the assumptions they assume are probably the most applicable.


Outcomes will probably be introduced within the type of a reduced money move evaluation for just one kW utility photo voltaic PV over a one yr development interval adopted by an working interval that lasts for so long as the plant is worthwhile or as much as a most of 40 years. The funding is made within the first yr, adopted by the annual receipt of revenues from electrical energy gross sales and cost of working and upkeep (O&M) prices.

Capital prices are taken as $1800/kW. This was discovered to be a very good international common when adjusting for buying energy parity. O&M prices are taken as 1% of the capital value per yr and these prices are assumed to extend linearly by 1% per yr. Plant output is assumed to fall by 2% within the first yr and linearly by Zero.eight% per yr afterwards.  Inverter alternative each 15 years is included at a price of $100/kW (hardware and set up).

After the preliminary $1800 capital funding, the annual money flows from electrical energy gross sales at a mean wholesale worth of $60/MWh and a capability issue of 18% are proven under. The linear decline in plant efficiency is clearly seen, in addition to the linear improve in O&M (though O&M prices are comparatively small). Inverter alternative prices are additionally notable. Word that the 18% capability issue is chosen to be optimistic subsequent to the worldwide common that has hovered round 15% for the previous four years in line with BP knowledge.

Utilizing this info, a cumulative money circulate curve could be constructed (under). As proven, the preliminary $1800 funding is recovered in yr 28 when no discounting is utilized (low cost fee of Zero%). When a reduction fee of 1.four% is utilized, the web return on funding is zero. In different phrases, this evaluation would return a levelized value of electrical energy of $60/MWh if the low cost fee is about to 1.four%. Beneath a extra lifelike low cost price of eight%, the preliminary funding can’t be recovered.

Subsequently, the consequences of the worth declines and price will increase associated to intermittency (mentioned within the earlier article) are included. Firstly, the added value of grid connection is included as an up-front value. It’s assumed that the typical distance between the photo voltaic farm and the buyer is 100 km, yielding an added capital value of $200/kW at a transmission value of $2/kW/km.

Secondly, balancing prices are assumed to scale instantly with the wind power market share, including $Zero.three/MWh for each proportion level of market share. That is about half the present balancing value in Germany.

Thirdly, the worth decline of solar energy is modelled in accordance with the next market worth issue. At market shares greater than 15%, the linear development is extrapolated. It must be talked about that this development is consultant for Europe, China and Japan (representing 74% of present put in capability) the place photo voltaic capability elements are fairly low. Markets just like the US South-West, Australia and the Center East will see much less pronounced worth declines ensuing from greater capability elements and a greater match with seasonal demand.

​Wind and photo voltaic worth elements (a worth issue of 1 is for a generator with a continuing output) as a perform of their respective market shares (supply).

The next annual money flows are generated when these assumptions are utilized to a plant constructed when the photo voltaic market share is 2% (present international common) and growing by 1% per yr (as much as a most of 40%). The extra speedy decline in income (brought on by the worth decline) and the elevated balancing prices are clearly seen.

As proven within the cumulative money stream evaluation under, not even half of the preliminary funding can now be recovered, even underneath a Zero% low cost price. The plant begins making a loss on the time of the primary inverter alternative at yr 15 as declining revenues fall under growing prices.

Impact of the low cost fee

The impact of low cost price on the typical electrical energy worth required is proven under with and with out the worth declines and price will increase from intermittency. Observe that the typical electrical energy worth required is used right here as an alternative of the levelized value of electrical energy to account for the worth decline of solar energy with growing market share. This measure may be interpreted as the typical market worth over a whole yr that may yield a zero return on funding with a specified low cost fee. The precise electrical energy worth acquired by the photo voltaic farm might be decrease.

​The graph exhibits that the required electrical energy worth virtually quadruples because the low cost price is elevated from Zero% to 15%. Inclusion of the worth decline, balancing prices and grid prices will increase the required electrical energy worth by about $60/MWh at Zero% low cost fee with a average growing development in the direction of greater low cost charges. This impression is double that of wind energy due to photo voltaic’s extra pronounced intermittency and excessive correlation with different photo voltaic turbines.

Quantifying the danger

Subsequent, the affect of the danger of accountability for worth declines and price will increase brought on by intermittency will probably be quantified. This quantification is completed by figuring out the low cost fee giving zero return on funding when the typical electrical energy worth is about to $60/MWh. The annualized return on funding is then quantified because the low cost price minus 2% to account for margin erosion from technological enhancements of latest crops that come on-line in the course of the plant lifetime in addition to monetary/legislative prices (paying the bankers and legal professionals concerned in establishing financing for the plant).

As proven under, the funding return is rather less than Zero% when photo voltaic farms carry no accountability for intermittency prices (blue bar). The sensitivity to the three totally different intermittency results is proven by the orange bars. When a 100 km grid connection is included, the annualized funding return drops by solely Zero.6%. A a lot bigger eight% drop happens when the worth decline is added. Additional addition of balancing prices additionally has a big impact, decreasing the annualized funding return to -13.5%.

​The magnitude of the drop in funding returns is strongly influenced by the speed of solar energy enlargement over the lifetime of the plant (gray bars). Extra photo voltaic on the grid will scale back the worth and improve the balancing prices of all photo voltaic turbines. A rise within the fee of photo voltaic enlargement from Zero.5% to 1% per yr lowers the funding return by 7%, whereas an extra improve in enlargement price to 1.5% per yr cuts one other 5% off the annualized return.

The impact of added grid enlargement prices (yellow bars) is smaller. Growing the required grid connection from 100 km to 500 km (thus growing the added up-front value from $200/kW to $1000/kW) solely decreases the annualized funding return by slightly over 2%.

Lastly, the impact of balancing prices is proven by the inexperienced bars. Each improve of $Zero.2/MWh per % of wind market share decreases the funding return by a bit of over 2.5%.


This text has quantified the massive unfavorable results of photo voltaic intermittency on challenge economics. The potential that these prices will ultimately be pretty attributed to photo voltaic turbines presents a serious danger for photo voltaic farm buyers.

Even when these intermittency results are utterly ignored, the worldwide common photo voltaic farm doesn’t give any return on funding with out direct subsidization. As all the time, nevertheless, I’ve to emphasize that there are places the place photo voltaic is rather more engaging. For instance, the US South-West can obtain very spectacular capability elements as much as 30% because of a superb photo voltaic useful resource and excessive inverter loading ratios (which additionally will increase capital prices to about $2200). Underneath these assumptions, the annualized funding return quantities to 2.2% (with no accountability for intermittency results). Such excessive capability elements may also considerably scale back the worth decline.

When intermittency prices are appropriately accounted for, the funding returns fall drastically – considerably greater than for wind energy. The annualized return on funding drops from -Zero.6% to -13.5% when intermittency prices and worth declines are accounted for underneath the base-case assumptions. This very giant decline could be moderated by battery storage methods due to photo voltaic’s common every day manufacturing cycle. A future article will discover this potential mitigating impact.

Probably the most influential issue within the evaluation is the speed of solar energy enlargement. Greater enlargement charges result in bigger funding losses. Apparently, this dynamic truly reduces the funding danger as a result of the regular will increase in photo voltaic market share that trigger this danger won’t happen if worth declines and integration prices are pretty assigned to photo voltaic turbines.

This reinforces the sooner notion that continued solar energy enlargement would require perpetual subsidies. If solar energy is to have the impression envisioned by inexperienced advocates, the massive funding losses brought on by their worth declines and integration prices will have to be borne by different sectors of the financial system for many years to return.

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Schalk Cloete is a Analysis Scientist at Sintef.