Raising an array to let crops grow underneath changes the economics twice over: more steel per kWp, less electricity per hectare, and a rainfall problem nobody plans for. What decides whether the trade is worth making.
On a conventional ground-mounted plant the steel is a modest line item. Lift the same array to four metres, widen the rows so light reaches the ground, and the structure becomes the largest single cost in the project while the electricity yield per hectare falls. That trade, more steel for less power in exchange for keeping the land in production, is the entire subject. Everything else in an agrivoltaic design is an argument about where to set it.
Bangladesh faces a fundamental tension between its renewable energy ambitions and its food security imperative. With 170 million people depending on a land area of just 147,000 sq km, much of it flood-prone, the country cannot afford to convert agricultural land to solar farms. Agrivoltaics (also called agri-PV or dual-use solar) resolves this tension by raising solar panels high enough above the ground to allow crops to grow beneath them, generating both food and electricity from the same land.
In an agrivoltaic system, solar panels are mounted on raised structures (typically 2–4 metres above ground) with wider spacing than conventional ground-mounted solar. This allows sunlight to reach the crops below, either directly through the gaps between panels, or as diffuse light that passes through semi-transparent panels. The partial shading provided by the panels can actually benefit certain crops by reducing heat stress, water evaporation, and soil moisture loss.
Two numbers control the design. Clearance height is set by what has to pass underneath, a power tiller, a sprayer, a person with a load on their head, and by how the shadow behaves: a low array throws a hard-edged shadow that sits on the same plants all day, while a higher array smears the same shadow over a wider strip so every plant receives intermittent shade rather than a few receiving permanent shade. Row pitch sets the share of annual light that reaches the ground at all. Widening the pitch is the direct lever on crop yield and the direct penalty on generation per hectare.
Get both decided from the crop plan before anyone draws a single line electrical diagram. Retrofitting height into a structure that has already been costed is not a small change: it drives foundation size, member sections, wind loading and the whole erection method.
| Crop type | Shade tolerance | Agrivoltaic suitability | Potential yield impact |
|---|---|---|---|
| Leafy vegetables (spinach, lettuce) | High | Excellent | +10–30% in summer |
| Root vegetables (radish, carrot) | Medium | Good | Neutral to +10% |
| Legumes (beans, lentils) | Medium | Good | Neutral |
| Rice (Boro season) | Low | Limited | -5 to -15% |
| Fruits (tomato, chili) | Medium | Good | Neutral to +15% |
| Medicinal herbs | High | Excellent | +20–40% |
The pattern in that table is not arbitrary. Leafy and understorey crops reach their light saturation point well below full tropical noon sun, so shaving the top off the middle of the day costs them very little photosynthesis while saving them water and heat stress. Crops that use the full peak, paddy above all, pay for every hour of shade. If the land is producing Boro rice and the yield matters, agrivoltaics is the wrong answer on that plot and an honest designer will say so.
There is Bangladeshi evidence to work from. SREDA and the Bangladesh Agricultural Research Institute (BARI) have conducted pilot agrivoltaic projects in Rajshahi and Comilla districts, demonstrating that leafy vegetables grown under solar panels in summer show improved yields due to reduced heat stress. The International Rice Research Institute (IRRI) has also studied agrivoltaic rice cultivation in South Asia, finding that carefully designed systems with 30–40% shading can maintain acceptable rice yields while generating significant electricity.
A raised, widely spaced array is a far harder structural problem than a roof plant. The modules sit at the top of tall columns, so wind load produces a large overturning moment on every foundation, and Bangladesh's design wind is not gentle. The soil is frequently soft alluvium with poor bearing capacity that gets worse when the monsoon saturates it, so foundations are deeper, wider and more expensive than a standard ground-mount drawing assumes. Piles are often the honest answer rather than pads.
A module is an impermeable sheet tilted over a crop. In monsoon rainfall it does not spread water evenly, it collects it and delivers it as a line of concentrated runoff along each lower module edge. Underneath, the ground develops wet erosion strips directly below the drip line and dry strips beneath the panel centres, which is a worse growing environment than either uniform sun or uniform shade. This is a routine failure on early agrivoltaic plots and it is entirely designable-out.
For a typical 1-hectare smallholder farm in Bangladesh, an agrivoltaic system with 50 kWp of solar panels could generate approximately 63,000 kWh per year, worth approximately BDT 5–7 lakh at the grid tariff. Combined with continued crop production (even at slightly reduced yields for some crops), the total income from the land increases significantly. Farmers can sell electricity through net-metering or to the local utility under the Rural Electrification Board (REB) framework.
Three things decide whether that figure is real on a given plot, and none of them is the panel. First, the connection: on a rural feeder the constraint is usually what the distribution utility will accept for export, not what the array can produce, and that approval has to be pursued before the structure is ordered. Second, tenure: a 25-year steel structure cannot sensibly be built by a sharecropper on someone else's land, so the ownership of the land, the crop and the electricity have to be three settled questions with three named parties. Third, exit: what happens to the structure at the end of the arrangement, who removes it, and what condition the land is returned in.
Agrivoltaics is early here, and the sensible first projects are the ones where somebody was going to build a structure anyway or already wants shade. Horticulture and nursery operations that already run shade houses. Agro-processing sites with adjacent land and a real daytime load to absorb the generation. Poultry and dairy yards. Land around existing ground-mounted assets. In those cases the raised structure is not a pure cost imposed on the electricity, it is doing two jobs, and the arithmetic stops being marginal. Starting with a wide open paddy field is the hardest possible version of this and the least likely to work.